linux/fs/ext4/inode.c
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   1/*
   2 *  linux/fs/ext4/inode.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 *
   9 *  from
  10 *
  11 *  linux/fs/minix/inode.c
  12 *
  13 *  Copyright (C) 1991, 1992  Linus Torvalds
  14 *
  15 *  64-bit file support on 64-bit platforms by Jakub Jelinek
  16 *      (jj@sunsite.ms.mff.cuni.cz)
  17 *
  18 *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
  19 */
  20
  21#include <linux/module.h>
  22#include <linux/fs.h>
  23#include <linux/time.h>
  24#include <linux/jbd2.h>
  25#include <linux/highuid.h>
  26#include <linux/pagemap.h>
  27#include <linux/quotaops.h>
  28#include <linux/string.h>
  29#include <linux/buffer_head.h>
  30#include <linux/writeback.h>
  31#include <linux/pagevec.h>
  32#include <linux/mpage.h>
  33#include <linux/namei.h>
  34#include <linux/uio.h>
  35#include <linux/bio.h>
  36#include <linux/workqueue.h>
  37#include <linux/kernel.h>
  38#include <linux/printk.h>
  39#include <linux/slab.h>
  40#include <linux/ratelimit.h>
  41
  42#include "ext4_jbd2.h"
  43#include "xattr.h"
  44#include "acl.h"
  45#include "ext4_extents.h"
  46#include "truncate.h"
  47
  48#include <trace/events/ext4.h>
  49
  50#define MPAGE_DA_EXTENT_TAIL 0x01
  51
  52static inline int ext4_begin_ordered_truncate(struct inode *inode,
  53                                              loff_t new_size)
  54{
  55        trace_ext4_begin_ordered_truncate(inode, new_size);
  56        /*
  57         * If jinode is zero, then we never opened the file for
  58         * writing, so there's no need to call
  59         * jbd2_journal_begin_ordered_truncate() since there's no
  60         * outstanding writes we need to flush.
  61         */
  62        if (!EXT4_I(inode)->jinode)
  63                return 0;
  64        return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
  65                                                   EXT4_I(inode)->jinode,
  66                                                   new_size);
  67}
  68
  69static void ext4_invalidatepage(struct page *page, unsigned long offset);
  70static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
  71                                   struct buffer_head *bh_result, int create);
  72static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
  73static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
  74static int __ext4_journalled_writepage(struct page *page, unsigned int len);
  75static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
  76
  77/*
  78 * Test whether an inode is a fast symlink.
  79 */
  80static int ext4_inode_is_fast_symlink(struct inode *inode)
  81{
  82        int ea_blocks = EXT4_I(inode)->i_file_acl ?
  83                (inode->i_sb->s_blocksize >> 9) : 0;
  84
  85        return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
  86}
  87
  88/*
  89 * Restart the transaction associated with *handle.  This does a commit,
  90 * so before we call here everything must be consistently dirtied against
  91 * this transaction.
  92 */
  93int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
  94                                 int nblocks)
  95{
  96        int ret;
  97
  98        /*
  99         * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
 100         * moment, get_block can be called only for blocks inside i_size since
 101         * page cache has been already dropped and writes are blocked by
 102         * i_mutex. So we can safely drop the i_data_sem here.
 103         */
 104        BUG_ON(EXT4_JOURNAL(inode) == NULL);
 105        jbd_debug(2, "restarting handle %p\n", handle);
 106        up_write(&EXT4_I(inode)->i_data_sem);
 107        ret = ext4_journal_restart(handle, nblocks);
 108        down_write(&EXT4_I(inode)->i_data_sem);
 109        ext4_discard_preallocations(inode);
 110
 111        return ret;
 112}
 113
 114/*
 115 * Called at the last iput() if i_nlink is zero.
 116 */
 117void ext4_evict_inode(struct inode *inode)
 118{
 119        handle_t *handle;
 120        int err;
 121
 122        trace_ext4_evict_inode(inode);
 123
 124        ext4_ioend_wait(inode);
 125
 126        if (inode->i_nlink) {
 127                /*
 128                 * When journalling data dirty buffers are tracked only in the
 129                 * journal. So although mm thinks everything is clean and
 130                 * ready for reaping the inode might still have some pages to
 131                 * write in the running transaction or waiting to be
 132                 * checkpointed. Thus calling jbd2_journal_invalidatepage()
 133                 * (via truncate_inode_pages()) to discard these buffers can
 134                 * cause data loss. Also even if we did not discard these
 135                 * buffers, we would have no way to find them after the inode
 136                 * is reaped and thus user could see stale data if he tries to
 137                 * read them before the transaction is checkpointed. So be
 138                 * careful and force everything to disk here... We use
 139                 * ei->i_datasync_tid to store the newest transaction
 140                 * containing inode's data.
 141                 *
 142                 * Note that directories do not have this problem because they
 143                 * don't use page cache.
 144                 */
 145                if (ext4_should_journal_data(inode) &&
 146                    (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
 147                        journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
 148                        tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
 149
 150                        jbd2_log_start_commit(journal, commit_tid);
 151                        jbd2_log_wait_commit(journal, commit_tid);
 152                        filemap_write_and_wait(&inode->i_data);
 153                }
 154                truncate_inode_pages(&inode->i_data, 0);
 155                goto no_delete;
 156        }
 157
 158        if (!is_bad_inode(inode))
 159                dquot_initialize(inode);
 160
 161        if (ext4_should_order_data(inode))
 162                ext4_begin_ordered_truncate(inode, 0);
 163        truncate_inode_pages(&inode->i_data, 0);
 164
 165        if (is_bad_inode(inode))
 166                goto no_delete;
 167
 168        handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3);
 169        if (IS_ERR(handle)) {
 170                ext4_std_error(inode->i_sb, PTR_ERR(handle));
 171                /*
 172                 * If we're going to skip the normal cleanup, we still need to
 173                 * make sure that the in-core orphan linked list is properly
 174                 * cleaned up.
 175                 */
 176                ext4_orphan_del(NULL, inode);
 177                goto no_delete;
 178        }
 179
 180        if (IS_SYNC(inode))
 181                ext4_handle_sync(handle);
 182        inode->i_size = 0;
 183        err = ext4_mark_inode_dirty(handle, inode);
 184        if (err) {
 185                ext4_warning(inode->i_sb,
 186                             "couldn't mark inode dirty (err %d)", err);
 187                goto stop_handle;
 188        }
 189        if (inode->i_blocks)
 190                ext4_truncate(inode);
 191
 192        /*
 193         * ext4_ext_truncate() doesn't reserve any slop when it
 194         * restarts journal transactions; therefore there may not be
 195         * enough credits left in the handle to remove the inode from
 196         * the orphan list and set the dtime field.
 197         */
 198        if (!ext4_handle_has_enough_credits(handle, 3)) {
 199                err = ext4_journal_extend(handle, 3);
 200                if (err > 0)
 201                        err = ext4_journal_restart(handle, 3);
 202                if (err != 0) {
 203                        ext4_warning(inode->i_sb,
 204                                     "couldn't extend journal (err %d)", err);
 205                stop_handle:
 206                        ext4_journal_stop(handle);
 207                        ext4_orphan_del(NULL, inode);
 208                        goto no_delete;
 209                }
 210        }
 211
 212        /*
 213         * Kill off the orphan record which ext4_truncate created.
 214         * AKPM: I think this can be inside the above `if'.
 215         * Note that ext4_orphan_del() has to be able to cope with the
 216         * deletion of a non-existent orphan - this is because we don't
 217         * know if ext4_truncate() actually created an orphan record.
 218         * (Well, we could do this if we need to, but heck - it works)
 219         */
 220        ext4_orphan_del(handle, inode);
 221        EXT4_I(inode)->i_dtime  = get_seconds();
 222
 223        /*
 224         * One subtle ordering requirement: if anything has gone wrong
 225         * (transaction abort, IO errors, whatever), then we can still
 226         * do these next steps (the fs will already have been marked as
 227         * having errors), but we can't free the inode if the mark_dirty
 228         * fails.
 229         */
 230        if (ext4_mark_inode_dirty(handle, inode))
 231                /* If that failed, just do the required in-core inode clear. */
 232                ext4_clear_inode(inode);
 233        else
 234                ext4_free_inode(handle, inode);
 235        ext4_journal_stop(handle);
 236        return;
 237no_delete:
 238        ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
 239}
 240
 241#ifdef CONFIG_QUOTA
 242qsize_t *ext4_get_reserved_space(struct inode *inode)
 243{
 244        return &EXT4_I(inode)->i_reserved_quota;
 245}
 246#endif
 247
 248/*
 249 * Calculate the number of metadata blocks need to reserve
 250 * to allocate a block located at @lblock
 251 */
 252static int ext4_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
 253{
 254        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
 255                return ext4_ext_calc_metadata_amount(inode, lblock);
 256
 257        return ext4_ind_calc_metadata_amount(inode, lblock);
 258}
 259
 260/*
 261 * Called with i_data_sem down, which is important since we can call
 262 * ext4_discard_preallocations() from here.
 263 */
 264void ext4_da_update_reserve_space(struct inode *inode,
 265                                        int used, int quota_claim)
 266{
 267        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 268        struct ext4_inode_info *ei = EXT4_I(inode);
 269
 270        spin_lock(&ei->i_block_reservation_lock);
 271        trace_ext4_da_update_reserve_space(inode, used);
 272        if (unlikely(used > ei->i_reserved_data_blocks)) {
 273                ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
 274                         "with only %d reserved data blocks\n",
 275                         __func__, inode->i_ino, used,
 276                         ei->i_reserved_data_blocks);
 277                WARN_ON(1);
 278                used = ei->i_reserved_data_blocks;
 279        }
 280
 281        /* Update per-inode reservations */
 282        ei->i_reserved_data_blocks -= used;
 283        ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
 284        percpu_counter_sub(&sbi->s_dirtyblocks_counter,
 285                           used + ei->i_allocated_meta_blocks);
 286        ei->i_allocated_meta_blocks = 0;
 287
 288        if (ei->i_reserved_data_blocks == 0) {
 289                /*
 290                 * We can release all of the reserved metadata blocks
 291                 * only when we have written all of the delayed
 292                 * allocation blocks.
 293                 */
 294                percpu_counter_sub(&sbi->s_dirtyblocks_counter,
 295                                   ei->i_reserved_meta_blocks);
 296                ei->i_reserved_meta_blocks = 0;
 297                ei->i_da_metadata_calc_len = 0;
 298        }
 299        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 300
 301        /* Update quota subsystem for data blocks */
 302        if (quota_claim)
 303                dquot_claim_block(inode, used);
 304        else {
 305                /*
 306                 * We did fallocate with an offset that is already delayed
 307                 * allocated. So on delayed allocated writeback we should
 308                 * not re-claim the quota for fallocated blocks.
 309                 */
 310                dquot_release_reservation_block(inode, used);
 311        }
 312
 313        /*
 314         * If we have done all the pending block allocations and if
 315         * there aren't any writers on the inode, we can discard the
 316         * inode's preallocations.
 317         */
 318        if ((ei->i_reserved_data_blocks == 0) &&
 319            (atomic_read(&inode->i_writecount) == 0))
 320                ext4_discard_preallocations(inode);
 321}
 322
 323static int __check_block_validity(struct inode *inode, const char *func,
 324                                unsigned int line,
 325                                struct ext4_map_blocks *map)
 326{
 327        if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
 328                                   map->m_len)) {
 329                ext4_error_inode(inode, func, line, map->m_pblk,
 330                                 "lblock %lu mapped to illegal pblock "
 331                                 "(length %d)", (unsigned long) map->m_lblk,
 332                                 map->m_len);
 333                return -EIO;
 334        }
 335        return 0;
 336}
 337
 338#define check_block_validity(inode, map)        \
 339        __check_block_validity((inode), __func__, __LINE__, (map))
 340
 341/*
 342 * Return the number of contiguous dirty pages in a given inode
 343 * starting at page frame idx.
 344 */
 345static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
 346                                    unsigned int max_pages)
 347{
 348        struct address_space *mapping = inode->i_mapping;
 349        pgoff_t index;
 350        struct pagevec pvec;
 351        pgoff_t num = 0;
 352        int i, nr_pages, done = 0;
 353
 354        if (max_pages == 0)
 355                return 0;
 356        pagevec_init(&pvec, 0);
 357        while (!done) {
 358                index = idx;
 359                nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 360                                              PAGECACHE_TAG_DIRTY,
 361                                              (pgoff_t)PAGEVEC_SIZE);
 362                if (nr_pages == 0)
 363                        break;
 364                for (i = 0; i < nr_pages; i++) {
 365                        struct page *page = pvec.pages[i];
 366                        struct buffer_head *bh, *head;
 367
 368                        lock_page(page);
 369                        if (unlikely(page->mapping != mapping) ||
 370                            !PageDirty(page) ||
 371                            PageWriteback(page) ||
 372                            page->index != idx) {
 373                                done = 1;
 374                                unlock_page(page);
 375                                break;
 376                        }
 377                        if (page_has_buffers(page)) {
 378                                bh = head = page_buffers(page);
 379                                do {
 380                                        if (!buffer_delay(bh) &&
 381                                            !buffer_unwritten(bh))
 382                                                done = 1;
 383                                        bh = bh->b_this_page;
 384                                } while (!done && (bh != head));
 385                        }
 386                        unlock_page(page);
 387                        if (done)
 388                                break;
 389                        idx++;
 390                        num++;
 391                        if (num >= max_pages) {
 392                                done = 1;
 393                                break;
 394                        }
 395                }
 396                pagevec_release(&pvec);
 397        }
 398        return num;
 399}
 400
 401/*
 402 * The ext4_map_blocks() function tries to look up the requested blocks,
 403 * and returns if the blocks are already mapped.
 404 *
 405 * Otherwise it takes the write lock of the i_data_sem and allocate blocks
 406 * and store the allocated blocks in the result buffer head and mark it
 407 * mapped.
 408 *
 409 * If file type is extents based, it will call ext4_ext_map_blocks(),
 410 * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
 411 * based files
 412 *
 413 * On success, it returns the number of blocks being mapped or allocate.
 414 * if create==0 and the blocks are pre-allocated and uninitialized block,
 415 * the result buffer head is unmapped. If the create ==1, it will make sure
 416 * the buffer head is mapped.
 417 *
 418 * It returns 0 if plain look up failed (blocks have not been allocated), in
 419 * that casem, buffer head is unmapped
 420 *
 421 * It returns the error in case of allocation failure.
 422 */
 423int ext4_map_blocks(handle_t *handle, struct inode *inode,
 424                    struct ext4_map_blocks *map, int flags)
 425{
 426        int retval;
 427
 428        map->m_flags = 0;
 429        ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
 430                  "logical block %lu\n", inode->i_ino, flags, map->m_len,
 431                  (unsigned long) map->m_lblk);
 432        /*
 433         * Try to see if we can get the block without requesting a new
 434         * file system block.
 435         */
 436        down_read((&EXT4_I(inode)->i_data_sem));
 437        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
 438                retval = ext4_ext_map_blocks(handle, inode, map, 0);
 439        } else {
 440                retval = ext4_ind_map_blocks(handle, inode, map, 0);
 441        }
 442        up_read((&EXT4_I(inode)->i_data_sem));
 443
 444        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
 445                int ret = check_block_validity(inode, map);
 446                if (ret != 0)
 447                        return ret;
 448        }
 449
 450        /* If it is only a block(s) look up */
 451        if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
 452                return retval;
 453
 454        /*
 455         * Returns if the blocks have already allocated
 456         *
 457         * Note that if blocks have been preallocated
 458         * ext4_ext_get_block() returns th create = 0
 459         * with buffer head unmapped.
 460         */
 461        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
 462                return retval;
 463
 464        /*
 465         * When we call get_blocks without the create flag, the
 466         * BH_Unwritten flag could have gotten set if the blocks
 467         * requested were part of a uninitialized extent.  We need to
 468         * clear this flag now that we are committed to convert all or
 469         * part of the uninitialized extent to be an initialized
 470         * extent.  This is because we need to avoid the combination
 471         * of BH_Unwritten and BH_Mapped flags being simultaneously
 472         * set on the buffer_head.
 473         */
 474        map->m_flags &= ~EXT4_MAP_UNWRITTEN;
 475
 476        /*
 477         * New blocks allocate and/or writing to uninitialized extent
 478         * will possibly result in updating i_data, so we take
 479         * the write lock of i_data_sem, and call get_blocks()
 480         * with create == 1 flag.
 481         */
 482        down_write((&EXT4_I(inode)->i_data_sem));
 483
 484        /*
 485         * if the caller is from delayed allocation writeout path
 486         * we have already reserved fs blocks for allocation
 487         * let the underlying get_block() function know to
 488         * avoid double accounting
 489         */
 490        if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
 491                ext4_set_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
 492        /*
 493         * We need to check for EXT4 here because migrate
 494         * could have changed the inode type in between
 495         */
 496        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
 497                retval = ext4_ext_map_blocks(handle, inode, map, flags);
 498        } else {
 499                retval = ext4_ind_map_blocks(handle, inode, map, flags);
 500
 501                if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
 502                        /*
 503                         * We allocated new blocks which will result in
 504                         * i_data's format changing.  Force the migrate
 505                         * to fail by clearing migrate flags
 506                         */
 507                        ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 508                }
 509
 510                /*
 511                 * Update reserved blocks/metadata blocks after successful
 512                 * block allocation which had been deferred till now. We don't
 513                 * support fallocate for non extent files. So we can update
 514                 * reserve space here.
 515                 */
 516                if ((retval > 0) &&
 517                        (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
 518                        ext4_da_update_reserve_space(inode, retval, 1);
 519        }
 520        if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
 521                ext4_clear_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
 522
 523        up_write((&EXT4_I(inode)->i_data_sem));
 524        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
 525                int ret = check_block_validity(inode, map);
 526                if (ret != 0)
 527                        return ret;
 528        }
 529        return retval;
 530}
 531
 532/* Maximum number of blocks we map for direct IO at once. */
 533#define DIO_MAX_BLOCKS 4096
 534
 535static int _ext4_get_block(struct inode *inode, sector_t iblock,
 536                           struct buffer_head *bh, int flags)
 537{
 538        handle_t *handle = ext4_journal_current_handle();
 539        struct ext4_map_blocks map;
 540        int ret = 0, started = 0;
 541        int dio_credits;
 542
 543        map.m_lblk = iblock;
 544        map.m_len = bh->b_size >> inode->i_blkbits;
 545
 546        if (flags && !handle) {
 547                /* Direct IO write... */
 548                if (map.m_len > DIO_MAX_BLOCKS)
 549                        map.m_len = DIO_MAX_BLOCKS;
 550                dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
 551                handle = ext4_journal_start(inode, dio_credits);
 552                if (IS_ERR(handle)) {
 553                        ret = PTR_ERR(handle);
 554                        return ret;
 555                }
 556                started = 1;
 557        }
 558
 559        ret = ext4_map_blocks(handle, inode, &map, flags);
 560        if (ret > 0) {
 561                map_bh(bh, inode->i_sb, map.m_pblk);
 562                bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
 563                bh->b_size = inode->i_sb->s_blocksize * map.m_len;
 564                ret = 0;
 565        }
 566        if (started)
 567                ext4_journal_stop(handle);
 568        return ret;
 569}
 570
 571int ext4_get_block(struct inode *inode, sector_t iblock,
 572                   struct buffer_head *bh, int create)
 573{
 574        return _ext4_get_block(inode, iblock, bh,
 575                               create ? EXT4_GET_BLOCKS_CREATE : 0);
 576}
 577
 578/*
 579 * `handle' can be NULL if create is zero
 580 */
 581struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
 582                                ext4_lblk_t block, int create, int *errp)
 583{
 584        struct ext4_map_blocks map;
 585        struct buffer_head *bh;
 586        int fatal = 0, err;
 587
 588        J_ASSERT(handle != NULL || create == 0);
 589
 590        map.m_lblk = block;
 591        map.m_len = 1;
 592        err = ext4_map_blocks(handle, inode, &map,
 593                              create ? EXT4_GET_BLOCKS_CREATE : 0);
 594
 595        if (err < 0)
 596                *errp = err;
 597        if (err <= 0)
 598                return NULL;
 599        *errp = 0;
 600
 601        bh = sb_getblk(inode->i_sb, map.m_pblk);
 602        if (!bh) {
 603                *errp = -EIO;
 604                return NULL;
 605        }
 606        if (map.m_flags & EXT4_MAP_NEW) {
 607                J_ASSERT(create != 0);
 608                J_ASSERT(handle != NULL);
 609
 610                /*
 611                 * Now that we do not always journal data, we should
 612                 * keep in mind whether this should always journal the
 613                 * new buffer as metadata.  For now, regular file
 614                 * writes use ext4_get_block instead, so it's not a
 615                 * problem.
 616                 */
 617                lock_buffer(bh);
 618                BUFFER_TRACE(bh, "call get_create_access");
 619                fatal = ext4_journal_get_create_access(handle, bh);
 620                if (!fatal && !buffer_uptodate(bh)) {
 621                        memset(bh->b_data, 0, inode->i_sb->s_blocksize);
 622                        set_buffer_uptodate(bh);
 623                }
 624                unlock_buffer(bh);
 625                BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
 626                err = ext4_handle_dirty_metadata(handle, inode, bh);
 627                if (!fatal)
 628                        fatal = err;
 629        } else {
 630                BUFFER_TRACE(bh, "not a new buffer");
 631        }
 632        if (fatal) {
 633                *errp = fatal;
 634                brelse(bh);
 635                bh = NULL;
 636        }
 637        return bh;
 638}
 639
 640struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
 641                               ext4_lblk_t block, int create, int *err)
 642{
 643        struct buffer_head *bh;
 644
 645        bh = ext4_getblk(handle, inode, block, create, err);
 646        if (!bh)
 647                return bh;
 648        if (buffer_uptodate(bh))
 649                return bh;
 650        ll_rw_block(READ | REQ_META | REQ_PRIO, 1, &bh);
 651        wait_on_buffer(bh);
 652        if (buffer_uptodate(bh))
 653                return bh;
 654        put_bh(bh);
 655        *err = -EIO;
 656        return NULL;
 657}
 658
 659static int walk_page_buffers(handle_t *handle,
 660                             struct buffer_head *head,
 661                             unsigned from,
 662                             unsigned to,
 663                             int *partial,
 664                             int (*fn)(handle_t *handle,
 665                                       struct buffer_head *bh))
 666{
 667        struct buffer_head *bh;
 668        unsigned block_start, block_end;
 669        unsigned blocksize = head->b_size;
 670        int err, ret = 0;
 671        struct buffer_head *next;
 672
 673        for (bh = head, block_start = 0;
 674             ret == 0 && (bh != head || !block_start);
 675             block_start = block_end, bh = next) {
 676                next = bh->b_this_page;
 677                block_end = block_start + blocksize;
 678                if (block_end <= from || block_start >= to) {
 679                        if (partial && !buffer_uptodate(bh))
 680                                *partial = 1;
 681                        continue;
 682                }
 683                err = (*fn)(handle, bh);
 684                if (!ret)
 685                        ret = err;
 686        }
 687        return ret;
 688}
 689
 690/*
 691 * To preserve ordering, it is essential that the hole instantiation and
 692 * the data write be encapsulated in a single transaction.  We cannot
 693 * close off a transaction and start a new one between the ext4_get_block()
 694 * and the commit_write().  So doing the jbd2_journal_start at the start of
 695 * prepare_write() is the right place.
 696 *
 697 * Also, this function can nest inside ext4_writepage() ->
 698 * block_write_full_page(). In that case, we *know* that ext4_writepage()
 699 * has generated enough buffer credits to do the whole page.  So we won't
 700 * block on the journal in that case, which is good, because the caller may
 701 * be PF_MEMALLOC.
 702 *
 703 * By accident, ext4 can be reentered when a transaction is open via
 704 * quota file writes.  If we were to commit the transaction while thus
 705 * reentered, there can be a deadlock - we would be holding a quota
 706 * lock, and the commit would never complete if another thread had a
 707 * transaction open and was blocking on the quota lock - a ranking
 708 * violation.
 709 *
 710 * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
 711 * will _not_ run commit under these circumstances because handle->h_ref
 712 * is elevated.  We'll still have enough credits for the tiny quotafile
 713 * write.
 714 */
 715static int do_journal_get_write_access(handle_t *handle,
 716                                       struct buffer_head *bh)
 717{
 718        int dirty = buffer_dirty(bh);
 719        int ret;
 720
 721        if (!buffer_mapped(bh) || buffer_freed(bh))
 722                return 0;
 723        /*
 724         * __block_write_begin() could have dirtied some buffers. Clean
 725         * the dirty bit as jbd2_journal_get_write_access() could complain
 726         * otherwise about fs integrity issues. Setting of the dirty bit
 727         * by __block_write_begin() isn't a real problem here as we clear
 728         * the bit before releasing a page lock and thus writeback cannot
 729         * ever write the buffer.
 730         */
 731        if (dirty)
 732                clear_buffer_dirty(bh);
 733        ret = ext4_journal_get_write_access(handle, bh);
 734        if (!ret && dirty)
 735                ret = ext4_handle_dirty_metadata(handle, NULL, bh);
 736        return ret;
 737}
 738
 739static int ext4_get_block_write(struct inode *inode, sector_t iblock,
 740                   struct buffer_head *bh_result, int create);
 741static int ext4_write_begin(struct file *file, struct address_space *mapping,
 742                            loff_t pos, unsigned len, unsigned flags,
 743                            struct page **pagep, void **fsdata)
 744{
 745        struct inode *inode = mapping->host;
 746        int ret, needed_blocks;
 747        handle_t *handle;
 748        int retries = 0;
 749        struct page *page;
 750        pgoff_t index;
 751        unsigned from, to;
 752
 753        trace_ext4_write_begin(inode, pos, len, flags);
 754        /*
 755         * Reserve one block more for addition to orphan list in case
 756         * we allocate blocks but write fails for some reason
 757         */
 758        needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
 759        index = pos >> PAGE_CACHE_SHIFT;
 760        from = pos & (PAGE_CACHE_SIZE - 1);
 761        to = from + len;
 762
 763retry:
 764        handle = ext4_journal_start(inode, needed_blocks);
 765        if (IS_ERR(handle)) {
 766                ret = PTR_ERR(handle);
 767                goto out;
 768        }
 769
 770        /* We cannot recurse into the filesystem as the transaction is already
 771         * started */
 772        flags |= AOP_FLAG_NOFS;
 773
 774        page = grab_cache_page_write_begin(mapping, index, flags);
 775        if (!page) {
 776                ext4_journal_stop(handle);
 777                ret = -ENOMEM;
 778                goto out;
 779        }
 780        *pagep = page;
 781
 782        if (ext4_should_dioread_nolock(inode))
 783                ret = __block_write_begin(page, pos, len, ext4_get_block_write);
 784        else
 785                ret = __block_write_begin(page, pos, len, ext4_get_block);
 786
 787        if (!ret && ext4_should_journal_data(inode)) {
 788                ret = walk_page_buffers(handle, page_buffers(page),
 789                                from, to, NULL, do_journal_get_write_access);
 790        }
 791
 792        if (ret) {
 793                unlock_page(page);
 794                page_cache_release(page);
 795                /*
 796                 * __block_write_begin may have instantiated a few blocks
 797                 * outside i_size.  Trim these off again. Don't need
 798                 * i_size_read because we hold i_mutex.
 799                 *
 800                 * Add inode to orphan list in case we crash before
 801                 * truncate finishes
 802                 */
 803                if (pos + len > inode->i_size && ext4_can_truncate(inode))
 804                        ext4_orphan_add(handle, inode);
 805
 806                ext4_journal_stop(handle);
 807                if (pos + len > inode->i_size) {
 808                        ext4_truncate_failed_write(inode);
 809                        /*
 810                         * If truncate failed early the inode might
 811                         * still be on the orphan list; we need to
 812                         * make sure the inode is removed from the
 813                         * orphan list in that case.
 814                         */
 815                        if (inode->i_nlink)
 816                                ext4_orphan_del(NULL, inode);
 817                }
 818        }
 819
 820        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 821                goto retry;
 822out:
 823        return ret;
 824}
 825
 826/* For write_end() in data=journal mode */
 827static int write_end_fn(handle_t *handle, struct buffer_head *bh)
 828{
 829        if (!buffer_mapped(bh) || buffer_freed(bh))
 830                return 0;
 831        set_buffer_uptodate(bh);
 832        return ext4_handle_dirty_metadata(handle, NULL, bh);
 833}
 834
 835static int ext4_generic_write_end(struct file *file,
 836                                  struct address_space *mapping,
 837                                  loff_t pos, unsigned len, unsigned copied,
 838                                  struct page *page, void *fsdata)
 839{
 840        int i_size_changed = 0;
 841        struct inode *inode = mapping->host;
 842        handle_t *handle = ext4_journal_current_handle();
 843
 844        copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
 845
 846        /*
 847         * No need to use i_size_read() here, the i_size
 848         * cannot change under us because we hold i_mutex.
 849         *
 850         * But it's important to update i_size while still holding page lock:
 851         * page writeout could otherwise come in and zero beyond i_size.
 852         */
 853        if (pos + copied > inode->i_size) {
 854                i_size_write(inode, pos + copied);
 855                i_size_changed = 1;
 856        }
 857
 858        if (pos + copied >  EXT4_I(inode)->i_disksize) {
 859                /* We need to mark inode dirty even if
 860                 * new_i_size is less that inode->i_size
 861                 * bu greater than i_disksize.(hint delalloc)
 862                 */
 863                ext4_update_i_disksize(inode, (pos + copied));
 864                i_size_changed = 1;
 865        }
 866        unlock_page(page);
 867        page_cache_release(page);
 868
 869        /*
 870         * Don't mark the inode dirty under page lock. First, it unnecessarily
 871         * makes the holding time of page lock longer. Second, it forces lock
 872         * ordering of page lock and transaction start for journaling
 873         * filesystems.
 874         */
 875        if (i_size_changed)
 876                ext4_mark_inode_dirty(handle, inode);
 877
 878        return copied;
 879}
 880
 881/*
 882 * We need to pick up the new inode size which generic_commit_write gave us
 883 * `file' can be NULL - eg, when called from page_symlink().
 884 *
 885 * ext4 never places buffers on inode->i_mapping->private_list.  metadata
 886 * buffers are managed internally.
 887 */
 888static int ext4_ordered_write_end(struct file *file,
 889                                  struct address_space *mapping,
 890                                  loff_t pos, unsigned len, unsigned copied,
 891                                  struct page *page, void *fsdata)
 892{
 893        handle_t *handle = ext4_journal_current_handle();
 894        struct inode *inode = mapping->host;
 895        int ret = 0, ret2;
 896
 897        trace_ext4_ordered_write_end(inode, pos, len, copied);
 898        ret = ext4_jbd2_file_inode(handle, inode);
 899
 900        if (ret == 0) {
 901                ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
 902                                                        page, fsdata);
 903                copied = ret2;
 904                if (pos + len > inode->i_size && ext4_can_truncate(inode))
 905                        /* if we have allocated more blocks and copied
 906                         * less. We will have blocks allocated outside
 907                         * inode->i_size. So truncate them
 908                         */
 909                        ext4_orphan_add(handle, inode);
 910                if (ret2 < 0)
 911                        ret = ret2;
 912        }
 913        ret2 = ext4_journal_stop(handle);
 914        if (!ret)
 915                ret = ret2;
 916
 917        if (pos + len > inode->i_size) {
 918                ext4_truncate_failed_write(inode);
 919                /*
 920                 * If truncate failed early the inode might still be
 921                 * on the orphan list; we need to make sure the inode
 922                 * is removed from the orphan list in that case.
 923                 */
 924                if (inode->i_nlink)
 925                        ext4_orphan_del(NULL, inode);
 926        }
 927
 928
 929        return ret ? ret : copied;
 930}
 931
 932static int ext4_writeback_write_end(struct file *file,
 933                                    struct address_space *mapping,
 934                                    loff_t pos, unsigned len, unsigned copied,
 935                                    struct page *page, void *fsdata)
 936{
 937        handle_t *handle = ext4_journal_current_handle();
 938        struct inode *inode = mapping->host;
 939        int ret = 0, ret2;
 940
 941        trace_ext4_writeback_write_end(inode, pos, len, copied);
 942        ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
 943                                                        page, fsdata);
 944        copied = ret2;
 945        if (pos + len > inode->i_size && ext4_can_truncate(inode))
 946                /* if we have allocated more blocks and copied
 947                 * less. We will have blocks allocated outside
 948                 * inode->i_size. So truncate them
 949                 */
 950                ext4_orphan_add(handle, inode);
 951
 952        if (ret2 < 0)
 953                ret = ret2;
 954
 955        ret2 = ext4_journal_stop(handle);
 956        if (!ret)
 957                ret = ret2;
 958
 959        if (pos + len > inode->i_size) {
 960                ext4_truncate_failed_write(inode);
 961                /*
 962                 * If truncate failed early the inode might still be
 963                 * on the orphan list; we need to make sure the inode
 964                 * is removed from the orphan list in that case.
 965                 */
 966                if (inode->i_nlink)
 967                        ext4_orphan_del(NULL, inode);
 968        }
 969
 970        return ret ? ret : copied;
 971}
 972
 973static int ext4_journalled_write_end(struct file *file,
 974                                     struct address_space *mapping,
 975                                     loff_t pos, unsigned len, unsigned copied,
 976                                     struct page *page, void *fsdata)
 977{
 978        handle_t *handle = ext4_journal_current_handle();
 979        struct inode *inode = mapping->host;
 980        int ret = 0, ret2;
 981        int partial = 0;
 982        unsigned from, to;
 983        loff_t new_i_size;
 984
 985        trace_ext4_journalled_write_end(inode, pos, len, copied);
 986        from = pos & (PAGE_CACHE_SIZE - 1);
 987        to = from + len;
 988
 989        BUG_ON(!ext4_handle_valid(handle));
 990
 991        if (copied < len) {
 992                if (!PageUptodate(page))
 993                        copied = 0;
 994                page_zero_new_buffers(page, from+copied, to);
 995        }
 996
 997        ret = walk_page_buffers(handle, page_buffers(page), from,
 998                                to, &partial, write_end_fn);
 999        if (!partial)
1000                SetPageUptodate(page);
1001        new_i_size = pos + copied;
1002        if (new_i_size > inode->i_size)
1003                i_size_write(inode, pos+copied);
1004        ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1005        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1006        if (new_i_size > EXT4_I(inode)->i_disksize) {
1007                ext4_update_i_disksize(inode, new_i_size);
1008                ret2 = ext4_mark_inode_dirty(handle, inode);
1009                if (!ret)
1010                        ret = ret2;
1011        }
1012
1013        unlock_page(page);
1014        page_cache_release(page);
1015        if (pos + len > inode->i_size && ext4_can_truncate(inode))
1016                /* if we have allocated more blocks and copied
1017                 * less. We will have blocks allocated outside
1018                 * inode->i_size. So truncate them
1019                 */
1020                ext4_orphan_add(handle, inode);
1021
1022        ret2 = ext4_journal_stop(handle);
1023        if (!ret)
1024                ret = ret2;
1025        if (pos + len > inode->i_size) {
1026                ext4_truncate_failed_write(inode);
1027                /*
1028                 * If truncate failed early the inode might still be
1029                 * on the orphan list; we need to make sure the inode
1030                 * is removed from the orphan list in that case.
1031                 */
1032                if (inode->i_nlink)
1033                        ext4_orphan_del(NULL, inode);
1034        }
1035
1036        return ret ? ret : copied;
1037}
1038
1039/*
1040 * Reserve a single block located at lblock
1041 */
1042static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
1043{
1044        int retries = 0;
1045        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1046        struct ext4_inode_info *ei = EXT4_I(inode);
1047        unsigned long md_needed;
1048        int ret;
1049
1050        /*
1051         * recalculate the amount of metadata blocks to reserve
1052         * in order to allocate nrblocks
1053         * worse case is one extent per block
1054         */
1055repeat:
1056        spin_lock(&ei->i_block_reservation_lock);
1057        md_needed = ext4_calc_metadata_amount(inode, lblock);
1058        trace_ext4_da_reserve_space(inode, md_needed);
1059        spin_unlock(&ei->i_block_reservation_lock);
1060
1061        /*
1062         * We will charge metadata quota at writeout time; this saves
1063         * us from metadata over-estimation, though we may go over by
1064         * a small amount in the end.  Here we just reserve for data.
1065         */
1066        ret = dquot_reserve_block(inode, 1);
1067        if (ret)
1068                return ret;
1069        /*
1070         * We do still charge estimated metadata to the sb though;
1071         * we cannot afford to run out of free blocks.
1072         */
1073        if (ext4_claim_free_blocks(sbi, md_needed + 1, 0)) {
1074                dquot_release_reservation_block(inode, 1);
1075                if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1076                        yield();
1077                        goto repeat;
1078                }
1079                return -ENOSPC;
1080        }
1081        spin_lock(&ei->i_block_reservation_lock);
1082        ei->i_reserved_data_blocks++;
1083        ei->i_reserved_meta_blocks += md_needed;
1084        spin_unlock(&ei->i_block_reservation_lock);
1085
1086        return 0;       /* success */
1087}
1088
1089static void ext4_da_release_space(struct inode *inode, int to_free)
1090{
1091        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1092        struct ext4_inode_info *ei = EXT4_I(inode);
1093
1094        if (!to_free)
1095                return;         /* Nothing to release, exit */
1096
1097        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1098
1099        trace_ext4_da_release_space(inode, to_free);
1100        if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1101                /*
1102                 * if there aren't enough reserved blocks, then the
1103                 * counter is messed up somewhere.  Since this
1104                 * function is called from invalidate page, it's
1105                 * harmless to return without any action.
1106                 */
1107                ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
1108                         "ino %lu, to_free %d with only %d reserved "
1109                         "data blocks\n", inode->i_ino, to_free,
1110                         ei->i_reserved_data_blocks);
1111                WARN_ON(1);
1112                to_free = ei->i_reserved_data_blocks;
1113        }
1114        ei->i_reserved_data_blocks -= to_free;
1115
1116        if (ei->i_reserved_data_blocks == 0) {
1117                /*
1118                 * We can release all of the reserved metadata blocks
1119                 * only when we have written all of the delayed
1120                 * allocation blocks.
1121                 */
1122                percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1123                                   ei->i_reserved_meta_blocks);
1124                ei->i_reserved_meta_blocks = 0;
1125                ei->i_da_metadata_calc_len = 0;
1126        }
1127
1128        /* update fs dirty data blocks counter */
1129        percpu_counter_sub(&sbi->s_dirtyblocks_counter, to_free);
1130
1131        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1132
1133        dquot_release_reservation_block(inode, to_free);
1134}
1135
1136static void ext4_da_page_release_reservation(struct page *page,
1137                                             unsigned long offset)
1138{
1139        int to_release = 0;
1140        struct buffer_head *head, *bh;
1141        unsigned int curr_off = 0;
1142
1143        head = page_buffers(page);
1144        bh = head;
1145        do {
1146                unsigned int next_off = curr_off + bh->b_size;
1147
1148                if ((offset <= curr_off) && (buffer_delay(bh))) {
1149                        to_release++;
1150                        clear_buffer_delay(bh);
1151                }
1152                curr_off = next_off;
1153        } while ((bh = bh->b_this_page) != head);
1154        ext4_da_release_space(page->mapping->host, to_release);
1155}
1156
1157/*
1158 * Delayed allocation stuff
1159 */
1160
1161/*
1162 * mpage_da_submit_io - walks through extent of pages and try to write
1163 * them with writepage() call back
1164 *
1165 * @mpd->inode: inode
1166 * @mpd->first_page: first page of the extent
1167 * @mpd->next_page: page after the last page of the extent
1168 *
1169 * By the time mpage_da_submit_io() is called we expect all blocks
1170 * to be allocated. this may be wrong if allocation failed.
1171 *
1172 * As pages are already locked by write_cache_pages(), we can't use it
1173 */
1174static int mpage_da_submit_io(struct mpage_da_data *mpd,
1175                              struct ext4_map_blocks *map)
1176{
1177        struct pagevec pvec;
1178        unsigned long index, end;
1179        int ret = 0, err, nr_pages, i;
1180        struct inode *inode = mpd->inode;
1181        struct address_space *mapping = inode->i_mapping;
1182        loff_t size = i_size_read(inode);
1183        unsigned int len, block_start;
1184        struct buffer_head *bh, *page_bufs = NULL;
1185        int journal_data = ext4_should_journal_data(inode);
1186        sector_t pblock = 0, cur_logical = 0;
1187        struct ext4_io_submit io_submit;
1188
1189        BUG_ON(mpd->next_page <= mpd->first_page);
1190        memset(&io_submit, 0, sizeof(io_submit));
1191        /*
1192         * We need to start from the first_page to the next_page - 1
1193         * to make sure we also write the mapped dirty buffer_heads.
1194         * If we look at mpd->b_blocknr we would only be looking
1195         * at the currently mapped buffer_heads.
1196         */
1197        index = mpd->first_page;
1198        end = mpd->next_page - 1;
1199
1200        pagevec_init(&pvec, 0);
1201        while (index <= end) {
1202                nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1203                if (nr_pages == 0)
1204                        break;
1205                for (i = 0; i < nr_pages; i++) {
1206                        int commit_write = 0, skip_page = 0;
1207                        struct page *page = pvec.pages[i];
1208
1209                        index = page->index;
1210                        if (index > end)
1211                                break;
1212
1213                        if (index == size >> PAGE_CACHE_SHIFT)
1214                                len = size & ~PAGE_CACHE_MASK;
1215                        else
1216                                len = PAGE_CACHE_SIZE;
1217                        if (map) {
1218                                cur_logical = index << (PAGE_CACHE_SHIFT -
1219                                                        inode->i_blkbits);
1220                                pblock = map->m_pblk + (cur_logical -
1221                                                        map->m_lblk);
1222                        }
1223                        index++;
1224
1225                        BUG_ON(!PageLocked(page));
1226                        BUG_ON(PageWriteback(page));
1227
1228                        /*
1229                         * If the page does not have buffers (for
1230                         * whatever reason), try to create them using
1231                         * __block_write_begin.  If this fails,
1232                         * skip the page and move on.
1233                         */
1234                        if (!page_has_buffers(page)) {
1235                                if (__block_write_begin(page, 0, len,
1236                                                noalloc_get_block_write)) {
1237                                skip_page:
1238                                        unlock_page(page);
1239                                        continue;
1240                                }
1241                                commit_write = 1;
1242                        }
1243
1244                        bh = page_bufs = page_buffers(page);
1245                        block_start = 0;
1246                        do {
1247                                if (!bh)
1248                                        goto skip_page;
1249                                if (map && (cur_logical >= map->m_lblk) &&
1250                                    (cur_logical <= (map->m_lblk +
1251                                                     (map->m_len - 1)))) {
1252                                        if (buffer_delay(bh)) {
1253                                                clear_buffer_delay(bh);
1254                                                bh->b_blocknr = pblock;
1255                                        }
1256                                        if (buffer_unwritten(bh) ||
1257                                            buffer_mapped(bh))
1258                                                BUG_ON(bh->b_blocknr != pblock);
1259                                        if (map->m_flags & EXT4_MAP_UNINIT)
1260                                                set_buffer_uninit(bh);
1261                                        clear_buffer_unwritten(bh);
1262                                }
1263
1264                                /* skip page if block allocation undone */
1265                                if (buffer_delay(bh) || buffer_unwritten(bh))
1266                                        skip_page = 1;
1267                                bh = bh->b_this_page;
1268                                block_start += bh->b_size;
1269                                cur_logical++;
1270                                pblock++;
1271                        } while (bh != page_bufs);
1272
1273                        if (skip_page)
1274                                goto skip_page;
1275
1276                        if (commit_write)
1277                                /* mark the buffer_heads as dirty & uptodate */
1278                                block_commit_write(page, 0, len);
1279
1280                        clear_page_dirty_for_io(page);
1281                        /*
1282                         * Delalloc doesn't support data journalling,
1283                         * but eventually maybe we'll lift this
1284                         * restriction.
1285                         */
1286                        if (unlikely(journal_data && PageChecked(page)))
1287                                err = __ext4_journalled_writepage(page, len);
1288                        else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
1289                                err = ext4_bio_write_page(&io_submit, page,
1290                                                          len, mpd->wbc);
1291                        else if (buffer_uninit(page_bufs)) {
1292                                ext4_set_bh_endio(page_bufs, inode);
1293                                err = block_write_full_page_endio(page,
1294                                        noalloc_get_block_write,
1295                                        mpd->wbc, ext4_end_io_buffer_write);
1296                        } else
1297                                err = block_write_full_page(page,
1298                                        noalloc_get_block_write, mpd->wbc);
1299
1300                        if (!err)
1301                                mpd->pages_written++;
1302                        /*
1303                         * In error case, we have to continue because
1304                         * remaining pages are still locked
1305                         */
1306                        if (ret == 0)
1307                                ret = err;
1308                }
1309                pagevec_release(&pvec);
1310        }
1311        ext4_io_submit(&io_submit);
1312        return ret;
1313}
1314
1315static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd)
1316{
1317        int nr_pages, i;
1318        pgoff_t index, end;
1319        struct pagevec pvec;
1320        struct inode *inode = mpd->inode;
1321        struct address_space *mapping = inode->i_mapping;
1322
1323        index = mpd->first_page;
1324        end   = mpd->next_page - 1;
1325        while (index <= end) {
1326                nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1327                if (nr_pages == 0)
1328                        break;
1329                for (i = 0; i < nr_pages; i++) {
1330                        struct page *page = pvec.pages[i];
1331                        if (page->index > end)
1332                                break;
1333                        BUG_ON(!PageLocked(page));
1334                        BUG_ON(PageWriteback(page));
1335                        block_invalidatepage(page, 0);
1336                        ClearPageUptodate(page);
1337                        unlock_page(page);
1338                }
1339                index = pvec.pages[nr_pages - 1]->index + 1;
1340                pagevec_release(&pvec);
1341        }
1342        return;
1343}
1344
1345static void ext4_print_free_blocks(struct inode *inode)
1346{
1347        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1348        printk(KERN_CRIT "Total free blocks count %lld\n",
1349               ext4_count_free_blocks(inode->i_sb));
1350        printk(KERN_CRIT "Free/Dirty block details\n");
1351        printk(KERN_CRIT "free_blocks=%lld\n",
1352               (long long) percpu_counter_sum(&sbi->s_freeblocks_counter));
1353        printk(KERN_CRIT "dirty_blocks=%lld\n",
1354               (long long) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
1355        printk(KERN_CRIT "Block reservation details\n");
1356        printk(KERN_CRIT "i_reserved_data_blocks=%u\n",
1357               EXT4_I(inode)->i_reserved_data_blocks);
1358        printk(KERN_CRIT "i_reserved_meta_blocks=%u\n",
1359               EXT4_I(inode)->i_reserved_meta_blocks);
1360        return;
1361}
1362
1363/*
1364 * mpage_da_map_and_submit - go through given space, map them
1365 *       if necessary, and then submit them for I/O
1366 *
1367 * @mpd - bh describing space
1368 *
1369 * The function skips space we know is already mapped to disk blocks.
1370 *
1371 */
1372static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
1373{
1374        int err, blks, get_blocks_flags;
1375        struct ext4_map_blocks map, *mapp = NULL;
1376        sector_t next = mpd->b_blocknr;
1377        unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
1378        loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
1379        handle_t *handle = NULL;
1380
1381        /*
1382         * If the blocks are mapped already, or we couldn't accumulate
1383         * any blocks, then proceed immediately to the submission stage.
1384         */
1385        if ((mpd->b_size == 0) ||
1386            ((mpd->b_state  & (1 << BH_Mapped)) &&
1387             !(mpd->b_state & (1 << BH_Delay)) &&
1388             !(mpd->b_state & (1 << BH_Unwritten))))
1389                goto submit_io;
1390
1391        handle = ext4_journal_current_handle();
1392        BUG_ON(!handle);
1393
1394        /*
1395         * Call ext4_map_blocks() to allocate any delayed allocation
1396         * blocks, or to convert an uninitialized extent to be
1397         * initialized (in the case where we have written into
1398         * one or more preallocated blocks).
1399         *
1400         * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
1401         * indicate that we are on the delayed allocation path.  This
1402         * affects functions in many different parts of the allocation
1403         * call path.  This flag exists primarily because we don't
1404         * want to change *many* call functions, so ext4_map_blocks()
1405         * will set the EXT4_STATE_DELALLOC_RESERVED flag once the
1406         * inode's allocation semaphore is taken.
1407         *
1408         * If the blocks in questions were delalloc blocks, set
1409         * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
1410         * variables are updated after the blocks have been allocated.
1411         */
1412        map.m_lblk = next;
1413        map.m_len = max_blocks;
1414        get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
1415        if (ext4_should_dioread_nolock(mpd->inode))
1416                get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
1417        if (mpd->b_state & (1 << BH_Delay))
1418                get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
1419
1420        blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
1421        if (blks < 0) {
1422                struct super_block *sb = mpd->inode->i_sb;
1423
1424                err = blks;
1425                /*
1426                 * If get block returns EAGAIN or ENOSPC and there
1427                 * appears to be free blocks we will just let
1428                 * mpage_da_submit_io() unlock all of the pages.
1429                 */
1430                if (err == -EAGAIN)
1431                        goto submit_io;
1432
1433                if (err == -ENOSPC &&
1434                    ext4_count_free_blocks(sb)) {
1435                        mpd->retval = err;
1436                        goto submit_io;
1437                }
1438
1439                /*
1440                 * get block failure will cause us to loop in
1441                 * writepages, because a_ops->writepage won't be able
1442                 * to make progress. The page will be redirtied by
1443                 * writepage and writepages will again try to write
1444                 * the same.
1445                 */
1446                if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
1447                        ext4_msg(sb, KERN_CRIT,
1448                                 "delayed block allocation failed for inode %lu "
1449                                 "at logical offset %llu with max blocks %zd "
1450                                 "with error %d", mpd->inode->i_ino,
1451                                 (unsigned long long) next,
1452                                 mpd->b_size >> mpd->inode->i_blkbits, err);
1453                        ext4_msg(sb, KERN_CRIT,
1454                                "This should not happen!! Data will be lost\n");
1455                        if (err == -ENOSPC)
1456                                ext4_print_free_blocks(mpd->inode);
1457                }
1458                /* invalidate all the pages */
1459                ext4_da_block_invalidatepages(mpd);
1460
1461                /* Mark this page range as having been completed */
1462                mpd->io_done = 1;
1463                return;
1464        }
1465        BUG_ON(blks == 0);
1466
1467        mapp = &map;
1468        if (map.m_flags & EXT4_MAP_NEW) {
1469                struct block_device *bdev = mpd->inode->i_sb->s_bdev;
1470                int i;
1471
1472                for (i = 0; i < map.m_len; i++)
1473                        unmap_underlying_metadata(bdev, map.m_pblk + i);
1474        }
1475
1476        if (ext4_should_order_data(mpd->inode)) {
1477                err = ext4_jbd2_file_inode(handle, mpd->inode);
1478                if (err)
1479                        /* This only happens if the journal is aborted */
1480                        return;
1481        }
1482
1483        /*
1484         * Update on-disk size along with block allocation.
1485         */
1486        disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
1487        if (disksize > i_size_read(mpd->inode))
1488                disksize = i_size_read(mpd->inode);
1489        if (disksize > EXT4_I(mpd->inode)->i_disksize) {
1490                ext4_update_i_disksize(mpd->inode, disksize);
1491                err = ext4_mark_inode_dirty(handle, mpd->inode);
1492                if (err)
1493                        ext4_error(mpd->inode->i_sb,
1494                                   "Failed to mark inode %lu dirty",
1495                                   mpd->inode->i_ino);
1496        }
1497
1498submit_io:
1499        mpage_da_submit_io(mpd, mapp);
1500        mpd->io_done = 1;
1501}
1502
1503#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
1504                (1 << BH_Delay) | (1 << BH_Unwritten))
1505
1506/*
1507 * mpage_add_bh_to_extent - try to add one more block to extent of blocks
1508 *
1509 * @mpd->lbh - extent of blocks
1510 * @logical - logical number of the block in the file
1511 * @bh - bh of the block (used to access block's state)
1512 *
1513 * the function is used to collect contig. blocks in same state
1514 */
1515static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
1516                                   sector_t logical, size_t b_size,
1517                                   unsigned long b_state)
1518{
1519        sector_t next;
1520        int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
1521
1522        /*
1523         * XXX Don't go larger than mballoc is willing to allocate
1524         * This is a stopgap solution.  We eventually need to fold
1525         * mpage_da_submit_io() into this function and then call
1526         * ext4_map_blocks() multiple times in a loop
1527         */
1528        if (nrblocks >= 8*1024*1024/mpd->inode->i_sb->s_blocksize)
1529                goto flush_it;
1530
1531        /* check if thereserved journal credits might overflow */
1532        if (!(ext4_test_inode_flag(mpd->inode, EXT4_INODE_EXTENTS))) {
1533                if (nrblocks >= EXT4_MAX_TRANS_DATA) {
1534                        /*
1535                         * With non-extent format we are limited by the journal
1536                         * credit available.  Total credit needed to insert
1537                         * nrblocks contiguous blocks is dependent on the
1538                         * nrblocks.  So limit nrblocks.
1539                         */
1540                        goto flush_it;
1541                } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
1542                                EXT4_MAX_TRANS_DATA) {
1543                        /*
1544                         * Adding the new buffer_head would make it cross the
1545                         * allowed limit for which we have journal credit
1546                         * reserved. So limit the new bh->b_size
1547                         */
1548                        b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
1549                                                mpd->inode->i_blkbits;
1550                        /* we will do mpage_da_submit_io in the next loop */
1551                }
1552        }
1553        /*
1554         * First block in the extent
1555         */
1556        if (mpd->b_size == 0) {
1557                mpd->b_blocknr = logical;
1558                mpd->b_size = b_size;
1559                mpd->b_state = b_state & BH_FLAGS;
1560                return;
1561        }
1562
1563        next = mpd->b_blocknr + nrblocks;
1564        /*
1565         * Can we merge the block to our big extent?
1566         */
1567        if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
1568                mpd->b_size += b_size;
1569                return;
1570        }
1571
1572flush_it:
1573        /*
1574         * We couldn't merge the block to our extent, so we
1575         * need to flush current  extent and start new one
1576         */
1577        mpage_da_map_and_submit(mpd);
1578        return;
1579}
1580
1581static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1582{
1583        return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1584}
1585
1586/*
1587 * This is a special get_blocks_t callback which is used by
1588 * ext4_da_write_begin().  It will either return mapped block or
1589 * reserve space for a single block.
1590 *
1591 * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1592 * We also have b_blocknr = -1 and b_bdev initialized properly
1593 *
1594 * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1595 * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1596 * initialized properly.
1597 */
1598static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1599                                  struct buffer_head *bh, int create)
1600{
1601        struct ext4_map_blocks map;
1602        int ret = 0;
1603        sector_t invalid_block = ~((sector_t) 0xffff);
1604
1605        if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1606                invalid_block = ~0;
1607
1608        BUG_ON(create == 0);
1609        BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1610
1611        map.m_lblk = iblock;
1612        map.m_len = 1;
1613
1614        /*
1615         * first, we need to know whether the block is allocated already
1616         * preallocated blocks are unmapped but should treated
1617         * the same as allocated blocks.
1618         */
1619        ret = ext4_map_blocks(NULL, inode, &map, 0);
1620        if (ret < 0)
1621                return ret;
1622        if (ret == 0) {
1623                if (buffer_delay(bh))
1624                        return 0; /* Not sure this could or should happen */
1625                /*
1626                 * XXX: __block_write_begin() unmaps passed block, is it OK?
1627                 */
1628                ret = ext4_da_reserve_space(inode, iblock);
1629                if (ret)
1630                        /* not enough space to reserve */
1631                        return ret;
1632
1633                map_bh(bh, inode->i_sb, invalid_block);
1634                set_buffer_new(bh);
1635                set_buffer_delay(bh);
1636                return 0;
1637        }
1638
1639        map_bh(bh, inode->i_sb, map.m_pblk);
1640        bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
1641
1642        if (buffer_unwritten(bh)) {
1643                /* A delayed write to unwritten bh should be marked
1644                 * new and mapped.  Mapped ensures that we don't do
1645                 * get_block multiple times when we write to the same
1646                 * offset and new ensures that we do proper zero out
1647                 * for partial write.
1648                 */
1649                set_buffer_new(bh);
1650                set_buffer_mapped(bh);
1651        }
1652        return 0;
1653}
1654
1655/*
1656 * This function is used as a standard get_block_t calback function
1657 * when there is no desire to allocate any blocks.  It is used as a
1658 * callback function for block_write_begin() and block_write_full_page().
1659 * These functions should only try to map a single block at a time.
1660 *
1661 * Since this function doesn't do block allocations even if the caller
1662 * requests it by passing in create=1, it is critically important that
1663 * any caller checks to make sure that any buffer heads are returned
1664 * by this function are either all already mapped or marked for
1665 * delayed allocation before calling  block_write_full_page().  Otherwise,
1666 * b_blocknr could be left unitialized, and the page write functions will
1667 * be taken by surprise.
1668 */
1669static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
1670                                   struct buffer_head *bh_result, int create)
1671{
1672        BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
1673        return _ext4_get_block(inode, iblock, bh_result, 0);
1674}
1675
1676static int bget_one(handle_t *handle, struct buffer_head *bh)
1677{
1678        get_bh(bh);
1679        return 0;
1680}
1681
1682static int bput_one(handle_t *handle, struct buffer_head *bh)
1683{
1684        put_bh(bh);
1685        return 0;
1686}
1687
1688static int __ext4_journalled_writepage(struct page *page,
1689                                       unsigned int len)
1690{
1691        struct address_space *mapping = page->mapping;
1692        struct inode *inode = mapping->host;
1693        struct buffer_head *page_bufs;
1694        handle_t *handle = NULL;
1695        int ret = 0;
1696        int err;
1697
1698        ClearPageChecked(page);
1699        page_bufs = page_buffers(page);
1700        BUG_ON(!page_bufs);
1701        walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
1702        /* As soon as we unlock the page, it can go away, but we have
1703         * references to buffers so we are safe */
1704        unlock_page(page);
1705
1706        handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1707        if (IS_ERR(handle)) {
1708                ret = PTR_ERR(handle);
1709                goto out;
1710        }
1711
1712        BUG_ON(!ext4_handle_valid(handle));
1713
1714        ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
1715                                do_journal_get_write_access);
1716
1717        err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
1718                                write_end_fn);
1719        if (ret == 0)
1720                ret = err;
1721        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1722        err = ext4_journal_stop(handle);
1723        if (!ret)
1724                ret = err;
1725
1726        walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
1727        ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1728out:
1729        return ret;
1730}
1731
1732static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
1733static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
1734
1735/*
1736 * Note that we don't need to start a transaction unless we're journaling data
1737 * because we should have holes filled from ext4_page_mkwrite(). We even don't
1738 * need to file the inode to the transaction's list in ordered mode because if
1739 * we are writing back data added by write(), the inode is already there and if
1740 * we are writing back data modified via mmap(), no one guarantees in which
1741 * transaction the data will hit the disk. In case we are journaling data, we
1742 * cannot start transaction directly because transaction start ranks above page
1743 * lock so we have to do some magic.
1744 *
1745 * This function can get called via...
1746 *   - ext4_da_writepages after taking page lock (have journal handle)
1747 *   - journal_submit_inode_data_buffers (no journal handle)
1748 *   - shrink_page_list via pdflush (no journal handle)
1749 *   - grab_page_cache when doing write_begin (have journal handle)
1750 *
1751 * We don't do any block allocation in this function. If we have page with
1752 * multiple blocks we need to write those buffer_heads that are mapped. This
1753 * is important for mmaped based write. So if we do with blocksize 1K
1754 * truncate(f, 1024);
1755 * a = mmap(f, 0, 4096);
1756 * a[0] = 'a';
1757 * truncate(f, 4096);
1758 * we have in the page first buffer_head mapped via page_mkwrite call back
1759 * but other bufer_heads would be unmapped but dirty(dirty done via the
1760 * do_wp_page). So writepage should write the first block. If we modify
1761 * the mmap area beyond 1024 we will again get a page_fault and the
1762 * page_mkwrite callback will do the block allocation and mark the
1763 * buffer_heads mapped.
1764 *
1765 * We redirty the page if we have any buffer_heads that is either delay or
1766 * unwritten in the page.
1767 *
1768 * We can get recursively called as show below.
1769 *
1770 *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1771 *              ext4_writepage()
1772 *
1773 * But since we don't do any block allocation we should not deadlock.
1774 * Page also have the dirty flag cleared so we don't get recurive page_lock.
1775 */
1776static int ext4_writepage(struct page *page,
1777                          struct writeback_control *wbc)
1778{
1779        int ret = 0, commit_write = 0;
1780        loff_t size;
1781        unsigned int len;
1782        struct buffer_head *page_bufs = NULL;
1783        struct inode *inode = page->mapping->host;
1784
1785        trace_ext4_writepage(page);
1786        size = i_size_read(inode);
1787        if (page->index == size >> PAGE_CACHE_SHIFT)
1788                len = size & ~PAGE_CACHE_MASK;
1789        else
1790                len = PAGE_CACHE_SIZE;
1791
1792        /*
1793         * If the page does not have buffers (for whatever reason),
1794         * try to create them using __block_write_begin.  If this
1795         * fails, redirty the page and move on.
1796         */
1797        if (!page_has_buffers(page)) {
1798                if (__block_write_begin(page, 0, len,
1799                                        noalloc_get_block_write)) {
1800                redirty_page:
1801                        redirty_page_for_writepage(wbc, page);
1802                        unlock_page(page);
1803                        return 0;
1804                }
1805                commit_write = 1;
1806        }
1807        page_bufs = page_buffers(page);
1808        if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
1809                              ext4_bh_delay_or_unwritten)) {
1810                /*
1811                 * We don't want to do block allocation, so redirty
1812                 * the page and return.  We may reach here when we do
1813                 * a journal commit via journal_submit_inode_data_buffers.
1814                 * We can also reach here via shrink_page_list
1815                 */
1816                goto redirty_page;
1817        }
1818        if (commit_write)
1819                /* now mark the buffer_heads as dirty and uptodate */
1820                block_commit_write(page, 0, len);
1821
1822        if (PageChecked(page) && ext4_should_journal_data(inode))
1823                /*
1824                 * It's mmapped pagecache.  Add buffers and journal it.  There
1825                 * doesn't seem much point in redirtying the page here.
1826                 */
1827                return __ext4_journalled_writepage(page, len);
1828
1829        if (buffer_uninit(page_bufs)) {
1830                ext4_set_bh_endio(page_bufs, inode);
1831                ret = block_write_full_page_endio(page, noalloc_get_block_write,
1832                                            wbc, ext4_end_io_buffer_write);
1833        } else
1834                ret = block_write_full_page(page, noalloc_get_block_write,
1835                                            wbc);
1836
1837        return ret;
1838}
1839
1840/*
1841 * This is called via ext4_da_writepages() to
1842 * calculate the total number of credits to reserve to fit
1843 * a single extent allocation into a single transaction,
1844 * ext4_da_writpeages() will loop calling this before
1845 * the block allocation.
1846 */
1847
1848static int ext4_da_writepages_trans_blocks(struct inode *inode)
1849{
1850        int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
1851
1852        /*
1853         * With non-extent format the journal credit needed to
1854         * insert nrblocks contiguous block is dependent on
1855         * number of contiguous block. So we will limit
1856         * number of contiguous block to a sane value
1857         */
1858        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
1859            (max_blocks > EXT4_MAX_TRANS_DATA))
1860                max_blocks = EXT4_MAX_TRANS_DATA;
1861
1862        return ext4_chunk_trans_blocks(inode, max_blocks);
1863}
1864
1865/*
1866 * write_cache_pages_da - walk the list of dirty pages of the given
1867 * address space and accumulate pages that need writing, and call
1868 * mpage_da_map_and_submit to map a single contiguous memory region
1869 * and then write them.
1870 */
1871static int write_cache_pages_da(struct address_space *mapping,
1872                                struct writeback_control *wbc,
1873                                struct mpage_da_data *mpd,
1874                                pgoff_t *done_index)
1875{
1876        struct buffer_head      *bh, *head;
1877        struct inode            *inode = mapping->host;
1878        struct pagevec          pvec;
1879        unsigned int            nr_pages;
1880        sector_t                logical;
1881        pgoff_t                 index, end;
1882        long                    nr_to_write = wbc->nr_to_write;
1883        int                     i, tag, ret = 0;
1884
1885        memset(mpd, 0, sizeof(struct mpage_da_data));
1886        mpd->wbc = wbc;
1887        mpd->inode = inode;
1888        pagevec_init(&pvec, 0);
1889        index = wbc->range_start >> PAGE_CACHE_SHIFT;
1890        end = wbc->range_end >> PAGE_CACHE_SHIFT;
1891
1892        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
1893                tag = PAGECACHE_TAG_TOWRITE;
1894        else
1895                tag = PAGECACHE_TAG_DIRTY;
1896
1897        *done_index = index;
1898        while (index <= end) {
1899                nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
1900                              min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
1901                if (nr_pages == 0)
1902                        return 0;
1903
1904                for (i = 0; i < nr_pages; i++) {
1905                        struct page *page = pvec.pages[i];
1906
1907                        /*
1908                         * At this point, the page may be truncated or
1909                         * invalidated (changing page->mapping to NULL), or
1910                         * even swizzled back from swapper_space to tmpfs file
1911                         * mapping. However, page->index will not change
1912                         * because we have a reference on the page.
1913                         */
1914                        if (page->index > end)
1915                                goto out;
1916
1917                        *done_index = page->index + 1;
1918
1919                        /*
1920                         * If we can't merge this page, and we have
1921                         * accumulated an contiguous region, write it
1922                         */
1923                        if ((mpd->next_page != page->index) &&
1924                            (mpd->next_page != mpd->first_page)) {
1925                                mpage_da_map_and_submit(mpd);
1926                                goto ret_extent_tail;
1927                        }
1928
1929                        lock_page(page);
1930
1931                        /*
1932                         * If the page is no longer dirty, or its
1933                         * mapping no longer corresponds to inode we
1934                         * are writing (which means it has been
1935                         * truncated or invalidated), or the page is
1936                         * already under writeback and we are not
1937                         * doing a data integrity writeback, skip the page
1938                         */
1939                        if (!PageDirty(page) ||
1940                            (PageWriteback(page) &&
1941                             (wbc->sync_mode == WB_SYNC_NONE)) ||
1942                            unlikely(page->mapping != mapping)) {
1943                                unlock_page(page);
1944                                continue;
1945                        }
1946
1947                        wait_on_page_writeback(page);
1948                        BUG_ON(PageWriteback(page));
1949
1950                        if (mpd->next_page != page->index)
1951                                mpd->first_page = page->index;
1952                        mpd->next_page = page->index + 1;
1953                        logical = (sector_t) page->index <<
1954                                (PAGE_CACHE_SHIFT - inode->i_blkbits);
1955
1956                        if (!page_has_buffers(page)) {
1957                                mpage_add_bh_to_extent(mpd, logical,
1958                                                       PAGE_CACHE_SIZE,
1959                                                       (1 << BH_Dirty) | (1 << BH_Uptodate));
1960                                if (mpd->io_done)
1961                                        goto ret_extent_tail;
1962                        } else {
1963                                /*
1964                                 * Page with regular buffer heads,
1965                                 * just add all dirty ones
1966                                 */
1967                                head = page_buffers(page);
1968                                bh = head;
1969                                do {
1970                                        BUG_ON(buffer_locked(bh));
1971                                        /*
1972                                         * We need to try to allocate
1973                                         * unmapped blocks in the same page.
1974                                         * Otherwise we won't make progress
1975                                         * with the page in ext4_writepage
1976                                         */
1977                                        if (ext4_bh_delay_or_unwritten(NULL, bh)) {
1978                                                mpage_add_bh_to_extent(mpd, logical,
1979                                                                       bh->b_size,
1980                                                                       bh->b_state);
1981                                                if (mpd->io_done)
1982                                                        goto ret_extent_tail;
1983                                        } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
1984                                                /*
1985                                                 * mapped dirty buffer. We need
1986                                                 * to update the b_state
1987                                                 * because we look at b_state
1988                                                 * in mpage_da_map_blocks.  We
1989                                                 * don't update b_size because
1990                                                 * if we find an unmapped
1991                                                 * buffer_head later we need to
1992                                                 * use the b_state flag of that
1993                                                 * buffer_head.
1994                                                 */
1995                                                if (mpd->b_size == 0)
1996                                                        mpd->b_state = bh->b_state & BH_FLAGS;
1997                                        }
1998                                        logical++;
1999                                } while ((bh = bh->b_this_page) != head);
2000                        }
2001
2002                        if (nr_to_write > 0) {
2003                                nr_to_write--;
2004                                if (nr_to_write == 0 &&
2005                                    wbc->sync_mode == WB_SYNC_NONE)
2006                                        /*
2007                                         * We stop writing back only if we are
2008                                         * not doing integrity sync. In case of
2009                                         * integrity sync we have to keep going
2010                                         * because someone may be concurrently
2011                                         * dirtying pages, and we might have
2012                                         * synced a lot of newly appeared dirty
2013                                         * pages, but have not synced all of the
2014                                         * old dirty pages.
2015                                         */
2016                                        goto out;
2017                        }
2018                }
2019                pagevec_release(&pvec);
2020                cond_resched();
2021        }
2022        return 0;
2023ret_extent_tail:
2024        ret = MPAGE_DA_EXTENT_TAIL;
2025out:
2026        pagevec_release(&pvec);
2027        cond_resched();
2028        return ret;
2029}
2030
2031
2032static int ext4_da_writepages(struct address_space *mapping,
2033                              struct writeback_control *wbc)
2034{
2035        pgoff_t index;
2036        int range_whole = 0;
2037        handle_t *handle = NULL;
2038        struct mpage_da_data mpd;
2039        struct inode *inode = mapping->host;
2040        int pages_written = 0;
2041        unsigned int max_pages;
2042        int range_cyclic, cycled = 1, io_done = 0;
2043        int needed_blocks, ret = 0;
2044        long desired_nr_to_write, nr_to_writebump = 0;
2045        loff_t range_start = wbc->range_start;
2046        struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2047        pgoff_t done_index = 0;
2048        pgoff_t end;
2049
2050        trace_ext4_da_writepages(inode, wbc);
2051
2052        /*
2053         * No pages to write? This is mainly a kludge to avoid starting
2054         * a transaction for special inodes like journal inode on last iput()
2055         * because that could violate lock ordering on umount
2056         */
2057        if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2058                return 0;
2059
2060        /*
2061         * If the filesystem has aborted, it is read-only, so return
2062         * right away instead of dumping stack traces later on that
2063         * will obscure the real source of the problem.  We test
2064         * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2065         * the latter could be true if the filesystem is mounted
2066         * read-only, and in that case, ext4_da_writepages should
2067         * *never* be called, so if that ever happens, we would want
2068         * the stack trace.
2069         */
2070        if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2071                return -EROFS;
2072
2073        if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2074                range_whole = 1;
2075
2076        range_cyclic = wbc->range_cyclic;
2077        if (wbc->range_cyclic) {
2078                index = mapping->writeback_index;
2079                if (index)
2080                        cycled = 0;
2081                wbc->range_start = index << PAGE_CACHE_SHIFT;
2082                wbc->range_end  = LLONG_MAX;
2083                wbc->range_cyclic = 0;
2084                end = -1;
2085        } else {
2086                index = wbc->range_start >> PAGE_CACHE_SHIFT;
2087                end = wbc->range_end >> PAGE_CACHE_SHIFT;
2088        }
2089
2090        /*
2091         * This works around two forms of stupidity.  The first is in
2092         * the writeback code, which caps the maximum number of pages
2093         * written to be 1024 pages.  This is wrong on multiple
2094         * levels; different architectues have a different page size,
2095         * which changes the maximum amount of data which gets
2096         * written.  Secondly, 4 megabytes is way too small.  XFS
2097         * forces this value to be 16 megabytes by multiplying
2098         * nr_to_write parameter by four, and then relies on its
2099         * allocator to allocate larger extents to make them
2100         * contiguous.  Unfortunately this brings us to the second
2101         * stupidity, which is that ext4's mballoc code only allocates
2102         * at most 2048 blocks.  So we force contiguous writes up to
2103         * the number of dirty blocks in the inode, or
2104         * sbi->max_writeback_mb_bump whichever is smaller.
2105         */
2106        max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2107        if (!range_cyclic && range_whole) {
2108                if (wbc->nr_to_write == LONG_MAX)
2109                        desired_nr_to_write = wbc->nr_to_write;
2110                else
2111                        desired_nr_to_write = wbc->nr_to_write * 8;
2112        } else
2113                desired_nr_to_write = ext4_num_dirty_pages(inode, index,
2114                                                           max_pages);
2115        if (desired_nr_to_write > max_pages)
2116                desired_nr_to_write = max_pages;
2117
2118        if (wbc->nr_to_write < desired_nr_to_write) {
2119                nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
2120                wbc->nr_to_write = desired_nr_to_write;
2121        }
2122
2123retry:
2124        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2125                tag_pages_for_writeback(mapping, index, end);
2126
2127        while (!ret && wbc->nr_to_write > 0) {
2128
2129                /*
2130                 * we  insert one extent at a time. So we need
2131                 * credit needed for single extent allocation.
2132                 * journalled mode is currently not supported
2133                 * by delalloc
2134                 */
2135                BUG_ON(ext4_should_journal_data(inode));
2136                needed_blocks = ext4_da_writepages_trans_blocks(inode);
2137
2138                /* start a new transaction*/
2139                handle = ext4_journal_start(inode, needed_blocks);
2140                if (IS_ERR(handle)) {
2141                        ret = PTR_ERR(handle);
2142                        ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2143                               "%ld pages, ino %lu; err %d", __func__,
2144                                wbc->nr_to_write, inode->i_ino, ret);
2145                        goto out_writepages;
2146                }
2147
2148                /*
2149                 * Now call write_cache_pages_da() to find the next
2150                 * contiguous region of logical blocks that need
2151                 * blocks to be allocated by ext4 and submit them.
2152                 */
2153                ret = write_cache_pages_da(mapping, wbc, &mpd, &done_index);
2154                /*
2155                 * If we have a contiguous extent of pages and we
2156                 * haven't done the I/O yet, map the blocks and submit
2157                 * them for I/O.
2158                 */
2159                if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2160                        mpage_da_map_and_submit(&mpd);
2161                        ret = MPAGE_DA_EXTENT_TAIL;
2162                }
2163                trace_ext4_da_write_pages(inode, &mpd);
2164                wbc->nr_to_write -= mpd.pages_written;
2165
2166                ext4_journal_stop(handle);
2167
2168                if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
2169                        /* commit the transaction which would
2170                         * free blocks released in the transaction
2171                         * and try again
2172                         */
2173                        jbd2_journal_force_commit_nested(sbi->s_journal);
2174                        ret = 0;
2175                } else if (ret == MPAGE_DA_EXTENT_TAIL) {
2176                        /*
2177                         * got one extent now try with
2178                         * rest of the pages
2179                         */
2180                        pages_written += mpd.pages_written;
2181                        ret = 0;
2182                        io_done = 1;
2183                } else if (wbc->nr_to_write)
2184                        /*
2185                         * There is no more writeout needed
2186                         * or we requested for a noblocking writeout
2187                         * and we found the device congested
2188                         */
2189                        break;
2190        }
2191        if (!io_done && !cycled) {
2192                cycled = 1;
2193                index = 0;
2194                wbc->range_start = index << PAGE_CACHE_SHIFT;
2195                wbc->range_end  = mapping->writeback_index - 1;
2196                goto retry;
2197        }
2198
2199        /* Update index */
2200        wbc->range_cyclic = range_cyclic;
2201        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2202                /*
2203                 * set the writeback_index so that range_cyclic
2204                 * mode will write it back later
2205                 */
2206                mapping->writeback_index = done_index;
2207
2208out_writepages:
2209        wbc->nr_to_write -= nr_to_writebump;
2210        wbc->range_start = range_start;
2211        trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
2212        return ret;
2213}
2214
2215#define FALL_BACK_TO_NONDELALLOC 1
2216static int ext4_nonda_switch(struct super_block *sb)
2217{
2218        s64 free_blocks, dirty_blocks;
2219        struct ext4_sb_info *sbi = EXT4_SB(sb);
2220
2221        /*
2222         * switch to non delalloc mode if we are running low
2223         * on free block. The free block accounting via percpu
2224         * counters can get slightly wrong with percpu_counter_batch getting
2225         * accumulated on each CPU without updating global counters
2226         * Delalloc need an accurate free block accounting. So switch
2227         * to non delalloc when we are near to error range.
2228         */
2229        free_blocks  = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
2230        dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyblocks_counter);
2231        if (2 * free_blocks < 3 * dirty_blocks ||
2232                free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
2233                /*
2234                 * free block count is less than 150% of dirty blocks
2235                 * or free blocks is less than watermark
2236                 */
2237                return 1;
2238        }
2239        /*
2240         * Even if we don't switch but are nearing capacity,
2241         * start pushing delalloc when 1/2 of free blocks are dirty.
2242         */
2243        if (free_blocks < 2 * dirty_blocks)
2244                writeback_inodes_sb_if_idle(sb);
2245
2246        return 0;
2247}
2248
2249static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2250                               loff_t pos, unsigned len, unsigned flags,
2251                               struct page **pagep, void **fsdata)
2252{
2253        int ret, retries = 0;
2254        struct page *page;
2255        pgoff_t index;
2256        struct inode *inode = mapping->host;
2257        handle_t *handle;
2258
2259        index = pos >> PAGE_CACHE_SHIFT;
2260
2261        if (ext4_nonda_switch(inode->i_sb)) {
2262                *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2263                return ext4_write_begin(file, mapping, pos,
2264                                        len, flags, pagep, fsdata);
2265        }
2266        *fsdata = (void *)0;
2267        trace_ext4_da_write_begin(inode, pos, len, flags);
2268retry:
2269        /*
2270         * With delayed allocation, we don't log the i_disksize update
2271         * if there is delayed block allocation. But we still need
2272         * to journalling the i_disksize update if writes to the end
2273         * of file which has an already mapped buffer.
2274         */
2275        handle = ext4_journal_start(inode, 1);
2276        if (IS_ERR(handle)) {
2277                ret = PTR_ERR(handle);
2278                goto out;
2279        }
2280        /* We cannot recurse into the filesystem as the transaction is already
2281         * started */
2282        flags |= AOP_FLAG_NOFS;
2283
2284        page = grab_cache_page_write_begin(mapping, index, flags);
2285        if (!page) {
2286                ext4_journal_stop(handle);
2287                ret = -ENOMEM;
2288                goto out;
2289        }
2290        *pagep = page;
2291
2292        ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
2293        if (ret < 0) {
2294                unlock_page(page);
2295                ext4_journal_stop(handle);
2296                page_cache_release(page);
2297                /*
2298                 * block_write_begin may have instantiated a few blocks
2299                 * outside i_size.  Trim these off again. Don't need
2300                 * i_size_read because we hold i_mutex.
2301                 */
2302                if (pos + len > inode->i_size)
2303                        ext4_truncate_failed_write(inode);
2304        }
2305
2306        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
2307                goto retry;
2308out:
2309        return ret;
2310}
2311
2312/*
2313 * Check if we should update i_disksize
2314 * when write to the end of file but not require block allocation
2315 */
2316static int ext4_da_should_update_i_disksize(struct page *page,
2317                                            unsigned long offset)
2318{
2319        struct buffer_head *bh;
2320        struct inode *inode = page->mapping->host;
2321        unsigned int idx;
2322        int i;
2323
2324        bh = page_buffers(page);
2325        idx = offset >> inode->i_blkbits;
2326
2327        for (i = 0; i < idx; i++)
2328                bh = bh->b_this_page;
2329
2330        if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
2331                return 0;
2332        return 1;
2333}
2334
2335static int ext4_da_write_end(struct file *file,
2336                             struct address_space *mapping,
2337                             loff_t pos, unsigned len, unsigned copied,
2338                             struct page *page, void *fsdata)
2339{
2340        struct inode *inode = mapping->host;
2341        int ret = 0, ret2;
2342        handle_t *handle = ext4_journal_current_handle();
2343        loff_t new_i_size;
2344        unsigned long start, end;
2345        int write_mode = (int)(unsigned long)fsdata;
2346
2347        if (write_mode == FALL_BACK_TO_NONDELALLOC) {
2348                if (ext4_should_order_data(inode)) {
2349                        return ext4_ordered_write_end(file, mapping, pos,
2350                                        len, copied, page, fsdata);
2351                } else if (ext4_should_writeback_data(inode)) {
2352                        return ext4_writeback_write_end(file, mapping, pos,
2353                                        len, copied, page, fsdata);
2354                } else {
2355                        BUG();
2356                }
2357        }
2358
2359        trace_ext4_da_write_end(inode, pos, len, copied);
2360        start = pos & (PAGE_CACHE_SIZE - 1);
2361        end = start + copied - 1;
2362
2363        /*
2364         * generic_write_end() will run mark_inode_dirty() if i_size
2365         * changes.  So let's piggyback the i_disksize mark_inode_dirty
2366         * into that.
2367         */
2368
2369        new_i_size = pos + copied;
2370        if (new_i_size > EXT4_I(inode)->i_disksize) {
2371                if (ext4_da_should_update_i_disksize(page, end)) {
2372                        down_write(&EXT4_I(inode)->i_data_sem);
2373                        if (new_i_size > EXT4_I(inode)->i_disksize) {
2374                                /*
2375                                 * Updating i_disksize when extending file
2376                                 * without needing block allocation
2377                                 */
2378                                if (ext4_should_order_data(inode))
2379                                        ret = ext4_jbd2_file_inode(handle,
2380                                                                   inode);
2381
2382                                EXT4_I(inode)->i_disksize = new_i_size;
2383                        }
2384                        up_write(&EXT4_I(inode)->i_data_sem);
2385                        /* We need to mark inode dirty even if
2386                         * new_i_size is less that inode->i_size
2387                         * bu greater than i_disksize.(hint delalloc)
2388                         */
2389                        ext4_mark_inode_dirty(handle, inode);
2390                }
2391        }
2392        ret2 = generic_write_end(file, mapping, pos, len, copied,
2393                                                        page, fsdata);
2394        copied = ret2;
2395        if (ret2 < 0)
2396                ret = ret2;
2397        ret2 = ext4_journal_stop(handle);
2398        if (!ret)
2399                ret = ret2;
2400
2401        return ret ? ret : copied;
2402}
2403
2404static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
2405{
2406        /*
2407         * Drop reserved blocks
2408         */
2409        BUG_ON(!PageLocked(page));
2410        if (!page_has_buffers(page))
2411                goto out;
2412
2413        ext4_da_page_release_reservation(page, offset);
2414
2415out:
2416        ext4_invalidatepage(page, offset);
2417
2418        return;
2419}
2420
2421/*
2422 * Force all delayed allocation blocks to be allocated for a given inode.
2423 */
2424int ext4_alloc_da_blocks(struct inode *inode)
2425{
2426        trace_ext4_alloc_da_blocks(inode);
2427
2428        if (!EXT4_I(inode)->i_reserved_data_blocks &&
2429            !EXT4_I(inode)->i_reserved_meta_blocks)
2430                return 0;
2431
2432        /*
2433         * We do something simple for now.  The filemap_flush() will
2434         * also start triggering a write of the data blocks, which is
2435         * not strictly speaking necessary (and for users of
2436         * laptop_mode, not even desirable).  However, to do otherwise
2437         * would require replicating code paths in:
2438         *
2439         * ext4_da_writepages() ->
2440         *    write_cache_pages() ---> (via passed in callback function)
2441         *        __mpage_da_writepage() -->
2442         *           mpage_add_bh_to_extent()
2443         *           mpage_da_map_blocks()
2444         *
2445         * The problem is that write_cache_pages(), located in
2446         * mm/page-writeback.c, marks pages clean in preparation for
2447         * doing I/O, which is not desirable if we're not planning on
2448         * doing I/O at all.
2449         *
2450         * We could call write_cache_pages(), and then redirty all of
2451         * the pages by calling redirty_page_for_writepage() but that
2452         * would be ugly in the extreme.  So instead we would need to
2453         * replicate parts of the code in the above functions,
2454         * simplifying them because we wouldn't actually intend to
2455         * write out the pages, but rather only collect contiguous
2456         * logical block extents, call the multi-block allocator, and
2457         * then update the buffer heads with the block allocations.
2458         *
2459         * For now, though, we'll cheat by calling filemap_flush(),
2460         * which will map the blocks, and start the I/O, but not
2461         * actually wait for the I/O to complete.
2462         */
2463        return filemap_flush(inode->i_mapping);
2464}
2465
2466/*
2467 * bmap() is special.  It gets used by applications such as lilo and by
2468 * the swapper to find the on-disk block of a specific piece of data.
2469 *
2470 * Naturally, this is dangerous if the block concerned is still in the
2471 * journal.  If somebody makes a swapfile on an ext4 data-journaling
2472 * filesystem and enables swap, then they may get a nasty shock when the
2473 * data getting swapped to that swapfile suddenly gets overwritten by
2474 * the original zero's written out previously to the journal and
2475 * awaiting writeback in the kernel's buffer cache.
2476 *
2477 * So, if we see any bmap calls here on a modified, data-journaled file,
2478 * take extra steps to flush any blocks which might be in the cache.
2479 */
2480static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
2481{
2482        struct inode *inode = mapping->host;
2483        journal_t *journal;
2484        int err;
2485
2486        if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
2487                        test_opt(inode->i_sb, DELALLOC)) {
2488                /*
2489                 * With delalloc we want to sync the file
2490                 * so that we can make sure we allocate
2491                 * blocks for file
2492                 */
2493                filemap_write_and_wait(mapping);
2494        }
2495
2496        if (EXT4_JOURNAL(inode) &&
2497            ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
2498                /*
2499                 * This is a REALLY heavyweight approach, but the use of
2500                 * bmap on dirty files is expected to be extremely rare:
2501                 * only if we run lilo or swapon on a freshly made file
2502                 * do we expect this to happen.
2503                 *
2504                 * (bmap requires CAP_SYS_RAWIO so this does not
2505                 * represent an unprivileged user DOS attack --- we'd be
2506                 * in trouble if mortal users could trigger this path at
2507                 * will.)
2508                 *
2509                 * NB. EXT4_STATE_JDATA is not set on files other than
2510                 * regular files.  If somebody wants to bmap a directory
2511                 * or symlink and gets confused because the buffer
2512                 * hasn't yet been flushed to disk, they deserve
2513                 * everything they get.
2514                 */
2515
2516                ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
2517                journal = EXT4_JOURNAL(inode);
2518                jbd2_journal_lock_updates(journal);
2519                err = jbd2_journal_flush(journal);
2520                jbd2_journal_unlock_updates(journal);
2521
2522                if (err)
2523                        return 0;
2524        }
2525
2526        return generic_block_bmap(mapping, block, ext4_get_block);
2527}
2528
2529static int ext4_readpage(struct file *file, struct page *page)
2530{
2531        trace_ext4_readpage(page);
2532        return mpage_readpage(page, ext4_get_block);
2533}
2534
2535static int
2536ext4_readpages(struct file *file, struct address_space *mapping,
2537                struct list_head *pages, unsigned nr_pages)
2538{
2539        return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
2540}
2541
2542static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
2543{
2544        struct buffer_head *head, *bh;
2545        unsigned int curr_off = 0;
2546
2547        if (!page_has_buffers(page))
2548                return;
2549        head = bh = page_buffers(page);
2550        do {
2551                if (offset <= curr_off && test_clear_buffer_uninit(bh)
2552                                        && bh->b_private) {
2553                        ext4_free_io_end(bh->b_private);
2554                        bh->b_private = NULL;
2555                        bh->b_end_io = NULL;
2556                }
2557                curr_off = curr_off + bh->b_size;
2558                bh = bh->b_this_page;
2559        } while (bh != head);
2560}
2561
2562static void ext4_invalidatepage(struct page *page, unsigned long offset)
2563{
2564        journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2565
2566        trace_ext4_invalidatepage(page, offset);
2567
2568        /*
2569         * free any io_end structure allocated for buffers to be discarded
2570         */
2571        if (ext4_should_dioread_nolock(page->mapping->host))
2572                ext4_invalidatepage_free_endio(page, offset);
2573        /*
2574         * If it's a full truncate we just forget about the pending dirtying
2575         */
2576        if (offset == 0)
2577                ClearPageChecked(page);
2578
2579        if (journal)
2580                jbd2_journal_invalidatepage(journal, page, offset);
2581        else
2582                block_invalidatepage(page, offset);
2583}
2584
2585static int ext4_releasepage(struct page *page, gfp_t wait)
2586{
2587        journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2588
2589        trace_ext4_releasepage(page);
2590
2591        WARN_ON(PageChecked(page));
2592        if (!page_has_buffers(page))
2593                return 0;
2594        if (journal)
2595                return jbd2_journal_try_to_free_buffers(journal, page, wait);
2596        else
2597                return try_to_free_buffers(page);
2598}
2599
2600/*
2601 * ext4_get_block used when preparing for a DIO write or buffer write.
2602 * We allocate an uinitialized extent if blocks haven't been allocated.
2603 * The extent will be converted to initialized after the IO is complete.
2604 */
2605static int ext4_get_block_write(struct inode *inode, sector_t iblock,
2606                   struct buffer_head *bh_result, int create)
2607{
2608        ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
2609                   inode->i_ino, create);
2610        return _ext4_get_block(inode, iblock, bh_result,
2611                               EXT4_GET_BLOCKS_IO_CREATE_EXT);
2612}
2613
2614static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
2615                            ssize_t size, void *private, int ret,
2616                            bool is_async)
2617{
2618        struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
2619        ext4_io_end_t *io_end = iocb->private;
2620        struct workqueue_struct *wq;
2621        unsigned long flags;
2622        struct ext4_inode_info *ei;
2623
2624        /* if not async direct IO or dio with 0 bytes write, just return */
2625        if (!io_end || !size)
2626                goto out;
2627
2628        ext_debug("ext4_end_io_dio(): io_end 0x%p"
2629                  "for inode %lu, iocb 0x%p, offset %llu, size %llu\n",
2630                  iocb->private, io_end->inode->i_ino, iocb, offset,
2631                  size);
2632
2633        /* if not aio dio with unwritten extents, just free io and return */
2634        if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
2635                ext4_free_io_end(io_end);
2636                iocb->private = NULL;
2637out:
2638                if (is_async)
2639                        aio_complete(iocb, ret, 0);
2640                inode_dio_done(inode);
2641                return;
2642        }
2643
2644        io_end->offset = offset;
2645        io_end->size = size;
2646        if (is_async) {
2647                io_end->iocb = iocb;
2648                io_end->result = ret;
2649        }
2650        wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
2651
2652        /* Add the io_end to per-inode completed aio dio list*/
2653        ei = EXT4_I(io_end->inode);
2654        spin_lock_irqsave(&ei->i_completed_io_lock, flags);
2655        list_add_tail(&io_end->list, &ei->i_completed_io_list);
2656        spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
2657
2658        /* queue the work to convert unwritten extents to written */
2659        queue_work(wq, &io_end->work);
2660        iocb->private = NULL;
2661
2662        /* XXX: probably should move into the real I/O completion handler */
2663        inode_dio_done(inode);
2664}
2665
2666static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
2667{
2668        ext4_io_end_t *io_end = bh->b_private;
2669        struct workqueue_struct *wq;
2670        struct inode *inode;
2671        unsigned long flags;
2672
2673        if (!test_clear_buffer_uninit(bh) || !io_end)
2674                goto out;
2675
2676        if (!(io_end->inode->i_sb->s_flags & MS_ACTIVE)) {
2677                printk("sb umounted, discard end_io request for inode %lu\n",
2678                        io_end->inode->i_ino);
2679                ext4_free_io_end(io_end);
2680                goto out;
2681        }
2682
2683        /*
2684         * It may be over-defensive here to check EXT4_IO_END_UNWRITTEN now,
2685         * but being more careful is always safe for the future change.
2686         */
2687        inode = io_end->inode;
2688        if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
2689                io_end->flag |= EXT4_IO_END_UNWRITTEN;
2690                atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
2691        }
2692
2693        /* Add the io_end to per-inode completed io list*/
2694        spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
2695        list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
2696        spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
2697
2698        wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
2699        /* queue the work to convert unwritten extents to written */
2700        queue_work(wq, &io_end->work);
2701out:
2702        bh->b_private = NULL;
2703        bh->b_end_io = NULL;
2704        clear_buffer_uninit(bh);
2705        end_buffer_async_write(bh, uptodate);
2706}
2707
2708static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode)
2709{
2710        ext4_io_end_t *io_end;
2711        struct page *page = bh->b_page;
2712        loff_t offset = (sector_t)page->index << PAGE_CACHE_SHIFT;
2713        size_t size = bh->b_size;
2714
2715retry:
2716        io_end = ext4_init_io_end(inode, GFP_ATOMIC);
2717        if (!io_end) {
2718                pr_warn_ratelimited("%s: allocation fail\n", __func__);
2719                schedule();
2720                goto retry;
2721        }
2722        io_end->offset = offset;
2723        io_end->size = size;
2724        /*
2725         * We need to hold a reference to the page to make sure it
2726         * doesn't get evicted before ext4_end_io_work() has a chance
2727         * to convert the extent from written to unwritten.
2728         */
2729        io_end->page = page;
2730        get_page(io_end->page);
2731
2732        bh->b_private = io_end;
2733        bh->b_end_io = ext4_end_io_buffer_write;
2734        return 0;
2735}
2736
2737/*
2738 * For ext4 extent files, ext4 will do direct-io write to holes,
2739 * preallocated extents, and those write extend the file, no need to
2740 * fall back to buffered IO.
2741 *
2742 * For holes, we fallocate those blocks, mark them as uninitialized
2743 * If those blocks were preallocated, we mark sure they are splited, but
2744 * still keep the range to write as uninitialized.
2745 *
2746 * The unwrritten extents will be converted to written when DIO is completed.
2747 * For async direct IO, since the IO may still pending when return, we
2748 * set up an end_io call back function, which will do the conversion
2749 * when async direct IO completed.
2750 *
2751 * If the O_DIRECT write will extend the file then add this inode to the
2752 * orphan list.  So recovery will truncate it back to the original size
2753 * if the machine crashes during the write.
2754 *
2755 */
2756static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
2757                              const struct iovec *iov, loff_t offset,
2758                              unsigned long nr_segs)
2759{
2760        struct file *file = iocb->ki_filp;
2761        struct inode *inode = file->f_mapping->host;
2762        ssize_t ret;
2763        size_t count = iov_length(iov, nr_segs);
2764
2765        loff_t final_size = offset + count;
2766        if (rw == WRITE && final_size <= inode->i_size) {
2767                /*
2768                 * We could direct write to holes and fallocate.
2769                 *
2770                 * Allocated blocks to fill the hole are marked as uninitialized
2771                 * to prevent parallel buffered read to expose the stale data
2772                 * before DIO complete the data IO.
2773                 *
2774                 * As to previously fallocated extents, ext4 get_block
2775                 * will just simply mark the buffer mapped but still
2776                 * keep the extents uninitialized.
2777                 *
2778                 * for non AIO case, we will convert those unwritten extents
2779                 * to written after return back from blockdev_direct_IO.
2780                 *
2781                 * for async DIO, the conversion needs to be defered when
2782                 * the IO is completed. The ext4 end_io callback function
2783                 * will be called to take care of the conversion work.
2784                 * Here for async case, we allocate an io_end structure to
2785                 * hook to the iocb.
2786                 */
2787                iocb->private = NULL;
2788                EXT4_I(inode)->cur_aio_dio = NULL;
2789                if (!is_sync_kiocb(iocb)) {
2790                        iocb->private = ext4_init_io_end(inode, GFP_NOFS);
2791                        if (!iocb->private)
2792                                return -ENOMEM;
2793                        /*
2794                         * we save the io structure for current async
2795                         * direct IO, so that later ext4_map_blocks()
2796                         * could flag the io structure whether there
2797                         * is a unwritten extents needs to be converted
2798                         * when IO is completed.
2799                         */
2800                        EXT4_I(inode)->cur_aio_dio = iocb->private;
2801                }
2802
2803                ret = __blockdev_direct_IO(rw, iocb, inode,
2804                                         inode->i_sb->s_bdev, iov,
2805                                         offset, nr_segs,
2806                                         ext4_get_block_write,
2807                                         ext4_end_io_dio,
2808                                         NULL,
2809                                         DIO_LOCKING | DIO_SKIP_HOLES);
2810                if (iocb->private)
2811                        EXT4_I(inode)->cur_aio_dio = NULL;
2812                /*
2813                 * The io_end structure takes a reference to the inode,
2814                 * that structure needs to be destroyed and the
2815                 * reference to the inode need to be dropped, when IO is
2816                 * complete, even with 0 byte write, or failed.
2817                 *
2818                 * In the successful AIO DIO case, the io_end structure will be
2819                 * desctroyed and the reference to the inode will be dropped
2820                 * after the end_io call back function is called.
2821                 *
2822                 * In the case there is 0 byte write, or error case, since
2823                 * VFS direct IO won't invoke the end_io call back function,
2824                 * we need to free the end_io structure here.
2825                 */
2826                if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
2827                        ext4_free_io_end(iocb->private);
2828                        iocb->private = NULL;
2829                } else if (ret > 0 && ext4_test_inode_state(inode,
2830                                                EXT4_STATE_DIO_UNWRITTEN)) {
2831                        int err;
2832                        /*
2833                         * for non AIO case, since the IO is already
2834                         * completed, we could do the conversion right here
2835                         */
2836                        err = ext4_convert_unwritten_extents(inode,
2837                                                             offset, ret);
2838                        if (err < 0)
2839                                ret = err;
2840                        ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
2841                }
2842                return ret;
2843        }
2844
2845        /* for write the the end of file case, we fall back to old way */
2846        return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
2847}
2848
2849static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
2850                              const struct iovec *iov, loff_t offset,
2851                              unsigned long nr_segs)
2852{
2853        struct file *file = iocb->ki_filp;
2854        struct inode *inode = file->f_mapping->host;
2855        ssize_t ret;
2856
2857        trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
2858        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
2859                ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
2860        else
2861                ret = ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
2862        trace_ext4_direct_IO_exit(inode, offset,
2863                                iov_length(iov, nr_segs), rw, ret);
2864        return ret;
2865}
2866
2867/*
2868 * Pages can be marked dirty completely asynchronously from ext4's journalling
2869 * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
2870 * much here because ->set_page_dirty is called under VFS locks.  The page is
2871 * not necessarily locked.
2872 *
2873 * We cannot just dirty the page and leave attached buffers clean, because the
2874 * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
2875 * or jbddirty because all the journalling code will explode.
2876 *
2877 * So what we do is to mark the page "pending dirty" and next time writepage
2878 * is called, propagate that into the buffers appropriately.
2879 */
2880static int ext4_journalled_set_page_dirty(struct page *page)
2881{
2882        SetPageChecked(page);
2883        return __set_page_dirty_nobuffers(page);
2884}
2885
2886static const struct address_space_operations ext4_ordered_aops = {
2887        .readpage               = ext4_readpage,
2888        .readpages              = ext4_readpages,
2889        .writepage              = ext4_writepage,
2890        .write_begin            = ext4_write_begin,
2891        .write_end              = ext4_ordered_write_end,
2892        .bmap                   = ext4_bmap,
2893        .invalidatepage         = ext4_invalidatepage,
2894        .releasepage            = ext4_releasepage,
2895        .direct_IO              = ext4_direct_IO,
2896        .migratepage            = buffer_migrate_page,
2897        .is_partially_uptodate  = block_is_partially_uptodate,
2898        .error_remove_page      = generic_error_remove_page,
2899};
2900
2901static const struct address_space_operations ext4_writeback_aops = {
2902        .readpage               = ext4_readpage,
2903        .readpages              = ext4_readpages,
2904        .writepage              = ext4_writepage,
2905        .write_begin            = ext4_write_begin,
2906        .write_end              = ext4_writeback_write_end,
2907        .bmap                   = ext4_bmap,
2908        .invalidatepage         = ext4_invalidatepage,
2909        .releasepage            = ext4_releasepage,
2910        .direct_IO              = ext4_direct_IO,
2911        .migratepage            = buffer_migrate_page,
2912        .is_partially_uptodate  = block_is_partially_uptodate,
2913        .error_remove_page      = generic_error_remove_page,
2914};
2915
2916static const struct address_space_operations ext4_journalled_aops = {
2917        .readpage               = ext4_readpage,
2918        .readpages              = ext4_readpages,
2919        .writepage              = ext4_writepage,
2920        .write_begin            = ext4_write_begin,
2921        .write_end              = ext4_journalled_write_end,
2922        .set_page_dirty         = ext4_journalled_set_page_dirty,
2923        .bmap                   = ext4_bmap,
2924        .invalidatepage         = ext4_invalidatepage,
2925        .releasepage            = ext4_releasepage,
2926        .is_partially_uptodate  = block_is_partially_uptodate,
2927        .error_remove_page      = generic_error_remove_page,
2928};
2929
2930static const struct address_space_operations ext4_da_aops = {
2931        .readpage               = ext4_readpage,
2932        .readpages              = ext4_readpages,
2933        .writepage              = ext4_writepage,
2934        .writepages             = ext4_da_writepages,
2935        .write_begin            = ext4_da_write_begin,
2936        .write_end              = ext4_da_write_end,
2937        .bmap                   = ext4_bmap,
2938        .invalidatepage         = ext4_da_invalidatepage,
2939        .releasepage            = ext4_releasepage,
2940        .direct_IO              = ext4_direct_IO,
2941        .migratepage            = buffer_migrate_page,
2942        .is_partially_uptodate  = block_is_partially_uptodate,
2943        .error_remove_page      = generic_error_remove_page,
2944};
2945
2946void ext4_set_aops(struct inode *inode)
2947{
2948        if (ext4_should_order_data(inode) &&
2949                test_opt(inode->i_sb, DELALLOC))
2950                inode->i_mapping->a_ops = &ext4_da_aops;
2951        else if (ext4_should_order_data(inode))
2952                inode->i_mapping->a_ops = &ext4_ordered_aops;
2953        else if (ext4_should_writeback_data(inode) &&
2954                 test_opt(inode->i_sb, DELALLOC))
2955                inode->i_mapping->a_ops = &ext4_da_aops;
2956        else if (ext4_should_writeback_data(inode))
2957                inode->i_mapping->a_ops = &ext4_writeback_aops;
2958        else
2959                inode->i_mapping->a_ops = &ext4_journalled_aops;
2960}
2961
2962/*
2963 * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
2964 * up to the end of the block which corresponds to `from'.
2965 * This required during truncate. We need to physically zero the tail end
2966 * of that block so it doesn't yield old data if the file is later grown.
2967 */
2968int ext4_block_truncate_page(handle_t *handle,
2969                struct address_space *mapping, loff_t from)
2970{
2971        unsigned offset = from & (PAGE_CACHE_SIZE-1);
2972        unsigned length;
2973        unsigned blocksize;
2974        struct inode *inode = mapping->host;
2975
2976        blocksize = inode->i_sb->s_blocksize;
2977        length = blocksize - (offset & (blocksize - 1));
2978
2979        return ext4_block_zero_page_range(handle, mapping, from, length);
2980}
2981
2982/*
2983 * ext4_block_zero_page_range() zeros out a mapping of length 'length'
2984 * starting from file offset 'from'.  The range to be zero'd must
2985 * be contained with in one block.  If the specified range exceeds
2986 * the end of the block it will be shortened to end of the block
2987 * that cooresponds to 'from'
2988 */
2989int ext4_block_zero_page_range(handle_t *handle,
2990                struct address_space *mapping, loff_t from, loff_t length)
2991{
2992        ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
2993        unsigned offset = from & (PAGE_CACHE_SIZE-1);
2994        unsigned blocksize, max, pos;
2995        ext4_lblk_t iblock;
2996        struct inode *inode = mapping->host;
2997        struct buffer_head *bh;
2998        struct page *page;
2999        int err = 0;
3000
3001        page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
3002                                   mapping_gfp_mask(mapping) & ~__GFP_FS);
3003        if (!page)
3004                return -EINVAL;
3005
3006        blocksize = inode->i_sb->s_blocksize;
3007        max = blocksize - (offset & (blocksize - 1));
3008
3009        /*
3010         * correct length if it does not fall between
3011         * 'from' and the end of the block
3012         */
3013        if (length > max || length < 0)
3014                length = max;
3015
3016        iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
3017
3018        if (!page_has_buffers(page))
3019                create_empty_buffers(page, blocksize, 0);
3020
3021        /* Find the buffer that contains "offset" */
3022        bh = page_buffers(page);
3023        pos = blocksize;
3024        while (offset >= pos) {
3025                bh = bh->b_this_page;
3026                iblock++;
3027                pos += blocksize;
3028        }
3029
3030        err = 0;
3031        if (buffer_freed(bh)) {
3032                BUFFER_TRACE(bh, "freed: skip");
3033                goto unlock;
3034        }
3035
3036        if (!buffer_mapped(bh)) {
3037                BUFFER_TRACE(bh, "unmapped");
3038                ext4_get_block(inode, iblock, bh, 0);
3039                /* unmapped? It's a hole - nothing to do */
3040                if (!buffer_mapped(bh)) {
3041                        BUFFER_TRACE(bh, "still unmapped");
3042                        goto unlock;
3043                }
3044        }
3045
3046        /* Ok, it's mapped. Make sure it's up-to-date */
3047        if (PageUptodate(page))
3048                set_buffer_uptodate(bh);
3049
3050        if (!buffer_uptodate(bh)) {
3051                err = -EIO;
3052                ll_rw_block(READ, 1, &bh);
3053                wait_on_buffer(bh);
3054                /* Uhhuh. Read error. Complain and punt. */
3055                if (!buffer_uptodate(bh))
3056                        goto unlock;
3057        }
3058
3059        if (ext4_should_journal_data(inode)) {
3060                BUFFER_TRACE(bh, "get write access");
3061                err = ext4_journal_get_write_access(handle, bh);
3062                if (err)
3063                        goto unlock;
3064        }
3065
3066        zero_user(page, offset, length);
3067
3068        BUFFER_TRACE(bh, "zeroed end of block");
3069
3070        err = 0;
3071        if (ext4_should_journal_data(inode)) {
3072                err = ext4_handle_dirty_metadata(handle, inode, bh);
3073        } else {
3074                if (ext4_should_order_data(inode) && EXT4_I(inode)->jinode)
3075                        err = ext4_jbd2_file_inode(handle, inode);
3076                mark_buffer_dirty(bh);
3077        }
3078
3079unlock:
3080        unlock_page(page);
3081        page_cache_release(page);
3082        return err;
3083}
3084
3085int ext4_can_truncate(struct inode *inode)
3086{
3087        if (S_ISREG(inode->i_mode))
3088                return 1;
3089        if (S_ISDIR(inode->i_mode))
3090                return 1;
3091        if (S_ISLNK(inode->i_mode))
3092                return !ext4_inode_is_fast_symlink(inode);
3093        return 0;
3094}
3095
3096/*
3097 * ext4_punch_hole: punches a hole in a file by releaseing the blocks
3098 * associated with the given offset and length
3099 *
3100 * @inode:  File inode
3101 * @offset: The offset where the hole will begin
3102 * @len:    The length of the hole
3103 *
3104 * Returns: 0 on sucess or negative on failure
3105 */
3106
3107int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
3108{
3109        struct inode *inode = file->f_path.dentry->d_inode;
3110        if (!S_ISREG(inode->i_mode))
3111                return -ENOTSUPP;
3112
3113        if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
3114                /* TODO: Add support for non extent hole punching */
3115                return -ENOTSUPP;
3116        }
3117
3118        return ext4_ext_punch_hole(file, offset, length);
3119}
3120
3121/*
3122 * ext4_truncate()
3123 *
3124 * We block out ext4_get_block() block instantiations across the entire
3125 * transaction, and VFS/VM ensures that ext4_truncate() cannot run
3126 * simultaneously on behalf of the same inode.
3127 *
3128 * As we work through the truncate and commmit bits of it to the journal there
3129 * is one core, guiding principle: the file's tree must always be consistent on
3130 * disk.  We must be able to restart the truncate after a crash.
3131 *
3132 * The file's tree may be transiently inconsistent in memory (although it
3133 * probably isn't), but whenever we close off and commit a journal transaction,
3134 * the contents of (the filesystem + the journal) must be consistent and
3135 * restartable.  It's pretty simple, really: bottom up, right to left (although
3136 * left-to-right works OK too).
3137 *
3138 * Note that at recovery time, journal replay occurs *before* the restart of
3139 * truncate against the orphan inode list.
3140 *
3141 * The committed inode has the new, desired i_size (which is the same as
3142 * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
3143 * that this inode's truncate did not complete and it will again call
3144 * ext4_truncate() to have another go.  So there will be instantiated blocks
3145 * to the right of the truncation point in a crashed ext4 filesystem.  But
3146 * that's fine - as long as they are linked from the inode, the post-crash
3147 * ext4_truncate() run will find them and release them.
3148 */
3149void ext4_truncate(struct inode *inode)
3150{
3151        trace_ext4_truncate_enter(inode);
3152
3153        if (!ext4_can_truncate(inode))
3154                return;
3155
3156        ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
3157
3158        if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
3159                ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
3160
3161        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3162                ext4_ext_truncate(inode);
3163        else
3164                ext4_ind_truncate(inode);
3165
3166        trace_ext4_truncate_exit(inode);
3167}
3168
3169/*
3170 * ext4_get_inode_loc returns with an extra refcount against the inode's
3171 * underlying buffer_head on success. If 'in_mem' is true, we have all
3172 * data in memory that is needed to recreate the on-disk version of this
3173 * inode.
3174 */
3175static int __ext4_get_inode_loc(struct inode *inode,
3176                                struct ext4_iloc *iloc, int in_mem)
3177{
3178        struct ext4_group_desc  *gdp;
3179        struct buffer_head      *bh;
3180        struct super_block      *sb = inode->i_sb;
3181        ext4_fsblk_t            block;
3182        int                     inodes_per_block, inode_offset;
3183
3184        iloc->bh = NULL;
3185        if (!ext4_valid_inum(sb, inode->i_ino))
3186                return -EIO;
3187
3188        iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
3189        gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
3190        if (!gdp)
3191                return -EIO;
3192
3193        /*
3194         * Figure out the offset within the block group inode table
3195         */
3196        inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
3197        inode_offset = ((inode->i_ino - 1) %
3198                        EXT4_INODES_PER_GROUP(sb));
3199        block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
3200        iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
3201
3202        bh = sb_getblk(sb, block);
3203        if (!bh) {
3204                EXT4_ERROR_INODE_BLOCK(inode, block,
3205                                       "unable to read itable block");
3206                return -EIO;
3207        }
3208        if (!buffer_uptodate(bh)) {
3209                lock_buffer(bh);
3210
3211                /*
3212                 * If the buffer has the write error flag, we have failed
3213                 * to write out another inode in the same block.  In this
3214                 * case, we don't have to read the block because we may
3215                 * read the old inode data successfully.
3216                 */
3217                if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
3218                        set_buffer_uptodate(bh);
3219
3220                if (buffer_uptodate(bh)) {
3221                        /* someone brought it uptodate while we waited */
3222                        unlock_buffer(bh);
3223                        goto has_buffer;
3224                }
3225
3226                /*
3227                 * If we have all information of the inode in memory and this
3228                 * is the only valid inode in the block, we need not read the
3229                 * block.
3230                 */
3231                if (in_mem) {
3232                        struct buffer_head *bitmap_bh;
3233                        int i, start;
3234
3235                        start = inode_offset & ~(inodes_per_block - 1);
3236
3237                        /* Is the inode bitmap in cache? */
3238                        bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
3239                        if (!bitmap_bh)
3240                                goto make_io;
3241
3242                        /*
3243                         * If the inode bitmap isn't in cache then the
3244                         * optimisation may end up performing two reads instead
3245                         * of one, so skip it.
3246                         */
3247                        if (!buffer_uptodate(bitmap_bh)) {
3248                                brelse(bitmap_bh);
3249                                goto make_io;
3250                        }
3251                        for (i = start; i < start + inodes_per_block; i++) {
3252                                if (i == inode_offset)
3253                                        continue;
3254                                if (ext4_test_bit(i, bitmap_bh->b_data))
3255                                        break;
3256                        }
3257                        brelse(bitmap_bh);
3258                        if (i == start + inodes_per_block) {
3259                                /* all other inodes are free, so skip I/O */
3260                                memset(bh->b_data, 0, bh->b_size);
3261                                set_buffer_uptodate(bh);
3262                                unlock_buffer(bh);
3263                                goto has_buffer;
3264                        }
3265                }
3266
3267make_io:
3268                /*
3269                 * If we need to do any I/O, try to pre-readahead extra
3270                 * blocks from the inode table.
3271                 */
3272                if (EXT4_SB(sb)->s_inode_readahead_blks) {
3273                        ext4_fsblk_t b, end, table;
3274                        unsigned num;
3275
3276                        table = ext4_inode_table(sb, gdp);
3277                        /* s_inode_readahead_blks is always a power of 2 */
3278                        b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1);
3279                        if (table > b)
3280                                b = table;
3281                        end = b + EXT4_SB(sb)->s_inode_readahead_blks;
3282                        num = EXT4_INODES_PER_GROUP(sb);
3283                        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
3284                                       EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
3285                                num -= ext4_itable_unused_count(sb, gdp);
3286                        table += num / inodes_per_block;
3287                        if (end > table)
3288                                end = table;
3289                        while (b <= end)
3290                                sb_breadahead(sb, b++);
3291                }
3292
3293                /*
3294                 * There are other valid inodes in the buffer, this inode
3295                 * has in-inode xattrs, or we don't have this inode in memory.
3296                 * Read the block from disk.
3297                 */
3298                trace_ext4_load_inode(inode);
3299                get_bh(bh);
3300                bh->b_end_io = end_buffer_read_sync;
3301                submit_bh(READ | REQ_META | REQ_PRIO, bh);
3302                wait_on_buffer(bh);
3303                if (!buffer_uptodate(bh)) {
3304                        EXT4_ERROR_INODE_BLOCK(inode, block,
3305                                               "unable to read itable block");
3306                        brelse(bh);
3307                        return -EIO;
3308                }
3309        }
3310has_buffer:
3311        iloc->bh = bh;
3312        return 0;
3313}
3314
3315int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
3316{
3317        /* We have all inode data except xattrs in memory here. */
3318        return __ext4_get_inode_loc(inode, iloc,
3319                !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
3320}
3321
3322void ext4_set_inode_flags(struct inode *inode)
3323{
3324        unsigned int flags = EXT4_I(inode)->i_flags;
3325
3326        inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
3327        if (flags & EXT4_SYNC_FL)
3328                inode->i_flags |= S_SYNC;
3329        if (flags & EXT4_APPEND_FL)
3330                inode->i_flags |= S_APPEND;
3331        if (flags & EXT4_IMMUTABLE_FL)
3332                inode->i_flags |= S_IMMUTABLE;
3333        if (flags & EXT4_NOATIME_FL)
3334                inode->i_flags |= S_NOATIME;
3335        if (flags & EXT4_DIRSYNC_FL)
3336                inode->i_flags |= S_DIRSYNC;
3337}
3338
3339/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
3340void ext4_get_inode_flags(struct ext4_inode_info *ei)
3341{
3342        unsigned int vfs_fl;
3343        unsigned long old_fl, new_fl;
3344
3345        do {
3346                vfs_fl = ei->vfs_inode.i_flags;
3347                old_fl = ei->i_flags;
3348                new_fl = old_fl & ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
3349                                EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|
3350                                EXT4_DIRSYNC_FL);
3351                if (vfs_fl & S_SYNC)
3352                        new_fl |= EXT4_SYNC_FL;
3353                if (vfs_fl & S_APPEND)
3354                        new_fl |= EXT4_APPEND_FL;
3355                if (vfs_fl & S_IMMUTABLE)
3356                        new_fl |= EXT4_IMMUTABLE_FL;
3357                if (vfs_fl & S_NOATIME)
3358                        new_fl |= EXT4_NOATIME_FL;
3359                if (vfs_fl & S_DIRSYNC)
3360                        new_fl |= EXT4_DIRSYNC_FL;
3361        } while (cmpxchg(&ei->i_flags, old_fl, new_fl) != old_fl);
3362}
3363
3364static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
3365                                  struct ext4_inode_info *ei)
3366{
3367        blkcnt_t i_blocks ;
3368        struct inode *inode = &(ei->vfs_inode);
3369        struct super_block *sb = inode->i_sb;
3370
3371        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
3372                                EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
3373                /* we are using combined 48 bit field */
3374                i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
3375                                        le32_to_cpu(raw_inode->i_blocks_lo);
3376                if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
3377                        /* i_blocks represent file system block size */
3378                        return i_blocks  << (inode->i_blkbits - 9);
3379                } else {
3380                        return i_blocks;
3381                }
3382        } else {
3383                return le32_to_cpu(raw_inode->i_blocks_lo);
3384        }
3385}
3386
3387struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
3388{
3389        struct ext4_iloc iloc;
3390        struct ext4_inode *raw_inode;
3391        struct ext4_inode_info *ei;
3392        struct inode *inode;
3393        journal_t *journal = EXT4_SB(sb)->s_journal;
3394        long ret;
3395        int block;
3396
3397        inode = iget_locked(sb, ino);
3398        if (!inode)
3399                return ERR_PTR(-ENOMEM);
3400        if (!(inode->i_state & I_NEW))
3401                return inode;
3402
3403        ei = EXT4_I(inode);
3404        iloc.bh = NULL;
3405
3406        ret = __ext4_get_inode_loc(inode, &iloc, 0);
3407        if (ret < 0)
3408                goto bad_inode;
3409        raw_inode = ext4_raw_inode(&iloc);
3410        inode->i_mode = le16_to_cpu(raw_inode->i_mode);
3411        inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
3412        inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
3413        if (!(test_opt(inode->i_sb, NO_UID32))) {
3414                inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
3415                inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
3416        }
3417        inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
3418
3419        ext4_clear_state_flags(ei);     /* Only relevant on 32-bit archs */
3420        ei->i_dir_start_lookup = 0;
3421        ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
3422        /* We now have enough fields to check if the inode was active or not.
3423         * This is needed because nfsd might try to access dead inodes
3424         * the test is that same one that e2fsck uses
3425         * NeilBrown 1999oct15
3426         */
3427        if (inode->i_nlink == 0) {
3428                if (inode->i_mode == 0 ||
3429                    !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
3430                        /* this inode is deleted */
3431                        ret = -ESTALE;
3432                        goto bad_inode;
3433                }
3434                /* The only unlinked inodes we let through here have
3435                 * valid i_mode and are being read by the orphan
3436                 * recovery code: that's fine, we're about to complete
3437                 * the process of deleting those. */
3438        }
3439        ei->i_flags = le32_to_cpu(raw_inode->i_flags);
3440        inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
3441        ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
3442        if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT))
3443                ei->i_file_acl |=
3444                        ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
3445        inode->i_size = ext4_isize(raw_inode);
3446        ei->i_disksize = inode->i_size;
3447#ifdef CONFIG_QUOTA
3448        ei->i_reserved_quota = 0;
3449#endif
3450        inode->i_generation = le32_to_cpu(raw_inode->i_generation);
3451        ei->i_block_group = iloc.block_group;
3452        ei->i_last_alloc_group = ~0;
3453        /*
3454         * NOTE! The in-memory inode i_data array is in little-endian order
3455         * even on big-endian machines: we do NOT byteswap the block numbers!
3456         */
3457        for (block = 0; block < EXT4_N_BLOCKS; block++)
3458                ei->i_data[block] = raw_inode->i_block[block];
3459        INIT_LIST_HEAD(&ei->i_orphan);
3460
3461        /*
3462         * Set transaction id's of transactions that have to be committed
3463         * to finish f[data]sync. We set them to currently running transaction
3464         * as we cannot be sure that the inode or some of its metadata isn't
3465         * part of the transaction - the inode could have been reclaimed and
3466         * now it is reread from disk.
3467         */
3468        if (journal) {
3469                transaction_t *transaction;
3470                tid_t tid;
3471
3472                read_lock(&journal->j_state_lock);
3473                if (journal->j_running_transaction)
3474                        transaction = journal->j_running_transaction;
3475                else
3476                        transaction = journal->j_committing_transaction;
3477                if (transaction)
3478                        tid = transaction->t_tid;
3479                else
3480                        tid = journal->j_commit_sequence;
3481                read_unlock(&journal->j_state_lock);
3482                ei->i_sync_tid = tid;
3483                ei->i_datasync_tid = tid;
3484        }
3485
3486        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
3487                ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
3488                if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
3489                    EXT4_INODE_SIZE(inode->i_sb)) {
3490                        ret = -EIO;
3491                        goto bad_inode;
3492                }
3493                if (ei->i_extra_isize == 0) {
3494                        /* The extra space is currently unused. Use it. */
3495                        ei->i_extra_isize = sizeof(struct ext4_inode) -
3496                                            EXT4_GOOD_OLD_INODE_SIZE;
3497                } else {
3498                        __le32 *magic = (void *)raw_inode +
3499                                        EXT4_GOOD_OLD_INODE_SIZE +
3500                                        ei->i_extra_isize;
3501                        if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
3502                                ext4_set_inode_state(inode, EXT4_STATE_XATTR);
3503                }
3504        } else
3505                ei->i_extra_isize = 0;
3506
3507        EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
3508        EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
3509        EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
3510        EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
3511
3512        inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
3513        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
3514                if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
3515                        inode->i_version |=
3516                        (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
3517        }
3518
3519        ret = 0;
3520        if (ei->i_file_acl &&
3521            !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
3522                EXT4_ERROR_INODE(inode, "bad extended attribute block %llu",
3523                                 ei->i_file_acl);
3524                ret = -EIO;
3525                goto bad_inode;
3526        } else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
3527                if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
3528                    (S_ISLNK(inode->i_mode) &&
3529                     !ext4_inode_is_fast_symlink(inode)))
3530                        /* Validate extent which is part of inode */
3531                        ret = ext4_ext_check_inode(inode);
3532        } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
3533                   (S_ISLNK(inode->i_mode) &&
3534                    !ext4_inode_is_fast_symlink(inode))) {
3535                /* Validate block references which are part of inode */
3536                ret = ext4_ind_check_inode(inode);
3537        }
3538        if (ret)
3539                goto bad_inode;
3540
3541        if (S_ISREG(inode->i_mode)) {
3542                inode->i_op = &ext4_file_inode_operations;
3543                inode->i_fop = &ext4_file_operations;
3544                ext4_set_aops(inode);
3545        } else if (S_ISDIR(inode->i_mode)) {
3546                inode->i_op = &ext4_dir_inode_operations;
3547                inode->i_fop = &ext4_dir_operations;
3548        } else if (S_ISLNK(inode->i_mode)) {
3549                if (ext4_inode_is_fast_symlink(inode)) {
3550                        inode->i_op = &ext4_fast_symlink_inode_operations;
3551                        nd_terminate_link(ei->i_data, inode->i_size,
3552                                sizeof(ei->i_data) - 1);
3553                } else {
3554                        inode->i_op = &ext4_symlink_inode_operations;
3555                        ext4_set_aops(inode);
3556                }
3557        } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
3558              S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
3559                inode->i_op = &ext4_special_inode_operations;
3560                if (raw_inode->i_block[0])
3561                        init_special_inode(inode, inode->i_mode,
3562                           old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
3563                else
3564                        init_special_inode(inode, inode->i_mode,
3565                           new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
3566        } else {
3567                ret = -EIO;
3568                EXT4_ERROR_INODE(inode, "bogus i_mode (%o)", inode->i_mode);
3569                goto bad_inode;
3570        }
3571        brelse(iloc.bh);
3572        ext4_set_inode_flags(inode);
3573        unlock_new_inode(inode);
3574        return inode;
3575
3576bad_inode:
3577        brelse(iloc.bh);
3578        iget_failed(inode);
3579        return ERR_PTR(ret);
3580}
3581
3582static int ext4_inode_blocks_set(handle_t *handle,
3583                                struct ext4_inode *raw_inode,
3584                                struct ext4_inode_info *ei)
3585{
3586        struct inode *inode = &(ei->vfs_inode);
3587        u64 i_blocks = inode->i_blocks;
3588        struct super_block *sb = inode->i_sb;
3589
3590        if (i_blocks <= ~0U) {
3591                /*
3592                 * i_blocks can be represnted in a 32 bit variable
3593                 * as multiple of 512 bytes
3594                 */
3595                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
3596                raw_inode->i_blocks_high = 0;
3597                ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
3598                return 0;
3599        }
3600        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE))
3601                return -EFBIG;
3602
3603        if (i_blocks <= 0xffffffffffffULL) {
3604                /*
3605                 * i_blocks can be represented in a 48 bit variable
3606                 * as multiple of 512 bytes
3607                 */
3608                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
3609                raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
3610                ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
3611        } else {
3612                ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
3613                /* i_block is stored in file system block size */
3614                i_blocks = i_blocks >> (inode->i_blkbits - 9);
3615                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
3616                raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
3617        }
3618        return 0;
3619}
3620
3621/*
3622 * Post the struct inode info into an on-disk inode location in the
3623 * buffer-cache.  This gobbles the caller's reference to the
3624 * buffer_head in the inode location struct.
3625 *
3626 * The caller must have write access to iloc->bh.
3627 */
3628static int ext4_do_update_inode(handle_t *handle,
3629                                struct inode *inode,
3630                                struct ext4_iloc *iloc)
3631{
3632        struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
3633        struct ext4_inode_info *ei = EXT4_I(inode);
3634        struct buffer_head *bh = iloc->bh;
3635        int err = 0, rc, block;
3636
3637        /* For fields not not tracking in the in-memory inode,
3638         * initialise them to zero for new inodes. */
3639        if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
3640                memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
3641
3642        ext4_get_inode_flags(ei);
3643        raw_inode->i_mode = cpu_to_le16(inode->i_mode);
3644        if (!(test_opt(inode->i_sb, NO_UID32))) {
3645                raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
3646                raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
3647/*
3648 * Fix up interoperability with old kernels. Otherwise, old inodes get
3649 * re-used with the upper 16 bits of the uid/gid intact
3650 */
3651                if (!ei->i_dtime) {
3652                        raw_inode->i_uid_high =
3653                                cpu_to_le16(high_16_bits(inode->i_uid));
3654                        raw_inode->i_gid_high =
3655                                cpu_to_le16(high_16_bits(inode->i_gid));
3656                } else {
3657                        raw_inode->i_uid_high = 0;
3658                        raw_inode->i_gid_high = 0;
3659                }
3660        } else {
3661                raw_inode->i_uid_low =
3662                        cpu_to_le16(fs_high2lowuid(inode->i_uid));
3663                raw_inode->i_gid_low =
3664                        cpu_to_le16(fs_high2lowgid(inode->i_gid));
3665                raw_inode->i_uid_high = 0;
3666                raw_inode->i_gid_high = 0;
3667        }
3668        raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
3669
3670        EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
3671        EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
3672        EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
3673        EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
3674
3675        if (ext4_inode_blocks_set(handle, raw_inode, ei))
3676                goto out_brelse;
3677        raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
3678        raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
3679        if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
3680            cpu_to_le32(EXT4_OS_HURD))
3681                raw_inode->i_file_acl_high =
3682                        cpu_to_le16(ei->i_file_acl >> 32);
3683        raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
3684        ext4_isize_set(raw_inode, ei->i_disksize);
3685        if (ei->i_disksize > 0x7fffffffULL) {
3686                struct super_block *sb = inode->i_sb;
3687                if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
3688                                EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
3689                                EXT4_SB(sb)->s_es->s_rev_level ==
3690                                cpu_to_le32(EXT4_GOOD_OLD_REV)) {
3691                        /* If this is the first large file
3692                         * created, add a flag to the superblock.
3693                         */
3694                        err = ext4_journal_get_write_access(handle,
3695                                        EXT4_SB(sb)->s_sbh);
3696                        if (err)
3697                                goto out_brelse;
3698                        ext4_update_dynamic_rev(sb);
3699                        EXT4_SET_RO_COMPAT_FEATURE(sb,
3700                                        EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
3701                        sb->s_dirt = 1;
3702                        ext4_handle_sync(handle);
3703                        err = ext4_handle_dirty_metadata(handle, NULL,
3704                                        EXT4_SB(sb)->s_sbh);
3705                }
3706        }
3707        raw_inode->i_generation = cpu_to_le32(inode->i_generation);
3708        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
3709                if (old_valid_dev(inode->i_rdev)) {
3710                        raw_inode->i_block[0] =
3711                                cpu_to_le32(old_encode_dev(inode->i_rdev));
3712                        raw_inode->i_block[1] = 0;
3713                } else {
3714                        raw_inode->i_block[0] = 0;
3715                        raw_inode->i_block[1] =
3716                                cpu_to_le32(new_encode_dev(inode->i_rdev));
3717                        raw_inode->i_block[2] = 0;
3718                }
3719        } else
3720                for (block = 0; block < EXT4_N_BLOCKS; block++)
3721                        raw_inode->i_block[block] = ei->i_data[block];
3722
3723        raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
3724        if (ei->i_extra_isize) {
3725                if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
3726                        raw_inode->i_version_hi =
3727                        cpu_to_le32(inode->i_version >> 32);
3728                raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
3729        }
3730
3731        BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
3732        rc = ext4_handle_dirty_metadata(handle, NULL, bh);
3733        if (!err)
3734                err = rc;
3735        ext4_clear_inode_state(inode, EXT4_STATE_NEW);
3736
3737        ext4_update_inode_fsync_trans(handle, inode, 0);
3738out_brelse:
3739        brelse(bh);
3740        ext4_std_error(inode->i_sb, err);
3741        return err;
3742}
3743
3744/*
3745 * ext4_write_inode()
3746 *
3747 * We are called from a few places:
3748 *
3749 * - Within generic_file_write() for O_SYNC files.
3750 *   Here, there will be no transaction running. We wait for any running
3751 *   trasnaction to commit.
3752 *
3753 * - Within sys_sync(), kupdate and such.
3754 *   We wait on commit, if tol to.
3755 *
3756 * - Within prune_icache() (PF_MEMALLOC == true)
3757 *   Here we simply return.  We can't afford to block kswapd on the
3758 *   journal commit.
3759 *
3760 * In all cases it is actually safe for us to return without doing anything,
3761 * because the inode has been copied into a raw inode buffer in
3762 * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
3763 * knfsd.
3764 *
3765 * Note that we are absolutely dependent upon all inode dirtiers doing the
3766 * right thing: they *must* call mark_inode_dirty() after dirtying info in
3767 * which we are interested.
3768 *
3769 * It would be a bug for them to not do this.  The code:
3770 *
3771 *      mark_inode_dirty(inode)
3772 *      stuff();
3773 *      inode->i_size = expr;
3774 *
3775 * is in error because a kswapd-driven write_inode() could occur while
3776 * `stuff()' is running, and the new i_size will be lost.  Plus the inode
3777 * will no longer be on the superblock's dirty inode list.
3778 */
3779int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
3780{
3781        int err;
3782
3783        if (current->flags & PF_MEMALLOC)
3784                return 0;
3785
3786        if (EXT4_SB(inode->i_sb)->s_journal) {
3787                if (ext4_journal_current_handle()) {
3788                        jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
3789                        dump_stack();
3790                        return -EIO;
3791                }
3792
3793                if (wbc->sync_mode != WB_SYNC_ALL)
3794                        return 0;
3795
3796                err = ext4_force_commit(inode->i_sb);
3797        } else {
3798                struct ext4_iloc iloc;
3799
3800                err = __ext4_get_inode_loc(inode, &iloc, 0);
3801                if (err)
3802                        return err;
3803                if (wbc->sync_mode == WB_SYNC_ALL)
3804                        sync_dirty_buffer(iloc.bh);
3805                if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
3806                        EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
3807                                         "IO error syncing inode");
3808                        err = -EIO;
3809                }
3810                brelse(iloc.bh);
3811        }
3812        return err;
3813}
3814
3815/*
3816 * ext4_setattr()
3817 *
3818 * Called from notify_change.
3819 *
3820 * We want to trap VFS attempts to truncate the file as soon as
3821 * possible.  In particular, we want to make sure that when the VFS
3822 * shrinks i_size, we put the inode on the orphan list and modify
3823 * i_disksize immediately, so that during the subsequent flushing of
3824 * dirty pages and freeing of disk blocks, we can guarantee that any
3825 * commit will leave the blocks being flushed in an unused state on
3826 * disk.  (On recovery, the inode will get truncated and the blocks will
3827 * be freed, so we have a strong guarantee that no future commit will
3828 * leave these blocks visible to the user.)
3829 *
3830 * Another thing we have to assure is that if we are in ordered mode
3831 * and inode is still attached to the committing transaction, we must
3832 * we start writeout of all the dirty pages which are being truncated.
3833 * This way we are sure that all the data written in the previous
3834 * transaction are already on disk (truncate waits for pages under
3835 * writeback).
3836 *
3837 * Called with inode->i_mutex down.
3838 */
3839int ext4_setattr(struct dentry *dentry, struct iattr *attr)
3840{
3841        struct inode *inode = dentry->d_inode;
3842        int error, rc = 0;
3843        int orphan = 0;
3844        const unsigned int ia_valid = attr->ia_valid;
3845
3846        error = inode_change_ok(inode, attr);
3847        if (error)
3848                return error;
3849
3850        if (is_quota_modification(inode, attr))
3851                dquot_initialize(inode);
3852        if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
3853                (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
3854                handle_t *handle;
3855
3856                /* (user+group)*(old+new) structure, inode write (sb,
3857                 * inode block, ? - but truncate inode update has it) */
3858                handle = ext4_journal_start(inode, (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)+
3859                                        EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb))+3);
3860                if (IS_ERR(handle)) {
3861                        error = PTR_ERR(handle);
3862                        goto err_out;
3863                }
3864                error = dquot_transfer(inode, attr);
3865                if (error) {
3866                        ext4_journal_stop(handle);
3867                        return error;
3868                }
3869                /* Update corresponding info in inode so that everything is in
3870                 * one transaction */
3871                if (attr->ia_valid & ATTR_UID)
3872                        inode->i_uid = attr->ia_uid;
3873                if (attr->ia_valid & ATTR_GID)
3874                        inode->i_gid = attr->ia_gid;
3875                error = ext4_mark_inode_dirty(handle, inode);
3876                ext4_journal_stop(handle);
3877        }
3878
3879        if (attr->ia_valid & ATTR_SIZE) {
3880                inode_dio_wait(inode);
3881
3882                if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
3883                        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3884
3885                        if (attr->ia_size > sbi->s_bitmap_maxbytes)
3886                                return -EFBIG;
3887                }
3888        }
3889
3890        if (S_ISREG(inode->i_mode) &&
3891            attr->ia_valid & ATTR_SIZE &&
3892            (attr->ia_size < inode->i_size)) {
3893                handle_t *handle;
3894
3895                handle = ext4_journal_start(inode, 3);
3896                if (IS_ERR(handle)) {
3897                        error = PTR_ERR(handle);
3898                        goto err_out;
3899                }
3900                if (ext4_handle_valid(handle)) {
3901                        error = ext4_orphan_add(handle, inode);
3902                        orphan = 1;
3903                }
3904                EXT4_I(inode)->i_disksize = attr->ia_size;
3905                rc = ext4_mark_inode_dirty(handle, inode);
3906                if (!error)
3907                        error = rc;
3908                ext4_journal_stop(handle);
3909
3910                if (ext4_should_order_data(inode)) {
3911                        error = ext4_begin_ordered_truncate(inode,
3912                                                            attr->ia_size);
3913                        if (error) {
3914                                /* Do as much error cleanup as possible */
3915                                handle = ext4_journal_start(inode, 3);
3916                                if (IS_ERR(handle)) {
3917                                        ext4_orphan_del(NULL, inode);
3918                                        goto err_out;
3919                                }
3920                                ext4_orphan_del(handle, inode);
3921                                orphan = 0;
3922                                ext4_journal_stop(handle);
3923                                goto err_out;
3924                        }
3925                }
3926        }
3927
3928        if (attr->ia_valid & ATTR_SIZE) {
3929                if (attr->ia_size != i_size_read(inode)) {
3930                        truncate_setsize(inode, attr->ia_size);
3931                        ext4_truncate(inode);
3932                } else if (ext4_test_inode_flag(inode, EXT4_INODE_EOFBLOCKS))
3933                        ext4_truncate(inode);
3934        }
3935
3936        if (!rc) {
3937                setattr_copy(inode, attr);
3938                mark_inode_dirty(inode);
3939        }
3940
3941        /*
3942         * If the call to ext4_truncate failed to get a transaction handle at
3943         * all, we need to clean up the in-core orphan list manually.
3944         */
3945        if (orphan && inode->i_nlink)
3946                ext4_orphan_del(NULL, inode);
3947
3948        if (!rc && (ia_valid & ATTR_MODE))
3949                rc = ext4_acl_chmod(inode);
3950
3951err_out:
3952        ext4_std_error(inode->i_sb, error);
3953        if (!error)
3954                error = rc;
3955        return error;
3956}
3957
3958int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
3959                 struct kstat *stat)
3960{
3961        struct inode *inode;
3962        unsigned long delalloc_blocks;
3963
3964        inode = dentry->d_inode;
3965        generic_fillattr(inode, stat);
3966
3967        /*
3968         * We can't update i_blocks if the block allocation is delayed
3969         * otherwise in the case of system crash before the real block
3970         * allocation is done, we will have i_blocks inconsistent with
3971         * on-disk file blocks.
3972         * We always keep i_blocks updated together with real
3973         * allocation. But to not confuse with user, stat
3974         * will return the blocks that include the delayed allocation
3975         * blocks for this file.
3976         */
3977        delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks;
3978
3979        stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
3980        return 0;
3981}
3982
3983static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
3984{
3985        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
3986                return ext4_ind_trans_blocks(inode, nrblocks, chunk);
3987        return ext4_ext_index_trans_blocks(inode, nrblocks, chunk);
3988}
3989
3990/*
3991 * Account for index blocks, block groups bitmaps and block group
3992 * descriptor blocks if modify datablocks and index blocks
3993 * worse case, the indexs blocks spread over different block groups
3994 *
3995 * If datablocks are discontiguous, they are possible to spread over
3996 * different block groups too. If they are contiuguous, with flexbg,
3997 * they could still across block group boundary.
3998 *
3999 * Also account for superblock, inode, quota and xattr blocks
4000 */
4001static int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
4002{
4003        ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
4004        int gdpblocks;
4005        int idxblocks;
4006        int ret = 0;
4007
4008        /*
4009         * How many index blocks need to touch to modify nrblocks?
4010         * The "Chunk" flag indicating whether the nrblocks is
4011         * physically contiguous on disk
4012         *
4013         * For Direct IO and fallocate, they calls get_block to allocate
4014         * one single extent at a time, so they could set the "Chunk" flag
4015         */
4016        idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk);
4017
4018        ret = idxblocks;
4019
4020        /*
4021         * Now let's see how many group bitmaps and group descriptors need
4022         * to account
4023         */
4024        groups = idxblocks;
4025        if (chunk)
4026                groups += 1;
4027        else
4028                groups += nrblocks;
4029
4030        gdpblocks = groups;
4031        if (groups > ngroups)
4032                groups = ngroups;
4033        if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
4034                gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
4035
4036        /* bitmaps and block group descriptor blocks */
4037        ret += groups + gdpblocks;
4038
4039        /* Blocks for super block, inode, quota and xattr blocks */
4040        ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
4041
4042        return ret;
4043}
4044
4045/*
4046 * Calculate the total number of credits to reserve to fit
4047 * the modification of a single pages into a single transaction,
4048 * which may include multiple chunks of block allocations.
4049 *
4050 * This could be called via ext4_write_begin()
4051 *
4052 * We need to consider the worse case, when
4053 * one new block per extent.
4054 */
4055int ext4_writepage_trans_blocks(struct inode *inode)
4056{
4057        int bpp = ext4_journal_blocks_per_page(inode);
4058        int ret;
4059
4060        ret = ext4_meta_trans_blocks(inode, bpp, 0);
4061
4062        /* Account for data blocks for journalled mode */
4063        if (ext4_should_journal_data(inode))
4064                ret += bpp;
4065        return ret;
4066}
4067
4068/*
4069 * Calculate the journal credits for a chunk of data modification.
4070 *
4071 * This is called from DIO, fallocate or whoever calling
4072 * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
4073 *
4074 * journal buffers for data blocks are not included here, as DIO
4075 * and fallocate do no need to journal data buffers.
4076 */
4077int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
4078{
4079        return ext4_meta_trans_blocks(inode, nrblocks, 1);
4080}
4081
4082/*
4083 * The caller must have previously called ext4_reserve_inode_write().
4084 * Give this, we know that the caller already has write access to iloc->bh.
4085 */
4086int ext4_mark_iloc_dirty(handle_t *handle,
4087                         struct inode *inode, struct ext4_iloc *iloc)
4088{
4089        int err = 0;
4090
4091        if (test_opt(inode->i_sb, I_VERSION))
4092                inode_inc_iversion(inode);
4093
4094        /* the do_update_inode consumes one bh->b_count */
4095        get_bh(iloc->bh);
4096
4097        /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
4098        err = ext4_do_update_inode(handle, inode, iloc);
4099        put_bh(iloc->bh);
4100        return err;
4101}
4102
4103/*
4104 * On success, We end up with an outstanding reference count against
4105 * iloc->bh.  This _must_ be cleaned up later.
4106 */
4107
4108int
4109ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
4110                         struct ext4_iloc *iloc)
4111{
4112        int err;
4113
4114        err = ext4_get_inode_loc(inode, iloc);
4115        if (!err) {
4116                BUFFER_TRACE(iloc->bh, "get_write_access");
4117                err = ext4_journal_get_write_access(handle, iloc->bh);
4118                if (err) {
4119                        brelse(iloc->bh);
4120                        iloc->bh = NULL;
4121                }
4122        }
4123        ext4_std_error(inode->i_sb, err);
4124        return err;
4125}
4126
4127/*
4128 * Expand an inode by new_extra_isize bytes.
4129 * Returns 0 on success or negative error number on failure.
4130 */
4131static int ext4_expand_extra_isize(struct inode *inode,
4132                                   unsigned int new_extra_isize,
4133                                   struct ext4_iloc iloc,
4134                                   handle_t *handle)
4135{
4136        struct ext4_inode *raw_inode;
4137        struct ext4_xattr_ibody_header *header;
4138
4139        if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
4140                return 0;
4141
4142        raw_inode = ext4_raw_inode(&iloc);
4143
4144        header = IHDR(inode, raw_inode);
4145
4146        /* No extended attributes present */
4147        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
4148            header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
4149                memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
4150                        new_extra_isize);
4151                EXT4_I(inode)->i_extra_isize = new_extra_isize;
4152                return 0;
4153        }
4154
4155        /* try to expand with EAs present */
4156        return ext4_expand_extra_isize_ea(inode, new_extra_isize,
4157                                          raw_inode, handle);
4158}
4159
4160/*
4161 * What we do here is to mark the in-core inode as clean with respect to inode
4162 * dirtiness (it may still be data-dirty).
4163 * This means that the in-core inode may be reaped by prune_icache
4164 * without having to perform any I/O.  This is a very good thing,
4165 * because *any* task may call prune_icache - even ones which
4166 * have a transaction open against a different journal.
4167 *
4168 * Is this cheating?  Not really.  Sure, we haven't written the
4169 * inode out, but prune_icache isn't a user-visible syncing function.
4170 * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
4171 * we start and wait on commits.
4172 *
4173 * Is this efficient/effective?  Well, we're being nice to the system
4174 * by cleaning up our inodes proactively so they can be reaped
4175 * without I/O.  But we are potentially leaving up to five seconds'
4176 * worth of inodes floating about which prune_icache wants us to
4177 * write out.  One way to fix that would be to get prune_icache()
4178 * to do a write_super() to free up some memory.  It has the desired
4179 * effect.
4180 */
4181int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
4182{
4183        struct ext4_iloc iloc;
4184        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4185        static unsigned int mnt_count;
4186        int err, ret;
4187
4188        might_sleep();
4189        trace_ext4_mark_inode_dirty(inode, _RET_IP_);
4190        err = ext4_reserve_inode_write(handle, inode, &iloc);
4191        if (ext4_handle_valid(handle) &&
4192            EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
4193            !ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
4194                /*
4195                 * We need extra buffer credits since we may write into EA block
4196                 * with this same handle. If journal_extend fails, then it will
4197                 * only result in a minor loss of functionality for that inode.
4198                 * If this is felt to be critical, then e2fsck should be run to
4199                 * force a large enough s_min_extra_isize.
4200                 */
4201                if ((jbd2_journal_extend(handle,
4202                             EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
4203                        ret = ext4_expand_extra_isize(inode,
4204                                                      sbi->s_want_extra_isize,
4205                                                      iloc, handle);
4206                        if (ret) {
4207                                ext4_set_inode_state(inode,
4208                                                     EXT4_STATE_NO_EXPAND);
4209                                if (mnt_count !=
4210                                        le16_to_cpu(sbi->s_es->s_mnt_count)) {
4211                                        ext4_warning(inode->i_sb,
4212                                        "Unable to expand inode %lu. Delete"
4213                                        " some EAs or run e2fsck.",
4214                                        inode->i_ino);
4215                                        mnt_count =
4216                                          le16_to_cpu(sbi->s_es->s_mnt_count);
4217                                }
4218                        }
4219                }
4220        }
4221        if (!err)
4222                err = ext4_mark_iloc_dirty(handle, inode, &iloc);
4223        return err;
4224}
4225
4226/*
4227 * ext4_dirty_inode() is called from __mark_inode_dirty()
4228 *
4229 * We're really interested in the case where a file is being extended.
4230 * i_size has been changed by generic_commit_write() and we thus need
4231 * to include the updated inode in the current transaction.
4232 *
4233 * Also, dquot_alloc_block() will always dirty the inode when blocks
4234 * are allocated to the file.
4235 *
4236 * If the inode is marked synchronous, we don't honour that here - doing
4237 * so would cause a commit on atime updates, which we don't bother doing.
4238 * We handle synchronous inodes at the highest possible level.
4239 */
4240void ext4_dirty_inode(struct inode *inode, int flags)
4241{
4242        handle_t *handle;
4243
4244        handle = ext4_journal_start(inode, 2);
4245        if (IS_ERR(handle))
4246                goto out;
4247
4248        ext4_mark_inode_dirty(handle, inode);
4249
4250        ext4_journal_stop(handle);
4251out:
4252        return;
4253}
4254
4255#if 0
4256/*
4257 * Bind an inode's backing buffer_head into this transaction, to prevent
4258 * it from being flushed to disk early.  Unlike
4259 * ext4_reserve_inode_write, this leaves behind no bh reference and
4260 * returns no iloc structure, so the caller needs to repeat the iloc
4261 * lookup to mark the inode dirty later.
4262 */
4263static int ext4_pin_inode(handle_t *handle, struct inode *inode)
4264{
4265        struct ext4_iloc iloc;
4266
4267        int err = 0;
4268        if (handle) {
4269                err = ext4_get_inode_loc(inode, &iloc);
4270                if (!err) {
4271                        BUFFER_TRACE(iloc.bh, "get_write_access");
4272                        err = jbd2_journal_get_write_access(handle, iloc.bh);
4273                        if (!err)
4274                                err = ext4_handle_dirty_metadata(handle,
4275                                                                 NULL,
4276                                                                 iloc.bh);
4277                        brelse(iloc.bh);
4278                }
4279        }
4280        ext4_std_error(inode->i_sb, err);
4281        return err;
4282}
4283#endif
4284
4285int ext4_change_inode_journal_flag(struct inode *inode, int val)
4286{
4287        journal_t *journal;
4288        handle_t *handle;
4289        int err;
4290
4291        /*
4292         * We have to be very careful here: changing a data block's
4293         * journaling status dynamically is dangerous.  If we write a
4294         * data block to the journal, change the status and then delete
4295         * that block, we risk forgetting to revoke the old log record
4296         * from the journal and so a subsequent replay can corrupt data.
4297         * So, first we make sure that the journal is empty and that
4298         * nobody is changing anything.
4299         */
4300
4301        journal = EXT4_JOURNAL(inode);
4302        if (!journal)
4303                return 0;
4304        if (is_journal_aborted(journal))
4305                return -EROFS;
4306
4307        jbd2_journal_lock_updates(journal);
4308        jbd2_journal_flush(journal);
4309
4310        /*
4311         * OK, there are no updates running now, and all cached data is
4312         * synced to disk.  We are now in a completely consistent state
4313         * which doesn't have anything in the journal, and we know that
4314         * no filesystem updates are running, so it is safe to modify
4315         * the inode's in-core data-journaling state flag now.
4316         */
4317
4318        if (val)
4319                ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
4320        else
4321                ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
4322        ext4_set_aops(inode);
4323
4324        jbd2_journal_unlock_updates(journal);
4325
4326        /* Finally we can mark the inode as dirty. */
4327
4328        handle = ext4_journal_start(inode, 1);
4329        if (IS_ERR(handle))
4330                return PTR_ERR(handle);
4331
4332        err = ext4_mark_inode_dirty(handle, inode);
4333        ext4_handle_sync(handle);
4334        ext4_journal_stop(handle);
4335        ext4_std_error(inode->i_sb, err);
4336
4337        return err;
4338}
4339
4340static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
4341{
4342        return !buffer_mapped(bh);
4343}
4344
4345int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
4346{
4347        struct page *page = vmf->page;
4348        loff_t size;
4349        unsigned long len;
4350        int ret;
4351        struct file *file = vma->vm_file;
4352        struct inode *inode = file->f_path.dentry->d_inode;
4353        struct address_space *mapping = inode->i_mapping;
4354        handle_t *handle;
4355        get_block_t *get_block;
4356        int retries = 0;
4357
4358        /*
4359         * This check is racy but catches the common case. We rely on
4360         * __block_page_mkwrite() to do a reliable check.
4361         */
4362        vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
4363        /* Delalloc case is easy... */
4364        if (test_opt(inode->i_sb, DELALLOC) &&
4365            !ext4_should_journal_data(inode) &&
4366            !ext4_nonda_switch(inode->i_sb)) {
4367                do {
4368                        ret = __block_page_mkwrite(vma, vmf,
4369                                                   ext4_da_get_block_prep);
4370                } while (ret == -ENOSPC &&
4371                       ext4_should_retry_alloc(inode->i_sb, &retries));
4372                goto out_ret;
4373        }
4374
4375        lock_page(page);
4376        size = i_size_read(inode);
4377        /* Page got truncated from under us? */
4378        if (page->mapping != mapping || page_offset(page) > size) {
4379                unlock_page(page);
4380                ret = VM_FAULT_NOPAGE;
4381                goto out;
4382        }
4383
4384        if (page->index == size >> PAGE_CACHE_SHIFT)
4385                len = size & ~PAGE_CACHE_MASK;
4386        else
4387                len = PAGE_CACHE_SIZE;
4388        /*
4389         * Return if we have all the buffers mapped. This avoids the need to do
4390         * journal_start/journal_stop which can block and take a long time
4391         */
4392        if (page_has_buffers(page)) {
4393                if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
4394                                        ext4_bh_unmapped)) {
4395                        /* Wait so that we don't change page under IO */
4396                        wait_on_page_writeback(page);
4397                        ret = VM_FAULT_LOCKED;
4398                        goto out;
4399                }
4400        }
4401        unlock_page(page);
4402        /* OK, we need to fill the hole... */
4403        if (ext4_should_dioread_nolock(inode))
4404                get_block = ext4_get_block_write;
4405        else
4406                get_block = ext4_get_block;
4407retry_alloc:
4408        handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
4409        if (IS_ERR(handle)) {
4410                ret = VM_FAULT_SIGBUS;
4411                goto out;
4412        }
4413        ret = __block_page_mkwrite(vma, vmf, get_block);
4414        if (!ret && ext4_should_journal_data(inode)) {
4415                if (walk_page_buffers(handle, page_buffers(page), 0,
4416                          PAGE_CACHE_SIZE, NULL, do_journal_get_write_access)) {
4417                        unlock_page(page);
4418                        ret = VM_FAULT_SIGBUS;
4419                        goto out;
4420                }
4421                ext4_set_inode_state(inode, EXT4_STATE_JDATA);
4422        }
4423        ext4_journal_stop(handle);
4424        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
4425                goto retry_alloc;
4426out_ret:
4427        ret = block_page_mkwrite_return(ret);
4428out:
4429        return ret;
4430}
4431