linux/fs/gfs2/aops.c
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   1/*
   2 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   4 *
   5 * This copyrighted material is made available to anyone wishing to use,
   6 * modify, copy, or redistribute it subject to the terms and conditions
   7 * of the GNU General Public License version 2.
   8 */
   9
  10#include <linux/sched.h>
  11#include <linux/slab.h>
  12#include <linux/spinlock.h>
  13#include <linux/completion.h>
  14#include <linux/buffer_head.h>
  15#include <linux/pagemap.h>
  16#include <linux/pagevec.h>
  17#include <linux/mpage.h>
  18#include <linux/fs.h>
  19#include <linux/writeback.h>
  20#include <linux/swap.h>
  21#include <linux/gfs2_ondisk.h>
  22#include <linux/backing-dev.h>
  23
  24#include "gfs2.h"
  25#include "incore.h"
  26#include "bmap.h"
  27#include "glock.h"
  28#include "inode.h"
  29#include "log.h"
  30#include "meta_io.h"
  31#include "quota.h"
  32#include "trans.h"
  33#include "rgrp.h"
  34#include "super.h"
  35#include "util.h"
  36#include "glops.h"
  37
  38
  39void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  40                            unsigned int from, unsigned int to)
  41{
  42        struct buffer_head *head = page_buffers(page);
  43        unsigned int bsize = head->b_size;
  44        struct buffer_head *bh;
  45        unsigned int start, end;
  46
  47        for (bh = head, start = 0; bh != head || !start;
  48             bh = bh->b_this_page, start = end) {
  49                end = start + bsize;
  50                if (end <= from || start >= to)
  51                        continue;
  52                if (gfs2_is_jdata(ip))
  53                        set_buffer_uptodate(bh);
  54                gfs2_trans_add_bh(ip->i_gl, bh, 0);
  55        }
  56}
  57
  58/**
  59 * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  60 * @inode: The inode
  61 * @lblock: The block number to look up
  62 * @bh_result: The buffer head to return the result in
  63 * @create: Non-zero if we may add block to the file
  64 *
  65 * Returns: errno
  66 */
  67
  68static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  69                                  struct buffer_head *bh_result, int create)
  70{
  71        int error;
  72
  73        error = gfs2_block_map(inode, lblock, bh_result, 0);
  74        if (error)
  75                return error;
  76        if (!buffer_mapped(bh_result))
  77                return -EIO;
  78        return 0;
  79}
  80
  81static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  82                                 struct buffer_head *bh_result, int create)
  83{
  84        return gfs2_block_map(inode, lblock, bh_result, 0);
  85}
  86
  87/**
  88 * gfs2_writepage_common - Common bits of writepage
  89 * @page: The page to be written
  90 * @wbc: The writeback control
  91 *
  92 * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
  93 */
  94
  95static int gfs2_writepage_common(struct page *page,
  96                                 struct writeback_control *wbc)
  97{
  98        struct inode *inode = page->mapping->host;
  99        struct gfs2_inode *ip = GFS2_I(inode);
 100        struct gfs2_sbd *sdp = GFS2_SB(inode);
 101        loff_t i_size = i_size_read(inode);
 102        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 103        unsigned offset;
 104
 105        if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 106                goto out;
 107        if (current->journal_info)
 108                goto redirty;
 109        /* Is the page fully outside i_size? (truncate in progress) */
 110        offset = i_size & (PAGE_CACHE_SIZE-1);
 111        if (page->index > end_index || (page->index == end_index && !offset)) {
 112                page->mapping->a_ops->invalidatepage(page, 0);
 113                goto out;
 114        }
 115        return 1;
 116redirty:
 117        redirty_page_for_writepage(wbc, page);
 118out:
 119        unlock_page(page);
 120        return 0;
 121}
 122
 123/**
 124 * gfs2_writeback_writepage - Write page for writeback mappings
 125 * @page: The page
 126 * @wbc: The writeback control
 127 *
 128 */
 129
 130static int gfs2_writeback_writepage(struct page *page,
 131                                    struct writeback_control *wbc)
 132{
 133        int ret;
 134
 135        ret = gfs2_writepage_common(page, wbc);
 136        if (ret <= 0)
 137                return ret;
 138
 139        return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
 140}
 141
 142/**
 143 * gfs2_ordered_writepage - Write page for ordered data files
 144 * @page: The page to write
 145 * @wbc: The writeback control
 146 *
 147 */
 148
 149static int gfs2_ordered_writepage(struct page *page,
 150                                  struct writeback_control *wbc)
 151{
 152        struct inode *inode = page->mapping->host;
 153        struct gfs2_inode *ip = GFS2_I(inode);
 154        int ret;
 155
 156        ret = gfs2_writepage_common(page, wbc);
 157        if (ret <= 0)
 158                return ret;
 159
 160        if (!page_has_buffers(page)) {
 161                create_empty_buffers(page, inode->i_sb->s_blocksize,
 162                                     (1 << BH_Dirty)|(1 << BH_Uptodate));
 163        }
 164        gfs2_page_add_databufs(ip, page, 0, inode->i_sb->s_blocksize-1);
 165        return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 166}
 167
 168/**
 169 * __gfs2_jdata_writepage - The core of jdata writepage
 170 * @page: The page to write
 171 * @wbc: The writeback control
 172 *
 173 * This is shared between writepage and writepages and implements the
 174 * core of the writepage operation. If a transaction is required then
 175 * PageChecked will have been set and the transaction will have
 176 * already been started before this is called.
 177 */
 178
 179static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 180{
 181        struct inode *inode = page->mapping->host;
 182        struct gfs2_inode *ip = GFS2_I(inode);
 183        struct gfs2_sbd *sdp = GFS2_SB(inode);
 184
 185        if (PageChecked(page)) {
 186                ClearPageChecked(page);
 187                if (!page_has_buffers(page)) {
 188                        create_empty_buffers(page, inode->i_sb->s_blocksize,
 189                                             (1 << BH_Dirty)|(1 << BH_Uptodate));
 190                }
 191                gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 192        }
 193        return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 194}
 195
 196/**
 197 * gfs2_jdata_writepage - Write complete page
 198 * @page: Page to write
 199 *
 200 * Returns: errno
 201 *
 202 */
 203
 204static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 205{
 206        struct inode *inode = page->mapping->host;
 207        struct gfs2_sbd *sdp = GFS2_SB(inode);
 208        int ret;
 209        int done_trans = 0;
 210
 211        if (PageChecked(page)) {
 212                if (wbc->sync_mode != WB_SYNC_ALL)
 213                        goto out_ignore;
 214                ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 215                if (ret)
 216                        goto out_ignore;
 217                done_trans = 1;
 218        }
 219        ret = gfs2_writepage_common(page, wbc);
 220        if (ret > 0)
 221                ret = __gfs2_jdata_writepage(page, wbc);
 222        if (done_trans)
 223                gfs2_trans_end(sdp);
 224        return ret;
 225
 226out_ignore:
 227        redirty_page_for_writepage(wbc, page);
 228        unlock_page(page);
 229        return 0;
 230}
 231
 232/**
 233 * gfs2_writeback_writepages - Write a bunch of dirty pages back to disk
 234 * @mapping: The mapping to write
 235 * @wbc: Write-back control
 236 *
 237 * For the data=writeback case we can already ignore buffer heads
 238 * and write whole extents at once. This is a big reduction in the
 239 * number of I/O requests we send and the bmap calls we make in this case.
 240 */
 241static int gfs2_writeback_writepages(struct address_space *mapping,
 242                                     struct writeback_control *wbc)
 243{
 244        return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 245}
 246
 247/**
 248 * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 249 * @mapping: The mapping
 250 * @wbc: The writeback control
 251 * @writepage: The writepage function to call for each page
 252 * @pvec: The vector of pages
 253 * @nr_pages: The number of pages to write
 254 *
 255 * Returns: non-zero if loop should terminate, zero otherwise
 256 */
 257
 258static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 259                                    struct writeback_control *wbc,
 260                                    struct pagevec *pvec,
 261                                    int nr_pages, pgoff_t end)
 262{
 263        struct inode *inode = mapping->host;
 264        struct gfs2_sbd *sdp = GFS2_SB(inode);
 265        loff_t i_size = i_size_read(inode);
 266        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 267        unsigned offset = i_size & (PAGE_CACHE_SIZE-1);
 268        unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
 269        int i;
 270        int ret;
 271
 272        ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 273        if (ret < 0)
 274                return ret;
 275
 276        for(i = 0; i < nr_pages; i++) {
 277                struct page *page = pvec->pages[i];
 278
 279                lock_page(page);
 280
 281                if (unlikely(page->mapping != mapping)) {
 282                        unlock_page(page);
 283                        continue;
 284                }
 285
 286                if (!wbc->range_cyclic && page->index > end) {
 287                        ret = 1;
 288                        unlock_page(page);
 289                        continue;
 290                }
 291
 292                if (wbc->sync_mode != WB_SYNC_NONE)
 293                        wait_on_page_writeback(page);
 294
 295                if (PageWriteback(page) ||
 296                    !clear_page_dirty_for_io(page)) {
 297                        unlock_page(page);
 298                        continue;
 299                }
 300
 301                /* Is the page fully outside i_size? (truncate in progress) */
 302                if (page->index > end_index || (page->index == end_index && !offset)) {
 303                        page->mapping->a_ops->invalidatepage(page, 0);
 304                        unlock_page(page);
 305                        continue;
 306                }
 307
 308                ret = __gfs2_jdata_writepage(page, wbc);
 309
 310                if (ret || (--(wbc->nr_to_write) <= 0))
 311                        ret = 1;
 312        }
 313        gfs2_trans_end(sdp);
 314        return ret;
 315}
 316
 317/**
 318 * gfs2_write_cache_jdata - Like write_cache_pages but different
 319 * @mapping: The mapping to write
 320 * @wbc: The writeback control
 321 * @writepage: The writepage function to call
 322 * @data: The data to pass to writepage
 323 *
 324 * The reason that we use our own function here is that we need to
 325 * start transactions before we grab page locks. This allows us
 326 * to get the ordering right.
 327 */
 328
 329static int gfs2_write_cache_jdata(struct address_space *mapping,
 330                                  struct writeback_control *wbc)
 331{
 332        int ret = 0;
 333        int done = 0;
 334        struct pagevec pvec;
 335        int nr_pages;
 336        pgoff_t index;
 337        pgoff_t end;
 338        int scanned = 0;
 339        int range_whole = 0;
 340
 341        pagevec_init(&pvec, 0);
 342        if (wbc->range_cyclic) {
 343                index = mapping->writeback_index; /* Start from prev offset */
 344                end = -1;
 345        } else {
 346                index = wbc->range_start >> PAGE_CACHE_SHIFT;
 347                end = wbc->range_end >> PAGE_CACHE_SHIFT;
 348                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 349                        range_whole = 1;
 350                scanned = 1;
 351        }
 352
 353retry:
 354         while (!done && (index <= end) &&
 355                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 356                                               PAGECACHE_TAG_DIRTY,
 357                                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
 358                scanned = 1;
 359                ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end);
 360                if (ret)
 361                        done = 1;
 362                if (ret > 0)
 363                        ret = 0;
 364
 365                pagevec_release(&pvec);
 366                cond_resched();
 367        }
 368
 369        if (!scanned && !done) {
 370                /*
 371                 * We hit the last page and there is more work to be done: wrap
 372                 * back to the start of the file
 373                 */
 374                scanned = 1;
 375                index = 0;
 376                goto retry;
 377        }
 378
 379        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 380                mapping->writeback_index = index;
 381        return ret;
 382}
 383
 384
 385/**
 386 * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 387 * @mapping: The mapping to write
 388 * @wbc: The writeback control
 389 * 
 390 */
 391
 392static int gfs2_jdata_writepages(struct address_space *mapping,
 393                                 struct writeback_control *wbc)
 394{
 395        struct gfs2_inode *ip = GFS2_I(mapping->host);
 396        struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 397        int ret;
 398
 399        ret = gfs2_write_cache_jdata(mapping, wbc);
 400        if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 401                gfs2_log_flush(sdp, ip->i_gl);
 402                ret = gfs2_write_cache_jdata(mapping, wbc);
 403        }
 404        return ret;
 405}
 406
 407/**
 408 * stuffed_readpage - Fill in a Linux page with stuffed file data
 409 * @ip: the inode
 410 * @page: the page
 411 *
 412 * Returns: errno
 413 */
 414
 415static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 416{
 417        struct buffer_head *dibh;
 418        u64 dsize = i_size_read(&ip->i_inode);
 419        void *kaddr;
 420        int error;
 421
 422        /*
 423         * Due to the order of unstuffing files and ->fault(), we can be
 424         * asked for a zero page in the case of a stuffed file being extended,
 425         * so we need to supply one here. It doesn't happen often.
 426         */
 427        if (unlikely(page->index)) {
 428                zero_user(page, 0, PAGE_CACHE_SIZE);
 429                SetPageUptodate(page);
 430                return 0;
 431        }
 432
 433        error = gfs2_meta_inode_buffer(ip, &dibh);
 434        if (error)
 435                return error;
 436
 437        kaddr = kmap_atomic(page, KM_USER0);
 438        if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
 439                dsize = (dibh->b_size - sizeof(struct gfs2_dinode));
 440        memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 441        memset(kaddr + dsize, 0, PAGE_CACHE_SIZE - dsize);
 442        kunmap_atomic(kaddr, KM_USER0);
 443        flush_dcache_page(page);
 444        brelse(dibh);
 445        SetPageUptodate(page);
 446
 447        return 0;
 448}
 449
 450
 451/**
 452 * __gfs2_readpage - readpage
 453 * @file: The file to read a page for
 454 * @page: The page to read
 455 *
 456 * This is the core of gfs2's readpage. Its used by the internal file
 457 * reading code as in that case we already hold the glock. Also its
 458 * called by gfs2_readpage() once the required lock has been granted.
 459 *
 460 */
 461
 462static int __gfs2_readpage(void *file, struct page *page)
 463{
 464        struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 465        struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 466        int error;
 467
 468        if (gfs2_is_stuffed(ip)) {
 469                error = stuffed_readpage(ip, page);
 470                unlock_page(page);
 471        } else {
 472                error = mpage_readpage(page, gfs2_block_map);
 473        }
 474
 475        if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 476                return -EIO;
 477
 478        return error;
 479}
 480
 481/**
 482 * gfs2_readpage - read a page of a file
 483 * @file: The file to read
 484 * @page: The page of the file
 485 *
 486 * This deals with the locking required. We have to unlock and
 487 * relock the page in order to get the locking in the right
 488 * order.
 489 */
 490
 491static int gfs2_readpage(struct file *file, struct page *page)
 492{
 493        struct address_space *mapping = page->mapping;
 494        struct gfs2_inode *ip = GFS2_I(mapping->host);
 495        struct gfs2_holder gh;
 496        int error;
 497
 498        unlock_page(page);
 499        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 500        error = gfs2_glock_nq(&gh);
 501        if (unlikely(error))
 502                goto out;
 503        error = AOP_TRUNCATED_PAGE;
 504        lock_page(page);
 505        if (page->mapping == mapping && !PageUptodate(page))
 506                error = __gfs2_readpage(file, page);
 507        else
 508                unlock_page(page);
 509        gfs2_glock_dq(&gh);
 510out:
 511        gfs2_holder_uninit(&gh);
 512        if (error && error != AOP_TRUNCATED_PAGE)
 513                lock_page(page);
 514        return error;
 515}
 516
 517/**
 518 * gfs2_internal_read - read an internal file
 519 * @ip: The gfs2 inode
 520 * @ra_state: The readahead state (or NULL for no readahead)
 521 * @buf: The buffer to fill
 522 * @pos: The file position
 523 * @size: The amount to read
 524 *
 525 */
 526
 527int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state,
 528                       char *buf, loff_t *pos, unsigned size)
 529{
 530        struct address_space *mapping = ip->i_inode.i_mapping;
 531        unsigned long index = *pos / PAGE_CACHE_SIZE;
 532        unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
 533        unsigned copied = 0;
 534        unsigned amt;
 535        struct page *page;
 536        void *p;
 537
 538        do {
 539                amt = size - copied;
 540                if (offset + size > PAGE_CACHE_SIZE)
 541                        amt = PAGE_CACHE_SIZE - offset;
 542                page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 543                if (IS_ERR(page))
 544                        return PTR_ERR(page);
 545                p = kmap_atomic(page, KM_USER0);
 546                memcpy(buf + copied, p + offset, amt);
 547                kunmap_atomic(p, KM_USER0);
 548                mark_page_accessed(page);
 549                page_cache_release(page);
 550                copied += amt;
 551                index++;
 552                offset = 0;
 553        } while(copied < size);
 554        (*pos) += size;
 555        return size;
 556}
 557
 558/**
 559 * gfs2_readpages - Read a bunch of pages at once
 560 *
 561 * Some notes:
 562 * 1. This is only for readahead, so we can simply ignore any things
 563 *    which are slightly inconvenient (such as locking conflicts between
 564 *    the page lock and the glock) and return having done no I/O. Its
 565 *    obviously not something we'd want to do on too regular a basis.
 566 *    Any I/O we ignore at this time will be done via readpage later.
 567 * 2. We don't handle stuffed files here we let readpage do the honours.
 568 * 3. mpage_readpages() does most of the heavy lifting in the common case.
 569 * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 570 */
 571
 572static int gfs2_readpages(struct file *file, struct address_space *mapping,
 573                          struct list_head *pages, unsigned nr_pages)
 574{
 575        struct inode *inode = mapping->host;
 576        struct gfs2_inode *ip = GFS2_I(inode);
 577        struct gfs2_sbd *sdp = GFS2_SB(inode);
 578        struct gfs2_holder gh;
 579        int ret;
 580
 581        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 582        ret = gfs2_glock_nq(&gh);
 583        if (unlikely(ret))
 584                goto out_uninit;
 585        if (!gfs2_is_stuffed(ip))
 586                ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
 587        gfs2_glock_dq(&gh);
 588out_uninit:
 589        gfs2_holder_uninit(&gh);
 590        if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 591                ret = -EIO;
 592        return ret;
 593}
 594
 595/**
 596 * gfs2_write_begin - Begin to write to a file
 597 * @file: The file to write to
 598 * @mapping: The mapping in which to write
 599 * @pos: The file offset at which to start writing
 600 * @len: Length of the write
 601 * @flags: Various flags
 602 * @pagep: Pointer to return the page
 603 * @fsdata: Pointer to return fs data (unused by GFS2)
 604 *
 605 * Returns: errno
 606 */
 607
 608static int gfs2_write_begin(struct file *file, struct address_space *mapping,
 609                            loff_t pos, unsigned len, unsigned flags,
 610                            struct page **pagep, void **fsdata)
 611{
 612        struct gfs2_inode *ip = GFS2_I(mapping->host);
 613        struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 614        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 615        unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
 616        int alloc_required;
 617        int error = 0;
 618        struct gfs2_alloc *al = NULL;
 619        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 620        unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 621        struct page *page;
 622
 623        gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
 624        error = gfs2_glock_nq(&ip->i_gh);
 625        if (unlikely(error))
 626                goto out_uninit;
 627        if (&ip->i_inode == sdp->sd_rindex) {
 628                error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
 629                                           GL_NOCACHE, &m_ip->i_gh);
 630                if (unlikely(error)) {
 631                        gfs2_glock_dq(&ip->i_gh);
 632                        goto out_uninit;
 633                }
 634        }
 635
 636        alloc_required = gfs2_write_alloc_required(ip, pos, len);
 637
 638        if (alloc_required || gfs2_is_jdata(ip))
 639                gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
 640
 641        if (alloc_required) {
 642                al = gfs2_alloc_get(ip);
 643                if (!al) {
 644                        error = -ENOMEM;
 645                        goto out_unlock;
 646                }
 647
 648                error = gfs2_quota_lock_check(ip);
 649                if (error)
 650                        goto out_alloc_put;
 651
 652                al->al_requested = data_blocks + ind_blocks;
 653                error = gfs2_inplace_reserve(ip);
 654                if (error)
 655                        goto out_qunlock;
 656        }
 657
 658        rblocks = RES_DINODE + ind_blocks;
 659        if (gfs2_is_jdata(ip))
 660                rblocks += data_blocks ? data_blocks : 1;
 661        if (ind_blocks || data_blocks)
 662                rblocks += RES_STATFS + RES_QUOTA;
 663        if (&ip->i_inode == sdp->sd_rindex)
 664                rblocks += 2 * RES_STATFS;
 665        if (alloc_required)
 666                rblocks += gfs2_rg_blocks(al);
 667
 668        error = gfs2_trans_begin(sdp, rblocks,
 669                                 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
 670        if (error)
 671                goto out_trans_fail;
 672
 673        error = -ENOMEM;
 674        flags |= AOP_FLAG_NOFS;
 675        page = grab_cache_page_write_begin(mapping, index, flags);
 676        *pagep = page;
 677        if (unlikely(!page))
 678                goto out_endtrans;
 679
 680        if (gfs2_is_stuffed(ip)) {
 681                error = 0;
 682                if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 683                        error = gfs2_unstuff_dinode(ip, page);
 684                        if (error == 0)
 685                                goto prepare_write;
 686                } else if (!PageUptodate(page)) {
 687                        error = stuffed_readpage(ip, page);
 688                }
 689                goto out;
 690        }
 691
 692prepare_write:
 693        error = __block_write_begin(page, from, len, gfs2_block_map);
 694out:
 695        if (error == 0)
 696                return 0;
 697
 698        unlock_page(page);
 699        page_cache_release(page);
 700
 701        gfs2_trans_end(sdp);
 702        if (pos + len > ip->i_inode.i_size)
 703                gfs2_trim_blocks(&ip->i_inode);
 704        goto out_trans_fail;
 705
 706out_endtrans:
 707        gfs2_trans_end(sdp);
 708out_trans_fail:
 709        if (alloc_required) {
 710                gfs2_inplace_release(ip);
 711out_qunlock:
 712                gfs2_quota_unlock(ip);
 713out_alloc_put:
 714                gfs2_alloc_put(ip);
 715        }
 716out_unlock:
 717        if (&ip->i_inode == sdp->sd_rindex) {
 718                gfs2_glock_dq(&m_ip->i_gh);
 719                gfs2_holder_uninit(&m_ip->i_gh);
 720        }
 721        gfs2_glock_dq(&ip->i_gh);
 722out_uninit:
 723        gfs2_holder_uninit(&ip->i_gh);
 724        return error;
 725}
 726
 727/**
 728 * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 729 * @inode: the rindex inode
 730 */
 731static void adjust_fs_space(struct inode *inode)
 732{
 733        struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 734        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 735        struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 736        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 737        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 738        struct buffer_head *m_bh, *l_bh;
 739        u64 fs_total, new_free;
 740
 741        /* Total up the file system space, according to the latest rindex. */
 742        fs_total = gfs2_ri_total(sdp);
 743        if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 744                return;
 745
 746        spin_lock(&sdp->sd_statfs_spin);
 747        gfs2_statfs_change_in(m_sc, m_bh->b_data +
 748                              sizeof(struct gfs2_dinode));
 749        if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 750                new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 751        else
 752                new_free = 0;
 753        spin_unlock(&sdp->sd_statfs_spin);
 754        fs_warn(sdp, "File system extended by %llu blocks.\n",
 755                (unsigned long long)new_free);
 756        gfs2_statfs_change(sdp, new_free, new_free, 0);
 757
 758        if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
 759                goto out;
 760        update_statfs(sdp, m_bh, l_bh);
 761        brelse(l_bh);
 762out:
 763        brelse(m_bh);
 764}
 765
 766/**
 767 * gfs2_stuffed_write_end - Write end for stuffed files
 768 * @inode: The inode
 769 * @dibh: The buffer_head containing the on-disk inode
 770 * @pos: The file position
 771 * @len: The length of the write
 772 * @copied: How much was actually copied by the VFS
 773 * @page: The page
 774 *
 775 * This copies the data from the page into the inode block after
 776 * the inode data structure itself.
 777 *
 778 * Returns: errno
 779 */
 780static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
 781                                  loff_t pos, unsigned len, unsigned copied,
 782                                  struct page *page)
 783{
 784        struct gfs2_inode *ip = GFS2_I(inode);
 785        struct gfs2_sbd *sdp = GFS2_SB(inode);
 786        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 787        u64 to = pos + copied;
 788        void *kaddr;
 789        unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
 790        struct gfs2_dinode *di = (struct gfs2_dinode *)dibh->b_data;
 791
 792        BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
 793        kaddr = kmap_atomic(page, KM_USER0);
 794        memcpy(buf + pos, kaddr + pos, copied);
 795        memset(kaddr + pos + copied, 0, len - copied);
 796        flush_dcache_page(page);
 797        kunmap_atomic(kaddr, KM_USER0);
 798
 799        if (!PageUptodate(page))
 800                SetPageUptodate(page);
 801        unlock_page(page);
 802        page_cache_release(page);
 803
 804        if (copied) {
 805                if (inode->i_size < to)
 806                        i_size_write(inode, to);
 807                gfs2_dinode_out(ip, di);
 808                mark_inode_dirty(inode);
 809        }
 810
 811        if (inode == sdp->sd_rindex) {
 812                adjust_fs_space(inode);
 813                ip->i_gh.gh_flags |= GL_NOCACHE;
 814        }
 815
 816        brelse(dibh);
 817        gfs2_trans_end(sdp);
 818        if (inode == sdp->sd_rindex) {
 819                gfs2_glock_dq(&m_ip->i_gh);
 820                gfs2_holder_uninit(&m_ip->i_gh);
 821        }
 822        gfs2_glock_dq(&ip->i_gh);
 823        gfs2_holder_uninit(&ip->i_gh);
 824        return copied;
 825}
 826
 827/**
 828 * gfs2_write_end
 829 * @file: The file to write to
 830 * @mapping: The address space to write to
 831 * @pos: The file position
 832 * @len: The length of the data
 833 * @copied:
 834 * @page: The page that has been written
 835 * @fsdata: The fsdata (unused in GFS2)
 836 *
 837 * The main write_end function for GFS2. We have a separate one for
 838 * stuffed files as they are slightly different, otherwise we just
 839 * put our locking around the VFS provided functions.
 840 *
 841 * Returns: errno
 842 */
 843
 844static int gfs2_write_end(struct file *file, struct address_space *mapping,
 845                          loff_t pos, unsigned len, unsigned copied,
 846                          struct page *page, void *fsdata)
 847{
 848        struct inode *inode = page->mapping->host;
 849        struct gfs2_inode *ip = GFS2_I(inode);
 850        struct gfs2_sbd *sdp = GFS2_SB(inode);
 851        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 852        struct buffer_head *dibh;
 853        struct gfs2_alloc *al = ip->i_alloc;
 854        unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
 855        unsigned int to = from + len;
 856        int ret;
 857
 858        BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
 859
 860        ret = gfs2_meta_inode_buffer(ip, &dibh);
 861        if (unlikely(ret)) {
 862                unlock_page(page);
 863                page_cache_release(page);
 864                goto failed;
 865        }
 866
 867        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 868
 869        if (gfs2_is_stuffed(ip))
 870                return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
 871
 872        if (!gfs2_is_writeback(ip))
 873                gfs2_page_add_databufs(ip, page, from, to);
 874
 875        ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 876        if (ret > 0) {
 877                gfs2_dinode_out(ip, dibh->b_data);
 878                mark_inode_dirty(inode);
 879        }
 880
 881        if (inode == sdp->sd_rindex) {
 882                adjust_fs_space(inode);
 883                ip->i_gh.gh_flags |= GL_NOCACHE;
 884        }
 885
 886        brelse(dibh);
 887failed:
 888        gfs2_trans_end(sdp);
 889        if (al) {
 890                gfs2_inplace_release(ip);
 891                gfs2_quota_unlock(ip);
 892                gfs2_alloc_put(ip);
 893        }
 894        if (inode == sdp->sd_rindex) {
 895                gfs2_glock_dq(&m_ip->i_gh);
 896                gfs2_holder_uninit(&m_ip->i_gh);
 897        }
 898        gfs2_glock_dq(&ip->i_gh);
 899        gfs2_holder_uninit(&ip->i_gh);
 900        return ret;
 901}
 902
 903/**
 904 * gfs2_set_page_dirty - Page dirtying function
 905 * @page: The page to dirty
 906 *
 907 * Returns: 1 if it dirtyed the page, or 0 otherwise
 908 */
 909 
 910static int gfs2_set_page_dirty(struct page *page)
 911{
 912        SetPageChecked(page);
 913        return __set_page_dirty_buffers(page);
 914}
 915
 916/**
 917 * gfs2_bmap - Block map function
 918 * @mapping: Address space info
 919 * @lblock: The block to map
 920 *
 921 * Returns: The disk address for the block or 0 on hole or error
 922 */
 923
 924static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 925{
 926        struct gfs2_inode *ip = GFS2_I(mapping->host);
 927        struct gfs2_holder i_gh;
 928        sector_t dblock = 0;
 929        int error;
 930
 931        error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 932        if (error)
 933                return 0;
 934
 935        if (!gfs2_is_stuffed(ip))
 936                dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
 937
 938        gfs2_glock_dq_uninit(&i_gh);
 939
 940        return dblock;
 941}
 942
 943static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 944{
 945        struct gfs2_bufdata *bd;
 946
 947        lock_buffer(bh);
 948        gfs2_log_lock(sdp);
 949        clear_buffer_dirty(bh);
 950        bd = bh->b_private;
 951        if (bd) {
 952                if (!list_empty(&bd->bd_le.le_list) && !buffer_pinned(bh))
 953                        list_del_init(&bd->bd_le.le_list);
 954                else
 955                        gfs2_remove_from_journal(bh, current->journal_info, 0);
 956        }
 957        bh->b_bdev = NULL;
 958        clear_buffer_mapped(bh);
 959        clear_buffer_req(bh);
 960        clear_buffer_new(bh);
 961        gfs2_log_unlock(sdp);
 962        unlock_buffer(bh);
 963}
 964
 965static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 966{
 967        struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 968        struct buffer_head *bh, *head;
 969        unsigned long pos = 0;
 970
 971        BUG_ON(!PageLocked(page));
 972        if (offset == 0)
 973                ClearPageChecked(page);
 974        if (!page_has_buffers(page))
 975                goto out;
 976
 977        bh = head = page_buffers(page);
 978        do {
 979                if (offset <= pos)
 980                        gfs2_discard(sdp, bh);
 981                pos += bh->b_size;
 982                bh = bh->b_this_page;
 983        } while (bh != head);
 984out:
 985        if (offset == 0)
 986                try_to_release_page(page, 0);
 987}
 988
 989/**
 990 * gfs2_ok_for_dio - check that dio is valid on this file
 991 * @ip: The inode
 992 * @rw: READ or WRITE
 993 * @offset: The offset at which we are reading or writing
 994 *
 995 * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 996 *          1 (to accept the i/o request)
 997 */
 998static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 999{
1000        /*
1001         * Should we return an error here? I can't see that O_DIRECT for
1002         * a stuffed file makes any sense. For now we'll silently fall
1003         * back to buffered I/O
1004         */
1005        if (gfs2_is_stuffed(ip))
1006                return 0;
1007
1008        if (offset >= i_size_read(&ip->i_inode))
1009                return 0;
1010        return 1;
1011}
1012
1013
1014
1015static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
1016                              const struct iovec *iov, loff_t offset,
1017                              unsigned long nr_segs)
1018{
1019        struct file *file = iocb->ki_filp;
1020        struct inode *inode = file->f_mapping->host;
1021        struct gfs2_inode *ip = GFS2_I(inode);
1022        struct gfs2_holder gh;
1023        int rv;
1024
1025        /*
1026         * Deferred lock, even if its a write, since we do no allocation
1027         * on this path. All we need change is atime, and this lock mode
1028         * ensures that other nodes have flushed their buffered read caches
1029         * (i.e. their page cache entries for this inode). We do not,
1030         * unfortunately have the option of only flushing a range like
1031         * the VFS does.
1032         */
1033        gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1034        rv = gfs2_glock_nq(&gh);
1035        if (rv)
1036                return rv;
1037        rv = gfs2_ok_for_dio(ip, rw, offset);
1038        if (rv != 1)
1039                goto out; /* dio not valid, fall back to buffered i/o */
1040
1041        rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
1042                                  offset, nr_segs, gfs2_get_block_direct,
1043                                  NULL, NULL, 0);
1044out:
1045        gfs2_glock_dq_m(1, &gh);
1046        gfs2_holder_uninit(&gh);
1047        return rv;
1048}
1049
1050/**
1051 * gfs2_releasepage - free the metadata associated with a page
1052 * @page: the page that's being released
1053 * @gfp_mask: passed from Linux VFS, ignored by us
1054 *
1055 * Call try_to_free_buffers() if the buffers in this page can be
1056 * released.
1057 *
1058 * Returns: 0
1059 */
1060
1061int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1062{
1063        struct address_space *mapping = page->mapping;
1064        struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1065        struct buffer_head *bh, *head;
1066        struct gfs2_bufdata *bd;
1067
1068        if (!page_has_buffers(page))
1069                return 0;
1070
1071        gfs2_log_lock(sdp);
1072        spin_lock(&sdp->sd_ail_lock);
1073        head = bh = page_buffers(page);
1074        do {
1075                if (atomic_read(&bh->b_count))
1076                        goto cannot_release;
1077                bd = bh->b_private;
1078                if (bd && bd->bd_ail)
1079                        goto cannot_release;
1080                if (buffer_pinned(bh) || buffer_dirty(bh))
1081                        goto not_possible;
1082                bh = bh->b_this_page;
1083        } while(bh != head);
1084        spin_unlock(&sdp->sd_ail_lock);
1085        gfs2_log_unlock(sdp);
1086
1087        head = bh = page_buffers(page);
1088        do {
1089                gfs2_log_lock(sdp);
1090                bd = bh->b_private;
1091                if (bd) {
1092                        gfs2_assert_warn(sdp, bd->bd_bh == bh);
1093                        gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
1094                        if (!list_empty(&bd->bd_le.le_list)) {
1095                                if (!buffer_pinned(bh))
1096                                        list_del_init(&bd->bd_le.le_list);
1097                                else
1098                                        bd = NULL;
1099                        }
1100                        if (bd)
1101                                bd->bd_bh = NULL;
1102                        bh->b_private = NULL;
1103                }
1104                gfs2_log_unlock(sdp);
1105                if (bd)
1106                        kmem_cache_free(gfs2_bufdata_cachep, bd);
1107
1108                bh = bh->b_this_page;
1109        } while (bh != head);
1110
1111        return try_to_free_buffers(page);
1112
1113not_possible: /* Should never happen */
1114        WARN_ON(buffer_dirty(bh));
1115        WARN_ON(buffer_pinned(bh));
1116cannot_release:
1117        spin_unlock(&sdp->sd_ail_lock);
1118        gfs2_log_unlock(sdp);
1119        return 0;
1120}
1121
1122static const struct address_space_operations gfs2_writeback_aops = {
1123        .writepage = gfs2_writeback_writepage,
1124        .writepages = gfs2_writeback_writepages,
1125        .readpage = gfs2_readpage,
1126        .readpages = gfs2_readpages,
1127        .write_begin = gfs2_write_begin,
1128        .write_end = gfs2_write_end,
1129        .bmap = gfs2_bmap,
1130        .invalidatepage = gfs2_invalidatepage,
1131        .releasepage = gfs2_releasepage,
1132        .direct_IO = gfs2_direct_IO,
1133        .migratepage = buffer_migrate_page,
1134        .is_partially_uptodate = block_is_partially_uptodate,
1135        .error_remove_page = generic_error_remove_page,
1136};
1137
1138static const struct address_space_operations gfs2_ordered_aops = {
1139        .writepage = gfs2_ordered_writepage,
1140        .readpage = gfs2_readpage,
1141        .readpages = gfs2_readpages,
1142        .write_begin = gfs2_write_begin,
1143        .write_end = gfs2_write_end,
1144        .set_page_dirty = gfs2_set_page_dirty,
1145        .bmap = gfs2_bmap,
1146        .invalidatepage = gfs2_invalidatepage,
1147        .releasepage = gfs2_releasepage,
1148        .direct_IO = gfs2_direct_IO,
1149        .migratepage = buffer_migrate_page,
1150        .is_partially_uptodate = block_is_partially_uptodate,
1151        .error_remove_page = generic_error_remove_page,
1152};
1153
1154static const struct address_space_operations gfs2_jdata_aops = {
1155        .writepage = gfs2_jdata_writepage,
1156        .writepages = gfs2_jdata_writepages,
1157        .readpage = gfs2_readpage,
1158        .readpages = gfs2_readpages,
1159        .write_begin = gfs2_write_begin,
1160        .write_end = gfs2_write_end,
1161        .set_page_dirty = gfs2_set_page_dirty,
1162        .bmap = gfs2_bmap,
1163        .invalidatepage = gfs2_invalidatepage,
1164        .releasepage = gfs2_releasepage,
1165        .is_partially_uptodate = block_is_partially_uptodate,
1166        .error_remove_page = generic_error_remove_page,
1167};
1168
1169void gfs2_set_aops(struct inode *inode)
1170{
1171        struct gfs2_inode *ip = GFS2_I(inode);
1172
1173        if (gfs2_is_writeback(ip))
1174                inode->i_mapping->a_ops = &gfs2_writeback_aops;
1175        else if (gfs2_is_ordered(ip))
1176                inode->i_mapping->a_ops = &gfs2_ordered_aops;
1177        else if (gfs2_is_jdata(ip))
1178                inode->i_mapping->a_ops = &gfs2_jdata_aops;
1179        else
1180                BUG();
1181}
1182
1183