linux/fs/nilfs2/segment.c
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   1/*
   2 * segment.c - NILFS segment constructor.
   3 *
   4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19 *
  20 * Written by Ryusuke Konishi <ryusuke@osrg.net>
  21 *
  22 */
  23
  24#include <linux/pagemap.h>
  25#include <linux/buffer_head.h>
  26#include <linux/writeback.h>
  27#include <linux/bio.h>
  28#include <linux/completion.h>
  29#include <linux/blkdev.h>
  30#include <linux/backing-dev.h>
  31#include <linux/freezer.h>
  32#include <linux/kthread.h>
  33#include <linux/crc32.h>
  34#include <linux/pagevec.h>
  35#include "nilfs.h"
  36#include "btnode.h"
  37#include "page.h"
  38#include "segment.h"
  39#include "sufile.h"
  40#include "cpfile.h"
  41#include "ifile.h"
  42#include "segbuf.h"
  43
  44
  45/*
  46 * Segment constructor
  47 */
  48#define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
  49
  50#define SC_MAX_SEGDELTA 64   /* Upper limit of the number of segments
  51                                appended in collection retry loop */
  52
  53/* Construction mode */
  54enum {
  55        SC_LSEG_SR = 1, /* Make a logical segment having a super root */
  56        SC_LSEG_DSYNC,  /* Flush data blocks of a given file and make
  57                           a logical segment without a super root */
  58        SC_FLUSH_FILE,  /* Flush data files, leads to segment writes without
  59                           creating a checkpoint */
  60        SC_FLUSH_DAT,   /* Flush DAT file. This also creates segments without
  61                           a checkpoint */
  62};
  63
  64/* Stage numbers of dirty block collection */
  65enum {
  66        NILFS_ST_INIT = 0,
  67        NILFS_ST_GC,            /* Collecting dirty blocks for GC */
  68        NILFS_ST_FILE,
  69        NILFS_ST_IFILE,
  70        NILFS_ST_CPFILE,
  71        NILFS_ST_SUFILE,
  72        NILFS_ST_DAT,
  73        NILFS_ST_SR,            /* Super root */
  74        NILFS_ST_DSYNC,         /* Data sync blocks */
  75        NILFS_ST_DONE,
  76};
  77
  78/* State flags of collection */
  79#define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
  80#define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
  81#define NILFS_CF_SUFREED        0x0004  /* segment usages has been freed */
  82#define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
  83
  84/* Operations depending on the construction mode and file type */
  85struct nilfs_sc_operations {
  86        int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
  87                            struct inode *);
  88        int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
  89                            struct inode *);
  90        int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
  91                            struct inode *);
  92        void (*write_data_binfo)(struct nilfs_sc_info *,
  93                                 struct nilfs_segsum_pointer *,
  94                                 union nilfs_binfo *);
  95        void (*write_node_binfo)(struct nilfs_sc_info *,
  96                                 struct nilfs_segsum_pointer *,
  97                                 union nilfs_binfo *);
  98};
  99
 100/*
 101 * Other definitions
 102 */
 103static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
 104static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
 105static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
 106static void nilfs_dispose_list(struct nilfs_sb_info *, struct list_head *,
 107                               int);
 108
 109#define nilfs_cnt32_gt(a, b)   \
 110        (typecheck(__u32, a) && typecheck(__u32, b) && \
 111         ((__s32)(b) - (__s32)(a) < 0))
 112#define nilfs_cnt32_ge(a, b)   \
 113        (typecheck(__u32, a) && typecheck(__u32, b) && \
 114         ((__s32)(a) - (__s32)(b) >= 0))
 115#define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
 116#define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
 117
 118/*
 119 * Transaction
 120 */
 121static struct kmem_cache *nilfs_transaction_cachep;
 122
 123/**
 124 * nilfs_init_transaction_cache - create a cache for nilfs_transaction_info
 125 *
 126 * nilfs_init_transaction_cache() creates a slab cache for the struct
 127 * nilfs_transaction_info.
 128 *
 129 * Return Value: On success, it returns 0. On error, one of the following
 130 * negative error code is returned.
 131 *
 132 * %-ENOMEM - Insufficient memory available.
 133 */
 134int nilfs_init_transaction_cache(void)
 135{
 136        nilfs_transaction_cachep =
 137                kmem_cache_create("nilfs2_transaction_cache",
 138                                  sizeof(struct nilfs_transaction_info),
 139                                  0, SLAB_RECLAIM_ACCOUNT, NULL);
 140        return (nilfs_transaction_cachep == NULL) ? -ENOMEM : 0;
 141}
 142
 143/**
 144 * nilfs_detroy_transaction_cache - destroy the cache for transaction info
 145 *
 146 * nilfs_destroy_transaction_cache() frees the slab cache for the struct
 147 * nilfs_transaction_info.
 148 */
 149void nilfs_destroy_transaction_cache(void)
 150{
 151        kmem_cache_destroy(nilfs_transaction_cachep);
 152}
 153
 154static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
 155{
 156        struct nilfs_transaction_info *cur_ti = current->journal_info;
 157        void *save = NULL;
 158
 159        if (cur_ti) {
 160                if (cur_ti->ti_magic == NILFS_TI_MAGIC)
 161                        return ++cur_ti->ti_count;
 162                else {
 163                        /*
 164                         * If journal_info field is occupied by other FS,
 165                         * it is saved and will be restored on
 166                         * nilfs_transaction_commit().
 167                         */
 168                        printk(KERN_WARNING
 169                               "NILFS warning: journal info from a different "
 170                               "FS\n");
 171                        save = current->journal_info;
 172                }
 173        }
 174        if (!ti) {
 175                ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
 176                if (!ti)
 177                        return -ENOMEM;
 178                ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
 179        } else {
 180                ti->ti_flags = 0;
 181        }
 182        ti->ti_count = 0;
 183        ti->ti_save = save;
 184        ti->ti_magic = NILFS_TI_MAGIC;
 185        current->journal_info = ti;
 186        return 0;
 187}
 188
 189/**
 190 * nilfs_transaction_begin - start indivisible file operations.
 191 * @sb: super block
 192 * @ti: nilfs_transaction_info
 193 * @vacancy_check: flags for vacancy rate checks
 194 *
 195 * nilfs_transaction_begin() acquires a reader/writer semaphore, called
 196 * the segment semaphore, to make a segment construction and write tasks
 197 * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
 198 * The region enclosed by these two functions can be nested.  To avoid a
 199 * deadlock, the semaphore is only acquired or released in the outermost call.
 200 *
 201 * This function allocates a nilfs_transaction_info struct to keep context
 202 * information on it.  It is initialized and hooked onto the current task in
 203 * the outermost call.  If a pre-allocated struct is given to @ti, it is used
 204 * instead; othewise a new struct is assigned from a slab.
 205 *
 206 * When @vacancy_check flag is set, this function will check the amount of
 207 * free space, and will wait for the GC to reclaim disk space if low capacity.
 208 *
 209 * Return Value: On success, 0 is returned. On error, one of the following
 210 * negative error code is returned.
 211 *
 212 * %-ENOMEM - Insufficient memory available.
 213 *
 214 * %-ENOSPC - No space left on device
 215 */
 216int nilfs_transaction_begin(struct super_block *sb,
 217                            struct nilfs_transaction_info *ti,
 218                            int vacancy_check)
 219{
 220        struct nilfs_sb_info *sbi;
 221        struct the_nilfs *nilfs;
 222        int ret = nilfs_prepare_segment_lock(ti);
 223
 224        if (unlikely(ret < 0))
 225                return ret;
 226        if (ret > 0)
 227                return 0;
 228
 229        sbi = NILFS_SB(sb);
 230        nilfs = sbi->s_nilfs;
 231        down_read(&nilfs->ns_segctor_sem);
 232        if (vacancy_check && nilfs_near_disk_full(nilfs)) {
 233                up_read(&nilfs->ns_segctor_sem);
 234                ret = -ENOSPC;
 235                goto failed;
 236        }
 237        return 0;
 238
 239 failed:
 240        ti = current->journal_info;
 241        current->journal_info = ti->ti_save;
 242        if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 243                kmem_cache_free(nilfs_transaction_cachep, ti);
 244        return ret;
 245}
 246
 247/**
 248 * nilfs_transaction_commit - commit indivisible file operations.
 249 * @sb: super block
 250 *
 251 * nilfs_transaction_commit() releases the read semaphore which is
 252 * acquired by nilfs_transaction_begin(). This is only performed
 253 * in outermost call of this function.  If a commit flag is set,
 254 * nilfs_transaction_commit() sets a timer to start the segment
 255 * constructor.  If a sync flag is set, it starts construction
 256 * directly.
 257 */
 258int nilfs_transaction_commit(struct super_block *sb)
 259{
 260        struct nilfs_transaction_info *ti = current->journal_info;
 261        struct nilfs_sb_info *sbi;
 262        struct nilfs_sc_info *sci;
 263        int err = 0;
 264
 265        BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 266        ti->ti_flags |= NILFS_TI_COMMIT;
 267        if (ti->ti_count > 0) {
 268                ti->ti_count--;
 269                return 0;
 270        }
 271        sbi = NILFS_SB(sb);
 272        sci = NILFS_SC(sbi);
 273        if (sci != NULL) {
 274                if (ti->ti_flags & NILFS_TI_COMMIT)
 275                        nilfs_segctor_start_timer(sci);
 276                if (atomic_read(&sbi->s_nilfs->ns_ndirtyblks) >
 277                    sci->sc_watermark)
 278                        nilfs_segctor_do_flush(sci, 0);
 279        }
 280        up_read(&sbi->s_nilfs->ns_segctor_sem);
 281        current->journal_info = ti->ti_save;
 282
 283        if (ti->ti_flags & NILFS_TI_SYNC)
 284                err = nilfs_construct_segment(sb);
 285        if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 286                kmem_cache_free(nilfs_transaction_cachep, ti);
 287        return err;
 288}
 289
 290void nilfs_transaction_abort(struct super_block *sb)
 291{
 292        struct nilfs_transaction_info *ti = current->journal_info;
 293
 294        BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 295        if (ti->ti_count > 0) {
 296                ti->ti_count--;
 297                return;
 298        }
 299        up_read(&NILFS_SB(sb)->s_nilfs->ns_segctor_sem);
 300
 301        current->journal_info = ti->ti_save;
 302        if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
 303                kmem_cache_free(nilfs_transaction_cachep, ti);
 304}
 305
 306void nilfs_relax_pressure_in_lock(struct super_block *sb)
 307{
 308        struct nilfs_sb_info *sbi = NILFS_SB(sb);
 309        struct nilfs_sc_info *sci = NILFS_SC(sbi);
 310        struct the_nilfs *nilfs = sbi->s_nilfs;
 311
 312        if (!sci || !sci->sc_flush_request)
 313                return;
 314
 315        set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
 316        up_read(&nilfs->ns_segctor_sem);
 317
 318        down_write(&nilfs->ns_segctor_sem);
 319        if (sci->sc_flush_request &&
 320            test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
 321                struct nilfs_transaction_info *ti = current->journal_info;
 322
 323                ti->ti_flags |= NILFS_TI_WRITER;
 324                nilfs_segctor_do_immediate_flush(sci);
 325                ti->ti_flags &= ~NILFS_TI_WRITER;
 326        }
 327        downgrade_write(&nilfs->ns_segctor_sem);
 328}
 329
 330static void nilfs_transaction_lock(struct nilfs_sb_info *sbi,
 331                                   struct nilfs_transaction_info *ti,
 332                                   int gcflag)
 333{
 334        struct nilfs_transaction_info *cur_ti = current->journal_info;
 335
 336        WARN_ON(cur_ti);
 337        ti->ti_flags = NILFS_TI_WRITER;
 338        ti->ti_count = 0;
 339        ti->ti_save = cur_ti;
 340        ti->ti_magic = NILFS_TI_MAGIC;
 341        INIT_LIST_HEAD(&ti->ti_garbage);
 342        current->journal_info = ti;
 343
 344        for (;;) {
 345                down_write(&sbi->s_nilfs->ns_segctor_sem);
 346                if (!test_bit(NILFS_SC_PRIOR_FLUSH, &NILFS_SC(sbi)->sc_flags))
 347                        break;
 348
 349                nilfs_segctor_do_immediate_flush(NILFS_SC(sbi));
 350
 351                up_write(&sbi->s_nilfs->ns_segctor_sem);
 352                yield();
 353        }
 354        if (gcflag)
 355                ti->ti_flags |= NILFS_TI_GC;
 356}
 357
 358static void nilfs_transaction_unlock(struct nilfs_sb_info *sbi)
 359{
 360        struct nilfs_transaction_info *ti = current->journal_info;
 361
 362        BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
 363        BUG_ON(ti->ti_count > 0);
 364
 365        up_write(&sbi->s_nilfs->ns_segctor_sem);
 366        current->journal_info = ti->ti_save;
 367        if (!list_empty(&ti->ti_garbage))
 368                nilfs_dispose_list(sbi, &ti->ti_garbage, 0);
 369}
 370
 371static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
 372                                            struct nilfs_segsum_pointer *ssp,
 373                                            unsigned bytes)
 374{
 375        struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 376        unsigned blocksize = sci->sc_super->s_blocksize;
 377        void *p;
 378
 379        if (unlikely(ssp->offset + bytes > blocksize)) {
 380                ssp->offset = 0;
 381                BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
 382                                               &segbuf->sb_segsum_buffers));
 383                ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
 384        }
 385        p = ssp->bh->b_data + ssp->offset;
 386        ssp->offset += bytes;
 387        return p;
 388}
 389
 390/**
 391 * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
 392 * @sci: nilfs_sc_info
 393 */
 394static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
 395{
 396        struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 397        struct buffer_head *sumbh;
 398        unsigned sumbytes;
 399        unsigned flags = 0;
 400        int err;
 401
 402        if (nilfs_doing_gc())
 403                flags = NILFS_SS_GC;
 404        err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime);
 405        if (unlikely(err))
 406                return err;
 407
 408        sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
 409        sumbytes = segbuf->sb_sum.sumbytes;
 410        sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
 411        sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
 412        sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
 413        return 0;
 414}
 415
 416static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
 417{
 418        sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
 419        if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
 420                return -E2BIG; /* The current segment is filled up
 421                                  (internal code) */
 422        sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
 423        return nilfs_segctor_reset_segment_buffer(sci);
 424}
 425
 426static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
 427{
 428        struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
 429        int err;
 430
 431        if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
 432                err = nilfs_segctor_feed_segment(sci);
 433                if (err)
 434                        return err;
 435                segbuf = sci->sc_curseg;
 436        }
 437        err = nilfs_segbuf_extend_payload(segbuf, &sci->sc_super_root);
 438        if (likely(!err))
 439                segbuf->sb_sum.flags |= NILFS_SS_SR;
 440        return err;
 441}
 442
 443/*
 444 * Functions for making segment summary and payloads
 445 */
 446static int nilfs_segctor_segsum_block_required(
 447        struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
 448        unsigned binfo_size)
 449{
 450        unsigned blocksize = sci->sc_super->s_blocksize;
 451        /* Size of finfo and binfo is enough small against blocksize */
 452
 453        return ssp->offset + binfo_size +
 454                (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
 455                blocksize;
 456}
 457
 458static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
 459                                      struct inode *inode)
 460{
 461        sci->sc_curseg->sb_sum.nfinfo++;
 462        sci->sc_binfo_ptr = sci->sc_finfo_ptr;
 463        nilfs_segctor_map_segsum_entry(
 464                sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
 465
 466        if (inode->i_sb && !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
 467                set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
 468        /* skip finfo */
 469}
 470
 471static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
 472                                    struct inode *inode)
 473{
 474        struct nilfs_finfo *finfo;
 475        struct nilfs_inode_info *ii;
 476        struct nilfs_segment_buffer *segbuf;
 477
 478        if (sci->sc_blk_cnt == 0)
 479                return;
 480
 481        ii = NILFS_I(inode);
 482        finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
 483                                                 sizeof(*finfo));
 484        finfo->fi_ino = cpu_to_le64(inode->i_ino);
 485        finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
 486        finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
 487        finfo->fi_cno = cpu_to_le64(ii->i_cno);
 488
 489        segbuf = sci->sc_curseg;
 490        segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
 491                sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
 492        sci->sc_finfo_ptr = sci->sc_binfo_ptr;
 493        sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
 494}
 495
 496static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
 497                                        struct buffer_head *bh,
 498                                        struct inode *inode,
 499                                        unsigned binfo_size)
 500{
 501        struct nilfs_segment_buffer *segbuf;
 502        int required, err = 0;
 503
 504 retry:
 505        segbuf = sci->sc_curseg;
 506        required = nilfs_segctor_segsum_block_required(
 507                sci, &sci->sc_binfo_ptr, binfo_size);
 508        if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
 509                nilfs_segctor_end_finfo(sci, inode);
 510                err = nilfs_segctor_feed_segment(sci);
 511                if (err)
 512                        return err;
 513                goto retry;
 514        }
 515        if (unlikely(required)) {
 516                err = nilfs_segbuf_extend_segsum(segbuf);
 517                if (unlikely(err))
 518                        goto failed;
 519        }
 520        if (sci->sc_blk_cnt == 0)
 521                nilfs_segctor_begin_finfo(sci, inode);
 522
 523        nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
 524        /* Substitution to vblocknr is delayed until update_blocknr() */
 525        nilfs_segbuf_add_file_buffer(segbuf, bh);
 526        sci->sc_blk_cnt++;
 527 failed:
 528        return err;
 529}
 530
 531static int nilfs_handle_bmap_error(int err, const char *fname,
 532                                   struct inode *inode, struct super_block *sb)
 533{
 534        if (err == -EINVAL) {
 535                nilfs_error(sb, fname, "broken bmap (inode=%lu)\n",
 536                            inode->i_ino);
 537                err = -EIO;
 538        }
 539        return err;
 540}
 541
 542/*
 543 * Callback functions that enumerate, mark, and collect dirty blocks
 544 */
 545static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
 546                                   struct buffer_head *bh, struct inode *inode)
 547{
 548        int err;
 549
 550        err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 551        if (unlikely(err < 0))
 552                return nilfs_handle_bmap_error(err, __func__, inode,
 553                                               sci->sc_super);
 554
 555        err = nilfs_segctor_add_file_block(sci, bh, inode,
 556                                           sizeof(struct nilfs_binfo_v));
 557        if (!err)
 558                sci->sc_datablk_cnt++;
 559        return err;
 560}
 561
 562static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
 563                                   struct buffer_head *bh,
 564                                   struct inode *inode)
 565{
 566        int err;
 567
 568        err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 569        if (unlikely(err < 0))
 570                return nilfs_handle_bmap_error(err, __func__, inode,
 571                                               sci->sc_super);
 572        return 0;
 573}
 574
 575static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
 576                                   struct buffer_head *bh,
 577                                   struct inode *inode)
 578{
 579        WARN_ON(!buffer_dirty(bh));
 580        return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
 581}
 582
 583static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
 584                                        struct nilfs_segsum_pointer *ssp,
 585                                        union nilfs_binfo *binfo)
 586{
 587        struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
 588                sci, ssp, sizeof(*binfo_v));
 589        *binfo_v = binfo->bi_v;
 590}
 591
 592static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
 593                                        struct nilfs_segsum_pointer *ssp,
 594                                        union nilfs_binfo *binfo)
 595{
 596        __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
 597                sci, ssp, sizeof(*vblocknr));
 598        *vblocknr = binfo->bi_v.bi_vblocknr;
 599}
 600
 601struct nilfs_sc_operations nilfs_sc_file_ops = {
 602        .collect_data = nilfs_collect_file_data,
 603        .collect_node = nilfs_collect_file_node,
 604        .collect_bmap = nilfs_collect_file_bmap,
 605        .write_data_binfo = nilfs_write_file_data_binfo,
 606        .write_node_binfo = nilfs_write_file_node_binfo,
 607};
 608
 609static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
 610                                  struct buffer_head *bh, struct inode *inode)
 611{
 612        int err;
 613
 614        err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
 615        if (unlikely(err < 0))
 616                return nilfs_handle_bmap_error(err, __func__, inode,
 617                                               sci->sc_super);
 618
 619        err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
 620        if (!err)
 621                sci->sc_datablk_cnt++;
 622        return err;
 623}
 624
 625static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
 626                                  struct buffer_head *bh, struct inode *inode)
 627{
 628        WARN_ON(!buffer_dirty(bh));
 629        return nilfs_segctor_add_file_block(sci, bh, inode,
 630                                            sizeof(struct nilfs_binfo_dat));
 631}
 632
 633static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
 634                                       struct nilfs_segsum_pointer *ssp,
 635                                       union nilfs_binfo *binfo)
 636{
 637        __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
 638                                                          sizeof(*blkoff));
 639        *blkoff = binfo->bi_dat.bi_blkoff;
 640}
 641
 642static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
 643                                       struct nilfs_segsum_pointer *ssp,
 644                                       union nilfs_binfo *binfo)
 645{
 646        struct nilfs_binfo_dat *binfo_dat =
 647                nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
 648        *binfo_dat = binfo->bi_dat;
 649}
 650
 651struct nilfs_sc_operations nilfs_sc_dat_ops = {
 652        .collect_data = nilfs_collect_dat_data,
 653        .collect_node = nilfs_collect_file_node,
 654        .collect_bmap = nilfs_collect_dat_bmap,
 655        .write_data_binfo = nilfs_write_dat_data_binfo,
 656        .write_node_binfo = nilfs_write_dat_node_binfo,
 657};
 658
 659struct nilfs_sc_operations nilfs_sc_dsync_ops = {
 660        .collect_data = nilfs_collect_file_data,
 661        .collect_node = NULL,
 662        .collect_bmap = NULL,
 663        .write_data_binfo = nilfs_write_file_data_binfo,
 664        .write_node_binfo = NULL,
 665};
 666
 667static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
 668                                              struct list_head *listp,
 669                                              size_t nlimit,
 670                                              loff_t start, loff_t end)
 671{
 672        struct address_space *mapping = inode->i_mapping;
 673        struct pagevec pvec;
 674        pgoff_t index = 0, last = ULONG_MAX;
 675        size_t ndirties = 0;
 676        int i;
 677
 678        if (unlikely(start != 0 || end != LLONG_MAX)) {
 679                /*
 680                 * A valid range is given for sync-ing data pages. The
 681                 * range is rounded to per-page; extra dirty buffers
 682                 * may be included if blocksize < pagesize.
 683                 */
 684                index = start >> PAGE_SHIFT;
 685                last = end >> PAGE_SHIFT;
 686        }
 687        pagevec_init(&pvec, 0);
 688 repeat:
 689        if (unlikely(index > last) ||
 690            !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 691                                min_t(pgoff_t, last - index,
 692                                      PAGEVEC_SIZE - 1) + 1))
 693                return ndirties;
 694
 695        for (i = 0; i < pagevec_count(&pvec); i++) {
 696                struct buffer_head *bh, *head;
 697                struct page *page = pvec.pages[i];
 698
 699                if (unlikely(page->index > last))
 700                        break;
 701
 702                if (mapping->host) {
 703                        lock_page(page);
 704                        if (!page_has_buffers(page))
 705                                create_empty_buffers(page,
 706                                                     1 << inode->i_blkbits, 0);
 707                        unlock_page(page);
 708                }
 709
 710                bh = head = page_buffers(page);
 711                do {
 712                        if (!buffer_dirty(bh))
 713                                continue;
 714                        get_bh(bh);
 715                        list_add_tail(&bh->b_assoc_buffers, listp);
 716                        ndirties++;
 717                        if (unlikely(ndirties >= nlimit)) {
 718                                pagevec_release(&pvec);
 719                                cond_resched();
 720                                return ndirties;
 721                        }
 722                } while (bh = bh->b_this_page, bh != head);
 723        }
 724        pagevec_release(&pvec);
 725        cond_resched();
 726        goto repeat;
 727}
 728
 729static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
 730                                            struct list_head *listp)
 731{
 732        struct nilfs_inode_info *ii = NILFS_I(inode);
 733        struct address_space *mapping = &ii->i_btnode_cache;
 734        struct pagevec pvec;
 735        struct buffer_head *bh, *head;
 736        unsigned int i;
 737        pgoff_t index = 0;
 738
 739        pagevec_init(&pvec, 0);
 740
 741        while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 742                                  PAGEVEC_SIZE)) {
 743                for (i = 0; i < pagevec_count(&pvec); i++) {
 744                        bh = head = page_buffers(pvec.pages[i]);
 745                        do {
 746                                if (buffer_dirty(bh)) {
 747                                        get_bh(bh);
 748                                        list_add_tail(&bh->b_assoc_buffers,
 749                                                      listp);
 750                                }
 751                                bh = bh->b_this_page;
 752                        } while (bh != head);
 753                }
 754                pagevec_release(&pvec);
 755                cond_resched();
 756        }
 757}
 758
 759static void nilfs_dispose_list(struct nilfs_sb_info *sbi,
 760                               struct list_head *head, int force)
 761{
 762        struct nilfs_inode_info *ii, *n;
 763        struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
 764        unsigned nv = 0;
 765
 766        while (!list_empty(head)) {
 767                spin_lock(&sbi->s_inode_lock);
 768                list_for_each_entry_safe(ii, n, head, i_dirty) {
 769                        list_del_init(&ii->i_dirty);
 770                        if (force) {
 771                                if (unlikely(ii->i_bh)) {
 772                                        brelse(ii->i_bh);
 773                                        ii->i_bh = NULL;
 774                                }
 775                        } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
 776                                set_bit(NILFS_I_QUEUED, &ii->i_state);
 777                                list_add_tail(&ii->i_dirty,
 778                                              &sbi->s_dirty_files);
 779                                continue;
 780                        }
 781                        ivec[nv++] = ii;
 782                        if (nv == SC_N_INODEVEC)
 783                                break;
 784                }
 785                spin_unlock(&sbi->s_inode_lock);
 786
 787                for (pii = ivec; nv > 0; pii++, nv--)
 788                        iput(&(*pii)->vfs_inode);
 789        }
 790}
 791
 792static int nilfs_test_metadata_dirty(struct nilfs_sb_info *sbi)
 793{
 794        struct the_nilfs *nilfs = sbi->s_nilfs;
 795        int ret = 0;
 796
 797        if (nilfs_mdt_fetch_dirty(sbi->s_ifile))
 798                ret++;
 799        if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
 800                ret++;
 801        if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
 802                ret++;
 803        if (ret || nilfs_doing_gc())
 804                if (nilfs_mdt_fetch_dirty(nilfs_dat_inode(nilfs)))
 805                        ret++;
 806        return ret;
 807}
 808
 809static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
 810{
 811        return list_empty(&sci->sc_dirty_files) &&
 812                !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
 813                sci->sc_nfreesegs == 0 &&
 814                (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
 815}
 816
 817static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
 818{
 819        struct nilfs_sb_info *sbi = sci->sc_sbi;
 820        int ret = 0;
 821
 822        if (nilfs_test_metadata_dirty(sbi))
 823                set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
 824
 825        spin_lock(&sbi->s_inode_lock);
 826        if (list_empty(&sbi->s_dirty_files) && nilfs_segctor_clean(sci))
 827                ret++;
 828
 829        spin_unlock(&sbi->s_inode_lock);
 830        return ret;
 831}
 832
 833static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
 834{
 835        struct nilfs_sb_info *sbi = sci->sc_sbi;
 836        struct the_nilfs *nilfs = sbi->s_nilfs;
 837
 838        nilfs_mdt_clear_dirty(sbi->s_ifile);
 839        nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
 840        nilfs_mdt_clear_dirty(nilfs->ns_sufile);
 841        nilfs_mdt_clear_dirty(nilfs_dat_inode(nilfs));
 842}
 843
 844static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
 845{
 846        struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
 847        struct buffer_head *bh_cp;
 848        struct nilfs_checkpoint *raw_cp;
 849        int err;
 850
 851        /* XXX: this interface will be changed */
 852        err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
 853                                          &raw_cp, &bh_cp);
 854        if (likely(!err)) {
 855                /* The following code is duplicated with cpfile.  But, it is
 856                   needed to collect the checkpoint even if it was not newly
 857                   created */
 858                nilfs_mdt_mark_buffer_dirty(bh_cp);
 859                nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
 860                nilfs_cpfile_put_checkpoint(
 861                        nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
 862        } else
 863                WARN_ON(err == -EINVAL || err == -ENOENT);
 864
 865        return err;
 866}
 867
 868static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
 869{
 870        struct nilfs_sb_info *sbi = sci->sc_sbi;
 871        struct the_nilfs *nilfs = sbi->s_nilfs;
 872        struct buffer_head *bh_cp;
 873        struct nilfs_checkpoint *raw_cp;
 874        int err;
 875
 876        err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
 877                                          &raw_cp, &bh_cp);
 878        if (unlikely(err)) {
 879                WARN_ON(err == -EINVAL || err == -ENOENT);
 880                goto failed_ibh;
 881        }
 882        raw_cp->cp_snapshot_list.ssl_next = 0;
 883        raw_cp->cp_snapshot_list.ssl_prev = 0;
 884        raw_cp->cp_inodes_count =
 885                cpu_to_le64(atomic_read(&sbi->s_inodes_count));
 886        raw_cp->cp_blocks_count =
 887                cpu_to_le64(atomic_read(&sbi->s_blocks_count));
 888        raw_cp->cp_nblk_inc =
 889                cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
 890        raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
 891        raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
 892
 893        if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
 894                nilfs_checkpoint_clear_minor(raw_cp);
 895        else
 896                nilfs_checkpoint_set_minor(raw_cp);
 897
 898        nilfs_write_inode_common(sbi->s_ifile, &raw_cp->cp_ifile_inode, 1);
 899        nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
 900        return 0;
 901
 902 failed_ibh:
 903        return err;
 904}
 905
 906static void nilfs_fill_in_file_bmap(struct inode *ifile,
 907                                    struct nilfs_inode_info *ii)
 908
 909{
 910        struct buffer_head *ibh;
 911        struct nilfs_inode *raw_inode;
 912
 913        if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
 914                ibh = ii->i_bh;
 915                BUG_ON(!ibh);
 916                raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
 917                                                  ibh);
 918                nilfs_bmap_write(ii->i_bmap, raw_inode);
 919                nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
 920        }
 921}
 922
 923static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci,
 924                                            struct inode *ifile)
 925{
 926        struct nilfs_inode_info *ii;
 927
 928        list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
 929                nilfs_fill_in_file_bmap(ifile, ii);
 930                set_bit(NILFS_I_COLLECTED, &ii->i_state);
 931        }
 932}
 933
 934/*
 935 * CRC calculation routines
 936 */
 937static void nilfs_fill_in_super_root_crc(struct buffer_head *bh_sr, u32 seed)
 938{
 939        struct nilfs_super_root *raw_sr =
 940                (struct nilfs_super_root *)bh_sr->b_data;
 941        u32 crc;
 942
 943        crc = crc32_le(seed,
 944                       (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
 945                       NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
 946        raw_sr->sr_sum = cpu_to_le32(crc);
 947}
 948
 949static void nilfs_segctor_fill_in_checksums(struct nilfs_sc_info *sci,
 950                                            u32 seed)
 951{
 952        struct nilfs_segment_buffer *segbuf;
 953
 954        if (sci->sc_super_root)
 955                nilfs_fill_in_super_root_crc(sci->sc_super_root, seed);
 956
 957        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
 958                nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
 959                nilfs_segbuf_fill_in_data_crc(segbuf, seed);
 960        }
 961}
 962
 963static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
 964                                             struct the_nilfs *nilfs)
 965{
 966        struct buffer_head *bh_sr = sci->sc_super_root;
 967        struct nilfs_super_root *raw_sr =
 968                (struct nilfs_super_root *)bh_sr->b_data;
 969        unsigned isz = nilfs->ns_inode_size;
 970
 971        raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES);
 972        raw_sr->sr_nongc_ctime
 973                = cpu_to_le64(nilfs_doing_gc() ?
 974                              nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
 975        raw_sr->sr_flags = 0;
 976
 977        nilfs_mdt_write_inode_direct(
 978                nilfs_dat_inode(nilfs), bh_sr, NILFS_SR_DAT_OFFSET(isz));
 979        nilfs_mdt_write_inode_direct(
 980                nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(isz));
 981        nilfs_mdt_write_inode_direct(
 982                nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(isz));
 983}
 984
 985static void nilfs_redirty_inodes(struct list_head *head)
 986{
 987        struct nilfs_inode_info *ii;
 988
 989        list_for_each_entry(ii, head, i_dirty) {
 990                if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
 991                        clear_bit(NILFS_I_COLLECTED, &ii->i_state);
 992        }
 993}
 994
 995static void nilfs_drop_collected_inodes(struct list_head *head)
 996{
 997        struct nilfs_inode_info *ii;
 998
 999        list_for_each_entry(ii, head, i_dirty) {
1000                if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1001                        continue;
1002
1003                clear_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
1004                set_bit(NILFS_I_UPDATED, &ii->i_state);
1005        }
1006}
1007
1008static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1009                                       struct inode *inode,
1010                                       struct list_head *listp,
1011                                       int (*collect)(struct nilfs_sc_info *,
1012                                                      struct buffer_head *,
1013                                                      struct inode *))
1014{
1015        struct buffer_head *bh, *n;
1016        int err = 0;
1017
1018        if (collect) {
1019                list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1020                        list_del_init(&bh->b_assoc_buffers);
1021                        err = collect(sci, bh, inode);
1022                        brelse(bh);
1023                        if (unlikely(err))
1024                                goto dispose_buffers;
1025                }
1026                return 0;
1027        }
1028
1029 dispose_buffers:
1030        while (!list_empty(listp)) {
1031                bh = list_entry(listp->next, struct buffer_head,
1032                                b_assoc_buffers);
1033                list_del_init(&bh->b_assoc_buffers);
1034                brelse(bh);
1035        }
1036        return err;
1037}
1038
1039static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1040{
1041        /* Remaining number of blocks within segment buffer */
1042        return sci->sc_segbuf_nblocks -
1043                (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1044}
1045
1046static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1047                                   struct inode *inode,
1048                                   struct nilfs_sc_operations *sc_ops)
1049{
1050        LIST_HEAD(data_buffers);
1051        LIST_HEAD(node_buffers);
1052        int err;
1053
1054        if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1055                size_t n, rest = nilfs_segctor_buffer_rest(sci);
1056
1057                n = nilfs_lookup_dirty_data_buffers(
1058                        inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1059                if (n > rest) {
1060                        err = nilfs_segctor_apply_buffers(
1061                                sci, inode, &data_buffers,
1062                                sc_ops->collect_data);
1063                        BUG_ON(!err); /* always receive -E2BIG or true error */
1064                        goto break_or_fail;
1065                }
1066        }
1067        nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1068
1069        if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1070                err = nilfs_segctor_apply_buffers(
1071                        sci, inode, &data_buffers, sc_ops->collect_data);
1072                if (unlikely(err)) {
1073                        /* dispose node list */
1074                        nilfs_segctor_apply_buffers(
1075                                sci, inode, &node_buffers, NULL);
1076                        goto break_or_fail;
1077                }
1078                sci->sc_stage.flags |= NILFS_CF_NODE;
1079        }
1080        /* Collect node */
1081        err = nilfs_segctor_apply_buffers(
1082                sci, inode, &node_buffers, sc_ops->collect_node);
1083        if (unlikely(err))
1084                goto break_or_fail;
1085
1086        nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1087        err = nilfs_segctor_apply_buffers(
1088                sci, inode, &node_buffers, sc_ops->collect_bmap);
1089        if (unlikely(err))
1090                goto break_or_fail;
1091
1092        nilfs_segctor_end_finfo(sci, inode);
1093        sci->sc_stage.flags &= ~NILFS_CF_NODE;
1094
1095 break_or_fail:
1096        return err;
1097}
1098
1099static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1100                                         struct inode *inode)
1101{
1102        LIST_HEAD(data_buffers);
1103        size_t n, rest = nilfs_segctor_buffer_rest(sci);
1104        int err;
1105
1106        n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1107                                            sci->sc_dsync_start,
1108                                            sci->sc_dsync_end);
1109
1110        err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1111                                          nilfs_collect_file_data);
1112        if (!err) {
1113                nilfs_segctor_end_finfo(sci, inode);
1114                BUG_ON(n > rest);
1115                /* always receive -E2BIG or true error if n > rest */
1116        }
1117        return err;
1118}
1119
1120static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1121{
1122        struct nilfs_sb_info *sbi = sci->sc_sbi;
1123        struct the_nilfs *nilfs = sbi->s_nilfs;
1124        struct list_head *head;
1125        struct nilfs_inode_info *ii;
1126        size_t ndone;
1127        int err = 0;
1128
1129        switch (sci->sc_stage.scnt) {
1130        case NILFS_ST_INIT:
1131                /* Pre-processes */
1132                sci->sc_stage.flags = 0;
1133
1134                if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1135                        sci->sc_nblk_inc = 0;
1136                        sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1137                        if (mode == SC_LSEG_DSYNC) {
1138                                sci->sc_stage.scnt = NILFS_ST_DSYNC;
1139                                goto dsync_mode;
1140                        }
1141                }
1142
1143                sci->sc_stage.dirty_file_ptr = NULL;
1144                sci->sc_stage.gc_inode_ptr = NULL;
1145                if (mode == SC_FLUSH_DAT) {
1146                        sci->sc_stage.scnt = NILFS_ST_DAT;
1147                        goto dat_stage;
1148                }
1149                sci->sc_stage.scnt++;  /* Fall through */
1150        case NILFS_ST_GC:
1151                if (nilfs_doing_gc()) {
1152                        head = &sci->sc_gc_inodes;
1153                        ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1154                                                head, i_dirty);
1155                        list_for_each_entry_continue(ii, head, i_dirty) {
1156                                err = nilfs_segctor_scan_file(
1157                                        sci, &ii->vfs_inode,
1158                                        &nilfs_sc_file_ops);
1159                                if (unlikely(err)) {
1160                                        sci->sc_stage.gc_inode_ptr = list_entry(
1161                                                ii->i_dirty.prev,
1162                                                struct nilfs_inode_info,
1163                                                i_dirty);
1164                                        goto break_or_fail;
1165                                }
1166                                set_bit(NILFS_I_COLLECTED, &ii->i_state);
1167                        }
1168                        sci->sc_stage.gc_inode_ptr = NULL;
1169                }
1170                sci->sc_stage.scnt++;  /* Fall through */
1171        case NILFS_ST_FILE:
1172                head = &sci->sc_dirty_files;
1173                ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1174                                        i_dirty);
1175                list_for_each_entry_continue(ii, head, i_dirty) {
1176                        clear_bit(NILFS_I_DIRTY, &ii->i_state);
1177
1178                        err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1179                                                      &nilfs_sc_file_ops);
1180                        if (unlikely(err)) {
1181                                sci->sc_stage.dirty_file_ptr =
1182                                        list_entry(ii->i_dirty.prev,
1183                                                   struct nilfs_inode_info,
1184                                                   i_dirty);
1185                                goto break_or_fail;
1186                        }
1187                        /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1188                        /* XXX: required ? */
1189                }
1190                sci->sc_stage.dirty_file_ptr = NULL;
1191                if (mode == SC_FLUSH_FILE) {
1192                        sci->sc_stage.scnt = NILFS_ST_DONE;
1193                        return 0;
1194                }
1195                sci->sc_stage.scnt++;
1196                sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1197                /* Fall through */
1198        case NILFS_ST_IFILE:
1199                err = nilfs_segctor_scan_file(sci, sbi->s_ifile,
1200                                              &nilfs_sc_file_ops);
1201                if (unlikely(err))
1202                        break;
1203                sci->sc_stage.scnt++;
1204                /* Creating a checkpoint */
1205                err = nilfs_segctor_create_checkpoint(sci);
1206                if (unlikely(err))
1207                        break;
1208                /* Fall through */
1209        case NILFS_ST_CPFILE:
1210                err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1211                                              &nilfs_sc_file_ops);
1212                if (unlikely(err))
1213                        break;
1214                sci->sc_stage.scnt++;  /* Fall through */
1215        case NILFS_ST_SUFILE:
1216                err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1217                                         sci->sc_nfreesegs, &ndone);
1218                if (unlikely(err)) {
1219                        nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1220                                                  sci->sc_freesegs, ndone,
1221                                                  NULL);
1222                        break;
1223                }
1224                sci->sc_stage.flags |= NILFS_CF_SUFREED;
1225
1226                err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1227                                              &nilfs_sc_file_ops);
1228                if (unlikely(err))
1229                        break;
1230                sci->sc_stage.scnt++;  /* Fall through */
1231        case NILFS_ST_DAT:
1232 dat_stage:
1233                err = nilfs_segctor_scan_file(sci, nilfs_dat_inode(nilfs),
1234                                              &nilfs_sc_dat_ops);
1235                if (unlikely(err))
1236                        break;
1237                if (mode == SC_FLUSH_DAT) {
1238                        sci->sc_stage.scnt = NILFS_ST_DONE;
1239                        return 0;
1240                }
1241                sci->sc_stage.scnt++;  /* Fall through */
1242        case NILFS_ST_SR:
1243                if (mode == SC_LSEG_SR) {
1244                        /* Appending a super root */
1245                        err = nilfs_segctor_add_super_root(sci);
1246                        if (unlikely(err))
1247                                break;
1248                }
1249                /* End of a logical segment */
1250                sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1251                sci->sc_stage.scnt = NILFS_ST_DONE;
1252                return 0;
1253        case NILFS_ST_DSYNC:
1254 dsync_mode:
1255                sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1256                ii = sci->sc_dsync_inode;
1257                if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1258                        break;
1259
1260                err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1261                if (unlikely(err))
1262                        break;
1263                sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1264                sci->sc_stage.scnt = NILFS_ST_DONE;
1265                return 0;
1266        case NILFS_ST_DONE:
1267                return 0;
1268        default:
1269                BUG();
1270        }
1271
1272 break_or_fail:
1273        return err;
1274}
1275
1276static int nilfs_touch_segusage(struct inode *sufile, __u64 segnum)
1277{
1278        struct buffer_head *bh_su;
1279        struct nilfs_segment_usage *raw_su;
1280        int err;
1281
1282        err = nilfs_sufile_get_segment_usage(sufile, segnum, &raw_su, &bh_su);
1283        if (unlikely(err))
1284                return err;
1285        nilfs_mdt_mark_buffer_dirty(bh_su);
1286        nilfs_mdt_mark_dirty(sufile);
1287        nilfs_sufile_put_segment_usage(sufile, segnum, bh_su);
1288        return 0;
1289}
1290
1291static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1292                                            struct the_nilfs *nilfs)
1293{
1294        struct nilfs_segment_buffer *segbuf, *n;
1295        __u64 nextnum;
1296        int err;
1297
1298        if (list_empty(&sci->sc_segbufs)) {
1299                segbuf = nilfs_segbuf_new(sci->sc_super);
1300                if (unlikely(!segbuf))
1301                        return -ENOMEM;
1302                list_add(&segbuf->sb_list, &sci->sc_segbufs);
1303        } else
1304                segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1305
1306        nilfs_segbuf_map(segbuf, nilfs->ns_segnum, nilfs->ns_pseg_offset,
1307                         nilfs);
1308
1309        if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1310                nilfs_shift_to_next_segment(nilfs);
1311                nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1312        }
1313        sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1314
1315        err = nilfs_touch_segusage(nilfs->ns_sufile, segbuf->sb_segnum);
1316        if (unlikely(err))
1317                return err;
1318
1319        if (nilfs->ns_segnum == nilfs->ns_nextnum) {
1320                /* Start from the head of a new full segment */
1321                err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1322                if (unlikely(err))
1323                        return err;
1324        } else
1325                nextnum = nilfs->ns_nextnum;
1326
1327        segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1328        nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1329
1330        /* truncating segment buffers */
1331        list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
1332                                          sb_list) {
1333                list_del_init(&segbuf->sb_list);
1334                nilfs_segbuf_free(segbuf);
1335        }
1336        return 0;
1337}
1338
1339static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1340                                         struct the_nilfs *nilfs, int nadd)
1341{
1342        struct nilfs_segment_buffer *segbuf, *prev, *n;
1343        struct inode *sufile = nilfs->ns_sufile;
1344        __u64 nextnextnum;
1345        LIST_HEAD(list);
1346        int err, ret, i;
1347
1348        prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1349        /*
1350         * Since the segment specified with nextnum might be allocated during
1351         * the previous construction, the buffer including its segusage may
1352         * not be dirty.  The following call ensures that the buffer is dirty
1353         * and will pin the buffer on memory until the sufile is written.
1354         */
1355        err = nilfs_touch_segusage(sufile, prev->sb_nextnum);
1356        if (unlikely(err))
1357                return err;
1358
1359        for (i = 0; i < nadd; i++) {
1360                /* extend segment info */
1361                err = -ENOMEM;
1362                segbuf = nilfs_segbuf_new(sci->sc_super);
1363                if (unlikely(!segbuf))
1364                        goto failed;
1365
1366                /* map this buffer to region of segment on-disk */
1367                nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1368                sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1369
1370                /* allocate the next next full segment */
1371                err = nilfs_sufile_alloc(sufile, &nextnextnum);
1372                if (unlikely(err))
1373                        goto failed_segbuf;
1374
1375                segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1376                nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1377
1378                list_add_tail(&segbuf->sb_list, &list);
1379                prev = segbuf;
1380        }
1381        list_splice(&list, sci->sc_segbufs.prev);
1382        return 0;
1383
1384 failed_segbuf:
1385        nilfs_segbuf_free(segbuf);
1386 failed:
1387        list_for_each_entry_safe(segbuf, n, &list, sb_list) {
1388                ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1389                WARN_ON(ret); /* never fails */
1390                list_del_init(&segbuf->sb_list);
1391                nilfs_segbuf_free(segbuf);
1392        }
1393        return err;
1394}
1395
1396static void nilfs_segctor_free_incomplete_segments(struct nilfs_sc_info *sci,
1397                                                   struct the_nilfs *nilfs)
1398{
1399        struct nilfs_segment_buffer *segbuf;
1400        int ret, done = 0;
1401
1402        segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1403        if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1404                ret = nilfs_sufile_free(nilfs->ns_sufile, segbuf->sb_nextnum);
1405                WARN_ON(ret); /* never fails */
1406        }
1407        if (segbuf->sb_io_error) {
1408                /* Case 1: The first segment failed */
1409                if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1410                        /* Case 1a:  Partial segment appended into an existing
1411                           segment */
1412                        nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1413                                                segbuf->sb_fseg_end);
1414                else /* Case 1b:  New full segment */
1415                        set_nilfs_discontinued(nilfs);
1416                done++;
1417        }
1418
1419        list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1420                ret = nilfs_sufile_free(nilfs->ns_sufile, segbuf->sb_nextnum);
1421                WARN_ON(ret); /* never fails */
1422                if (!done && segbuf->sb_io_error) {
1423                        if (segbuf->sb_segnum != nilfs->ns_nextnum)
1424                                /* Case 2: extended segment (!= next) failed */
1425                                nilfs_sufile_set_error(nilfs->ns_sufile,
1426                                                       segbuf->sb_segnum);
1427                        done++;
1428                }
1429        }
1430}
1431
1432static void nilfs_segctor_clear_segment_buffers(struct nilfs_sc_info *sci)
1433{
1434        struct nilfs_segment_buffer *segbuf;
1435
1436        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list)
1437                nilfs_segbuf_clear(segbuf);
1438        sci->sc_super_root = NULL;
1439}
1440
1441static void nilfs_segctor_destroy_segment_buffers(struct nilfs_sc_info *sci)
1442{
1443        struct nilfs_segment_buffer *segbuf;
1444
1445        while (!list_empty(&sci->sc_segbufs)) {
1446                segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1447                list_del_init(&segbuf->sb_list);
1448                nilfs_segbuf_free(segbuf);
1449        }
1450        /* sci->sc_curseg = NULL; */
1451}
1452
1453static void nilfs_segctor_end_construction(struct nilfs_sc_info *sci,
1454                                           struct the_nilfs *nilfs, int err)
1455{
1456        if (unlikely(err)) {
1457                nilfs_segctor_free_incomplete_segments(sci, nilfs);
1458                if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1459                        int ret;
1460
1461                        ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1462                                                        sci->sc_freesegs,
1463                                                        sci->sc_nfreesegs,
1464                                                        NULL);
1465                        WARN_ON(ret); /* do not happen */
1466                }
1467        }
1468        nilfs_segctor_clear_segment_buffers(sci);
1469}
1470
1471static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1472                                          struct inode *sufile)
1473{
1474        struct nilfs_segment_buffer *segbuf;
1475        struct buffer_head *bh_su;
1476        struct nilfs_segment_usage *raw_su;
1477        unsigned long live_blocks;
1478        int ret;
1479
1480        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1481                ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
1482                                                     &raw_su, &bh_su);
1483                WARN_ON(ret); /* always succeed because bh_su is dirty */
1484                live_blocks = segbuf->sb_sum.nblocks +
1485                        (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1486                raw_su->su_lastmod = cpu_to_le64(sci->sc_seg_ctime);
1487                raw_su->su_nblocks = cpu_to_le32(live_blocks);
1488                nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum,
1489                                               bh_su);
1490        }
1491}
1492
1493static void nilfs_segctor_cancel_segusage(struct nilfs_sc_info *sci,
1494                                          struct inode *sufile)
1495{
1496        struct nilfs_segment_buffer *segbuf;
1497        struct buffer_head *bh_su;
1498        struct nilfs_segment_usage *raw_su;
1499        int ret;
1500
1501        segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1502        ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
1503                                             &raw_su, &bh_su);
1504        WARN_ON(ret); /* always succeed because bh_su is dirty */
1505        raw_su->su_nblocks = cpu_to_le32(segbuf->sb_pseg_start -
1506                                         segbuf->sb_fseg_start);
1507        nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum, bh_su);
1508
1509        list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1510                ret = nilfs_sufile_get_segment_usage(sufile, segbuf->sb_segnum,
1511                                                     &raw_su, &bh_su);
1512                WARN_ON(ret); /* always succeed */
1513                raw_su->su_nblocks = 0;
1514                nilfs_sufile_put_segment_usage(sufile, segbuf->sb_segnum,
1515                                               bh_su);
1516        }
1517}
1518
1519static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1520                                            struct nilfs_segment_buffer *last,
1521                                            struct inode *sufile)
1522{
1523        struct nilfs_segment_buffer *segbuf = last, *n;
1524        int ret;
1525
1526        list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
1527                                          sb_list) {
1528                list_del_init(&segbuf->sb_list);
1529                sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1530                ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1531                WARN_ON(ret);
1532                nilfs_segbuf_free(segbuf);
1533        }
1534}
1535
1536
1537static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1538                                 struct the_nilfs *nilfs, int mode)
1539{
1540        struct nilfs_cstage prev_stage = sci->sc_stage;
1541        int err, nadd = 1;
1542
1543        /* Collection retry loop */
1544        for (;;) {
1545                sci->sc_super_root = NULL;
1546                sci->sc_nblk_this_inc = 0;
1547                sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1548
1549                err = nilfs_segctor_reset_segment_buffer(sci);
1550                if (unlikely(err))
1551                        goto failed;
1552
1553                err = nilfs_segctor_collect_blocks(sci, mode);
1554                sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1555                if (!err)
1556                        break;
1557
1558                if (unlikely(err != -E2BIG))
1559                        goto failed;
1560
1561                /* The current segment is filled up */
1562                if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
1563                        break;
1564
1565                if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1566                        err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1567                                                        sci->sc_freesegs,
1568                                                        sci->sc_nfreesegs,
1569                                                        NULL);
1570                        WARN_ON(err); /* do not happen */
1571                }
1572                nilfs_segctor_clear_segment_buffers(sci);
1573
1574                err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1575                if (unlikely(err))
1576                        return err;
1577
1578                nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1579                sci->sc_stage = prev_stage;
1580        }
1581        nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1582        return 0;
1583
1584 failed:
1585        return err;
1586}
1587
1588static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1589                                      struct buffer_head *new_bh)
1590{
1591        BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1592
1593        list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1594        /* The caller must release old_bh */
1595}
1596
1597static int
1598nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1599                                     struct nilfs_segment_buffer *segbuf,
1600                                     int mode)
1601{
1602        struct inode *inode = NULL;
1603        sector_t blocknr;
1604        unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1605        unsigned long nblocks = 0, ndatablk = 0;
1606        struct nilfs_sc_operations *sc_op = NULL;
1607        struct nilfs_segsum_pointer ssp;
1608        struct nilfs_finfo *finfo = NULL;
1609        union nilfs_binfo binfo;
1610        struct buffer_head *bh, *bh_org;
1611        ino_t ino = 0;
1612        int err = 0;
1613
1614        if (!nfinfo)
1615                goto out;
1616
1617        blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1618        ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1619        ssp.offset = sizeof(struct nilfs_segment_summary);
1620
1621        list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1622                if (bh == sci->sc_super_root)
1623                        break;
1624                if (!finfo) {
1625                        finfo = nilfs_segctor_map_segsum_entry(
1626                                sci, &ssp, sizeof(*finfo));
1627                        ino = le64_to_cpu(finfo->fi_ino);
1628                        nblocks = le32_to_cpu(finfo->fi_nblocks);
1629                        ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1630
1631                        if (buffer_nilfs_node(bh))
1632                                inode = NILFS_BTNC_I(bh->b_page->mapping);
1633                        else
1634                                inode = NILFS_AS_I(bh->b_page->mapping);
1635
1636                        if (mode == SC_LSEG_DSYNC)
1637                                sc_op = &nilfs_sc_dsync_ops;
1638                        else if (ino == NILFS_DAT_INO)
1639                                sc_op = &nilfs_sc_dat_ops;
1640                        else /* file blocks */
1641                                sc_op = &nilfs_sc_file_ops;
1642                }
1643                bh_org = bh;
1644                get_bh(bh_org);
1645                err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1646                                        &binfo);
1647                if (bh != bh_org)
1648                        nilfs_list_replace_buffer(bh_org, bh);
1649                brelse(bh_org);
1650                if (unlikely(err))
1651                        goto failed_bmap;
1652
1653                if (ndatablk > 0)
1654                        sc_op->write_data_binfo(sci, &ssp, &binfo);
1655                else
1656                        sc_op->write_node_binfo(sci, &ssp, &binfo);
1657
1658                blocknr++;
1659                if (--nblocks == 0) {
1660                        finfo = NULL;
1661                        if (--nfinfo == 0)
1662                                break;
1663                } else if (ndatablk > 0)
1664                        ndatablk--;
1665        }
1666 out:
1667        return 0;
1668
1669 failed_bmap:
1670        err = nilfs_handle_bmap_error(err, __func__, inode, sci->sc_super);
1671        return err;
1672}
1673
1674static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1675{
1676        struct nilfs_segment_buffer *segbuf;
1677        int err;
1678
1679        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1680                err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1681                if (unlikely(err))
1682                        return err;
1683                nilfs_segbuf_fill_in_segsum(segbuf);
1684        }
1685        return 0;
1686}
1687
1688static int
1689nilfs_copy_replace_page_buffers(struct page *page, struct list_head *out)
1690{
1691        struct page *clone_page;
1692        struct buffer_head *bh, *head, *bh2;
1693        void *kaddr;
1694
1695        bh = head = page_buffers(page);
1696
1697        clone_page = nilfs_alloc_private_page(bh->b_bdev, bh->b_size, 0);
1698        if (unlikely(!clone_page))
1699                return -ENOMEM;
1700
1701        bh2 = page_buffers(clone_page);
1702        kaddr = kmap_atomic(page, KM_USER0);
1703        do {
1704                if (list_empty(&bh->b_assoc_buffers))
1705                        continue;
1706                get_bh(bh2);
1707                page_cache_get(clone_page); /* for each bh */
1708                memcpy(bh2->b_data, kaddr + bh_offset(bh), bh2->b_size);
1709                bh2->b_blocknr = bh->b_blocknr;
1710                list_replace(&bh->b_assoc_buffers, &bh2->b_assoc_buffers);
1711                list_add_tail(&bh->b_assoc_buffers, out);
1712        } while (bh = bh->b_this_page, bh2 = bh2->b_this_page, bh != head);
1713        kunmap_atomic(kaddr, KM_USER0);
1714
1715        if (!TestSetPageWriteback(clone_page))
1716                inc_zone_page_state(clone_page, NR_WRITEBACK);
1717        unlock_page(clone_page);
1718
1719        return 0;
1720}
1721
1722static int nilfs_test_page_to_be_frozen(struct page *page)
1723{
1724        struct address_space *mapping = page->mapping;
1725
1726        if (!mapping || !mapping->host || S_ISDIR(mapping->host->i_mode))
1727                return 0;
1728
1729        if (page_mapped(page)) {
1730                ClearPageChecked(page);
1731                return 1;
1732        }
1733        return PageChecked(page);
1734}
1735
1736static int nilfs_begin_page_io(struct page *page, struct list_head *out)
1737{
1738        if (!page || PageWriteback(page))
1739                /* For split b-tree node pages, this function may be called
1740                   twice.  We ignore the 2nd or later calls by this check. */
1741                return 0;
1742
1743        lock_page(page);
1744        clear_page_dirty_for_io(page);
1745        set_page_writeback(page);
1746        unlock_page(page);
1747
1748        if (nilfs_test_page_to_be_frozen(page)) {
1749                int err = nilfs_copy_replace_page_buffers(page, out);
1750                if (unlikely(err))
1751                        return err;
1752        }
1753        return 0;
1754}
1755
1756static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
1757                                       struct page **failed_page)
1758{
1759        struct nilfs_segment_buffer *segbuf;
1760        struct page *bd_page = NULL, *fs_page = NULL;
1761        struct list_head *list = &sci->sc_copied_buffers;
1762        int err;
1763
1764        *failed_page = NULL;
1765        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1766                struct buffer_head *bh;
1767
1768                list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1769                                    b_assoc_buffers) {
1770                        if (bh->b_page != bd_page) {
1771                                if (bd_page) {
1772                                        lock_page(bd_page);
1773                                        clear_page_dirty_for_io(bd_page);
1774                                        set_page_writeback(bd_page);
1775                                        unlock_page(bd_page);
1776                                }
1777                                bd_page = bh->b_page;
1778                        }
1779                }
1780
1781                list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1782                                    b_assoc_buffers) {
1783                        if (bh == sci->sc_super_root) {
1784                                if (bh->b_page != bd_page) {
1785                                        lock_page(bd_page);
1786                                        clear_page_dirty_for_io(bd_page);
1787                                        set_page_writeback(bd_page);
1788                                        unlock_page(bd_page);
1789                                        bd_page = bh->b_page;
1790                                }
1791                                break;
1792                        }
1793                        if (bh->b_page != fs_page) {
1794                                err = nilfs_begin_page_io(fs_page, list);
1795                                if (unlikely(err)) {
1796                                        *failed_page = fs_page;
1797                                        goto out;
1798                                }
1799                                fs_page = bh->b_page;
1800                        }
1801                }
1802        }
1803        if (bd_page) {
1804                lock_page(bd_page);
1805                clear_page_dirty_for_io(bd_page);
1806                set_page_writeback(bd_page);
1807                unlock_page(bd_page);
1808        }
1809        err = nilfs_begin_page_io(fs_page, list);
1810        if (unlikely(err))
1811                *failed_page = fs_page;
1812 out:
1813        return err;
1814}
1815
1816static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1817                               struct backing_dev_info *bdi)
1818{
1819        struct nilfs_segment_buffer *segbuf;
1820        struct nilfs_write_info wi;
1821        int err, res;
1822
1823        wi.sb = sci->sc_super;
1824        wi.bh_sr = sci->sc_super_root;
1825        wi.bdi = bdi;
1826
1827        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1828                nilfs_segbuf_prepare_write(segbuf, &wi);
1829                err = nilfs_segbuf_write(segbuf, &wi);
1830
1831                res = nilfs_segbuf_wait(segbuf, &wi);
1832                err = err ? : res;
1833                if (err)
1834                        return err;
1835        }
1836        return 0;
1837}
1838
1839static void __nilfs_end_page_io(struct page *page, int err)
1840{
1841        if (!err) {
1842                if (!nilfs_page_buffers_clean(page))
1843                        __set_page_dirty_nobuffers(page);
1844                ClearPageError(page);
1845        } else {
1846                __set_page_dirty_nobuffers(page);
1847                SetPageError(page);
1848        }
1849
1850        if (buffer_nilfs_allocated(page_buffers(page))) {
1851                if (TestClearPageWriteback(page))
1852                        dec_zone_page_state(page, NR_WRITEBACK);
1853        } else
1854                end_page_writeback(page);
1855}
1856
1857static void nilfs_end_page_io(struct page *page, int err)
1858{
1859        if (!page)
1860                return;
1861
1862        if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1863                /*
1864                 * For b-tree node pages, this function may be called twice
1865                 * or more because they might be split in a segment.
1866                 */
1867                if (PageDirty(page)) {
1868                        /*
1869                         * For pages holding split b-tree node buffers, dirty
1870                         * flag on the buffers may be cleared discretely.
1871                         * In that case, the page is once redirtied for
1872                         * remaining buffers, and it must be cancelled if
1873                         * all the buffers get cleaned later.
1874                         */
1875                        lock_page(page);
1876                        if (nilfs_page_buffers_clean(page))
1877                                __nilfs_clear_page_dirty(page);
1878                        unlock_page(page);
1879                }
1880                return;
1881        }
1882
1883        __nilfs_end_page_io(page, err);
1884}
1885
1886static void nilfs_clear_copied_buffers(struct list_head *list, int err)
1887{
1888        struct buffer_head *bh, *head;
1889        struct page *page;
1890
1891        while (!list_empty(list)) {
1892                bh = list_entry(list->next, struct buffer_head,
1893                                b_assoc_buffers);
1894                page = bh->b_page;
1895                page_cache_get(page);
1896                head = bh = page_buffers(page);
1897                do {
1898                        if (!list_empty(&bh->b_assoc_buffers)) {
1899                                list_del_init(&bh->b_assoc_buffers);
1900                                if (!err) {
1901                                        set_buffer_uptodate(bh);
1902                                        clear_buffer_dirty(bh);
1903                                        clear_buffer_nilfs_volatile(bh);
1904                                }
1905                                brelse(bh); /* for b_assoc_buffers */
1906                        }
1907                } while ((bh = bh->b_this_page) != head);
1908
1909                __nilfs_end_page_io(page, err);
1910                page_cache_release(page);
1911        }
1912}
1913
1914static void nilfs_segctor_abort_write(struct nilfs_sc_info *sci,
1915                                      struct page *failed_page, int err)
1916{
1917        struct nilfs_segment_buffer *segbuf;
1918        struct page *bd_page = NULL, *fs_page = NULL;
1919
1920        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1921                struct buffer_head *bh;
1922
1923                list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1924                                    b_assoc_buffers) {
1925                        if (bh->b_page != bd_page) {
1926                                if (bd_page)
1927                                        end_page_writeback(bd_page);
1928                                bd_page = bh->b_page;
1929                        }
1930                }
1931
1932                list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1933                                    b_assoc_buffers) {
1934                        if (bh == sci->sc_super_root) {
1935                                if (bh->b_page != bd_page) {
1936                                        end_page_writeback(bd_page);
1937                                        bd_page = bh->b_page;
1938                                }
1939                                break;
1940                        }
1941                        if (bh->b_page != fs_page) {
1942                                nilfs_end_page_io(fs_page, err);
1943                                if (fs_page && fs_page == failed_page)
1944                                        goto done;
1945                                fs_page = bh->b_page;
1946                        }
1947                }
1948        }
1949        if (bd_page)
1950                end_page_writeback(bd_page);
1951
1952        nilfs_end_page_io(fs_page, err);
1953 done:
1954        nilfs_clear_copied_buffers(&sci->sc_copied_buffers, err);
1955}
1956
1957static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1958                                   struct nilfs_segment_buffer *segbuf)
1959{
1960        nilfs->ns_segnum = segbuf->sb_segnum;
1961        nilfs->ns_nextnum = segbuf->sb_nextnum;
1962        nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1963                + segbuf->sb_sum.nblocks;
1964        nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1965        nilfs->ns_ctime = segbuf->sb_sum.ctime;
1966}
1967
1968static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1969{
1970        struct nilfs_segment_buffer *segbuf;
1971        struct page *bd_page = NULL, *fs_page = NULL;
1972        struct nilfs_sb_info *sbi = sci->sc_sbi;
1973        struct the_nilfs *nilfs = sbi->s_nilfs;
1974        int update_sr = (sci->sc_super_root != NULL);
1975
1976        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1977                struct buffer_head *bh;
1978
1979                list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1980                                    b_assoc_buffers) {
1981                        set_buffer_uptodate(bh);
1982                        clear_buffer_dirty(bh);
1983                        if (bh->b_page != bd_page) {
1984                                if (bd_page)
1985                                        end_page_writeback(bd_page);
1986                                bd_page = bh->b_page;
1987                        }
1988                }
1989                /*
1990                 * We assume that the buffers which belong to the same page
1991                 * continue over the buffer list.
1992                 * Under this assumption, the last BHs of pages is
1993                 * identifiable by the discontinuity of bh->b_page
1994                 * (page != fs_page).
1995                 *
1996                 * For B-tree node blocks, however, this assumption is not
1997                 * guaranteed.  The cleanup code of B-tree node pages needs
1998                 * special care.
1999                 */
2000                list_for_each_entry(bh, &segbuf->sb_payload_buffers,
2001                                    b_assoc_buffers) {
2002                        set_buffer_uptodate(bh);
2003                        clear_buffer_dirty(bh);
2004                        clear_buffer_nilfs_volatile(bh);
2005                        if (bh == sci->sc_super_root) {
2006                                if (bh->b_page != bd_page) {
2007                                        end_page_writeback(bd_page);
2008                                        bd_page = bh->b_page;
2009                                }
2010                                break;
2011                        }
2012                        if (bh->b_page != fs_page) {
2013                                nilfs_end_page_io(fs_page, 0);
2014                                fs_page = bh->b_page;
2015                        }
2016                }
2017
2018                if (!NILFS_SEG_SIMPLEX(&segbuf->sb_sum)) {
2019                        if (NILFS_SEG_LOGBGN(&segbuf->sb_sum)) {
2020                                set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
2021                                sci->sc_lseg_stime = jiffies;
2022                        }
2023                        if (NILFS_SEG_LOGEND(&segbuf->sb_sum))
2024                                clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
2025                }
2026        }
2027        /*
2028         * Since pages may continue over multiple segment buffers,
2029         * end of the last page must be checked outside of the loop.
2030         */
2031        if (bd_page)
2032                end_page_writeback(bd_page);
2033
2034        nilfs_end_page_io(fs_page, 0);
2035
2036        nilfs_clear_copied_buffers(&sci->sc_copied_buffers, 0);
2037
2038        nilfs_drop_collected_inodes(&sci->sc_dirty_files);
2039
2040        if (nilfs_doing_gc()) {
2041                nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
2042                if (update_sr)
2043                        nilfs_commit_gcdat_inode(nilfs);
2044        } else
2045                nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
2046
2047        sci->sc_nblk_inc += sci->sc_nblk_this_inc;
2048
2049        segbuf = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
2050        nilfs_set_next_segment(nilfs, segbuf);
2051
2052        if (update_sr) {
2053                nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
2054                                       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
2055                sbi->s_super->s_dirt = 1;
2056
2057                clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
2058                clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2059                set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
2060        } else
2061                clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
2062}
2063
2064static int nilfs_segctor_check_in_files(struct nilfs_sc_info *sci,
2065                                        struct nilfs_sb_info *sbi)
2066{
2067        struct nilfs_inode_info *ii, *n;
2068        __u64 cno = sbi->s_nilfs->ns_cno;
2069
2070        spin_lock(&sbi->s_inode_lock);
2071 retry:
2072        list_for_each_entry_safe(ii, n, &sbi->s_dirty_files, i_dirty) {
2073                if (!ii->i_bh) {
2074                        struct buffer_head *ibh;
2075                        int err;
2076
2077                        spin_unlock(&sbi->s_inode_lock);
2078                        err = nilfs_ifile_get_inode_block(
2079                                sbi->s_ifile, ii->vfs_inode.i_ino, &ibh);
2080                        if (unlikely(err)) {
2081                                nilfs_warning(sbi->s_super, __func__,
2082                                              "failed to get inode block.\n");
2083                                return err;
2084                        }
2085                        nilfs_mdt_mark_buffer_dirty(ibh);
2086                        nilfs_mdt_mark_dirty(sbi->s_ifile);
2087                        spin_lock(&sbi->s_inode_lock);
2088                        if (likely(!ii->i_bh))
2089                                ii->i_bh = ibh;
2090                        else
2091                                brelse(ibh);
2092                        goto retry;
2093                }
2094                ii->i_cno = cno;
2095
2096                clear_bit(NILFS_I_QUEUED, &ii->i_state);
2097                set_bit(NILFS_I_BUSY, &ii->i_state);
2098                list_del(&ii->i_dirty);
2099                list_add_tail(&ii->i_dirty, &sci->sc_dirty_files);
2100        }
2101        spin_unlock(&sbi->s_inode_lock);
2102
2103        NILFS_I(sbi->s_ifile)->i_cno = cno;
2104
2105        return 0;
2106}
2107
2108static void nilfs_segctor_check_out_files(struct nilfs_sc_info *sci,
2109                                          struct nilfs_sb_info *sbi)
2110{
2111        struct nilfs_transaction_info *ti = current->journal_info;
2112        struct nilfs_inode_info *ii, *n;
2113        __u64 cno = sbi->s_nilfs->ns_cno;
2114
2115        spin_lock(&sbi->s_inode_lock);
2116        list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
2117                if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
2118                    test_bit(NILFS_I_DIRTY, &ii->i_state)) {
2119                        /* The current checkpoint number (=nilfs->ns_cno) is
2120                           changed between check-in and check-out only if the
2121                           super root is written out.  So, we can update i_cno
2122                           for the inodes that remain in the dirty list. */
2123                        ii->i_cno = cno;
2124                        continue;
2125                }
2126                clear_bit(NILFS_I_BUSY, &ii->i_state);
2127                brelse(ii->i_bh);
2128                ii->i_bh = NULL;
2129                list_del(&ii->i_dirty);
2130                list_add_tail(&ii->i_dirty, &ti->ti_garbage);
2131        }
2132        spin_unlock(&sbi->s_inode_lock);
2133}
2134
2135/*
2136 * Main procedure of segment constructor
2137 */
2138static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2139{
2140        struct nilfs_sb_info *sbi = sci->sc_sbi;
2141        struct the_nilfs *nilfs = sbi->s_nilfs;
2142        struct page *failed_page;
2143        int err, has_sr = 0;
2144
2145        sci->sc_stage.scnt = NILFS_ST_INIT;
2146
2147        err = nilfs_segctor_check_in_files(sci, sbi);
2148        if (unlikely(err))
2149                goto out;
2150
2151        if (nilfs_test_metadata_dirty(sbi))
2152                set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2153
2154        if (nilfs_segctor_clean(sci))
2155                goto out;
2156
2157        do {
2158                sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2159
2160                err = nilfs_segctor_begin_construction(sci, nilfs);
2161                if (unlikely(err))
2162                        goto out;
2163
2164                /* Update time stamp */
2165                sci->sc_seg_ctime = get_seconds();
2166
2167                err = nilfs_segctor_collect(sci, nilfs, mode);
2168                if (unlikely(err))
2169                        goto failed;
2170
2171                has_sr = (sci->sc_super_root != NULL);
2172
2173                /* Avoid empty segment */
2174                if (sci->sc_stage.scnt == NILFS_ST_DONE &&
2175                    NILFS_SEG_EMPTY(&sci->sc_curseg->sb_sum)) {
2176                        nilfs_segctor_end_construction(sci, nilfs, 1);
2177                        goto out;
2178                }
2179
2180                err = nilfs_segctor_assign(sci, mode);
2181                if (unlikely(err))
2182                        goto failed;
2183
2184                if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2185                        nilfs_segctor_fill_in_file_bmap(sci, sbi->s_ifile);
2186
2187                if (has_sr) {
2188                        err = nilfs_segctor_fill_in_checkpoint(sci);
2189                        if (unlikely(err))
2190                                goto failed_to_make_up;
2191
2192                        nilfs_segctor_fill_in_super_root(sci, nilfs);
2193                }
2194                nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2195
2196                /* Write partial segments */
2197                err = nilfs_segctor_prepare_write(sci, &failed_page);
2198                if (unlikely(err))
2199                        goto failed_to_write;
2200
2201                nilfs_segctor_fill_in_checksums(sci, nilfs->ns_crc_seed);
2202
2203                err = nilfs_segctor_write(sci, nilfs->ns_bdi);
2204                if (unlikely(err))
2205                        goto failed_to_write;
2206
2207                nilfs_segctor_complete_write(sci);
2208
2209                /* Commit segments */
2210                if (has_sr)
2211                        nilfs_segctor_clear_metadata_dirty(sci);
2212
2213                nilfs_segctor_end_construction(sci, nilfs, 0);
2214
2215        } while (sci->sc_stage.scnt != NILFS_ST_DONE);
2216
2217 out:
2218        nilfs_segctor_destroy_segment_buffers(sci);
2219        nilfs_segctor_check_out_files(sci, sbi);
2220        return err;
2221
2222 failed_to_write:
2223        nilfs_segctor_abort_write(sci, failed_page, err);
2224        nilfs_segctor_cancel_segusage(sci, nilfs->ns_sufile);
2225
2226 failed_to_make_up:
2227        if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2228                nilfs_redirty_inodes(&sci->sc_dirty_files);
2229
2230 failed:
2231        if (nilfs_doing_gc())
2232                nilfs_redirty_inodes(&sci->sc_gc_inodes);
2233        nilfs_segctor_end_construction(sci, nilfs, err);
2234        goto out;
2235}
2236
2237/**
2238 * nilfs_secgtor_start_timer - set timer of background write
2239 * @sci: nilfs_sc_info
2240 *
2241 * If the timer has already been set, it ignores the new request.
2242 * This function MUST be called within a section locking the segment
2243 * semaphore.
2244 */
2245static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2246{
2247        spin_lock(&sci->sc_state_lock);
2248        if (sci->sc_timer && !(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2249                sci->sc_timer->expires = jiffies + sci->sc_interval;
2250                add_timer(sci->sc_timer);
2251                sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2252        }
2253        spin_unlock(&sci->sc_state_lock);
2254}
2255
2256static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2257{
2258        spin_lock(&sci->sc_state_lock);
2259        if (!(sci->sc_flush_request & (1 << bn))) {
2260                unsigned long prev_req = sci->sc_flush_request;
2261
2262                sci->sc_flush_request |= (1 << bn);
2263                if (!prev_req)
2264                        wake_up(&sci->sc_wait_daemon);
2265        }
2266        spin_unlock(&sci->sc_state_lock);
2267}
2268
2269/**
2270 * nilfs_flush_segment - trigger a segment construction for resource control
2271 * @sb: super block
2272 * @ino: inode number of the file to be flushed out.
2273 */
2274void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2275{
2276        struct nilfs_sb_info *sbi = NILFS_SB(sb);
2277        struct nilfs_sc_info *sci = NILFS_SC(sbi);
2278
2279        if (!sci || nilfs_doing_construction())
2280                return;
2281        nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2282                                        /* assign bit 0 to data files */
2283}
2284
2285struct nilfs_segctor_wait_request {
2286        wait_queue_t    wq;
2287        __u32           seq;
2288        int             err;
2289        atomic_t        done;
2290};
2291
2292static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2293{
2294        struct nilfs_segctor_wait_request wait_req;
2295        int err = 0;
2296
2297        spin_lock(&sci->sc_state_lock);
2298        init_wait(&wait_req.wq);
2299        wait_req.err = 0;
2300        atomic_set(&wait_req.done, 0);
2301        wait_req.seq = ++sci->sc_seq_request;
2302        spin_unlock(&sci->sc_state_lock);
2303
2304        init_waitqueue_entry(&wait_req.wq, current);
2305        add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2306        set_current_state(TASK_INTERRUPTIBLE);
2307        wake_up(&sci->sc_wait_daemon);
2308
2309        for (;;) {
2310                if (atomic_read(&wait_req.done)) {
2311                        err = wait_req.err;
2312                        break;
2313                }
2314                if (!signal_pending(current)) {
2315                        schedule();
2316                        continue;
2317                }
2318                err = -ERESTARTSYS;
2319                break;
2320        }
2321        finish_wait(&sci->sc_wait_request, &wait_req.wq);
2322        return err;
2323}
2324
2325static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2326{
2327        struct nilfs_segctor_wait_request *wrq, *n;
2328        unsigned long flags;
2329
2330        spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2331        list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
2332                                 wq.task_list) {
2333                if (!atomic_read(&wrq->done) &&
2334                    nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2335                        wrq->err = err;
2336                        atomic_set(&wrq->done, 1);
2337                }
2338                if (atomic_read(&wrq->done)) {
2339                        wrq->wq.func(&wrq->wq,
2340                                     TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2341                                     0, NULL);
2342                }
2343        }
2344        spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2345}
2346
2347/**
2348 * nilfs_construct_segment - construct a logical segment
2349 * @sb: super block
2350 *
2351 * Return Value: On success, 0 is retured. On errors, one of the following
2352 * negative error code is returned.
2353 *
2354 * %-EROFS - Read only filesystem.
2355 *
2356 * %-EIO - I/O error
2357 *
2358 * %-ENOSPC - No space left on device (only in a panic state).
2359 *
2360 * %-ERESTARTSYS - Interrupted.
2361 *
2362 * %-ENOMEM - Insufficient memory available.
2363 */
2364int nilfs_construct_segment(struct super_block *sb)
2365{
2366        struct nilfs_sb_info *sbi = NILFS_SB(sb);
2367        struct nilfs_sc_info *sci = NILFS_SC(sbi);
2368        struct nilfs_transaction_info *ti;
2369        int err;
2370
2371        if (!sci)
2372                return -EROFS;
2373
2374        /* A call inside transactions causes a deadlock. */
2375        BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2376
2377        err = nilfs_segctor_sync(sci);
2378        return err;
2379}
2380
2381/**
2382 * nilfs_construct_dsync_segment - construct a data-only logical segment
2383 * @sb: super block
2384 * @inode: inode whose data blocks should be written out
2385 * @start: start byte offset
2386 * @end: end byte offset (inclusive)
2387 *
2388 * Return Value: On success, 0 is retured. On errors, one of the following
2389 * negative error code is returned.
2390 *
2391 * %-EROFS - Read only filesystem.
2392 *
2393 * %-EIO - I/O error
2394 *
2395 * %-ENOSPC - No space left on device (only in a panic state).
2396 *
2397 * %-ERESTARTSYS - Interrupted.
2398 *
2399 * %-ENOMEM - Insufficient memory available.
2400 */
2401int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2402                                  loff_t start, loff_t end)
2403{
2404        struct nilfs_sb_info *sbi = NILFS_SB(sb);
2405        struct nilfs_sc_info *sci = NILFS_SC(sbi);
2406        struct nilfs_inode_info *ii;
2407        struct nilfs_transaction_info ti;
2408        int err = 0;
2409
2410        if (!sci)
2411                return -EROFS;
2412
2413        nilfs_transaction_lock(sbi, &ti, 0);
2414
2415        ii = NILFS_I(inode);
2416        if (test_bit(NILFS_I_INODE_DIRTY, &ii->i_state) ||
2417            nilfs_test_opt(sbi, STRICT_ORDER) ||
2418            test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2419            nilfs_discontinued(sbi->s_nilfs)) {
2420                nilfs_transaction_unlock(sbi);
2421                err = nilfs_segctor_sync(sci);
2422                return err;
2423        }
2424
2425        spin_lock(&sbi->s_inode_lock);
2426        if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2427            !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2428                spin_unlock(&sbi->s_inode_lock);
2429                nilfs_transaction_unlock(sbi);
2430                return 0;
2431        }
2432        spin_unlock(&sbi->s_inode_lock);
2433        sci->sc_dsync_inode = ii;
2434        sci->sc_dsync_start = start;
2435        sci->sc_dsync_end = end;
2436
2437        err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2438
2439        nilfs_transaction_unlock(sbi);
2440        return err;
2441}
2442
2443struct nilfs_segctor_req {
2444        int mode;
2445        __u32 seq_accepted;
2446        int sc_err;  /* construction failure */
2447        int sb_err;  /* super block writeback failure */
2448};
2449
2450#define FLUSH_FILE_BIT  (0x1) /* data file only */
2451#define FLUSH_DAT_BIT   (1 << NILFS_DAT_INO) /* DAT only */
2452
2453static void nilfs_segctor_accept(struct nilfs_sc_info *sci,
2454                                 struct nilfs_segctor_req *req)
2455{
2456        req->sc_err = req->sb_err = 0;
2457        spin_lock(&sci->sc_state_lock);
2458        req->seq_accepted = sci->sc_seq_request;
2459        spin_unlock(&sci->sc_state_lock);
2460
2461        if (sci->sc_timer)
2462                del_timer_sync(sci->sc_timer);
2463}
2464
2465static void nilfs_segctor_notify(struct nilfs_sc_info *sci,
2466                                 struct nilfs_segctor_req *req)
2467{
2468        /* Clear requests (even when the construction failed) */
2469        spin_lock(&sci->sc_state_lock);
2470
2471        if (req->mode == SC_LSEG_SR) {
2472                sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2473                sci->sc_seq_done = req->seq_accepted;
2474                nilfs_segctor_wakeup(sci, req->sc_err ? : req->sb_err);
2475                sci->sc_flush_request = 0;
2476        } else {
2477                if (req->mode == SC_FLUSH_FILE)
2478                        sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2479                else if (req->mode == SC_FLUSH_DAT)
2480                        sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2481
2482                /* re-enable timer if checkpoint creation was not done */
2483                if (sci->sc_timer && (sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2484                    time_before(jiffies, sci->sc_timer->expires))
2485                        add_timer(sci->sc_timer);
2486        }
2487        spin_unlock(&sci->sc_state_lock);
2488}
2489
2490static int nilfs_segctor_construct(struct nilfs_sc_info *sci,
2491                                   struct nilfs_segctor_req *req)
2492{
2493        struct nilfs_sb_info *sbi = sci->sc_sbi;
2494        struct the_nilfs *nilfs = sbi->s_nilfs;
2495        int err = 0;
2496
2497        if (nilfs_discontinued(nilfs))
2498                req->mode = SC_LSEG_SR;
2499        if (!nilfs_segctor_confirm(sci)) {
2500                err = nilfs_segctor_do_construct(sci, req->mode);
2501                req->sc_err = err;
2502        }
2503        if (likely(!err)) {
2504                if (req->mode != SC_FLUSH_DAT)
2505                        atomic_set(&nilfs->ns_ndirtyblks, 0);
2506                if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2507                    nilfs_discontinued(nilfs)) {
2508                        down_write(&nilfs->ns_sem);
2509                        req->sb_err = nilfs_commit_super(sbi,
2510                                        nilfs_altsb_need_update(nilfs));
2511                        up_write(&nilfs->ns_sem);
2512                }
2513        }
2514        return err;
2515}
2516
2517static void nilfs_construction_timeout(unsigned long data)
2518{
2519        struct task_struct *p = (struct task_struct *)data;
2520        wake_up_process(p);
2521}
2522
2523static void
2524nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2525{
2526        struct nilfs_inode_info *ii, *n;
2527
2528        list_for_each_entry_safe(ii, n, head, i_dirty) {
2529                if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2530                        continue;
2531                hlist_del_init(&ii->vfs_inode.i_hash);
2532                list_del_init(&ii->i_dirty);
2533                nilfs_clear_gcinode(&ii->vfs_inode);
2534        }
2535}
2536
2537int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2538                         void **kbufs)
2539{
2540        struct nilfs_sb_info *sbi = NILFS_SB(sb);
2541        struct nilfs_sc_info *sci = NILFS_SC(sbi);
2542        struct the_nilfs *nilfs = sbi->s_nilfs;
2543        struct nilfs_transaction_info ti;
2544        struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
2545        int err;
2546
2547        if (unlikely(!sci))
2548                return -EROFS;
2549
2550        nilfs_transaction_lock(sbi, &ti, 1);
2551
2552        err = nilfs_init_gcdat_inode(nilfs);
2553        if (unlikely(err))
2554                goto out_unlock;
2555
2556        err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2557        if (unlikely(err))
2558                goto out_unlock;
2559
2560        sci->sc_freesegs = kbufs[4];
2561        sci->sc_nfreesegs = argv[4].v_nmembs;
2562        list_splice_init(&nilfs->ns_gc_inodes, sci->sc_gc_inodes.prev);
2563
2564        for (;;) {
2565                nilfs_segctor_accept(sci, &req);
2566                err = nilfs_segctor_construct(sci, &req);
2567                nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2568                nilfs_segctor_notify(sci, &req);
2569
2570                if (likely(!err))
2571                        break;
2572
2573                nilfs_warning(sb, __func__,
2574                              "segment construction failed. (err=%d)", err);
2575                set_current_state(TASK_INTERRUPTIBLE);
2576                schedule_timeout(sci->sc_interval);
2577        }
2578
2579 out_unlock:
2580        sci->sc_freesegs = NULL;
2581        sci->sc_nfreesegs = 0;
2582        nilfs_clear_gcdat_inode(nilfs);
2583        nilfs_transaction_unlock(sbi);
2584        return err;
2585}
2586
2587static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2588{
2589        struct nilfs_sb_info *sbi = sci->sc_sbi;
2590        struct nilfs_transaction_info ti;
2591        struct nilfs_segctor_req req = { .mode = mode };
2592
2593        nilfs_transaction_lock(sbi, &ti, 0);
2594
2595        nilfs_segctor_accept(sci, &req);
2596        nilfs_segctor_construct(sci, &req);
2597        nilfs_segctor_notify(sci, &req);
2598
2599        /*
2600         * Unclosed segment should be retried.  We do this using sc_timer.
2601         * Timeout of sc_timer will invoke complete construction which leads
2602         * to close the current logical segment.
2603         */
2604        if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2605                nilfs_segctor_start_timer(sci);
2606
2607        nilfs_transaction_unlock(sbi);
2608}
2609
2610static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2611{
2612        int mode = 0;
2613        int err;
2614
2615        spin_lock(&sci->sc_state_lock);
2616        mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2617                SC_FLUSH_DAT : SC_FLUSH_FILE;
2618        spin_unlock(&sci->sc_state_lock);
2619
2620        if (mode) {
2621                err = nilfs_segctor_do_construct(sci, mode);
2622
2623                spin_lock(&sci->sc_state_lock);
2624                sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2625                        ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2626                spin_unlock(&sci->sc_state_lock);
2627        }
2628        clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2629}
2630
2631static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2632{
2633        if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2634            time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2635                if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2636                        return SC_FLUSH_FILE;
2637                else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2638                        return SC_FLUSH_DAT;
2639        }
2640        return SC_LSEG_SR;
2641}
2642
2643/**
2644 * nilfs_segctor_thread - main loop of the segment constructor thread.
2645 * @arg: pointer to a struct nilfs_sc_info.
2646 *
2647 * nilfs_segctor_thread() initializes a timer and serves as a daemon
2648 * to execute segment constructions.
2649 */
2650static int nilfs_segctor_thread(void *arg)
2651{
2652        struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2653        struct timer_list timer;
2654        int timeout = 0;
2655
2656        init_timer(&timer);
2657        timer.data = (unsigned long)current;
2658        timer.function = nilfs_construction_timeout;
2659        sci->sc_timer = &timer;
2660
2661        /* start sync. */
2662        sci->sc_task = current;
2663        wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2664        printk(KERN_INFO
2665               "segctord starting. Construction interval = %lu seconds, "
2666               "CP frequency < %lu seconds\n",
2667               sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2668
2669        spin_lock(&sci->sc_state_lock);
2670 loop:
2671        for (;;) {
2672                int mode;
2673
2674                if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2675                        goto end_thread;
2676
2677                if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2678                        mode = SC_LSEG_SR;
2679                else if (!sci->sc_flush_request)
2680                        break;
2681                else
2682                        mode = nilfs_segctor_flush_mode(sci);
2683
2684                spin_unlock(&sci->sc_state_lock);
2685                nilfs_segctor_thread_construct(sci, mode);
2686                spin_lock(&sci->sc_state_lock);
2687                timeout = 0;
2688        }
2689
2690
2691        if (freezing(current)) {
2692                spin_unlock(&sci->sc_state_lock);
2693                refrigerator();
2694                spin_lock(&sci->sc_state_lock);
2695        } else {
2696                DEFINE_WAIT(wait);
2697                int should_sleep = 1;
2698                struct the_nilfs *nilfs;
2699
2700                prepare_to_wait(&sci->sc_wait_daemon, &wait,
2701                                TASK_INTERRUPTIBLE);
2702
2703                if (sci->sc_seq_request != sci->sc_seq_done)
2704                        should_sleep = 0;
2705                else if (sci->sc_flush_request)
2706                        should_sleep = 0;
2707                else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2708                        should_sleep = time_before(jiffies,
2709                                                   sci->sc_timer->expires);
2710
2711                if (should_sleep) {
2712                        spin_unlock(&sci->sc_state_lock);
2713                        schedule();
2714                        spin_lock(&sci->sc_state_lock);
2715                }
2716                finish_wait(&sci->sc_wait_daemon, &wait);
2717                timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2718                           time_after_eq(jiffies, sci->sc_timer->expires));
2719                nilfs = sci->sc_sbi->s_nilfs;
2720                if (sci->sc_super->s_dirt && nilfs_sb_need_update(nilfs))
2721                        set_nilfs_discontinued(nilfs);
2722        }
2723        goto loop;
2724
2725 end_thread:
2726        spin_unlock(&sci->sc_state_lock);
2727        del_timer_sync(sci->sc_timer);
2728        sci->sc_timer = NULL;
2729
2730        /* end sync. */
2731        sci->sc_task = NULL;
2732        wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2733        return 0;
2734}
2735
2736static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2737{
2738        struct task_struct *t;
2739
2740        t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2741        if (IS_ERR(t)) {
2742                int err = PTR_ERR(t);
2743
2744                printk(KERN_ERR "NILFS: error %d creating segctord thread\n",
2745                       err);
2746                return err;
2747        }
2748        wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2749        return 0;
2750}
2751
2752static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2753{
2754        sci->sc_state |= NILFS_SEGCTOR_QUIT;
2755
2756        while (sci->sc_task) {
2757                wake_up(&sci->sc_wait_daemon);
2758                spin_unlock(&sci->sc_state_lock);
2759                wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2760                spin_lock(&sci->sc_state_lock);
2761        }
2762}
2763
2764static int nilfs_segctor_init(struct nilfs_sc_info *sci)
2765{
2766        sci->sc_seq_done = sci->sc_seq_request;
2767
2768        return nilfs_segctor_start_thread(sci);
2769}
2770
2771/*
2772 * Setup & clean-up functions
2773 */
2774static struct nilfs_sc_info *nilfs_segctor_new(struct nilfs_sb_info *sbi)
2775{
2776        struct nilfs_sc_info *sci;
2777
2778        sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2779        if (!sci)
2780                return NULL;
2781
2782        sci->sc_sbi = sbi;
2783        sci->sc_super = sbi->s_super;
2784
2785        init_waitqueue_head(&sci->sc_wait_request);
2786        init_waitqueue_head(&sci->sc_wait_daemon);
2787        init_waitqueue_head(&sci->sc_wait_task);
2788        spin_lock_init(&sci->sc_state_lock);
2789        INIT_LIST_HEAD(&sci->sc_dirty_files);
2790        INIT_LIST_HEAD(&sci->sc_segbufs);
2791        INIT_LIST_HEAD(&sci->sc_gc_inodes);
2792        INIT_LIST_HEAD(&sci->sc_copied_buffers);
2793
2794        sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2795        sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2796        sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2797
2798        if (sbi->s_interval)
2799                sci->sc_interval = sbi->s_interval;
2800        if (sbi->s_watermark)
2801                sci->sc_watermark = sbi->s_watermark;
2802        return sci;
2803}
2804
2805static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2806{
2807        int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2808
2809        /* The segctord thread was stopped and its timer was removed.
2810           But some tasks remain. */
2811        do {
2812                struct nilfs_sb_info *sbi = sci->sc_sbi;
2813                struct nilfs_transaction_info ti;
2814                struct nilfs_segctor_req req = { .mode = SC_LSEG_SR };
2815
2816                nilfs_transaction_lock(sbi, &ti, 0);
2817                nilfs_segctor_accept(sci, &req);
2818                ret = nilfs_segctor_construct(sci, &req);
2819                nilfs_segctor_notify(sci, &req);
2820                nilfs_transaction_unlock(sbi);
2821
2822        } while (ret && retrycount-- > 0);
2823}
2824
2825/**
2826 * nilfs_segctor_destroy - destroy the segment constructor.
2827 * @sci: nilfs_sc_info
2828 *
2829 * nilfs_segctor_destroy() kills the segctord thread and frees
2830 * the nilfs_sc_info struct.
2831 * Caller must hold the segment semaphore.
2832 */
2833static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2834{
2835        struct nilfs_sb_info *sbi = sci->sc_sbi;
2836        int flag;
2837
2838        up_write(&sbi->s_nilfs->ns_segctor_sem);
2839
2840        spin_lock(&sci->sc_state_lock);
2841        nilfs_segctor_kill_thread(sci);
2842        flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2843                || sci->sc_seq_request != sci->sc_seq_done);
2844        spin_unlock(&sci->sc_state_lock);
2845
2846        if (flag || nilfs_segctor_confirm(sci))
2847                nilfs_segctor_write_out(sci);
2848
2849        WARN_ON(!list_empty(&sci->sc_copied_buffers));
2850
2851        if (!list_empty(&sci->sc_dirty_files)) {
2852                nilfs_warning(sbi->s_super, __func__,
2853                              "dirty file(s) after the final construction\n");
2854                nilfs_dispose_list(sbi, &sci->sc_dirty_files, 1);
2855        }
2856
2857        WARN_ON(!list_empty(&sci->sc_segbufs));
2858
2859        down_write(&sbi->s_nilfs->ns_segctor_sem);
2860
2861        kfree(sci);
2862}
2863
2864/**
2865 * nilfs_attach_segment_constructor - attach a segment constructor
2866 * @sbi: nilfs_sb_info
2867 *
2868 * nilfs_attach_segment_constructor() allocates a struct nilfs_sc_info,
2869 * initilizes it, and starts the segment constructor.
2870 *
2871 * Return Value: On success, 0 is returned. On error, one of the following
2872 * negative error code is returned.
2873 *
2874 * %-ENOMEM - Insufficient memory available.
2875 */
2876int nilfs_attach_segment_constructor(struct nilfs_sb_info *sbi)
2877{
2878        struct the_nilfs *nilfs = sbi->s_nilfs;
2879        int err;
2880
2881        /* Each field of nilfs_segctor is cleared through the initialization
2882           of super-block info */
2883        sbi->s_sc_info = nilfs_segctor_new(sbi);
2884        if (!sbi->s_sc_info)
2885                return -ENOMEM;
2886
2887        nilfs_attach_writer(nilfs, sbi);
2888        err = nilfs_segctor_init(NILFS_SC(sbi));
2889        if (err) {
2890                nilfs_detach_writer(nilfs, sbi);
2891                kfree(sbi->s_sc_info);
2892                sbi->s_sc_info = NULL;
2893        }
2894        return err;
2895}
2896
2897/**
2898 * nilfs_detach_segment_constructor - destroy the segment constructor
2899 * @sbi: nilfs_sb_info
2900 *
2901 * nilfs_detach_segment_constructor() kills the segment constructor daemon,
2902 * frees the struct nilfs_sc_info, and destroy the dirty file list.
2903 */
2904void nilfs_detach_segment_constructor(struct nilfs_sb_info *sbi)
2905{
2906        struct the_nilfs *nilfs = sbi->s_nilfs;
2907        LIST_HEAD(garbage_list);
2908
2909        down_write(&nilfs->ns_segctor_sem);
2910        if (NILFS_SC(sbi)) {
2911                nilfs_segctor_destroy(NILFS_SC(sbi));
2912                sbi->s_sc_info = NULL;
2913        }
2914
2915        /* Force to free the list of dirty files */
2916        spin_lock(&sbi->s_inode_lock);
2917        if (!list_empty(&sbi->s_dirty_files)) {
2918                list_splice_init(&sbi->s_dirty_files, &garbage_list);
2919                nilfs_warning(sbi->s_super, __func__,
2920                              "Non empty dirty list after the last "
2921                              "segment construction\n");
2922        }
2923        spin_unlock(&sbi->s_inode_lock);
2924        up_write(&nilfs->ns_segctor_sem);
2925
2926        nilfs_dispose_list(sbi, &garbage_list, 1);
2927        nilfs_detach_writer(nilfs, sbi);
2928}
2929