fs/jbd2/commit.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * linux/fs/jbd2/commit.c
   4  *
   5  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
   6  *
   7  * Copyright 1998 Red Hat corp --- All Rights Reserved
   8  *
   9  * Journal commit routines for the generic filesystem journaling code;
  10  * part of the ext2fs journaling system.
  11  */
  12
  13 #include <linux/time.h>
  14 #include <linux/fs.h>
  15 #include <linux/jbd2.h>
  16 #include <linux/errno.h>
  17 #include <linux/slab.h>
  18 #include <linux/mm.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/crc32.h>
  22 #include <linux/writeback.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/bio.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/bitops.h>
  27 #include <trace/events/jbd2.h>
  28
  29 /*
  30  * IO end handler for temporary buffer_heads handling writes to the journal.
  31  */
  32 static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
  33 {
  34         struct buffer_head *orig_bh = bh->b_private;
  35
  36         BUFFER_TRACE(bh, "");
  37         if (uptodate)
  38                 set_buffer_uptodate(bh);
  39         else
  40                 clear_buffer_uptodate(bh);
  41         if (orig_bh) {
  42                 clear_bit_unlock(BH_Shadow, &orig_bh->b_state);
  43                 smp_mb__after_atomic();
  44                 wake_up_bit(&orig_bh->b_state, BH_Shadow);
  45         }
  46         unlock_buffer(bh);
  47 }
  48
  49 /*
  50  * When an ext4 file is truncated, it is possible that some pages are not
  51  * successfully freed, because they are attached to a committing transaction.
  52  * After the transaction commits, these pages are left on the LRU, with no
  53  * ->mapping, and with attached buffers.  These pages are trivially reclaimable
  54  * by the VM, but their apparent absence upsets the VM accounting, and it makes
  55  * the numbers in /proc/meminfo look odd.
  56  *
  57  * So here, we have a buffer which has just come off the forget list.  Look to
  58  * see if we can strip all buffers from the backing page.
  59  *
  60  * Called under lock_journal(), and possibly under journal_datalist_lock.  The
  61  * caller provided us with a ref against the buffer, and we drop that here.
  62  */
  63 static void release_buffer_page(struct buffer_head *bh)
  64 {
  65         struct page *page;
  66
  67         if (buffer_dirty(bh))
  68                 goto nope;
  69         if (atomic_read(&bh->b_count) != 1)
  70                 goto nope;
  71         page = bh->b_page;
  72         if (!page)
  73                 goto nope;
  74         if (page->mapping)
  75                 goto nope;
  76
  77         /* OK, it's a truncated page */
  78         if (!trylock_page(page))
  79                 goto nope;
  80
  81         get_page(page);
  82         __brelse(bh);
  83         try_to_free_buffers(page);
  84         unlock_page(page);
  85         put_page(page);
  86         return;
  87
  88 nope:
  89         __brelse(bh);
  90 }
  91
  92 static void jbd2_commit_block_csum_set(journal_t *j, struct buffer_head *bh)
  93 {
  94         struct commit_header *h;
  95         __u32 csum;
  96
  97         if (!jbd2_journal_has_csum_v2or3(j))
  98                 return;
  99
 100         h = (struct commit_header *)(bh->b_data);
 101         h->h_chksum_type = 0;
 102         h->h_chksum_size = 0;
 103         h->h_chksum[0] = 0;
 104         csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 105         h->h_chksum[0] = cpu_to_be32(csum);
 106 }
 107
 108 /*
 109  * Done it all: now submit the commit record.  We should have
 110  * cleaned up our previous buffers by now, so if we are in abort
 111  * mode we can now just skip the rest of the journal write
 112  * entirely.
 113  *
 114  * Returns 1 if the journal needs to be aborted or 0 on success
 115  */
 116 static int journal_submit_commit_record(journal_t *journal,
 117                                         transaction_t *commit_transaction,
 118                                         struct buffer_head **cbh,
 119                                         __u32 crc32_sum)
 120 {
 121         struct commit_header *tmp;
 122         struct buffer_head *bh;
 123         int ret;
 124         struct timespec64 now;
 125
 126         *cbh = NULL;
 127
 128         if (is_journal_aborted(journal))
 129                 return 0;
 130
 131         bh = jbd2_journal_get_descriptor_buffer(commit_transaction,
 132                                                 JBD2_COMMIT_BLOCK);
 133         if (!bh)
 134                 return 1;
 135
 136         tmp = (struct commit_header *)bh->b_data;
 137         ktime_get_coarse_real_ts64(&now);
 138         tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
 139         tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
 140
 141         if (jbd2_has_feature_checksum(journal)) {
 142                 tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
 143                 tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
 144                 tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
 145         }
 146         jbd2_commit_block_csum_set(journal, bh);
 147
 148         BUFFER_TRACE(bh, "submit commit block");
 149         lock_buffer(bh);
 150         clear_buffer_dirty(bh);
 151         set_buffer_uptodate(bh);
 152         bh->b_end_io = journal_end_buffer_io_sync;
 153
 154         if (journal->j_flags & JBD2_BARRIER &&
 155             !jbd2_has_feature_async_commit(journal))
 156                 ret = submit_bh(REQ_OP_WRITE,
 157                         REQ_SYNC | REQ_PREFLUSH | REQ_FUA, bh);
 158         else
 159                 ret = submit_bh(REQ_OP_WRITE, REQ_SYNC, bh);
 160
 161         *cbh = bh;
 162         return ret;
 163 }
 164
 165 /*
 166  * This function along with journal_submit_commit_record
 167  * allows to write the commit record asynchronously.
 168  */
 169 static int journal_wait_on_commit_record(journal_t *journal,
 170                                          struct buffer_head *bh)
 171 {
 172         int ret = 0;
 173
 174         clear_buffer_dirty(bh);
 175         wait_on_buffer(bh);
 176
 177         if (unlikely(!buffer_uptodate(bh)))
 178                 ret = -EIO;
 179         put_bh(bh);            /* One for getblk() */
 180
 181         return ret;
 182 }
 183
 184 /*
 185  * write the filemap data using writepage() address_space_operations.
 186  * We don't do block allocation here even for delalloc. We don't
 187  * use writepages() because with dealyed allocation we may be doing
 188  * block allocation in writepages().
 189  */
 190 static int journal_submit_inode_data_buffers(struct address_space *mapping,
 191                 loff_t dirty_start, loff_t dirty_end)
 192 {
 193         int ret;
 194         struct writeback_control wbc = {
 195                 .sync_mode =  WB_SYNC_ALL,
 196                 .nr_to_write = mapping->nrpages * 2,
 197                 .range_start = dirty_start,
 198                 .range_end = dirty_end,
 199         };
 200
 201         ret = generic_writepages(mapping, &wbc);
 202         return ret;
 203 }
 204
 205 /*
 206  * Submit all the data buffers of inode associated with the transaction to
 207  * disk.
 208  *
 209  * We are in a committing transaction. Therefore no new inode can be added to
 210  * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
 211  * operate on from being released while we write out pages.
 212  */
 213 static int journal_submit_data_buffers(journal_t *journal,
 214                 transaction_t *commit_transaction)
 215 {
 216         struct jbd2_inode *jinode;
 217         int err, ret = 0;
 218         struct address_space *mapping;
 219
 220         spin_lock(&journal->j_list_lock);
 221         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 222                 loff_t dirty_start = jinode->i_dirty_start;
 223                 loff_t dirty_end = jinode->i_dirty_end;
 224
 225                 if (!(jinode->i_flags & JI_WRITE_DATA))
 226                         continue;
 227                 mapping = jinode->i_vfs_inode->i_mapping;
 228                 jinode->i_flags |= JI_COMMIT_RUNNING;
 229                 spin_unlock(&journal->j_list_lock);
 230                 /*
 231                  * submit the inode data buffers. We use writepage
 232                  * instead of writepages. Because writepages can do
 233                  * block allocation  with delalloc. We need to write
 234                  * only allocated blocks here.
 235                  */
 236                 trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
 237                 err = journal_submit_inode_data_buffers(mapping, dirty_start,
 238                                 dirty_end);
 239                 if (!ret)
 240                         ret = err;
 241                 spin_lock(&journal->j_list_lock);
 242                 J_ASSERT(jinode->i_transaction == commit_transaction);
 243                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 244                 smp_mb();
 245                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 246         }
 247         spin_unlock(&journal->j_list_lock);
 248         return ret;
 249 }
 250
 251 /*
 252  * Wait for data submitted for writeout, refile inodes to proper
 253  * transaction if needed.
 254  *
 255  */
 256 static int journal_finish_inode_data_buffers(journal_t *journal,
 257                 transaction_t *commit_transaction)
 258 {
 259         struct jbd2_inode *jinode, *next_i;
 260         int err, ret = 0;
 261
 262         /* For locking, see the comment in journal_submit_data_buffers() */
 263         spin_lock(&journal->j_list_lock);
 264         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 265                 loff_t dirty_start = jinode->i_dirty_start;
 266                 loff_t dirty_end = jinode->i_dirty_end;
 267
 268                 if (!(jinode->i_flags & JI_WAIT_DATA))
 269                         continue;
 270                 jinode->i_flags |= JI_COMMIT_RUNNING;
 271                 spin_unlock(&journal->j_list_lock);
 272                 err = filemap_fdatawait_range_keep_errors(
 273                                 jinode->i_vfs_inode->i_mapping, dirty_start,
 274                                 dirty_end);
 275                 if (!ret)
 276                         ret = err;
 277                 spin_lock(&journal->j_list_lock);
 278                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 279                 smp_mb();
 280                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 281         }
 282
 283         /* Now refile inode to proper lists */
 284         list_for_each_entry_safe(jinode, next_i,
 285                                  &commit_transaction->t_inode_list, i_list) {
 286                 list_del(&jinode->i_list);
 287                 if (jinode->i_next_transaction) {
 288                         jinode->i_transaction = jinode->i_next_transaction;
 289                         jinode->i_next_transaction = NULL;
 290                         list_add(&jinode->i_list,
 291                                 &jinode->i_transaction->t_inode_list);
 292                 } else {
 293                         jinode->i_transaction = NULL;
 294                         jinode->i_dirty_start = 0;
 295                         jinode->i_dirty_end = 0;
 296                 }
 297         }
 298         spin_unlock(&journal->j_list_lock);
 299
 300         return ret;
 301 }
 302
 303 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 304 {
 305         struct page *page = bh->b_page;
 306         char *addr;
 307         __u32 checksum;
 308
 309         addr = kmap_atomic(page);
 310         checksum = crc32_be(crc32_sum,
 311                 (void *)(addr + offset_in_page(bh->b_data)), bh->b_size);
 312         kunmap_atomic(addr);
 313
 314         return checksum;
 315 }
 316
 317 static void write_tag_block(journal_t *j, journal_block_tag_t *tag,
 318                                    unsigned long long block)
 319 {
 320         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
 321         if (jbd2_has_feature_64bit(j))
 322                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 323 }
 324
 325 static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 326                                     struct buffer_head *bh, __u32 sequence)
 327 {
 328         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 329         struct page *page = bh->b_page;
 330         __u8 *addr;
 331         __u32 csum32;
 332         __be32 seq;
 333
 334         if (!jbd2_journal_has_csum_v2or3(j))
 335                 return;
 336
 337         seq = cpu_to_be32(sequence);
 338         addr = kmap_atomic(page);
 339         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 340         csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 341                              bh->b_size);
 342         kunmap_atomic(addr);
 343
 344         if (jbd2_has_feature_csum3(j))
 345                 tag3->t_checksum = cpu_to_be32(csum32);
 346         else
 347                 tag->t_checksum = cpu_to_be16(csum32);
 348 }
 349 /*
 350  * jbd2_journal_commit_transaction
 351  *
 352  * The primary function for committing a transaction to the log.  This
 353  * function is called by the journal thread to begin a complete commit.
 354  */
 355 void jbd2_journal_commit_transaction(journal_t *journal)
 356 {
 357         struct transaction_stats_s stats;
 358         transaction_t *commit_transaction;
 359         struct journal_head *jh;
 360         struct buffer_head *descriptor;
 361         struct buffer_head **wbuf = journal->j_wbuf;
 362         int bufs;
 363         int flags;
 364         int err;
 365         unsigned long long blocknr;
 366         ktime_t start_time;
 367         u64 commit_time;
 368         char *tagp = NULL;
 369         journal_block_tag_t *tag = NULL;
 370         int space_left = 0;
 371         int first_tag = 0;
 372         int tag_flag;
 373         int i;
 374         int tag_bytes = journal_tag_bytes(journal);
 375         struct buffer_head *cbh = NULL; /* For transactional checksums */
 376         __u32 crc32_sum = ~0;
 377         struct blk_plug plug;
 378         /* Tail of the journal */
 379         unsigned long first_block;
 380         tid_t first_tid;
 381         int update_tail;
 382         int csum_size = 0;
 383         LIST_HEAD(io_bufs);
 384         LIST_HEAD(log_bufs);
 385
 386         if (jbd2_journal_has_csum_v2or3(journal))
 387                 csum_size = sizeof(struct jbd2_journal_block_tail);
 388
 389         /*
 390          * First job: lock down the current transaction and wait for
 391          * all outstanding updates to complete.
 392          */
 393
 394         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 395         if (journal->j_flags & JBD2_FLUSHED) {
 396                 jbd_debug(3, "super block updated\n");
 397                 mutex_lock_io(&journal->j_checkpoint_mutex);
 398                 /*
 399                  * We hold j_checkpoint_mutex so tail cannot change under us.
 400                  * We don't need any special data guarantees for writing sb
 401                  * since journal is empty and it is ok for write to be
 402                  * flushed only with transaction commit.
 403                  */
 404                 jbd2_journal_update_sb_log_tail(journal,
 405                                                 journal->j_tail_sequence,
 406                                                 journal->j_tail,
 407                                                 REQ_SYNC);
 408                 mutex_unlock(&journal->j_checkpoint_mutex);
 409         } else {
 410                 jbd_debug(3, "superblock not updated\n");
 411         }
 412
 413         J_ASSERT(journal->j_running_transaction != NULL);
 414         J_ASSERT(journal->j_committing_transaction == NULL);
 415
 416         commit_transaction = journal->j_running_transaction;
 417
 418         trace_jbd2_start_commit(journal, commit_transaction);
 419         jbd_debug(1, "JBD2: starting commit of transaction %d\n",
 420                         commit_transaction->t_tid);
 421
 422         write_lock(&journal->j_state_lock);
 423         J_ASSERT(commit_transaction->t_state == T_RUNNING);
 424         commit_transaction->t_state = T_LOCKED;
 425
 426         trace_jbd2_commit_locking(journal, commit_transaction);
 427         stats.run.rs_wait = commit_transaction->t_max_wait;
 428         stats.run.rs_request_delay = 0;
 429         stats.run.rs_locked = jiffies;
 430         if (commit_transaction->t_requested)
 431                 stats.run.rs_request_delay =
 432                         jbd2_time_diff(commit_transaction->t_requested,
 433                                        stats.run.rs_locked);
 434         stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
 435                                               stats.run.rs_locked);
 436
 437         spin_lock(&commit_transaction->t_handle_lock);
 438         while (atomic_read(&commit_transaction->t_updates)) {
 439                 DEFINE_WAIT(wait);
 440
 441                 prepare_to_wait(&journal->j_wait_updates, &wait,
 442                                         TASK_UNINTERRUPTIBLE);
 443                 if (atomic_read(&commit_transaction->t_updates)) {
 444                         spin_unlock(&commit_transaction->t_handle_lock);
 445                         write_unlock(&journal->j_state_lock);
 446                         schedule();
 447                         write_lock(&journal->j_state_lock);
 448                         spin_lock(&commit_transaction->t_handle_lock);
 449                 }
 450                 finish_wait(&journal->j_wait_updates, &wait);
 451         }
 452         spin_unlock(&commit_transaction->t_handle_lock);
 453
 454         J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 455                         journal->j_max_transaction_buffers);
 456
 457         /*
 458          * First thing we are allowed to do is to discard any remaining
 459          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 460          * that there are no such buffers: if a large filesystem
 461          * operation like a truncate needs to split itself over multiple
 462          * transactions, then it may try to do a jbd2_journal_restart() while
 463          * there are still BJ_Reserved buffers outstanding.  These must
 464          * be released cleanly from the current transaction.
 465          *
 466          * In this case, the filesystem must still reserve write access
 467          * again before modifying the buffer in the new transaction, but
 468          * we do not require it to remember exactly which old buffers it
 469          * has reserved.  This is consistent with the existing behaviour
 470          * that multiple jbd2_journal_get_write_access() calls to the same
 471          * buffer are perfectly permissible.
 472          */
 473         while (commit_transaction->t_reserved_list) {
 474                 jh = commit_transaction->t_reserved_list;
 475                 JBUFFER_TRACE(jh, "reserved, unused: refile");
 476                 /*
 477                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 478                  * leave undo-committed data.
 479                  */
 480                 if (jh->b_committed_data) {
 481                         struct buffer_head *bh = jh2bh(jh);
 482
 483                         jbd_lock_bh_state(bh);
 484                         jbd2_free(jh->b_committed_data, bh->b_size);
 485                         jh->b_committed_data = NULL;
 486                         jbd_unlock_bh_state(bh);
 487                 }
 488                 jbd2_journal_refile_buffer(journal, jh);
 489         }
 490
 491         /*
 492          * Now try to drop any written-back buffers from the journal's
 493          * checkpoint lists.  We do this *before* commit because it potentially
 494          * frees some memory
 495          */
 496         spin_lock(&journal->j_list_lock);
 497         __jbd2_journal_clean_checkpoint_list(journal, false);
 498         spin_unlock(&journal->j_list_lock);
 499
 500         jbd_debug(3, "JBD2: commit phase 1\n");
 501
 502         /*
 503          * Clear revoked flag to reflect there is no revoked buffers
 504          * in the next transaction which is going to be started.
 505          */
 506         jbd2_clear_buffer_revoked_flags(journal);
 507
 508         /*
 509          * Switch to a new revoke table.
 510          */
 511         jbd2_journal_switch_revoke_table(journal);
 512
 513         /*
 514          * Reserved credits cannot be claimed anymore, free them
 515          */
 516         atomic_sub(atomic_read(&journal->j_reserved_credits),
 517                    &commit_transaction->t_outstanding_credits);
 518
 519         trace_jbd2_commit_flushing(journal, commit_transaction);
 520         stats.run.rs_flushing = jiffies;
 521         stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 522                                              stats.run.rs_flushing);
 523
 524         commit_transaction->t_state = T_FLUSH;
 525         journal->j_committing_transaction = commit_transaction;
 526         journal->j_running_transaction = NULL;
 527         start_time = ktime_get();
 528         commit_transaction->t_log_start = journal->j_head;
 529         wake_up(&journal->j_wait_transaction_locked);
 530         write_unlock(&journal->j_state_lock);
 531
 532         jbd_debug(3, "JBD2: commit phase 2a\n");
 533
 534         /*
 535          * Now start flushing things to disk, in the order they appear
 536          * on the transaction lists.  Data blocks go first.
 537          */
 538         err = journal_submit_data_buffers(journal, commit_transaction);
 539         if (err)
 540                 jbd2_journal_abort(journal, err);
 541
 542         blk_start_plug(&plug);
 543         jbd2_journal_write_revoke_records(commit_transaction, &log_bufs);
 544
 545         jbd_debug(3, "JBD2: commit phase 2b\n");
 546
 547         /*
 548          * Way to go: we have now written out all of the data for a
 549          * transaction!  Now comes the tricky part: we need to write out
 550          * metadata.  Loop over the transaction's entire buffer list:
 551          */
 552         write_lock(&journal->j_state_lock);
 553         commit_transaction->t_state = T_COMMIT;
 554         write_unlock(&journal->j_state_lock);
 555
 556         trace_jbd2_commit_logging(journal, commit_transaction);
 557         stats.run.rs_logging = jiffies;
 558         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 559                                                stats.run.rs_logging);
 560         stats.run.rs_blocks =
 561                 atomic_read(&commit_transaction->t_outstanding_credits);
 562         stats.run.rs_blocks_logged = 0;
 563
 564         J_ASSERT(commit_transaction->t_nr_buffers <=
 565                  atomic_read(&commit_transaction->t_outstanding_credits));
 566
 567         err = 0;
 568         bufs = 0;
 569         descriptor = NULL;
 570         while (commit_transaction->t_buffers) {
 571
 572                 /* Find the next buffer to be journaled... */
 573
 574                 jh = commit_transaction->t_buffers;
 575
 576                 /* If we're in abort mode, we just un-journal the buffer and
 577                    release it. */
 578
 579                 if (is_journal_aborted(journal)) {
 580                         clear_buffer_jbddirty(jh2bh(jh));
 581                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 582                         jbd2_buffer_abort_trigger(jh,
 583                                                   jh->b_frozen_data ?
 584                                                   jh->b_frozen_triggers :
 585                                                   jh->b_triggers);
 586                         jbd2_journal_refile_buffer(journal, jh);
 587                         /* If that was the last one, we need to clean up
 588                          * any descriptor buffers which may have been
 589                          * already allocated, even if we are now
 590                          * aborting. */
 591                         if (!commit_transaction->t_buffers)
 592                                 goto start_journal_io;
 593                         continue;
 594                 }
 595
 596                 /* Make sure we have a descriptor block in which to
 597                    record the metadata buffer. */
 598
 599                 if (!descriptor) {
 600                         J_ASSERT (bufs == 0);
 601
 602                         jbd_debug(4, "JBD2: get descriptor\n");
 603
 604                         descriptor = jbd2_journal_get_descriptor_buffer(
 605                                                         commit_transaction,
 606                                                         JBD2_DESCRIPTOR_BLOCK);
 607                         if (!descriptor) {
 608                                 jbd2_journal_abort(journal, -EIO);
 609                                 continue;
 610                         }
 611
 612                         jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 613                                 (unsigned long long)descriptor->b_blocknr,
 614                                 descriptor->b_data);
 615                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 616                         space_left = descriptor->b_size -
 617                                                 sizeof(journal_header_t);
 618                         first_tag = 1;
 619                         set_buffer_jwrite(descriptor);
 620                         set_buffer_dirty(descriptor);
 621                         wbuf[bufs++] = descriptor;
 622
 623                         /* Record it so that we can wait for IO
 624                            completion later */
 625                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 626                         jbd2_file_log_bh(&log_bufs, descriptor);
 627                 }
 628
 629                 /* Where is the buffer to be written? */
 630
 631                 err = jbd2_journal_next_log_block(journal, &blocknr);
 632                 /* If the block mapping failed, just abandon the buffer
 633                    and repeat this loop: we'll fall into the
 634                    refile-on-abort condition above. */
 635                 if (err) {
 636                         jbd2_journal_abort(journal, err);
 637                         continue;
 638                 }
 639
 640                 /*
 641                  * start_this_handle() uses t_outstanding_credits to determine
 642                  * the free space in the log, but this counter is changed
 643                  * by jbd2_journal_next_log_block() also.
 644                  */
 645                 atomic_dec(&commit_transaction->t_outstanding_credits);
 646
 647                 /* Bump b_count to prevent truncate from stumbling over
 648                    the shadowed buffer!  @@@ This can go if we ever get
 649                    rid of the shadow pairing of buffers. */
 650                 atomic_inc(&jh2bh(jh)->b_count);
 651
 652                 /*
 653                  * Make a temporary IO buffer with which to write it out
 654                  * (this will requeue the metadata buffer to BJ_Shadow).
 655                  */
 656                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 657                 JBUFFER_TRACE(jh, "ph3: write metadata");
 658                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 659                                                 jh, &wbuf[bufs], blocknr);
 660                 if (flags < 0) {
 661                         jbd2_journal_abort(journal, flags);
 662                         continue;
 663                 }
 664                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 665
 666                 /* Record the new block's tag in the current descriptor
 667                    buffer */
 668
 669                 tag_flag = 0;
 670                 if (flags & 1)
 671                         tag_flag |= JBD2_FLAG_ESCAPE;
 672                 if (!first_tag)
 673                         tag_flag |= JBD2_FLAG_SAME_UUID;
 674
 675                 tag = (journal_block_tag_t *) tagp;
 676                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 677                 tag->t_flags = cpu_to_be16(tag_flag);
 678                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 679                                         commit_transaction->t_tid);
 680                 tagp += tag_bytes;
 681                 space_left -= tag_bytes;
 682                 bufs++;
 683
 684                 if (first_tag) {
 685                         memcpy (tagp, journal->j_uuid, 16);
 686                         tagp += 16;
 687                         space_left -= 16;
 688                         first_tag = 0;
 689                 }
 690
 691                 /* If there's no more to do, or if the descriptor is full,
 692                    let the IO rip! */
 693
 694                 if (bufs == journal->j_wbufsize ||
 695                     commit_transaction->t_buffers == NULL ||
 696                     space_left < tag_bytes + 16 + csum_size) {
 697
 698                         jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 699
 700                         /* Write an end-of-descriptor marker before
 701                            submitting the IOs.  "tag" still points to
 702                            the last tag we set up. */
 703
 704                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 705 start_journal_io:
 706                         if (descriptor)
 707                                 jbd2_descriptor_block_csum_set(journal,
 708                                                         descriptor);
 709
 710                         for (i = 0; i < bufs; i++) {
 711                                 struct buffer_head *bh = wbuf[i];
 712                                 /*
 713                                  * Compute checksum.
 714                                  */
 715                                 if (jbd2_has_feature_checksum(journal)) {
 716                                         crc32_sum =
 717                                             jbd2_checksum_data(crc32_sum, bh);
 718                                 }
 719
 720                                 lock_buffer(bh);
 721                                 clear_buffer_dirty(bh);
 722                                 set_buffer_uptodate(bh);
 723                                 bh->b_end_io = journal_end_buffer_io_sync;
 724                                 submit_bh(REQ_OP_WRITE, REQ_SYNC, bh);
 725                         }
 726                         cond_resched();
 727
 728                         /* Force a new descriptor to be generated next
 729                            time round the loop. */
 730                         descriptor = NULL;
 731                         bufs = 0;
 732                 }
 733         }
 734
 735         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 736         if (err) {
 737                 printk(KERN_WARNING
 738                         "JBD2: Detected IO errors while flushing file data "
 739                        "on %s\n", journal->j_devname);
 740                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 741                         jbd2_journal_abort(journal, err);
 742                 err = 0;
 743         }
 744
 745         /*
 746          * Get current oldest transaction in the log before we issue flush
 747          * to the filesystem device. After the flush we can be sure that
 748          * blocks of all older transactions are checkpointed to persistent
 749          * storage and we will be safe to update journal start in the
 750          * superblock with the numbers we get here.
 751          */
 752         update_tail =
 753                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 754
 755         write_lock(&journal->j_state_lock);
 756         if (update_tail) {
 757                 long freed = first_block - journal->j_tail;
 758
 759                 if (first_block < journal->j_tail)
 760                         freed += journal->j_last - journal->j_first;
 761                 /* Update tail only if we free significant amount of space */
 762                 if (freed < journal->j_maxlen / 4)
 763                         update_tail = 0;
 764         }
 765         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 766         commit_transaction->t_state = T_COMMIT_DFLUSH;
 767         write_unlock(&journal->j_state_lock);
 768
 769         /*
 770          * If the journal is not located on the file system device,
 771          * then we must flush the file system device before we issue
 772          * the commit record
 773          */
 774         if (commit_transaction->t_need_data_flush &&
 775             (journal->j_fs_dev != journal->j_dev) &&
 776             (journal->j_flags & JBD2_BARRIER))
 777                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 778
 779         /* Done it all: now write the commit record asynchronously. */
 780         if (jbd2_has_feature_async_commit(journal)) {
 781                 err = journal_submit_commit_record(journal, commit_transaction,
 782                                                  &cbh, crc32_sum);
 783                 if (err)
 784                         jbd2_journal_abort(journal, err);
 785         }
 786
 787         blk_finish_plug(&plug);
 788
 789         /* Lo and behold: we have just managed to send a transaction to
 790            the log.  Before we can commit it, wait for the IO so far to
 791            complete.  Control buffers being written are on the
 792            transaction's t_log_list queue, and metadata buffers are on
 793            the io_bufs list.
 794
 795            Wait for the buffers in reverse order.  That way we are
 796            less likely to be woken up until all IOs have completed, and
 797            so we incur less scheduling load.
 798         */
 799
 800         jbd_debug(3, "JBD2: commit phase 3\n");
 801
 802         while (!list_empty(&io_bufs)) {
 803                 struct buffer_head *bh = list_entry(io_bufs.prev,
 804                                                     struct buffer_head,
 805                                                     b_assoc_buffers);
 806
 807                 wait_on_buffer(bh);
 808                 cond_resched();
 809
 810                 if (unlikely(!buffer_uptodate(bh)))
 811                         err = -EIO;
 812                 jbd2_unfile_log_bh(bh);
 813                 stats.run.rs_blocks_logged++;
 814
 815                 /*
 816                  * The list contains temporary buffer heads created by
 817                  * jbd2_journal_write_metadata_buffer().
 818                  */
 819                 BUFFER_TRACE(bh, "dumping temporary bh");
 820                 __brelse(bh);
 821                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 822                 free_buffer_head(bh);
 823
 824                 /* We also have to refile the corresponding shadowed buffer */
 825                 jh = commit_transaction->t_shadow_list->b_tprev;
 826                 bh = jh2bh(jh);
 827                 clear_buffer_jwrite(bh);
 828                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 829                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 830
 831                 /* The metadata is now released for reuse, but we need
 832                    to remember it against this transaction so that when
 833                    we finally commit, we can do any checkpointing
 834                    required. */
 835                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 836                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 837                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 838                 __brelse(bh);
 839         }
 840
 841         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 842
 843         jbd_debug(3, "JBD2: commit phase 4\n");
 844
 845         /* Here we wait for the revoke record and descriptor record buffers */
 846         while (!list_empty(&log_bufs)) {
 847                 struct buffer_head *bh;
 848
 849                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 850                 wait_on_buffer(bh);
 851                 cond_resched();
 852
 853                 if (unlikely(!buffer_uptodate(bh)))
 854                         err = -EIO;
 855
 856                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 857                 clear_buffer_jwrite(bh);
 858                 jbd2_unfile_log_bh(bh);
 859                 stats.run.rs_blocks_logged++;
 860                 __brelse(bh);           /* One for getblk */
 861                 /* AKPM: bforget here */
 862         }
 863
 864         if (err)
 865                 jbd2_journal_abort(journal, err);
 866
 867         jbd_debug(3, "JBD2: commit phase 5\n");
 868         write_lock(&journal->j_state_lock);
 869         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 870         commit_transaction->t_state = T_COMMIT_JFLUSH;
 871         write_unlock(&journal->j_state_lock);
 872
 873         if (!jbd2_has_feature_async_commit(journal)) {
 874                 err = journal_submit_commit_record(journal, commit_transaction,
 875                                                 &cbh, crc32_sum);
 876                 if (err)
 877                         jbd2_journal_abort(journal, err);
 878         }
 879         if (cbh)
 880                 err = journal_wait_on_commit_record(journal, cbh);
 881         stats.run.rs_blocks_logged++;
 882         if (jbd2_has_feature_async_commit(journal) &&
 883             journal->j_flags & JBD2_BARRIER) {
 884                 blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 885         }
 886
 887         if (err)
 888                 jbd2_journal_abort(journal, err);
 889
 890         /*
 891          * Now disk caches for filesystem device are flushed so we are safe to
 892          * erase checkpointed transactions from the log by updating journal
 893          * superblock.
 894          */
 895         if (update_tail)
 896                 jbd2_update_log_tail(journal, first_tid, first_block);
 897
 898         /* End of a transaction!  Finally, we can do checkpoint
 899            processing: any buffers committed as a result of this
 900            transaction can be removed from any checkpoint list it was on
 901            before. */
 902
 903         jbd_debug(3, "JBD2: commit phase 6\n");
 904
 905         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 906         J_ASSERT(commit_transaction->t_buffers == NULL);
 907         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 908         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 909
 910 restart_loop:
 911         /*
 912          * As there are other places (journal_unmap_buffer()) adding buffers
 913          * to this list we have to be careful and hold the j_list_lock.
 914          */
 915         spin_lock(&journal->j_list_lock);
 916         while (commit_transaction->t_forget) {
 917                 transaction_t *cp_transaction;
 918                 struct buffer_head *bh;
 919                 int try_to_free = 0;
 920
 921                 jh = commit_transaction->t_forget;
 922                 spin_unlock(&journal->j_list_lock);
 923                 bh = jh2bh(jh);
 924                 /*
 925                  * Get a reference so that bh cannot be freed before we are
 926                  * done with it.
 927                  */
 928                 get_bh(bh);
 929                 jbd_lock_bh_state(bh);
 930                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 931
 932                 /*
 933                  * If there is undo-protected committed data against
 934                  * this buffer, then we can remove it now.  If it is a
 935                  * buffer needing such protection, the old frozen_data
 936                  * field now points to a committed version of the
 937                  * buffer, so rotate that field to the new committed
 938                  * data.
 939                  *
 940                  * Otherwise, we can just throw away the frozen data now.
 941                  *
 942                  * We also know that the frozen data has already fired
 943                  * its triggers if they exist, so we can clear that too.
 944                  */
 945                 if (jh->b_committed_data) {
 946                         jbd2_free(jh->b_committed_data, bh->b_size);
 947                         jh->b_committed_data = NULL;
 948                         if (jh->b_frozen_data) {
 949                                 jh->b_committed_data = jh->b_frozen_data;
 950                                 jh->b_frozen_data = NULL;
 951                                 jh->b_frozen_triggers = NULL;
 952                         }
 953                 } else if (jh->b_frozen_data) {
 954                         jbd2_free(jh->b_frozen_data, bh->b_size);
 955                         jh->b_frozen_data = NULL;
 956                         jh->b_frozen_triggers = NULL;
 957                 }
 958
 959                 spin_lock(&journal->j_list_lock);
 960                 cp_transaction = jh->b_cp_transaction;
 961                 if (cp_transaction) {
 962                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 963                         cp_transaction->t_chp_stats.cs_dropped++;
 964                         __jbd2_journal_remove_checkpoint(jh);
 965                 }
 966
 967                 /* Only re-checkpoint the buffer_head if it is marked
 968                  * dirty.  If the buffer was added to the BJ_Forget list
 969                  * by jbd2_journal_forget, it may no longer be dirty and
 970                  * there's no point in keeping a checkpoint record for
 971                  * it. */
 972
 973                 /*
 974                  * A buffer which has been freed while still being journaled
 975                  * by a previous transaction, refile the buffer to BJ_Forget of
 976                  * the running transaction. If the just committed transaction
 977                  * contains "add to orphan" operation, we can completely
 978                  * invalidate the buffer now. We are rather through in that
 979                  * since the buffer may be still accessible when blocksize <
 980                  * pagesize and it is attached to the last partial page.
 981                  */
 982                 if (buffer_freed(bh) && !jh->b_next_transaction) {
 983                         struct address_space *mapping;
 984
 985                         clear_buffer_freed(bh);
 986                         clear_buffer_jbddirty(bh);
 987
 988                         /*
 989                          * Block device buffers need to stay mapped all the
 990                          * time, so it is enough to clear buffer_jbddirty and
 991                          * buffer_freed bits. For the file mapping buffers (i.e.
 992                          * journalled data) we need to unmap buffer and clear
 993                          * more bits. We also need to be careful about the check
 994                          * because the data page mapping can get cleared under
 995                          * our hands. Note that if mapping == NULL, we don't
 996                          * need to make buffer unmapped because the page is
 997                          * already detached from the mapping and buffers cannot
 998                          * get reused.
 999                          */
1000                         mapping = READ_ONCE(bh->b_page->mapping);
1001                         if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {
1002                                 clear_buffer_mapped(bh);
1003                                 clear_buffer_new(bh);
1004                                 clear_buffer_req(bh);
1005                                 bh->b_bdev = NULL;
1006                         }
1007                 }
1008
1009                 if (buffer_jbddirty(bh)) {
1010                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1011                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1012                         if (is_journal_aborted(journal))
1013                                 clear_buffer_jbddirty(bh);
1014                 } else {
1015                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1016                         /*
1017                          * The buffer on BJ_Forget list and not jbddirty means
1018                          * it has been freed by this transaction and hence it
1019                          * could not have been reallocated until this
1020                          * transaction has committed. *BUT* it could be
1021                          * reallocated once we have written all the data to
1022                          * disk and before we process the buffer on BJ_Forget
1023                          * list.
1024                          */
1025                         if (!jh->b_next_transaction)
1026                                 try_to_free = 1;
1027                 }
1028                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1029                 __jbd2_journal_refile_buffer(jh);
1030                 jbd_unlock_bh_state(bh);
1031                 if (try_to_free)
1032                         release_buffer_page(bh);        /* Drops bh reference */
1033                 else
1034                         __brelse(bh);
1035                 cond_resched_lock(&journal->j_list_lock);
1036         }
1037         spin_unlock(&journal->j_list_lock);
1038         /*
1039          * This is a bit sleazy.  We use j_list_lock to protect transition
1040          * of a transaction into T_FINISHED state and calling
1041          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1042          * other checkpointing code processing the transaction...
1043          */
1044         write_lock(&journal->j_state_lock);
1045         spin_lock(&journal->j_list_lock);
1046         /*
1047          * Now recheck if some buffers did not get attached to the transaction
1048          * while the lock was dropped...
1049          */
1050         if (commit_transaction->t_forget) {
1051                 spin_unlock(&journal->j_list_lock);
1052                 write_unlock(&journal->j_state_lock);
1053                 goto restart_loop;
1054         }
1055
1056         /* Add the transaction to the checkpoint list
1057          * __journal_remove_checkpoint() can not destroy transaction
1058          * under us because it is not marked as T_FINISHED yet */
1059         if (journal->j_checkpoint_transactions == NULL) {
1060                 journal->j_checkpoint_transactions = commit_transaction;
1061                 commit_transaction->t_cpnext = commit_transaction;
1062                 commit_transaction->t_cpprev = commit_transaction;
1063         } else {
1064                 commit_transaction->t_cpnext =
1065                         journal->j_checkpoint_transactions;
1066                 commit_transaction->t_cpprev =
1067                         commit_transaction->t_cpnext->t_cpprev;
1068                 commit_transaction->t_cpnext->t_cpprev =
1069                         commit_transaction;
1070                 commit_transaction->t_cpprev->t_cpnext =
1071                                 commit_transaction;
1072         }
1073         spin_unlock(&journal->j_list_lock);
1074
1075         /* Done with this transaction! */
1076
1077         jbd_debug(3, "JBD2: commit phase 7\n");
1078
1079         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1080
1081         commit_transaction->t_start = jiffies;
1082         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1083                                               commit_transaction->t_start);
1084
1085         /*
1086          * File the transaction statistics
1087          */
1088         stats.ts_tid = commit_transaction->t_tid;
1089         stats.run.rs_handle_count =
1090                 atomic_read(&commit_transaction->t_handle_count);
1091         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1092                              commit_transaction->t_tid, &stats.run);
1093         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1094
1095         commit_transaction->t_state = T_COMMIT_CALLBACK;
1096         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1097         journal->j_commit_sequence = commit_transaction->t_tid;
1098         journal->j_committing_transaction = NULL;
1099         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1100
1101         /*
1102          * weight the commit time higher than the average time so we don't
1103          * react too strongly to vast changes in the commit time
1104          */
1105         if (likely(journal->j_average_commit_time))
1106                 journal->j_average_commit_time = (commit_time +
1107                                 journal->j_average_commit_time*3) / 4;
1108         else
1109                 journal->j_average_commit_time = commit_time;
1110
1111         write_unlock(&journal->j_state_lock);
1112
1113         if (journal->j_commit_callback)
1114                 journal->j_commit_callback(journal, commit_transaction);
1115
1116         trace_jbd2_end_commit(journal, commit_transaction);
1117         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1118                   journal->j_commit_sequence, journal->j_tail_sequence);
1119
1120         write_lock(&journal->j_state_lock);
1121         spin_lock(&journal->j_list_lock);
1122         commit_transaction->t_state = T_FINISHED;
1123         /* Check if the transaction can be dropped now that we are finished */
1124         if (commit_transaction->t_checkpoint_list == NULL &&
1125             commit_transaction->t_checkpoint_io_list == NULL) {
1126                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1127                 jbd2_journal_free_transaction(commit_transaction);
1128         }
1129         spin_unlock(&journal->j_list_lock);
1130         write_unlock(&journal->j_state_lock);
1131         wake_up(&journal->j_wait_done_commit);
1132
1133         /*
1134          * Calculate overall stats
1135          */
1136         spin_lock(&journal->j_history_lock);
1137         journal->j_stats.ts_tid++;
1138         journal->j_stats.ts_requested += stats.ts_requested;
1139         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1140         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1141         journal->j_stats.run.rs_running += stats.run.rs_running;
1142         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1143         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1144         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1145         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1146         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1147         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1148         spin_unlock(&journal->j_history_lock);
1149 }