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 delayed 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         commit_transaction->t_state = T_SWITCH;
 454         write_unlock(&journal->j_state_lock);
 455
 456         J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 457                         journal->j_max_transaction_buffers);
 458
 459         /*
 460          * First thing we are allowed to do is to discard any remaining
 461          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 462          * that there are no such buffers: if a large filesystem
 463          * operation like a truncate needs to split itself over multiple
 464          * transactions, then it may try to do a jbd2_journal_restart() while
 465          * there are still BJ_Reserved buffers outstanding.  These must
 466          * be released cleanly from the current transaction.
 467          *
 468          * In this case, the filesystem must still reserve write access
 469          * again before modifying the buffer in the new transaction, but
 470          * we do not require it to remember exactly which old buffers it
 471          * has reserved.  This is consistent with the existing behaviour
 472          * that multiple jbd2_journal_get_write_access() calls to the same
 473          * buffer are perfectly permissible.
 474          */
 475         while (commit_transaction->t_reserved_list) {
 476                 jh = commit_transaction->t_reserved_list;
 477                 JBUFFER_TRACE(jh, "reserved, unused: refile");
 478                 /*
 479                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 480                  * leave undo-committed data.
 481                  */
 482                 if (jh->b_committed_data) {
 483                         struct buffer_head *bh = jh2bh(jh);
 484
 485                         spin_lock(&jh->b_state_lock);
 486                         jbd2_free(jh->b_committed_data, bh->b_size);
 487                         jh->b_committed_data = NULL;
 488                         spin_unlock(&jh->b_state_lock);
 489                 }
 490                 jbd2_journal_refile_buffer(journal, jh);
 491         }
 492
 493         /*
 494          * Now try to drop any written-back buffers from the journal's
 495          * checkpoint lists.  We do this *before* commit because it potentially
 496          * frees some memory
 497          */
 498         spin_lock(&journal->j_list_lock);
 499         __jbd2_journal_clean_checkpoint_list(journal, false);
 500         spin_unlock(&journal->j_list_lock);
 501
 502         jbd_debug(3, "JBD2: commit phase 1\n");
 503
 504         /*
 505          * Clear revoked flag to reflect there is no revoked buffers
 506          * in the next transaction which is going to be started.
 507          */
 508         jbd2_clear_buffer_revoked_flags(journal);
 509
 510         /*
 511          * Switch to a new revoke table.
 512          */
 513         jbd2_journal_switch_revoke_table(journal);
 514
 515         /*
 516          * Reserved credits cannot be claimed anymore, free them
 517          */
 518         atomic_sub(atomic_read(&journal->j_reserved_credits),
 519                    &commit_transaction->t_outstanding_credits);
 520
 521         write_lock(&journal->j_state_lock);
 522         trace_jbd2_commit_flushing(journal, commit_transaction);
 523         stats.run.rs_flushing = jiffies;
 524         stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 525                                              stats.run.rs_flushing);
 526
 527         commit_transaction->t_state = T_FLUSH;
 528         journal->j_committing_transaction = commit_transaction;
 529         journal->j_running_transaction = NULL;
 530         start_time = ktime_get();
 531         commit_transaction->t_log_start = journal->j_head;
 532         wake_up(&journal->j_wait_transaction_locked);
 533         write_unlock(&journal->j_state_lock);
 534
 535         jbd_debug(3, "JBD2: commit phase 2a\n");
 536
 537         /*
 538          * Now start flushing things to disk, in the order they appear
 539          * on the transaction lists.  Data blocks go first.
 540          */
 541         err = journal_submit_data_buffers(journal, commit_transaction);
 542         if (err)
 543                 jbd2_journal_abort(journal, err);
 544
 545         blk_start_plug(&plug);
 546         jbd2_journal_write_revoke_records(commit_transaction, &log_bufs);
 547
 548         jbd_debug(3, "JBD2: commit phase 2b\n");
 549
 550         /*
 551          * Way to go: we have now written out all of the data for a
 552          * transaction!  Now comes the tricky part: we need to write out
 553          * metadata.  Loop over the transaction's entire buffer list:
 554          */
 555         write_lock(&journal->j_state_lock);
 556         commit_transaction->t_state = T_COMMIT;
 557         write_unlock(&journal->j_state_lock);
 558
 559         trace_jbd2_commit_logging(journal, commit_transaction);
 560         stats.run.rs_logging = jiffies;
 561         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 562                                                stats.run.rs_logging);
 563         stats.run.rs_blocks = commit_transaction->t_nr_buffers;
 564         stats.run.rs_blocks_logged = 0;
 565
 566         J_ASSERT(commit_transaction->t_nr_buffers <=
 567                  atomic_read(&commit_transaction->t_outstanding_credits));
 568
 569         err = 0;
 570         bufs = 0;
 571         descriptor = NULL;
 572         while (commit_transaction->t_buffers) {
 573
 574                 /* Find the next buffer to be journaled... */
 575
 576                 jh = commit_transaction->t_buffers;
 577
 578                 /* If we're in abort mode, we just un-journal the buffer and
 579                    release it. */
 580
 581                 if (is_journal_aborted(journal)) {
 582                         clear_buffer_jbddirty(jh2bh(jh));
 583                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 584                         jbd2_buffer_abort_trigger(jh,
 585                                                   jh->b_frozen_data ?
 586                                                   jh->b_frozen_triggers :
 587                                                   jh->b_triggers);
 588                         jbd2_journal_refile_buffer(journal, jh);
 589                         /* If that was the last one, we need to clean up
 590                          * any descriptor buffers which may have been
 591                          * already allocated, even if we are now
 592                          * aborting. */
 593                         if (!commit_transaction->t_buffers)
 594                                 goto start_journal_io;
 595                         continue;
 596                 }
 597
 598                 /* Make sure we have a descriptor block in which to
 599                    record the metadata buffer. */
 600
 601                 if (!descriptor) {
 602                         J_ASSERT (bufs == 0);
 603
 604                         jbd_debug(4, "JBD2: get descriptor\n");
 605
 606                         descriptor = jbd2_journal_get_descriptor_buffer(
 607                                                         commit_transaction,
 608                                                         JBD2_DESCRIPTOR_BLOCK);
 609                         if (!descriptor) {
 610                                 jbd2_journal_abort(journal, -EIO);
 611                                 continue;
 612                         }
 613
 614                         jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 615                                 (unsigned long long)descriptor->b_blocknr,
 616                                 descriptor->b_data);
 617                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 618                         space_left = descriptor->b_size -
 619                                                 sizeof(journal_header_t);
 620                         first_tag = 1;
 621                         set_buffer_jwrite(descriptor);
 622                         set_buffer_dirty(descriptor);
 623                         wbuf[bufs++] = descriptor;
 624
 625                         /* Record it so that we can wait for IO
 626                            completion later */
 627                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 628                         jbd2_file_log_bh(&log_bufs, descriptor);
 629                 }
 630
 631                 /* Where is the buffer to be written? */
 632
 633                 err = jbd2_journal_next_log_block(journal, &blocknr);
 634                 /* If the block mapping failed, just abandon the buffer
 635                    and repeat this loop: we'll fall into the
 636                    refile-on-abort condition above. */
 637                 if (err) {
 638                         jbd2_journal_abort(journal, err);
 639                         continue;
 640                 }
 641
 642                 /*
 643                  * start_this_handle() uses t_outstanding_credits to determine
 644                  * the free space in the log.
 645                  */
 646                 atomic_dec(&commit_transaction->t_outstanding_credits);
 647
 648                 /* Bump b_count to prevent truncate from stumbling over
 649                    the shadowed buffer!  @@@ This can go if we ever get
 650                    rid of the shadow pairing of buffers. */
 651                 atomic_inc(&jh2bh(jh)->b_count);
 652
 653                 /*
 654                  * Make a temporary IO buffer with which to write it out
 655                  * (this will requeue the metadata buffer to BJ_Shadow).
 656                  */
 657                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 658                 JBUFFER_TRACE(jh, "ph3: write metadata");
 659                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 660                                                 jh, &wbuf[bufs], blocknr);
 661                 if (flags < 0) {
 662                         jbd2_journal_abort(journal, flags);
 663                         continue;
 664                 }
 665                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 666
 667                 /* Record the new block's tag in the current descriptor
 668                    buffer */
 669
 670                 tag_flag = 0;
 671                 if (flags & 1)
 672                         tag_flag |= JBD2_FLAG_ESCAPE;
 673                 if (!first_tag)
 674                         tag_flag |= JBD2_FLAG_SAME_UUID;
 675
 676                 tag = (journal_block_tag_t *) tagp;
 677                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 678                 tag->t_flags = cpu_to_be16(tag_flag);
 679                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 680                                         commit_transaction->t_tid);
 681                 tagp += tag_bytes;
 682                 space_left -= tag_bytes;
 683                 bufs++;
 684
 685                 if (first_tag) {
 686                         memcpy (tagp, journal->j_uuid, 16);
 687                         tagp += 16;
 688                         space_left -= 16;
 689                         first_tag = 0;
 690                 }
 691
 692                 /* If there's no more to do, or if the descriptor is full,
 693                    let the IO rip! */
 694
 695                 if (bufs == journal->j_wbufsize ||
 696                     commit_transaction->t_buffers == NULL ||
 697                     space_left < tag_bytes + 16 + csum_size) {
 698
 699                         jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 700
 701                         /* Write an end-of-descriptor marker before
 702                            submitting the IOs.  "tag" still points to
 703                            the last tag we set up. */
 704
 705                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 706 start_journal_io:
 707                         if (descriptor)
 708                                 jbd2_descriptor_block_csum_set(journal,
 709                                                         descriptor);
 710
 711                         for (i = 0; i < bufs; i++) {
 712                                 struct buffer_head *bh = wbuf[i];
 713                                 /*
 714                                  * Compute checksum.
 715                                  */
 716                                 if (jbd2_has_feature_checksum(journal)) {
 717                                         crc32_sum =
 718                                             jbd2_checksum_data(crc32_sum, bh);
 719                                 }
 720
 721                                 lock_buffer(bh);
 722                                 clear_buffer_dirty(bh);
 723                                 set_buffer_uptodate(bh);
 724                                 bh->b_end_io = journal_end_buffer_io_sync;
 725                                 submit_bh(REQ_OP_WRITE, REQ_SYNC, bh);
 726                         }
 727                         cond_resched();
 728
 729                         /* Force a new descriptor to be generated next
 730                            time round the loop. */
 731                         descriptor = NULL;
 732                         bufs = 0;
 733                 }
 734         }
 735
 736         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 737         if (err) {
 738                 printk(KERN_WARNING
 739                         "JBD2: Detected IO errors while flushing file data "
 740                        "on %s\n", journal->j_devname);
 741                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 742                         jbd2_journal_abort(journal, err);
 743                 err = 0;
 744         }
 745
 746         /*
 747          * Get current oldest transaction in the log before we issue flush
 748          * to the filesystem device. After the flush we can be sure that
 749          * blocks of all older transactions are checkpointed to persistent
 750          * storage and we will be safe to update journal start in the
 751          * superblock with the numbers we get here.
 752          */
 753         update_tail =
 754                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 755
 756         write_lock(&journal->j_state_lock);
 757         if (update_tail) {
 758                 long freed = first_block - journal->j_tail;
 759
 760                 if (first_block < journal->j_tail)
 761                         freed += journal->j_last - journal->j_first;
 762                 /* Update tail only if we free significant amount of space */
 763                 if (freed < journal->j_maxlen / 4)
 764                         update_tail = 0;
 765         }
 766         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 767         commit_transaction->t_state = T_COMMIT_DFLUSH;
 768         write_unlock(&journal->j_state_lock);
 769
 770         /*
 771          * If the journal is not located on the file system device,
 772          * then we must flush the file system device before we issue
 773          * the commit record
 774          */
 775         if (commit_transaction->t_need_data_flush &&
 776             (journal->j_fs_dev != journal->j_dev) &&
 777             (journal->j_flags & JBD2_BARRIER))
 778                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 779
 780         /* Done it all: now write the commit record asynchronously. */
 781         if (jbd2_has_feature_async_commit(journal)) {
 782                 err = journal_submit_commit_record(journal, commit_transaction,
 783                                                  &cbh, crc32_sum);
 784                 if (err)
 785                         __jbd2_journal_abort_hard(journal);
 786         }
 787
 788         blk_finish_plug(&plug);
 789
 790         /* Lo and behold: we have just managed to send a transaction to
 791            the log.  Before we can commit it, wait for the IO so far to
 792            complete.  Control buffers being written are on the
 793            transaction's t_log_list queue, and metadata buffers are on
 794            the io_bufs list.
 795
 796            Wait for the buffers in reverse order.  That way we are
 797            less likely to be woken up until all IOs have completed, and
 798            so we incur less scheduling load.
 799         */
 800
 801         jbd_debug(3, "JBD2: commit phase 3\n");
 802
 803         while (!list_empty(&io_bufs)) {
 804                 struct buffer_head *bh = list_entry(io_bufs.prev,
 805                                                     struct buffer_head,
 806                                                     b_assoc_buffers);
 807
 808                 wait_on_buffer(bh);
 809                 cond_resched();
 810
 811                 if (unlikely(!buffer_uptodate(bh)))
 812                         err = -EIO;
 813                 jbd2_unfile_log_bh(bh);
 814                 stats.run.rs_blocks_logged++;
 815
 816                 /*
 817                  * The list contains temporary buffer heads created by
 818                  * jbd2_journal_write_metadata_buffer().
 819                  */
 820                 BUFFER_TRACE(bh, "dumping temporary bh");
 821                 __brelse(bh);
 822                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 823                 free_buffer_head(bh);
 824
 825                 /* We also have to refile the corresponding shadowed buffer */
 826                 jh = commit_transaction->t_shadow_list->b_tprev;
 827                 bh = jh2bh(jh);
 828                 clear_buffer_jwrite(bh);
 829                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 830                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 831
 832                 /* The metadata is now released for reuse, but we need
 833                    to remember it against this transaction so that when
 834                    we finally commit, we can do any checkpointing
 835                    required. */
 836                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 837                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 838                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 839                 __brelse(bh);
 840         }
 841
 842         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 843
 844         jbd_debug(3, "JBD2: commit phase 4\n");
 845
 846         /* Here we wait for the revoke record and descriptor record buffers */
 847         while (!list_empty(&log_bufs)) {
 848                 struct buffer_head *bh;
 849
 850                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 851                 wait_on_buffer(bh);
 852                 cond_resched();
 853
 854                 if (unlikely(!buffer_uptodate(bh)))
 855                         err = -EIO;
 856
 857                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 858                 clear_buffer_jwrite(bh);
 859                 jbd2_unfile_log_bh(bh);
 860                 stats.run.rs_blocks_logged++;
 861                 __brelse(bh);           /* One for getblk */
 862                 /* AKPM: bforget here */
 863         }
 864
 865         if (err)
 866                 jbd2_journal_abort(journal, err);
 867
 868         jbd_debug(3, "JBD2: commit phase 5\n");
 869         write_lock(&journal->j_state_lock);
 870         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 871         commit_transaction->t_state = T_COMMIT_JFLUSH;
 872         write_unlock(&journal->j_state_lock);
 873
 874         if (!jbd2_has_feature_async_commit(journal)) {
 875                 err = journal_submit_commit_record(journal, commit_transaction,
 876                                                 &cbh, crc32_sum);
 877                 if (err)
 878                         __jbd2_journal_abort_hard(journal);
 879         }
 880         if (cbh)
 881                 err = journal_wait_on_commit_record(journal, cbh);
 882         stats.run.rs_blocks_logged++;
 883         if (jbd2_has_feature_async_commit(journal) &&
 884             journal->j_flags & JBD2_BARRIER) {
 885                 blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 886         }
 887
 888         if (err)
 889                 jbd2_journal_abort(journal, err);
 890
 891         WARN_ON_ONCE(
 892                 atomic_read(&commit_transaction->t_outstanding_credits) < 0);
 893
 894         /*
 895          * Now disk caches for filesystem device are flushed so we are safe to
 896          * erase checkpointed transactions from the log by updating journal
 897          * superblock.
 898          */
 899         if (update_tail)
 900                 jbd2_update_log_tail(journal, first_tid, first_block);
 901
 902         /* End of a transaction!  Finally, we can do checkpoint
 903            processing: any buffers committed as a result of this
 904            transaction can be removed from any checkpoint list it was on
 905            before. */
 906
 907         jbd_debug(3, "JBD2: commit phase 6\n");
 908
 909         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 910         J_ASSERT(commit_transaction->t_buffers == NULL);
 911         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 912         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 913
 914 restart_loop:
 915         /*
 916          * As there are other places (journal_unmap_buffer()) adding buffers
 917          * to this list we have to be careful and hold the j_list_lock.
 918          */
 919         spin_lock(&journal->j_list_lock);
 920         while (commit_transaction->t_forget) {
 921                 transaction_t *cp_transaction;
 922                 struct buffer_head *bh;
 923                 int try_to_free = 0;
 924                 bool drop_ref;
 925
 926                 jh = commit_transaction->t_forget;
 927                 spin_unlock(&journal->j_list_lock);
 928                 bh = jh2bh(jh);
 929                 /*
 930                  * Get a reference so that bh cannot be freed before we are
 931                  * done with it.
 932                  */
 933                 get_bh(bh);
 934                 spin_lock(&jh->b_state_lock);
 935                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 936
 937                 /*
 938                  * If there is undo-protected committed data against
 939                  * this buffer, then we can remove it now.  If it is a
 940                  * buffer needing such protection, the old frozen_data
 941                  * field now points to a committed version of the
 942                  * buffer, so rotate that field to the new committed
 943                  * data.
 944                  *
 945                  * Otherwise, we can just throw away the frozen data now.
 946                  *
 947                  * We also know that the frozen data has already fired
 948                  * its triggers if they exist, so we can clear that too.
 949                  */
 950                 if (jh->b_committed_data) {
 951                         jbd2_free(jh->b_committed_data, bh->b_size);
 952                         jh->b_committed_data = NULL;
 953                         if (jh->b_frozen_data) {
 954                                 jh->b_committed_data = jh->b_frozen_data;
 955                                 jh->b_frozen_data = NULL;
 956                                 jh->b_frozen_triggers = NULL;
 957                         }
 958                 } else if (jh->b_frozen_data) {
 959                         jbd2_free(jh->b_frozen_data, bh->b_size);
 960                         jh->b_frozen_data = NULL;
 961                         jh->b_frozen_triggers = NULL;
 962                 }
 963
 964                 spin_lock(&journal->j_list_lock);
 965                 cp_transaction = jh->b_cp_transaction;
 966                 if (cp_transaction) {
 967                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 968                         cp_transaction->t_chp_stats.cs_dropped++;
 969                         __jbd2_journal_remove_checkpoint(jh);
 970                 }
 971
 972                 /* Only re-checkpoint the buffer_head if it is marked
 973                  * dirty.  If the buffer was added to the BJ_Forget list
 974                  * by jbd2_journal_forget, it may no longer be dirty and
 975                  * there's no point in keeping a checkpoint record for
 976                  * it. */
 977
 978                 /*
 979                 * A buffer which has been freed while still being journaled by
 980                 * a previous transaction.
 981                 */
 982                 if (buffer_freed(bh)) {
 983                         /*
 984                          * If the running transaction is the one containing
 985                          * "add to orphan" operation (b_next_transaction !=
 986                          * NULL), we have to wait for that transaction to
 987                          * commit before we can really get rid of the buffer.
 988                          * So just clear b_modified to not confuse transaction
 989                          * credit accounting and refile the buffer to
 990                          * BJ_Forget of the running transaction. If the just
 991                          * committed transaction contains "add to orphan"
 992                          * operation, we can completely invalidate the buffer
 993                          * now. We are rather through in that since the
 994                          * buffer may be still accessible when blocksize <
 995                          * pagesize and it is attached to the last partial
 996                          * page.
 997                          */
 998                         jh->b_modified = 0;
 999                         if (!jh->b_next_transaction) {
1000                                 clear_buffer_freed(bh);
1001                                 clear_buffer_jbddirty(bh);
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                 drop_ref = __jbd2_journal_refile_buffer(jh);
1030                 spin_unlock(&jh->b_state_lock);
1031                 if (drop_ref)
1032                         jbd2_journal_put_journal_head(jh);
1033                 if (try_to_free)
1034                         release_buffer_page(bh);        /* Drops bh reference */
1035                 else
1036                         __brelse(bh);
1037                 cond_resched_lock(&journal->j_list_lock);
1038         }
1039         spin_unlock(&journal->j_list_lock);
1040         /*
1041          * This is a bit sleazy.  We use j_list_lock to protect transition
1042          * of a transaction into T_FINISHED state and calling
1043          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1044          * other checkpointing code processing the transaction...
1045          */
1046         write_lock(&journal->j_state_lock);
1047         spin_lock(&journal->j_list_lock);
1048         /*
1049          * Now recheck if some buffers did not get attached to the transaction
1050          * while the lock was dropped...
1051          */
1052         if (commit_transaction->t_forget) {
1053                 spin_unlock(&journal->j_list_lock);
1054                 write_unlock(&journal->j_state_lock);
1055                 goto restart_loop;
1056         }
1057
1058         /* Add the transaction to the checkpoint list
1059          * __journal_remove_checkpoint() can not destroy transaction
1060          * under us because it is not marked as T_FINISHED yet */
1061         if (journal->j_checkpoint_transactions == NULL) {
1062                 journal->j_checkpoint_transactions = commit_transaction;
1063                 commit_transaction->t_cpnext = commit_transaction;
1064                 commit_transaction->t_cpprev = commit_transaction;
1065         } else {
1066                 commit_transaction->t_cpnext =
1067                         journal->j_checkpoint_transactions;
1068                 commit_transaction->t_cpprev =
1069                         commit_transaction->t_cpnext->t_cpprev;
1070                 commit_transaction->t_cpnext->t_cpprev =
1071                         commit_transaction;
1072                 commit_transaction->t_cpprev->t_cpnext =
1073                                 commit_transaction;
1074         }
1075         spin_unlock(&journal->j_list_lock);
1076
1077         /* Done with this transaction! */
1078
1079         jbd_debug(3, "JBD2: commit phase 7\n");
1080
1081         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1082
1083         commit_transaction->t_start = jiffies;
1084         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1085                                               commit_transaction->t_start);
1086
1087         /*
1088          * File the transaction statistics
1089          */
1090         stats.ts_tid = commit_transaction->t_tid;
1091         stats.run.rs_handle_count =
1092                 atomic_read(&commit_transaction->t_handle_count);
1093         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1094                              commit_transaction->t_tid, &stats.run);
1095         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1096
1097         commit_transaction->t_state = T_COMMIT_CALLBACK;
1098         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1099         journal->j_commit_sequence = commit_transaction->t_tid;
1100         journal->j_committing_transaction = NULL;
1101         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1102
1103         /*
1104          * weight the commit time higher than the average time so we don't
1105          * react too strongly to vast changes in the commit time
1106          */
1107         if (likely(journal->j_average_commit_time))
1108                 journal->j_average_commit_time = (commit_time +
1109                                 journal->j_average_commit_time*3) / 4;
1110         else
1111                 journal->j_average_commit_time = commit_time;
1112
1113         write_unlock(&journal->j_state_lock);
1114
1115         if (journal->j_commit_callback)
1116                 journal->j_commit_callback(journal, commit_transaction);
1117
1118         trace_jbd2_end_commit(journal, commit_transaction);
1119         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1120                   journal->j_commit_sequence, journal->j_tail_sequence);
1121
1122         write_lock(&journal->j_state_lock);
1123         spin_lock(&journal->j_list_lock);
1124         commit_transaction->t_state = T_FINISHED;
1125         /* Check if the transaction can be dropped now that we are finished */
1126         if (commit_transaction->t_checkpoint_list == NULL &&
1127             commit_transaction->t_checkpoint_io_list == NULL) {
1128                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1129                 jbd2_journal_free_transaction(commit_transaction);
1130         }
1131         spin_unlock(&journal->j_list_lock);
1132         write_unlock(&journal->j_state_lock);
1133         wake_up(&journal->j_wait_done_commit);
1134
1135         /*
1136          * Calculate overall stats
1137          */
1138         spin_lock(&journal->j_history_lock);
1139         journal->j_stats.ts_tid++;
1140         journal->j_stats.ts_requested += stats.ts_requested;
1141         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1142         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1143         journal->j_stats.run.rs_running += stats.run.rs_running;
1144         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1145         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1146         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1147         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1148         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1149         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1150         spin_unlock(&journal->j_history_lock);
1151 }