fs/jbd2/commit.c

   1 /*
   2  * linux/fs/jbd2/commit.c
   3  *
   4  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
   5  *
   6  * Copyright 1998 Red Hat corp --- All Rights Reserved
   7  *
   8  * This file is part of the Linux kernel and is made available under
   9  * the terms of the GNU General Public License, version 2, or at your
  10  * option, any later version, incorporated herein by reference.
  11  *
  12  * Journal commit routines for the generic filesystem journaling code;
  13  * part of the ext2fs journaling system.
  14  */
  15
  16 #include <linux/time.h>
  17 #include <linux/fs.h>
  18 #include <linux/jbd2.h>
  19 #include <linux/errno.h>
  20 #include <linux/slab.h>
  21 #include <linux/mm.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/jiffies.h>
  24 #include <linux/crc32.h>
  25 #include <linux/writeback.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/bio.h>
  28 #include <linux/blkdev.h>
  29 #include <linux/bitops.h>
  30 #include <trace/events/jbd2.h>
  31
  32 /*
  33  * IO end handler for temporary buffer_heads handling writes to the journal.
  34  */
  35 static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
  36 {
  37         struct buffer_head *orig_bh = bh->b_private;
  38
  39         BUFFER_TRACE(bh, "");
  40         if (uptodate)
  41                 set_buffer_uptodate(bh);
  42         else
  43                 clear_buffer_uptodate(bh);
  44         if (orig_bh) {
  45                 clear_bit_unlock(BH_Shadow, &orig_bh->b_state);
  46                 smp_mb__after_atomic();
  47                 wake_up_bit(&orig_bh->b_state, BH_Shadow);
  48         }
  49         unlock_buffer(bh);
  50 }
  51
  52 /*
  53  * When an ext4 file is truncated, it is possible that some pages are not
  54  * successfully freed, because they are attached to a committing transaction.
  55  * After the transaction commits, these pages are left on the LRU, with no
  56  * ->mapping, and with attached buffers.  These pages are trivially reclaimable
  57  * by the VM, but their apparent absence upsets the VM accounting, and it makes
  58  * the numbers in /proc/meminfo look odd.
  59  *
  60  * So here, we have a buffer which has just come off the forget list.  Look to
  61  * see if we can strip all buffers from the backing page.
  62  *
  63  * Called under lock_journal(), and possibly under journal_datalist_lock.  The
  64  * caller provided us with a ref against the buffer, and we drop that here.
  65  */
  66 static void release_buffer_page(struct buffer_head *bh)
  67 {
  68         struct page *page;
  69
  70         if (buffer_dirty(bh))
  71                 goto nope;
  72         if (atomic_read(&bh->b_count) != 1)
  73                 goto nope;
  74         page = bh->b_page;
  75         if (!page)
  76                 goto nope;
  77         if (page->mapping)
  78                 goto nope;
  79
  80         /* OK, it's a truncated page */
  81         if (!trylock_page(page))
  82                 goto nope;
  83
  84         page_cache_get(page);
  85         __brelse(bh);
  86         try_to_free_buffers(page);
  87         unlock_page(page);
  88         page_cache_release(page);
  89         return;
  90
  91 nope:
  92         __brelse(bh);
  93 }
  94
  95 static void jbd2_commit_block_csum_set(journal_t *j, struct buffer_head *bh)
  96 {
  97         struct commit_header *h;
  98         __u32 csum;
  99
 100         if (!jbd2_journal_has_csum_v2or3(j))
 101                 return;
 102
 103         h = (struct commit_header *)(bh->b_data);
 104         h->h_chksum_type = 0;
 105         h->h_chksum_size = 0;
 106         h->h_chksum[0] = 0;
 107         csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 108         h->h_chksum[0] = cpu_to_be32(csum);
 109 }
 110
 111 /*
 112  * Done it all: now submit the commit record.  We should have
 113  * cleaned up our previous buffers by now, so if we are in abort
 114  * mode we can now just skip the rest of the journal write
 115  * entirely.
 116  *
 117  * Returns 1 if the journal needs to be aborted or 0 on success
 118  */
 119 static int journal_submit_commit_record(journal_t *journal,
 120                                         transaction_t *commit_transaction,
 121                                         struct buffer_head **cbh,
 122                                         __u32 crc32_sum)
 123 {
 124         struct commit_header *tmp;
 125         struct buffer_head *bh;
 126         int ret;
 127         struct timespec now = current_kernel_time();
 128
 129         *cbh = NULL;
 130
 131         if (is_journal_aborted(journal))
 132                 return 0;
 133
 134         bh = jbd2_journal_get_descriptor_buffer(journal);
 135         if (!bh)
 136                 return 1;
 137
 138         tmp = (struct commit_header *)bh->b_data;
 139         tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
 140         tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
 141         tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
 142         tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
 143         tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
 144
 145         if (jbd2_has_feature_checksum(journal)) {
 146                 tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
 147                 tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
 148                 tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
 149         }
 150         jbd2_commit_block_csum_set(journal, bh);
 151
 152         BUFFER_TRACE(bh, "submit commit block");
 153         lock_buffer(bh);
 154         clear_buffer_dirty(bh);
 155         set_buffer_uptodate(bh);
 156         bh->b_end_io = journal_end_buffer_io_sync;
 157
 158         if (journal->j_flags & JBD2_BARRIER &&
 159             !jbd2_has_feature_async_commit(journal))
 160                 ret = submit_bh(WRITE_SYNC | WRITE_FLUSH_FUA, bh);
 161         else
 162                 ret = submit_bh(WRITE_SYNC, bh);
 163
 164         *cbh = bh;
 165         return ret;
 166 }
 167
 168 /*
 169  * This function along with journal_submit_commit_record
 170  * allows to write the commit record asynchronously.
 171  */
 172 static int journal_wait_on_commit_record(journal_t *journal,
 173                                          struct buffer_head *bh)
 174 {
 175         int ret = 0;
 176
 177         clear_buffer_dirty(bh);
 178         wait_on_buffer(bh);
 179
 180         if (unlikely(!buffer_uptodate(bh)))
 181                 ret = -EIO;
 182         put_bh(bh);            /* One for getblk() */
 183
 184         return ret;
 185 }
 186
 187 /*
 188  * write the filemap data using writepage() address_space_operations.
 189  * We don't do block allocation here even for delalloc. We don't
 190  * use writepages() because with dealyed allocation we may be doing
 191  * block allocation in writepages().
 192  */
 193 static int journal_submit_inode_data_buffers(struct address_space *mapping)
 194 {
 195         int ret;
 196         struct writeback_control wbc = {
 197                 .sync_mode =  WB_SYNC_ALL,
 198                 .nr_to_write = mapping->nrpages * 2,
 199                 .range_start = 0,
 200                 .range_end = i_size_read(mapping->host),
 201         };
 202
 203         ret = generic_writepages(mapping, &wbc);
 204         return ret;
 205 }
 206
 207 /*
 208  * Submit all the data buffers of inode associated with the transaction to
 209  * disk.
 210  *
 211  * We are in a committing transaction. Therefore no new inode can be added to
 212  * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
 213  * operate on from being released while we write out pages.
 214  */
 215 static int journal_submit_data_buffers(journal_t *journal,
 216                 transaction_t *commit_transaction)
 217 {
 218         struct jbd2_inode *jinode;
 219         int err, ret = 0;
 220         struct address_space *mapping;
 221
 222         spin_lock(&journal->j_list_lock);
 223         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 224                 mapping = jinode->i_vfs_inode->i_mapping;
 225                 set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 226                 spin_unlock(&journal->j_list_lock);
 227                 /*
 228                  * submit the inode data buffers. We use writepage
 229                  * instead of writepages. Because writepages can do
 230                  * block allocation  with delalloc. We need to write
 231                  * only allocated blocks here.
 232                  */
 233                 trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
 234                 err = journal_submit_inode_data_buffers(mapping);
 235                 if (!ret)
 236                         ret = err;
 237                 spin_lock(&journal->j_list_lock);
 238                 J_ASSERT(jinode->i_transaction == commit_transaction);
 239                 clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 240                 smp_mb__after_atomic();
 241                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 242         }
 243         spin_unlock(&journal->j_list_lock);
 244         return ret;
 245 }
 246
 247 /*
 248  * Wait for data submitted for writeout, refile inodes to proper
 249  * transaction if needed.
 250  *
 251  */
 252 static int journal_finish_inode_data_buffers(journal_t *journal,
 253                 transaction_t *commit_transaction)
 254 {
 255         struct jbd2_inode *jinode, *next_i;
 256         int err, ret = 0;
 257
 258         /* For locking, see the comment in journal_submit_data_buffers() */
 259         spin_lock(&journal->j_list_lock);
 260         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 261                 set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 262                 spin_unlock(&journal->j_list_lock);
 263                 err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping);
 264                 if (err) {
 265                         /*
 266                          * Because AS_EIO is cleared by
 267                          * filemap_fdatawait_range(), set it again so
 268                          * that user process can get -EIO from fsync().
 269                          */
 270                         set_bit(AS_EIO,
 271                                 &jinode->i_vfs_inode->i_mapping->flags);
 272
 273                         if (!ret)
 274                                 ret = err;
 275                 }
 276                 spin_lock(&journal->j_list_lock);
 277                 clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 278                 smp_mb__after_atomic();
 279                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 280         }
 281
 282         /* Now refile inode to proper lists */
 283         list_for_each_entry_safe(jinode, next_i,
 284                                  &commit_transaction->t_inode_list, i_list) {
 285                 list_del(&jinode->i_list);
 286                 if (jinode->i_next_transaction) {
 287                         jinode->i_transaction = jinode->i_next_transaction;
 288                         jinode->i_next_transaction = NULL;
 289                         list_add(&jinode->i_list,
 290                                 &jinode->i_transaction->t_inode_list);
 291                 } else {
 292                         jinode->i_transaction = NULL;
 293                 }
 294         }
 295         spin_unlock(&journal->j_list_lock);
 296
 297         return ret;
 298 }
 299
 300 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 301 {
 302         struct page *page = bh->b_page;
 303         char *addr;
 304         __u32 checksum;
 305
 306         addr = kmap_atomic(page);
 307         checksum = crc32_be(crc32_sum,
 308                 (void *)(addr + offset_in_page(bh->b_data)), bh->b_size);
 309         kunmap_atomic(addr);
 310
 311         return checksum;
 312 }
 313
 314 static void write_tag_block(journal_t *j, journal_block_tag_t *tag,
 315                                    unsigned long long block)
 316 {
 317         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
 318         if (jbd2_has_feature_64bit(j))
 319                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 320 }
 321
 322 static void jbd2_descr_block_csum_set(journal_t *j,
 323                                       struct buffer_head *bh)
 324 {
 325         struct jbd2_journal_block_tail *tail;
 326         __u32 csum;
 327
 328         if (!jbd2_journal_has_csum_v2or3(j))
 329                 return;
 330
 331         tail = (struct jbd2_journal_block_tail *)(bh->b_data + j->j_blocksize -
 332                         sizeof(struct jbd2_journal_block_tail));
 333         tail->t_checksum = 0;
 334         csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 335         tail->t_checksum = cpu_to_be32(csum);
 336 }
 337
 338 static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 339                                     struct buffer_head *bh, __u32 sequence)
 340 {
 341         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 342         struct page *page = bh->b_page;
 343         __u8 *addr;
 344         __u32 csum32;
 345         __be32 seq;
 346
 347         if (!jbd2_journal_has_csum_v2or3(j))
 348                 return;
 349
 350         seq = cpu_to_be32(sequence);
 351         addr = kmap_atomic(page);
 352         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 353         csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 354                              bh->b_size);
 355         kunmap_atomic(addr);
 356
 357         if (jbd2_has_feature_csum3(j))
 358                 tag3->t_checksum = cpu_to_be32(csum32);
 359         else
 360                 tag->t_checksum = cpu_to_be16(csum32);
 361 }
 362 /*
 363  * jbd2_journal_commit_transaction
 364  *
 365  * The primary function for committing a transaction to the log.  This
 366  * function is called by the journal thread to begin a complete commit.
 367  */
 368 void jbd2_journal_commit_transaction(journal_t *journal)
 369 {
 370         struct transaction_stats_s stats;
 371         transaction_t *commit_transaction;
 372         struct journal_head *jh;
 373         struct buffer_head *descriptor;
 374         struct buffer_head **wbuf = journal->j_wbuf;
 375         int bufs;
 376         int flags;
 377         int err;
 378         unsigned long long blocknr;
 379         ktime_t start_time;
 380         u64 commit_time;
 381         char *tagp = NULL;
 382         journal_header_t *header;
 383         journal_block_tag_t *tag = NULL;
 384         int space_left = 0;
 385         int first_tag = 0;
 386         int tag_flag;
 387         int i;
 388         int tag_bytes = journal_tag_bytes(journal);
 389         struct buffer_head *cbh = NULL; /* For transactional checksums */
 390         __u32 crc32_sum = ~0;
 391         struct blk_plug plug;
 392         /* Tail of the journal */
 393         unsigned long first_block;
 394         tid_t first_tid;
 395         int update_tail;
 396         int csum_size = 0;
 397         LIST_HEAD(io_bufs);
 398         LIST_HEAD(log_bufs);
 399
 400         if (jbd2_journal_has_csum_v2or3(journal))
 401                 csum_size = sizeof(struct jbd2_journal_block_tail);
 402
 403         /*
 404          * First job: lock down the current transaction and wait for
 405          * all outstanding updates to complete.
 406          */
 407
 408         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 409         if (journal->j_flags & JBD2_FLUSHED) {
 410                 jbd_debug(3, "super block updated\n");
 411                 mutex_lock(&journal->j_checkpoint_mutex);
 412                 /*
 413                  * We hold j_checkpoint_mutex so tail cannot change under us.
 414                  * We don't need any special data guarantees for writing sb
 415                  * since journal is empty and it is ok for write to be
 416                  * flushed only with transaction commit.
 417                  */
 418                 jbd2_journal_update_sb_log_tail(journal,
 419                                                 journal->j_tail_sequence,
 420                                                 journal->j_tail,
 421                                                 WRITE_SYNC);
 422                 mutex_unlock(&journal->j_checkpoint_mutex);
 423         } else {
 424                 jbd_debug(3, "superblock not updated\n");
 425         }
 426
 427         J_ASSERT(journal->j_running_transaction != NULL);
 428         J_ASSERT(journal->j_committing_transaction == NULL);
 429
 430         commit_transaction = journal->j_running_transaction;
 431
 432         trace_jbd2_start_commit(journal, commit_transaction);
 433         jbd_debug(1, "JBD2: starting commit of transaction %d\n",
 434                         commit_transaction->t_tid);
 435
 436         write_lock(&journal->j_state_lock);
 437         J_ASSERT(commit_transaction->t_state == T_RUNNING);
 438         commit_transaction->t_state = T_LOCKED;
 439
 440         trace_jbd2_commit_locking(journal, commit_transaction);
 441         stats.run.rs_wait = commit_transaction->t_max_wait;
 442         stats.run.rs_request_delay = 0;
 443         stats.run.rs_locked = jiffies;
 444         if (commit_transaction->t_requested)
 445                 stats.run.rs_request_delay =
 446                         jbd2_time_diff(commit_transaction->t_requested,
 447                                        stats.run.rs_locked);
 448         stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
 449                                               stats.run.rs_locked);
 450
 451         spin_lock(&commit_transaction->t_handle_lock);
 452         while (atomic_read(&commit_transaction->t_updates)) {
 453                 DEFINE_WAIT(wait);
 454
 455                 prepare_to_wait(&journal->j_wait_updates, &wait,
 456                                         TASK_UNINTERRUPTIBLE);
 457                 if (atomic_read(&commit_transaction->t_updates)) {
 458                         spin_unlock(&commit_transaction->t_handle_lock);
 459                         write_unlock(&journal->j_state_lock);
 460                         schedule();
 461                         write_lock(&journal->j_state_lock);
 462                         spin_lock(&commit_transaction->t_handle_lock);
 463                 }
 464                 finish_wait(&journal->j_wait_updates, &wait);
 465         }
 466         spin_unlock(&commit_transaction->t_handle_lock);
 467
 468         J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 469                         journal->j_max_transaction_buffers);
 470
 471         /*
 472          * First thing we are allowed to do is to discard any remaining
 473          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 474          * that there are no such buffers: if a large filesystem
 475          * operation like a truncate needs to split itself over multiple
 476          * transactions, then it may try to do a jbd2_journal_restart() while
 477          * there are still BJ_Reserved buffers outstanding.  These must
 478          * be released cleanly from the current transaction.
 479          *
 480          * In this case, the filesystem must still reserve write access
 481          * again before modifying the buffer in the new transaction, but
 482          * we do not require it to remember exactly which old buffers it
 483          * has reserved.  This is consistent with the existing behaviour
 484          * that multiple jbd2_journal_get_write_access() calls to the same
 485          * buffer are perfectly permissible.
 486          */
 487         while (commit_transaction->t_reserved_list) {
 488                 jh = commit_transaction->t_reserved_list;
 489                 JBUFFER_TRACE(jh, "reserved, unused: refile");
 490                 /*
 491                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 492                  * leave undo-committed data.
 493                  */
 494                 if (jh->b_committed_data) {
 495                         struct buffer_head *bh = jh2bh(jh);
 496
 497                         jbd_lock_bh_state(bh);
 498                         jbd2_free(jh->b_committed_data, bh->b_size);
 499                         jh->b_committed_data = NULL;
 500                         jbd_unlock_bh_state(bh);
 501                 }
 502                 jbd2_journal_refile_buffer(journal, jh);
 503         }
 504
 505         /*
 506          * Now try to drop any written-back buffers from the journal's
 507          * checkpoint lists.  We do this *before* commit because it potentially
 508          * frees some memory
 509          */
 510         spin_lock(&journal->j_list_lock);
 511         __jbd2_journal_clean_checkpoint_list(journal, false);
 512         spin_unlock(&journal->j_list_lock);
 513
 514         jbd_debug(3, "JBD2: commit phase 1\n");
 515
 516         /*
 517          * Clear revoked flag to reflect there is no revoked buffers
 518          * in the next transaction which is going to be started.
 519          */
 520         jbd2_clear_buffer_revoked_flags(journal);
 521
 522         /*
 523          * Switch to a new revoke table.
 524          */
 525         jbd2_journal_switch_revoke_table(journal);
 526
 527         /*
 528          * Reserved credits cannot be claimed anymore, free them
 529          */
 530         atomic_sub(atomic_read(&journal->j_reserved_credits),
 531                    &commit_transaction->t_outstanding_credits);
 532
 533         trace_jbd2_commit_flushing(journal, commit_transaction);
 534         stats.run.rs_flushing = jiffies;
 535         stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 536                                              stats.run.rs_flushing);
 537
 538         commit_transaction->t_state = T_FLUSH;
 539         journal->j_committing_transaction = commit_transaction;
 540         journal->j_running_transaction = NULL;
 541         start_time = ktime_get();
 542         commit_transaction->t_log_start = journal->j_head;
 543         wake_up(&journal->j_wait_transaction_locked);
 544         write_unlock(&journal->j_state_lock);
 545
 546         jbd_debug(3, "JBD2: commit phase 2a\n");
 547
 548         /*
 549          * Now start flushing things to disk, in the order they appear
 550          * on the transaction lists.  Data blocks go first.
 551          */
 552         err = journal_submit_data_buffers(journal, commit_transaction);
 553         if (err)
 554                 jbd2_journal_abort(journal, err);
 555
 556         blk_start_plug(&plug);
 557         jbd2_journal_write_revoke_records(commit_transaction, &log_bufs);
 558
 559         jbd_debug(3, "JBD2: commit phase 2b\n");
 560
 561         /*
 562          * Way to go: we have now written out all of the data for a
 563          * transaction!  Now comes the tricky part: we need to write out
 564          * metadata.  Loop over the transaction's entire buffer list:
 565          */
 566         write_lock(&journal->j_state_lock);
 567         commit_transaction->t_state = T_COMMIT;
 568         write_unlock(&journal->j_state_lock);
 569
 570         trace_jbd2_commit_logging(journal, commit_transaction);
 571         stats.run.rs_logging = jiffies;
 572         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 573                                                stats.run.rs_logging);
 574         stats.run.rs_blocks =
 575                 atomic_read(&commit_transaction->t_outstanding_credits);
 576         stats.run.rs_blocks_logged = 0;
 577
 578         J_ASSERT(commit_transaction->t_nr_buffers <=
 579                  atomic_read(&commit_transaction->t_outstanding_credits));
 580
 581         err = 0;
 582         bufs = 0;
 583         descriptor = NULL;
 584         while (commit_transaction->t_buffers) {
 585
 586                 /* Find the next buffer to be journaled... */
 587
 588                 jh = commit_transaction->t_buffers;
 589
 590                 /* If we're in abort mode, we just un-journal the buffer and
 591                    release it. */
 592
 593                 if (is_journal_aborted(journal)) {
 594                         clear_buffer_jbddirty(jh2bh(jh));
 595                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 596                         jbd2_buffer_abort_trigger(jh,
 597                                                   jh->b_frozen_data ?
 598                                                   jh->b_frozen_triggers :
 599                                                   jh->b_triggers);
 600                         jbd2_journal_refile_buffer(journal, jh);
 601                         /* If that was the last one, we need to clean up
 602                          * any descriptor buffers which may have been
 603                          * already allocated, even if we are now
 604                          * aborting. */
 605                         if (!commit_transaction->t_buffers)
 606                                 goto start_journal_io;
 607                         continue;
 608                 }
 609
 610                 /* Make sure we have a descriptor block in which to
 611                    record the metadata buffer. */
 612
 613                 if (!descriptor) {
 614                         J_ASSERT (bufs == 0);
 615
 616                         jbd_debug(4, "JBD2: get descriptor\n");
 617
 618                         descriptor = jbd2_journal_get_descriptor_buffer(journal);
 619                         if (!descriptor) {
 620                                 jbd2_journal_abort(journal, -EIO);
 621                                 continue;
 622                         }
 623
 624                         jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 625                                 (unsigned long long)descriptor->b_blocknr,
 626                                 descriptor->b_data);
 627                         header = (journal_header_t *)descriptor->b_data;
 628                         header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
 629                         header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK);
 630                         header->h_sequence  = cpu_to_be32(commit_transaction->t_tid);
 631
 632                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 633                         space_left = descriptor->b_size -
 634                                                 sizeof(journal_header_t);
 635                         first_tag = 1;
 636                         set_buffer_jwrite(descriptor);
 637                         set_buffer_dirty(descriptor);
 638                         wbuf[bufs++] = descriptor;
 639
 640                         /* Record it so that we can wait for IO
 641                            completion later */
 642                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 643                         jbd2_file_log_bh(&log_bufs, descriptor);
 644                 }
 645
 646                 /* Where is the buffer to be written? */
 647
 648                 err = jbd2_journal_next_log_block(journal, &blocknr);
 649                 /* If the block mapping failed, just abandon the buffer
 650                    and repeat this loop: we'll fall into the
 651                    refile-on-abort condition above. */
 652                 if (err) {
 653                         jbd2_journal_abort(journal, err);
 654                         continue;
 655                 }
 656
 657                 /*
 658                  * start_this_handle() uses t_outstanding_credits to determine
 659                  * the free space in the log, but this counter is changed
 660                  * by jbd2_journal_next_log_block() also.
 661                  */
 662                 atomic_dec(&commit_transaction->t_outstanding_credits);
 663
 664                 /* Bump b_count to prevent truncate from stumbling over
 665                    the shadowed buffer!  @@@ This can go if we ever get
 666                    rid of the shadow pairing of buffers. */
 667                 atomic_inc(&jh2bh(jh)->b_count);
 668
 669                 /*
 670                  * Make a temporary IO buffer with which to write it out
 671                  * (this will requeue the metadata buffer to BJ_Shadow).
 672                  */
 673                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 674                 JBUFFER_TRACE(jh, "ph3: write metadata");
 675                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 676                                                 jh, &wbuf[bufs], blocknr);
 677                 if (flags < 0) {
 678                         jbd2_journal_abort(journal, flags);
 679                         continue;
 680                 }
 681                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 682
 683                 /* Record the new block's tag in the current descriptor
 684                    buffer */
 685
 686                 tag_flag = 0;
 687                 if (flags & 1)
 688                         tag_flag |= JBD2_FLAG_ESCAPE;
 689                 if (!first_tag)
 690                         tag_flag |= JBD2_FLAG_SAME_UUID;
 691
 692                 tag = (journal_block_tag_t *) tagp;
 693                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 694                 tag->t_flags = cpu_to_be16(tag_flag);
 695                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 696                                         commit_transaction->t_tid);
 697                 tagp += tag_bytes;
 698                 space_left -= tag_bytes;
 699                 bufs++;
 700
 701                 if (first_tag) {
 702                         memcpy (tagp, journal->j_uuid, 16);
 703                         tagp += 16;
 704                         space_left -= 16;
 705                         first_tag = 0;
 706                 }
 707
 708                 /* If there's no more to do, or if the descriptor is full,
 709                    let the IO rip! */
 710
 711                 if (bufs == journal->j_wbufsize ||
 712                     commit_transaction->t_buffers == NULL ||
 713                     space_left < tag_bytes + 16 + csum_size) {
 714
 715                         jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 716
 717                         /* Write an end-of-descriptor marker before
 718                            submitting the IOs.  "tag" still points to
 719                            the last tag we set up. */
 720
 721                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 722
 723                         jbd2_descr_block_csum_set(journal, descriptor);
 724 start_journal_io:
 725                         for (i = 0; i < bufs; i++) {
 726                                 struct buffer_head *bh = wbuf[i];
 727                                 /*
 728                                  * Compute checksum.
 729                                  */
 730                                 if (jbd2_has_feature_checksum(journal)) {
 731                                         crc32_sum =
 732                                             jbd2_checksum_data(crc32_sum, bh);
 733                                 }
 734
 735                                 lock_buffer(bh);
 736                                 clear_buffer_dirty(bh);
 737                                 set_buffer_uptodate(bh);
 738                                 bh->b_end_io = journal_end_buffer_io_sync;
 739                                 submit_bh(WRITE_SYNC, bh);
 740                         }
 741                         cond_resched();
 742                         stats.run.rs_blocks_logged += bufs;
 743
 744                         /* Force a new descriptor to be generated next
 745                            time round the loop. */
 746                         descriptor = NULL;
 747                         bufs = 0;
 748                 }
 749         }
 750
 751         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 752         if (err) {
 753                 printk(KERN_WARNING
 754                         "JBD2: Detected IO errors while flushing file data "
 755                        "on %s\n", journal->j_devname);
 756                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 757                         jbd2_journal_abort(journal, err);
 758                 err = 0;
 759         }
 760
 761         /*
 762          * Get current oldest transaction in the log before we issue flush
 763          * to the filesystem device. After the flush we can be sure that
 764          * blocks of all older transactions are checkpointed to persistent
 765          * storage and we will be safe to update journal start in the
 766          * superblock with the numbers we get here.
 767          */
 768         update_tail =
 769                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 770
 771         write_lock(&journal->j_state_lock);
 772         if (update_tail) {
 773                 long freed = first_block - journal->j_tail;
 774
 775                 if (first_block < journal->j_tail)
 776                         freed += journal->j_last - journal->j_first;
 777                 /* Update tail only if we free significant amount of space */
 778                 if (freed < journal->j_maxlen / 4)
 779                         update_tail = 0;
 780         }
 781         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 782         commit_transaction->t_state = T_COMMIT_DFLUSH;
 783         write_unlock(&journal->j_state_lock);
 784
 785         /*
 786          * If the journal is not located on the file system device,
 787          * then we must flush the file system device before we issue
 788          * the commit record
 789          */
 790         if (commit_transaction->t_need_data_flush &&
 791             (journal->j_fs_dev != journal->j_dev) &&
 792             (journal->j_flags & JBD2_BARRIER))
 793                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 794
 795         /* Done it all: now write the commit record asynchronously. */
 796         if (jbd2_has_feature_async_commit(journal)) {
 797                 err = journal_submit_commit_record(journal, commit_transaction,
 798                                                  &cbh, crc32_sum);
 799                 if (err)
 800                         __jbd2_journal_abort_hard(journal);
 801         }
 802
 803         blk_finish_plug(&plug);
 804
 805         /* Lo and behold: we have just managed to send a transaction to
 806            the log.  Before we can commit it, wait for the IO so far to
 807            complete.  Control buffers being written are on the
 808            transaction's t_log_list queue, and metadata buffers are on
 809            the io_bufs list.
 810
 811            Wait for the buffers in reverse order.  That way we are
 812            less likely to be woken up until all IOs have completed, and
 813            so we incur less scheduling load.
 814         */
 815
 816         jbd_debug(3, "JBD2: commit phase 3\n");
 817
 818         while (!list_empty(&io_bufs)) {
 819                 struct buffer_head *bh = list_entry(io_bufs.prev,
 820                                                     struct buffer_head,
 821                                                     b_assoc_buffers);
 822
 823                 wait_on_buffer(bh);
 824                 cond_resched();
 825
 826                 if (unlikely(!buffer_uptodate(bh)))
 827                         err = -EIO;
 828                 jbd2_unfile_log_bh(bh);
 829
 830                 /*
 831                  * The list contains temporary buffer heads created by
 832                  * jbd2_journal_write_metadata_buffer().
 833                  */
 834                 BUFFER_TRACE(bh, "dumping temporary bh");
 835                 __brelse(bh);
 836                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 837                 free_buffer_head(bh);
 838
 839                 /* We also have to refile the corresponding shadowed buffer */
 840                 jh = commit_transaction->t_shadow_list->b_tprev;
 841                 bh = jh2bh(jh);
 842                 clear_buffer_jwrite(bh);
 843                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 844                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 845
 846                 /* The metadata is now released for reuse, but we need
 847                    to remember it against this transaction so that when
 848                    we finally commit, we can do any checkpointing
 849                    required. */
 850                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 851                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 852                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 853                 __brelse(bh);
 854         }
 855
 856         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 857
 858         jbd_debug(3, "JBD2: commit phase 4\n");
 859
 860         /* Here we wait for the revoke record and descriptor record buffers */
 861         while (!list_empty(&log_bufs)) {
 862                 struct buffer_head *bh;
 863
 864                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 865                 wait_on_buffer(bh);
 866                 cond_resched();
 867
 868                 if (unlikely(!buffer_uptodate(bh)))
 869                         err = -EIO;
 870
 871                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 872                 clear_buffer_jwrite(bh);
 873                 jbd2_unfile_log_bh(bh);
 874                 __brelse(bh);           /* One for getblk */
 875                 /* AKPM: bforget here */
 876         }
 877
 878         if (err)
 879                 jbd2_journal_abort(journal, err);
 880
 881         jbd_debug(3, "JBD2: commit phase 5\n");
 882         write_lock(&journal->j_state_lock);
 883         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 884         commit_transaction->t_state = T_COMMIT_JFLUSH;
 885         write_unlock(&journal->j_state_lock);
 886
 887         if (!jbd2_has_feature_async_commit(journal)) {
 888                 err = journal_submit_commit_record(journal, commit_transaction,
 889                                                 &cbh, crc32_sum);
 890                 if (err)
 891                         __jbd2_journal_abort_hard(journal);
 892         }
 893         if (cbh)
 894                 err = journal_wait_on_commit_record(journal, cbh);
 895         if (jbd2_has_feature_async_commit(journal) &&
 896             journal->j_flags & JBD2_BARRIER) {
 897                 blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 898         }
 899
 900         if (err)
 901                 jbd2_journal_abort(journal, err);
 902
 903         /*
 904          * Now disk caches for filesystem device are flushed so we are safe to
 905          * erase checkpointed transactions from the log by updating journal
 906          * superblock.
 907          */
 908         if (update_tail)
 909                 jbd2_update_log_tail(journal, first_tid, first_block);
 910
 911         /* End of a transaction!  Finally, we can do checkpoint
 912            processing: any buffers committed as a result of this
 913            transaction can be removed from any checkpoint list it was on
 914            before. */
 915
 916         jbd_debug(3, "JBD2: commit phase 6\n");
 917
 918         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 919         J_ASSERT(commit_transaction->t_buffers == NULL);
 920         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 921         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 922
 923 restart_loop:
 924         /*
 925          * As there are other places (journal_unmap_buffer()) adding buffers
 926          * to this list we have to be careful and hold the j_list_lock.
 927          */
 928         spin_lock(&journal->j_list_lock);
 929         while (commit_transaction->t_forget) {
 930                 transaction_t *cp_transaction;
 931                 struct buffer_head *bh;
 932                 int try_to_free = 0;
 933
 934                 jh = commit_transaction->t_forget;
 935                 spin_unlock(&journal->j_list_lock);
 936                 bh = jh2bh(jh);
 937                 /*
 938                  * Get a reference so that bh cannot be freed before we are
 939                  * done with it.
 940                  */
 941                 get_bh(bh);
 942                 jbd_lock_bh_state(bh);
 943                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 944
 945                 /*
 946                  * If there is undo-protected committed data against
 947                  * this buffer, then we can remove it now.  If it is a
 948                  * buffer needing such protection, the old frozen_data
 949                  * field now points to a committed version of the
 950                  * buffer, so rotate that field to the new committed
 951                  * data.
 952                  *
 953                  * Otherwise, we can just throw away the frozen data now.
 954                  *
 955                  * We also know that the frozen data has already fired
 956                  * its triggers if they exist, so we can clear that too.
 957                  */
 958                 if (jh->b_committed_data) {
 959                         jbd2_free(jh->b_committed_data, bh->b_size);
 960                         jh->b_committed_data = NULL;
 961                         if (jh->b_frozen_data) {
 962                                 jh->b_committed_data = jh->b_frozen_data;
 963                                 jh->b_frozen_data = NULL;
 964                                 jh->b_frozen_triggers = NULL;
 965                         }
 966                 } else if (jh->b_frozen_data) {
 967                         jbd2_free(jh->b_frozen_data, bh->b_size);
 968                         jh->b_frozen_data = NULL;
 969                         jh->b_frozen_triggers = NULL;
 970                 }
 971
 972                 spin_lock(&journal->j_list_lock);
 973                 cp_transaction = jh->b_cp_transaction;
 974                 if (cp_transaction) {
 975                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 976                         cp_transaction->t_chp_stats.cs_dropped++;
 977                         __jbd2_journal_remove_checkpoint(jh);
 978                 }
 979
 980                 /* Only re-checkpoint the buffer_head if it is marked
 981                  * dirty.  If the buffer was added to the BJ_Forget list
 982                  * by jbd2_journal_forget, it may no longer be dirty and
 983                  * there's no point in keeping a checkpoint record for
 984                  * it. */
 985
 986                 /*
 987                 * A buffer which has been freed while still being journaled by
 988                 * a previous transaction.
 989                 */
 990                 if (buffer_freed(bh)) {
 991                         /*
 992                          * If the running transaction is the one containing
 993                          * "add to orphan" operation (b_next_transaction !=
 994                          * NULL), we have to wait for that transaction to
 995                          * commit before we can really get rid of the buffer.
 996                          * So just clear b_modified to not confuse transaction
 997                          * credit accounting and refile the buffer to
 998                          * BJ_Forget of the running transaction. If the just
 999                          * committed transaction contains "add to orphan"
1000                          * operation, we can completely invalidate the buffer
1001                          * now. We are rather through in that since the
1002                          * buffer may be still accessible when blocksize <
1003                          * pagesize and it is attached to the last partial
1004                          * page.
1005                          */
1006                         jh->b_modified = 0;
1007                         if (!jh->b_next_transaction) {
1008                                 clear_buffer_freed(bh);
1009                                 clear_buffer_jbddirty(bh);
1010                                 clear_buffer_mapped(bh);
1011                                 clear_buffer_new(bh);
1012                                 clear_buffer_req(bh);
1013                                 bh->b_bdev = NULL;
1014                         }
1015                 }
1016
1017                 if (buffer_jbddirty(bh)) {
1018                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1019                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1020                         if (is_journal_aborted(journal))
1021                                 clear_buffer_jbddirty(bh);
1022                 } else {
1023                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1024                         /*
1025                          * The buffer on BJ_Forget list and not jbddirty means
1026                          * it has been freed by this transaction and hence it
1027                          * could not have been reallocated until this
1028                          * transaction has committed. *BUT* it could be
1029                          * reallocated once we have written all the data to
1030                          * disk and before we process the buffer on BJ_Forget
1031                          * list.
1032                          */
1033                         if (!jh->b_next_transaction)
1034                                 try_to_free = 1;
1035                 }
1036                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1037                 __jbd2_journal_refile_buffer(jh);
1038                 jbd_unlock_bh_state(bh);
1039                 if (try_to_free)
1040                         release_buffer_page(bh);        /* Drops bh reference */
1041                 else
1042                         __brelse(bh);
1043                 cond_resched_lock(&journal->j_list_lock);
1044         }
1045         spin_unlock(&journal->j_list_lock);
1046         /*
1047          * This is a bit sleazy.  We use j_list_lock to protect transition
1048          * of a transaction into T_FINISHED state and calling
1049          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1050          * other checkpointing code processing the transaction...
1051          */
1052         write_lock(&journal->j_state_lock);
1053         spin_lock(&journal->j_list_lock);
1054         /*
1055          * Now recheck if some buffers did not get attached to the transaction
1056          * while the lock was dropped...
1057          */
1058         if (commit_transaction->t_forget) {
1059                 spin_unlock(&journal->j_list_lock);
1060                 write_unlock(&journal->j_state_lock);
1061                 goto restart_loop;
1062         }
1063
1064         /* Add the transaction to the checkpoint list
1065          * __journal_remove_checkpoint() can not destroy transaction
1066          * under us because it is not marked as T_FINISHED yet */
1067         if (journal->j_checkpoint_transactions == NULL) {
1068                 journal->j_checkpoint_transactions = commit_transaction;
1069                 commit_transaction->t_cpnext = commit_transaction;
1070                 commit_transaction->t_cpprev = commit_transaction;
1071         } else {
1072                 commit_transaction->t_cpnext =
1073                         journal->j_checkpoint_transactions;
1074                 commit_transaction->t_cpprev =
1075                         commit_transaction->t_cpnext->t_cpprev;
1076                 commit_transaction->t_cpnext->t_cpprev =
1077                         commit_transaction;
1078                 commit_transaction->t_cpprev->t_cpnext =
1079                                 commit_transaction;
1080         }
1081         spin_unlock(&journal->j_list_lock);
1082
1083         /* Done with this transaction! */
1084
1085         jbd_debug(3, "JBD2: commit phase 7\n");
1086
1087         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1088
1089         commit_transaction->t_start = jiffies;
1090         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1091                                               commit_transaction->t_start);
1092
1093         /*
1094          * File the transaction statistics
1095          */
1096         stats.ts_tid = commit_transaction->t_tid;
1097         stats.run.rs_handle_count =
1098                 atomic_read(&commit_transaction->t_handle_count);
1099         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1100                              commit_transaction->t_tid, &stats.run);
1101         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1102
1103         commit_transaction->t_state = T_COMMIT_CALLBACK;
1104         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1105         journal->j_commit_sequence = commit_transaction->t_tid;
1106         journal->j_committing_transaction = NULL;
1107         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1108
1109         /*
1110          * weight the commit time higher than the average time so we don't
1111          * react too strongly to vast changes in the commit time
1112          */
1113         if (likely(journal->j_average_commit_time))
1114                 journal->j_average_commit_time = (commit_time +
1115                                 journal->j_average_commit_time*3) / 4;
1116         else
1117                 journal->j_average_commit_time = commit_time;
1118
1119         write_unlock(&journal->j_state_lock);
1120
1121         if (journal->j_commit_callback)
1122                 journal->j_commit_callback(journal, commit_transaction);
1123
1124         trace_jbd2_end_commit(journal, commit_transaction);
1125         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1126                   journal->j_commit_sequence, journal->j_tail_sequence);
1127
1128         write_lock(&journal->j_state_lock);
1129         spin_lock(&journal->j_list_lock);
1130         commit_transaction->t_state = T_FINISHED;
1131         /* Check if the transaction can be dropped now that we are finished */
1132         if (commit_transaction->t_checkpoint_list == NULL &&
1133             commit_transaction->t_checkpoint_io_list == NULL) {
1134                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1135                 jbd2_journal_free_transaction(commit_transaction);
1136         }
1137         spin_unlock(&journal->j_list_lock);
1138         write_unlock(&journal->j_state_lock);
1139         wake_up(&journal->j_wait_done_commit);
1140
1141         /*
1142          * Calculate overall stats
1143          */
1144         spin_lock(&journal->j_history_lock);
1145         journal->j_stats.ts_tid++;
1146         journal->j_stats.ts_requested += stats.ts_requested;
1147         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1148         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1149         journal->j_stats.run.rs_running += stats.run.rs_running;
1150         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1151         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1152         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1153         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1154         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1155         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1156         spin_unlock(&journal->j_history_lock);
1157 }