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         get_page(page);
  85         __brelse(bh);
  86         try_to_free_buffers(page);
  87         unlock_page(page);
  88         put_page(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(commit_transaction,
 135                                                 JBD2_COMMIT_BLOCK);
 136         if (!bh)
 137                 return 1;
 138
 139         tmp = (struct commit_header *)bh->b_data;
 140         tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
 141         tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
 142
 143         if (jbd2_has_feature_checksum(journal)) {
 144                 tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
 145                 tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
 146                 tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
 147         }
 148         jbd2_commit_block_csum_set(journal, bh);
 149
 150         BUFFER_TRACE(bh, "submit commit block");
 151         lock_buffer(bh);
 152         clear_buffer_dirty(bh);
 153         set_buffer_uptodate(bh);
 154         bh->b_end_io = journal_end_buffer_io_sync;
 155
 156         if (journal->j_flags & JBD2_BARRIER &&
 157             !jbd2_has_feature_async_commit(journal))
 158                 ret = submit_bh(WRITE_SYNC | WRITE_FLUSH_FUA, bh);
 159         else
 160                 ret = submit_bh(WRITE_SYNC, bh);
 161
 162         *cbh = bh;
 163         return ret;
 164 }
 165
 166 /*
 167  * This function along with journal_submit_commit_record
 168  * allows to write the commit record asynchronously.
 169  */
 170 static int journal_wait_on_commit_record(journal_t *journal,
 171                                          struct buffer_head *bh)
 172 {
 173         int ret = 0;
 174
 175         clear_buffer_dirty(bh);
 176         wait_on_buffer(bh);
 177
 178         if (unlikely(!buffer_uptodate(bh)))
 179                 ret = -EIO;
 180         put_bh(bh);            /* One for getblk() */
 181
 182         return ret;
 183 }
 184
 185 /*
 186  * write the filemap data using writepage() address_space_operations.
 187  * We don't do block allocation here even for delalloc. We don't
 188  * use writepages() because with dealyed allocation we may be doing
 189  * block allocation in writepages().
 190  */
 191 static int journal_submit_inode_data_buffers(struct address_space *mapping)
 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 = 0,
 198                 .range_end = i_size_read(mapping->host),
 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                 if (!(jinode->i_flags & JI_WRITE_DATA))
 223                         continue;
 224                 mapping = jinode->i_vfs_inode->i_mapping;
 225                 jinode->i_flags |= JI_COMMIT_RUNNING;
 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                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 240                 smp_mb();
 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                 if (!(jinode->i_flags & JI_WAIT_DATA))
 262                         continue;
 263                 jinode->i_flags |= JI_COMMIT_RUNNING;
 264                 spin_unlock(&journal->j_list_lock);
 265                 err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping);
 266                 if (err) {
 267                         /*
 268                          * Because AS_EIO is cleared by
 269                          * filemap_fdatawait_range(), set it again so
 270                          * that user process can get -EIO from fsync().
 271                          */
 272                         set_bit(AS_EIO,
 273                                 &jinode->i_vfs_inode->i_mapping->flags);
 274
 275                         if (!ret)
 276                                 ret = err;
 277                 }
 278                 spin_lock(&journal->j_list_lock);
 279                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 280                 smp_mb();
 281                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 282         }
 283
 284         /* Now refile inode to proper lists */
 285         list_for_each_entry_safe(jinode, next_i,
 286                                  &commit_transaction->t_inode_list, i_list) {
 287                 list_del(&jinode->i_list);
 288                 if (jinode->i_next_transaction) {
 289                         jinode->i_transaction = jinode->i_next_transaction;
 290                         jinode->i_next_transaction = NULL;
 291                         list_add(&jinode->i_list,
 292                                 &jinode->i_transaction->t_inode_list);
 293                 } else {
 294                         jinode->i_transaction = NULL;
 295                 }
 296         }
 297         spin_unlock(&journal->j_list_lock);
 298
 299         return ret;
 300 }
 301
 302 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 303 {
 304         struct page *page = bh->b_page;
 305         char *addr;
 306         __u32 checksum;
 307
 308         addr = kmap_atomic(page);
 309         checksum = crc32_be(crc32_sum,
 310                 (void *)(addr + offset_in_page(bh->b_data)), bh->b_size);
 311         kunmap_atomic(addr);
 312
 313         return checksum;
 314 }
 315
 316 static void write_tag_block(journal_t *j, journal_block_tag_t *tag,
 317                                    unsigned long long block)
 318 {
 319         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
 320         if (jbd2_has_feature_64bit(j))
 321                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 322 }
 323
 324 static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 325                                     struct buffer_head *bh, __u32 sequence)
 326 {
 327         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 328         struct page *page = bh->b_page;
 329         __u8 *addr;
 330         __u32 csum32;
 331         __be32 seq;
 332
 333         if (!jbd2_journal_has_csum_v2or3(j))
 334                 return;
 335
 336         seq = cpu_to_be32(sequence);
 337         addr = kmap_atomic(page);
 338         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 339         csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 340                              bh->b_size);
 341         kunmap_atomic(addr);
 342
 343         if (jbd2_has_feature_csum3(j))
 344                 tag3->t_checksum = cpu_to_be32(csum32);
 345         else
 346                 tag->t_checksum = cpu_to_be16(csum32);
 347 }
 348 /*
 349  * jbd2_journal_commit_transaction
 350  *
 351  * The primary function for committing a transaction to the log.  This
 352  * function is called by the journal thread to begin a complete commit.
 353  */
 354 void jbd2_journal_commit_transaction(journal_t *journal)
 355 {
 356         struct transaction_stats_s stats;
 357         transaction_t *commit_transaction;
 358         struct journal_head *jh;
 359         struct buffer_head *descriptor;
 360         struct buffer_head **wbuf = journal->j_wbuf;
 361         int bufs;
 362         int flags;
 363         int err;
 364         unsigned long long blocknr;
 365         ktime_t start_time;
 366         u64 commit_time;
 367         char *tagp = NULL;
 368         journal_block_tag_t *tag = NULL;
 369         int space_left = 0;
 370         int first_tag = 0;
 371         int tag_flag;
 372         int i;
 373         int tag_bytes = journal_tag_bytes(journal);
 374         struct buffer_head *cbh = NULL; /* For transactional checksums */
 375         __u32 crc32_sum = ~0;
 376         struct blk_plug plug;
 377         /* Tail of the journal */
 378         unsigned long first_block;
 379         tid_t first_tid;
 380         int update_tail;
 381         int csum_size = 0;
 382         LIST_HEAD(io_bufs);
 383         LIST_HEAD(log_bufs);
 384
 385         if (jbd2_journal_has_csum_v2or3(journal))
 386                 csum_size = sizeof(struct jbd2_journal_block_tail);
 387
 388         /*
 389          * First job: lock down the current transaction and wait for
 390          * all outstanding updates to complete.
 391          */
 392
 393         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 394         if (journal->j_flags & JBD2_FLUSHED) {
 395                 jbd_debug(3, "super block updated\n");
 396                 mutex_lock(&journal->j_checkpoint_mutex);
 397                 /*
 398                  * We hold j_checkpoint_mutex so tail cannot change under us.
 399                  * We don't need any special data guarantees for writing sb
 400                  * since journal is empty and it is ok for write to be
 401                  * flushed only with transaction commit.
 402                  */
 403                 jbd2_journal_update_sb_log_tail(journal,
 404                                                 journal->j_tail_sequence,
 405                                                 journal->j_tail,
 406                                                 WRITE_SYNC);
 407                 mutex_unlock(&journal->j_checkpoint_mutex);
 408         } else {
 409                 jbd_debug(3, "superblock not updated\n");
 410         }
 411
 412         J_ASSERT(journal->j_running_transaction != NULL);
 413         J_ASSERT(journal->j_committing_transaction == NULL);
 414
 415         commit_transaction = journal->j_running_transaction;
 416
 417         trace_jbd2_start_commit(journal, commit_transaction);
 418         jbd_debug(1, "JBD2: starting commit of transaction %d\n",
 419                         commit_transaction->t_tid);
 420
 421         write_lock(&journal->j_state_lock);
 422         J_ASSERT(commit_transaction->t_state == T_RUNNING);
 423         commit_transaction->t_state = T_LOCKED;
 424
 425         trace_jbd2_commit_locking(journal, commit_transaction);
 426         stats.run.rs_wait = commit_transaction->t_max_wait;
 427         stats.run.rs_request_delay = 0;
 428         stats.run.rs_locked = jiffies;
 429         if (commit_transaction->t_requested)
 430                 stats.run.rs_request_delay =
 431                         jbd2_time_diff(commit_transaction->t_requested,
 432                                        stats.run.rs_locked);
 433         stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
 434                                               stats.run.rs_locked);
 435
 436         spin_lock(&commit_transaction->t_handle_lock);
 437         while (atomic_read(&commit_transaction->t_updates)) {
 438                 DEFINE_WAIT(wait);
 439
 440                 prepare_to_wait(&journal->j_wait_updates, &wait,
 441                                         TASK_UNINTERRUPTIBLE);
 442                 if (atomic_read(&commit_transaction->t_updates)) {
 443                         spin_unlock(&commit_transaction->t_handle_lock);
 444                         write_unlock(&journal->j_state_lock);
 445                         schedule();
 446                         write_lock(&journal->j_state_lock);
 447                         spin_lock(&commit_transaction->t_handle_lock);
 448                 }
 449                 finish_wait(&journal->j_wait_updates, &wait);
 450         }
 451         spin_unlock(&commit_transaction->t_handle_lock);
 452
 453         J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 454                         journal->j_max_transaction_buffers);
 455
 456         /*
 457          * First thing we are allowed to do is to discard any remaining
 458          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 459          * that there are no such buffers: if a large filesystem
 460          * operation like a truncate needs to split itself over multiple
 461          * transactions, then it may try to do a jbd2_journal_restart() while
 462          * there are still BJ_Reserved buffers outstanding.  These must
 463          * be released cleanly from the current transaction.
 464          *
 465          * In this case, the filesystem must still reserve write access
 466          * again before modifying the buffer in the new transaction, but
 467          * we do not require it to remember exactly which old buffers it
 468          * has reserved.  This is consistent with the existing behaviour
 469          * that multiple jbd2_journal_get_write_access() calls to the same
 470          * buffer are perfectly permissible.
 471          */
 472         while (commit_transaction->t_reserved_list) {
 473                 jh = commit_transaction->t_reserved_list;
 474                 JBUFFER_TRACE(jh, "reserved, unused: refile");
 475                 /*
 476                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 477                  * leave undo-committed data.
 478                  */
 479                 if (jh->b_committed_data) {
 480                         struct buffer_head *bh = jh2bh(jh);
 481
 482                         jbd_lock_bh_state(bh);
 483                         jbd2_free(jh->b_committed_data, bh->b_size);
 484                         jh->b_committed_data = NULL;
 485                         jbd_unlock_bh_state(bh);
 486                 }
 487                 jbd2_journal_refile_buffer(journal, jh);
 488         }
 489
 490         /*
 491          * Now try to drop any written-back buffers from the journal's
 492          * checkpoint lists.  We do this *before* commit because it potentially
 493          * frees some memory
 494          */
 495         spin_lock(&journal->j_list_lock);
 496         __jbd2_journal_clean_checkpoint_list(journal, false);
 497         spin_unlock(&journal->j_list_lock);
 498
 499         jbd_debug(3, "JBD2: commit phase 1\n");
 500
 501         /*
 502          * Clear revoked flag to reflect there is no revoked buffers
 503          * in the next transaction which is going to be started.
 504          */
 505         jbd2_clear_buffer_revoked_flags(journal);
 506
 507         /*
 508          * Switch to a new revoke table.
 509          */
 510         jbd2_journal_switch_revoke_table(journal);
 511
 512         /*
 513          * Reserved credits cannot be claimed anymore, free them
 514          */
 515         atomic_sub(atomic_read(&journal->j_reserved_credits),
 516                    &commit_transaction->t_outstanding_credits);
 517
 518         trace_jbd2_commit_flushing(journal, commit_transaction);
 519         stats.run.rs_flushing = jiffies;
 520         stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 521                                              stats.run.rs_flushing);
 522
 523         commit_transaction->t_state = T_FLUSH;
 524         journal->j_committing_transaction = commit_transaction;
 525         journal->j_running_transaction = NULL;
 526         start_time = ktime_get();
 527         commit_transaction->t_log_start = journal->j_head;
 528         wake_up(&journal->j_wait_transaction_locked);
 529         write_unlock(&journal->j_state_lock);
 530
 531         jbd_debug(3, "JBD2: commit phase 2a\n");
 532
 533         /*
 534          * Now start flushing things to disk, in the order they appear
 535          * on the transaction lists.  Data blocks go first.
 536          */
 537         err = journal_submit_data_buffers(journal, commit_transaction);
 538         if (err)
 539                 jbd2_journal_abort(journal, err);
 540
 541         blk_start_plug(&plug);
 542         jbd2_journal_write_revoke_records(commit_transaction, &log_bufs);
 543
 544         jbd_debug(3, "JBD2: commit phase 2b\n");
 545
 546         /*
 547          * Way to go: we have now written out all of the data for a
 548          * transaction!  Now comes the tricky part: we need to write out
 549          * metadata.  Loop over the transaction's entire buffer list:
 550          */
 551         write_lock(&journal->j_state_lock);
 552         commit_transaction->t_state = T_COMMIT;
 553         write_unlock(&journal->j_state_lock);
 554
 555         trace_jbd2_commit_logging(journal, commit_transaction);
 556         stats.run.rs_logging = jiffies;
 557         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 558                                                stats.run.rs_logging);
 559         stats.run.rs_blocks =
 560                 atomic_read(&commit_transaction->t_outstanding_credits);
 561         stats.run.rs_blocks_logged = 0;
 562
 563         J_ASSERT(commit_transaction->t_nr_buffers <=
 564                  atomic_read(&commit_transaction->t_outstanding_credits));
 565
 566         err = 0;
 567         bufs = 0;
 568         descriptor = NULL;
 569         while (commit_transaction->t_buffers) {
 570
 571                 /* Find the next buffer to be journaled... */
 572
 573                 jh = commit_transaction->t_buffers;
 574
 575                 /* If we're in abort mode, we just un-journal the buffer and
 576                    release it. */
 577
 578                 if (is_journal_aborted(journal)) {
 579                         clear_buffer_jbddirty(jh2bh(jh));
 580                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 581                         jbd2_buffer_abort_trigger(jh,
 582                                                   jh->b_frozen_data ?
 583                                                   jh->b_frozen_triggers :
 584                                                   jh->b_triggers);
 585                         jbd2_journal_refile_buffer(journal, jh);
 586                         /* If that was the last one, we need to clean up
 587                          * any descriptor buffers which may have been
 588                          * already allocated, even if we are now
 589                          * aborting. */
 590                         if (!commit_transaction->t_buffers)
 591                                 goto start_journal_io;
 592                         continue;
 593                 }
 594
 595                 /* Make sure we have a descriptor block in which to
 596                    record the metadata buffer. */
 597
 598                 if (!descriptor) {
 599                         J_ASSERT (bufs == 0);
 600
 601                         jbd_debug(4, "JBD2: get descriptor\n");
 602
 603                         descriptor = jbd2_journal_get_descriptor_buffer(
 604                                                         commit_transaction,
 605                                                         JBD2_DESCRIPTOR_BLOCK);
 606                         if (!descriptor) {
 607                                 jbd2_journal_abort(journal, -EIO);
 608                                 continue;
 609                         }
 610
 611                         jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 612                                 (unsigned long long)descriptor->b_blocknr,
 613                                 descriptor->b_data);
 614                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 615                         space_left = descriptor->b_size -
 616                                                 sizeof(journal_header_t);
 617                         first_tag = 1;
 618                         set_buffer_jwrite(descriptor);
 619                         set_buffer_dirty(descriptor);
 620                         wbuf[bufs++] = descriptor;
 621
 622                         /* Record it so that we can wait for IO
 623                            completion later */
 624                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 625                         jbd2_file_log_bh(&log_bufs, descriptor);
 626                 }
 627
 628                 /* Where is the buffer to be written? */
 629
 630                 err = jbd2_journal_next_log_block(journal, &blocknr);
 631                 /* If the block mapping failed, just abandon the buffer
 632                    and repeat this loop: we'll fall into the
 633                    refile-on-abort condition above. */
 634                 if (err) {
 635                         jbd2_journal_abort(journal, err);
 636                         continue;
 637                 }
 638
 639                 /*
 640                  * start_this_handle() uses t_outstanding_credits to determine
 641                  * the free space in the log, but this counter is changed
 642                  * by jbd2_journal_next_log_block() also.
 643                  */
 644                 atomic_dec(&commit_transaction->t_outstanding_credits);
 645
 646                 /* Bump b_count to prevent truncate from stumbling over
 647                    the shadowed buffer!  @@@ This can go if we ever get
 648                    rid of the shadow pairing of buffers. */
 649                 atomic_inc(&jh2bh(jh)->b_count);
 650
 651                 /*
 652                  * Make a temporary IO buffer with which to write it out
 653                  * (this will requeue the metadata buffer to BJ_Shadow).
 654                  */
 655                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 656                 JBUFFER_TRACE(jh, "ph3: write metadata");
 657                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 658                                                 jh, &wbuf[bufs], blocknr);
 659                 if (flags < 0) {
 660                         jbd2_journal_abort(journal, flags);
 661                         continue;
 662                 }
 663                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 664
 665                 /* Record the new block's tag in the current descriptor
 666                    buffer */
 667
 668                 tag_flag = 0;
 669                 if (flags & 1)
 670                         tag_flag |= JBD2_FLAG_ESCAPE;
 671                 if (!first_tag)
 672                         tag_flag |= JBD2_FLAG_SAME_UUID;
 673
 674                 tag = (journal_block_tag_t *) tagp;
 675                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 676                 tag->t_flags = cpu_to_be16(tag_flag);
 677                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 678                                         commit_transaction->t_tid);
 679                 tagp += tag_bytes;
 680                 space_left -= tag_bytes;
 681                 bufs++;
 682
 683                 if (first_tag) {
 684                         memcpy (tagp, journal->j_uuid, 16);
 685                         tagp += 16;
 686                         space_left -= 16;
 687                         first_tag = 0;
 688                 }
 689
 690                 /* If there's no more to do, or if the descriptor is full,
 691                    let the IO rip! */
 692
 693                 if (bufs == journal->j_wbufsize ||
 694                     commit_transaction->t_buffers == NULL ||
 695                     space_left < tag_bytes + 16 + csum_size) {
 696
 697                         jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 698
 699                         /* Write an end-of-descriptor marker before
 700                            submitting the IOs.  "tag" still points to
 701                            the last tag we set up. */
 702
 703                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 704
 705                         jbd2_descriptor_block_csum_set(journal, descriptor);
 706 start_journal_io:
 707                         for (i = 0; i < bufs; i++) {
 708                                 struct buffer_head *bh = wbuf[i];
 709                                 /*
 710                                  * Compute checksum.
 711                                  */
 712                                 if (jbd2_has_feature_checksum(journal)) {
 713                                         crc32_sum =
 714                                             jbd2_checksum_data(crc32_sum, bh);
 715                                 }
 716
 717                                 lock_buffer(bh);
 718                                 clear_buffer_dirty(bh);
 719                                 set_buffer_uptodate(bh);
 720                                 bh->b_end_io = journal_end_buffer_io_sync;
 721                                 submit_bh(WRITE_SYNC, bh);
 722                         }
 723                         cond_resched();
 724                         stats.run.rs_blocks_logged += bufs;
 725
 726                         /* Force a new descriptor to be generated next
 727                            time round the loop. */
 728                         descriptor = NULL;
 729                         bufs = 0;
 730                 }
 731         }
 732
 733         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 734         if (err) {
 735                 printk(KERN_WARNING
 736                         "JBD2: Detected IO errors while flushing file data "
 737                        "on %s\n", journal->j_devname);
 738                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 739                         jbd2_journal_abort(journal, err);
 740                 err = 0;
 741         }
 742
 743         /*
 744          * Get current oldest transaction in the log before we issue flush
 745          * to the filesystem device. After the flush we can be sure that
 746          * blocks of all older transactions are checkpointed to persistent
 747          * storage and we will be safe to update journal start in the
 748          * superblock with the numbers we get here.
 749          */
 750         update_tail =
 751                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 752
 753         write_lock(&journal->j_state_lock);
 754         if (update_tail) {
 755                 long freed = first_block - journal->j_tail;
 756
 757                 if (first_block < journal->j_tail)
 758                         freed += journal->j_last - journal->j_first;
 759                 /* Update tail only if we free significant amount of space */
 760                 if (freed < journal->j_maxlen / 4)
 761                         update_tail = 0;
 762         }
 763         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 764         commit_transaction->t_state = T_COMMIT_DFLUSH;
 765         write_unlock(&journal->j_state_lock);
 766
 767         /*
 768          * If the journal is not located on the file system device,
 769          * then we must flush the file system device before we issue
 770          * the commit record
 771          */
 772         if (commit_transaction->t_need_data_flush &&
 773             (journal->j_fs_dev != journal->j_dev) &&
 774             (journal->j_flags & JBD2_BARRIER))
 775                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 776
 777         /* Done it all: now write the commit record asynchronously. */
 778         if (jbd2_has_feature_async_commit(journal)) {
 779                 err = journal_submit_commit_record(journal, commit_transaction,
 780                                                  &cbh, crc32_sum);
 781                 if (err)
 782                         __jbd2_journal_abort_hard(journal);
 783         }
 784
 785         blk_finish_plug(&plug);
 786
 787         /* Lo and behold: we have just managed to send a transaction to
 788            the log.  Before we can commit it, wait for the IO so far to
 789            complete.  Control buffers being written are on the
 790            transaction's t_log_list queue, and metadata buffers are on
 791            the io_bufs list.
 792
 793            Wait for the buffers in reverse order.  That way we are
 794            less likely to be woken up until all IOs have completed, and
 795            so we incur less scheduling load.
 796         */
 797
 798         jbd_debug(3, "JBD2: commit phase 3\n");
 799
 800         while (!list_empty(&io_bufs)) {
 801                 struct buffer_head *bh = list_entry(io_bufs.prev,
 802                                                     struct buffer_head,
 803                                                     b_assoc_buffers);
 804
 805                 wait_on_buffer(bh);
 806                 cond_resched();
 807
 808                 if (unlikely(!buffer_uptodate(bh)))
 809                         err = -EIO;
 810                 jbd2_unfile_log_bh(bh);
 811
 812                 /*
 813                  * The list contains temporary buffer heads created by
 814                  * jbd2_journal_write_metadata_buffer().
 815                  */
 816                 BUFFER_TRACE(bh, "dumping temporary bh");
 817                 __brelse(bh);
 818                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 819                 free_buffer_head(bh);
 820
 821                 /* We also have to refile the corresponding shadowed buffer */
 822                 jh = commit_transaction->t_shadow_list->b_tprev;
 823                 bh = jh2bh(jh);
 824                 clear_buffer_jwrite(bh);
 825                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 826                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 827
 828                 /* The metadata is now released for reuse, but we need
 829                    to remember it against this transaction so that when
 830                    we finally commit, we can do any checkpointing
 831                    required. */
 832                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 833                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 834                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 835                 __brelse(bh);
 836         }
 837
 838         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 839
 840         jbd_debug(3, "JBD2: commit phase 4\n");
 841
 842         /* Here we wait for the revoke record and descriptor record buffers */
 843         while (!list_empty(&log_bufs)) {
 844                 struct buffer_head *bh;
 845
 846                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 847                 wait_on_buffer(bh);
 848                 cond_resched();
 849
 850                 if (unlikely(!buffer_uptodate(bh)))
 851                         err = -EIO;
 852
 853                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 854                 clear_buffer_jwrite(bh);
 855                 jbd2_unfile_log_bh(bh);
 856                 __brelse(bh);           /* One for getblk */
 857                 /* AKPM: bforget here */
 858         }
 859
 860         if (err)
 861                 jbd2_journal_abort(journal, err);
 862
 863         jbd_debug(3, "JBD2: commit phase 5\n");
 864         write_lock(&journal->j_state_lock);
 865         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 866         commit_transaction->t_state = T_COMMIT_JFLUSH;
 867         write_unlock(&journal->j_state_lock);
 868
 869         if (!jbd2_has_feature_async_commit(journal)) {
 870                 err = journal_submit_commit_record(journal, commit_transaction,
 871                                                 &cbh, crc32_sum);
 872                 if (err)
 873                         __jbd2_journal_abort_hard(journal);
 874         }
 875         if (cbh)
 876                 err = journal_wait_on_commit_record(journal, cbh);
 877         if (jbd2_has_feature_async_commit(journal) &&
 878             journal->j_flags & JBD2_BARRIER) {
 879                 blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 880         }
 881
 882         if (err)
 883                 jbd2_journal_abort(journal, err);
 884
 885         /*
 886          * Now disk caches for filesystem device are flushed so we are safe to
 887          * erase checkpointed transactions from the log by updating journal
 888          * superblock.
 889          */
 890         if (update_tail)
 891                 jbd2_update_log_tail(journal, first_tid, first_block);
 892
 893         /* End of a transaction!  Finally, we can do checkpoint
 894            processing: any buffers committed as a result of this
 895            transaction can be removed from any checkpoint list it was on
 896            before. */
 897
 898         jbd_debug(3, "JBD2: commit phase 6\n");
 899
 900         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 901         J_ASSERT(commit_transaction->t_buffers == NULL);
 902         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 903         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 904
 905 restart_loop:
 906         /*
 907          * As there are other places (journal_unmap_buffer()) adding buffers
 908          * to this list we have to be careful and hold the j_list_lock.
 909          */
 910         spin_lock(&journal->j_list_lock);
 911         while (commit_transaction->t_forget) {
 912                 transaction_t *cp_transaction;
 913                 struct buffer_head *bh;
 914                 int try_to_free = 0;
 915
 916                 jh = commit_transaction->t_forget;
 917                 spin_unlock(&journal->j_list_lock);
 918                 bh = jh2bh(jh);
 919                 /*
 920                  * Get a reference so that bh cannot be freed before we are
 921                  * done with it.
 922                  */
 923                 get_bh(bh);
 924                 jbd_lock_bh_state(bh);
 925                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 926
 927                 /*
 928                  * If there is undo-protected committed data against
 929                  * this buffer, then we can remove it now.  If it is a
 930                  * buffer needing such protection, the old frozen_data
 931                  * field now points to a committed version of the
 932                  * buffer, so rotate that field to the new committed
 933                  * data.
 934                  *
 935                  * Otherwise, we can just throw away the frozen data now.
 936                  *
 937                  * We also know that the frozen data has already fired
 938                  * its triggers if they exist, so we can clear that too.
 939                  */
 940                 if (jh->b_committed_data) {
 941                         jbd2_free(jh->b_committed_data, bh->b_size);
 942                         jh->b_committed_data = NULL;
 943                         if (jh->b_frozen_data) {
 944                                 jh->b_committed_data = jh->b_frozen_data;
 945                                 jh->b_frozen_data = NULL;
 946                                 jh->b_frozen_triggers = NULL;
 947                         }
 948                 } else if (jh->b_frozen_data) {
 949                         jbd2_free(jh->b_frozen_data, bh->b_size);
 950                         jh->b_frozen_data = NULL;
 951                         jh->b_frozen_triggers = NULL;
 952                 }
 953
 954                 spin_lock(&journal->j_list_lock);
 955                 cp_transaction = jh->b_cp_transaction;
 956                 if (cp_transaction) {
 957                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 958                         cp_transaction->t_chp_stats.cs_dropped++;
 959                         __jbd2_journal_remove_checkpoint(jh);
 960                 }
 961
 962                 /* Only re-checkpoint the buffer_head if it is marked
 963                  * dirty.  If the buffer was added to the BJ_Forget list
 964                  * by jbd2_journal_forget, it may no longer be dirty and
 965                  * there's no point in keeping a checkpoint record for
 966                  * it. */
 967
 968                 /*
 969                 * A buffer which has been freed while still being journaled by
 970                 * a previous transaction.
 971                 */
 972                 if (buffer_freed(bh)) {
 973                         /*
 974                          * If the running transaction is the one containing
 975                          * "add to orphan" operation (b_next_transaction !=
 976                          * NULL), we have to wait for that transaction to
 977                          * commit before we can really get rid of the buffer.
 978                          * So just clear b_modified to not confuse transaction
 979                          * credit accounting and refile the buffer to
 980                          * BJ_Forget of the running transaction. If the just
 981                          * committed transaction contains "add to orphan"
 982                          * operation, we can completely invalidate the buffer
 983                          * now. We are rather through in that since the
 984                          * buffer may be still accessible when blocksize <
 985                          * pagesize and it is attached to the last partial
 986                          * page.
 987                          */
 988                         jh->b_modified = 0;
 989                         if (!jh->b_next_transaction) {
 990                                 clear_buffer_freed(bh);
 991                                 clear_buffer_jbddirty(bh);
 992                                 clear_buffer_mapped(bh);
 993                                 clear_buffer_new(bh);
 994                                 clear_buffer_req(bh);
 995                                 bh->b_bdev = NULL;
 996                         }
 997                 }
 998
 999                 if (buffer_jbddirty(bh)) {
1000                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1001                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1002                         if (is_journal_aborted(journal))
1003                                 clear_buffer_jbddirty(bh);
1004                 } else {
1005                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1006                         /*
1007                          * The buffer on BJ_Forget list and not jbddirty means
1008                          * it has been freed by this transaction and hence it
1009                          * could not have been reallocated until this
1010                          * transaction has committed. *BUT* it could be
1011                          * reallocated once we have written all the data to
1012                          * disk and before we process the buffer on BJ_Forget
1013                          * list.
1014                          */
1015                         if (!jh->b_next_transaction)
1016                                 try_to_free = 1;
1017                 }
1018                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1019                 __jbd2_journal_refile_buffer(jh);
1020                 jbd_unlock_bh_state(bh);
1021                 if (try_to_free)
1022                         release_buffer_page(bh);        /* Drops bh reference */
1023                 else
1024                         __brelse(bh);
1025                 cond_resched_lock(&journal->j_list_lock);
1026         }
1027         spin_unlock(&journal->j_list_lock);
1028         /*
1029          * This is a bit sleazy.  We use j_list_lock to protect transition
1030          * of a transaction into T_FINISHED state and calling
1031          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1032          * other checkpointing code processing the transaction...
1033          */
1034         write_lock(&journal->j_state_lock);
1035         spin_lock(&journal->j_list_lock);
1036         /*
1037          * Now recheck if some buffers did not get attached to the transaction
1038          * while the lock was dropped...
1039          */
1040         if (commit_transaction->t_forget) {
1041                 spin_unlock(&journal->j_list_lock);
1042                 write_unlock(&journal->j_state_lock);
1043                 goto restart_loop;
1044         }
1045
1046         /* Add the transaction to the checkpoint list
1047          * __journal_remove_checkpoint() can not destroy transaction
1048          * under us because it is not marked as T_FINISHED yet */
1049         if (journal->j_checkpoint_transactions == NULL) {
1050                 journal->j_checkpoint_transactions = commit_transaction;
1051                 commit_transaction->t_cpnext = commit_transaction;
1052                 commit_transaction->t_cpprev = commit_transaction;
1053         } else {
1054                 commit_transaction->t_cpnext =
1055                         journal->j_checkpoint_transactions;
1056                 commit_transaction->t_cpprev =
1057                         commit_transaction->t_cpnext->t_cpprev;
1058                 commit_transaction->t_cpnext->t_cpprev =
1059                         commit_transaction;
1060                 commit_transaction->t_cpprev->t_cpnext =
1061                                 commit_transaction;
1062         }
1063         spin_unlock(&journal->j_list_lock);
1064
1065         /* Done with this transaction! */
1066
1067         jbd_debug(3, "JBD2: commit phase 7\n");
1068
1069         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1070
1071         commit_transaction->t_start = jiffies;
1072         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1073                                               commit_transaction->t_start);
1074
1075         /*
1076          * File the transaction statistics
1077          */
1078         stats.ts_tid = commit_transaction->t_tid;
1079         stats.run.rs_handle_count =
1080                 atomic_read(&commit_transaction->t_handle_count);
1081         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1082                              commit_transaction->t_tid, &stats.run);
1083         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1084
1085         commit_transaction->t_state = T_COMMIT_CALLBACK;
1086         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1087         journal->j_commit_sequence = commit_transaction->t_tid;
1088         journal->j_committing_transaction = NULL;
1089         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1090
1091         /*
1092          * weight the commit time higher than the average time so we don't
1093          * react too strongly to vast changes in the commit time
1094          */
1095         if (likely(journal->j_average_commit_time))
1096                 journal->j_average_commit_time = (commit_time +
1097                                 journal->j_average_commit_time*3) / 4;
1098         else
1099                 journal->j_average_commit_time = commit_time;
1100
1101         write_unlock(&journal->j_state_lock);
1102
1103         if (journal->j_commit_callback)
1104                 journal->j_commit_callback(journal, commit_transaction);
1105
1106         trace_jbd2_end_commit(journal, commit_transaction);
1107         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1108                   journal->j_commit_sequence, journal->j_tail_sequence);
1109
1110         write_lock(&journal->j_state_lock);
1111         spin_lock(&journal->j_list_lock);
1112         commit_transaction->t_state = T_FINISHED;
1113         /* Check if the transaction can be dropped now that we are finished */
1114         if (commit_transaction->t_checkpoint_list == NULL &&
1115             commit_transaction->t_checkpoint_io_list == NULL) {
1116                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1117                 jbd2_journal_free_transaction(commit_transaction);
1118         }
1119         spin_unlock(&journal->j_list_lock);
1120         write_unlock(&journal->j_state_lock);
1121         wake_up(&journal->j_wait_done_commit);
1122
1123         /*
1124          * Calculate overall stats
1125          */
1126         spin_lock(&journal->j_history_lock);
1127         journal->j_stats.ts_tid++;
1128         journal->j_stats.ts_requested += stats.ts_requested;
1129         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1130         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1131         journal->j_stats.run.rs_running += stats.run.rs_running;
1132         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1133         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1134         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1135         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1136         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1137         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1138         spin_unlock(&journal->j_history_lock);
1139 }