kernel/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(journal, commit_transaction,
 558                                           &log_bufs, WRITE_SYNC);
 559
 560         jbd_debug(3, "JBD2: commit phase 2b\n");
 561
 562         /*
 563          * Way to go: we have now written out all of the data for a
 564          * transaction!  Now comes the tricky part: we need to write out
 565          * metadata.  Loop over the transaction's entire buffer list:
 566          */
 567         write_lock(&journal->j_state_lock);
 568         commit_transaction->t_state = T_COMMIT;
 569         write_unlock(&journal->j_state_lock);
 570
 571         trace_jbd2_commit_logging(journal, commit_transaction);
 572         stats.run.rs_logging = jiffies;
 573         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 574                                                stats.run.rs_logging);
 575         stats.run.rs_blocks =
 576                 atomic_read(&commit_transaction->t_outstanding_credits);
 577         stats.run.rs_blocks_logged = 0;
 578
 579         J_ASSERT(commit_transaction->t_nr_buffers <=
 580                  atomic_read(&commit_transaction->t_outstanding_credits));
 581
 582         err = 0;
 583         bufs = 0;
 584         descriptor = NULL;
 585         while (commit_transaction->t_buffers) {
 586
 587                 /* Find the next buffer to be journaled... */
 588
 589                 jh = commit_transaction->t_buffers;
 590
 591                 /* If we're in abort mode, we just un-journal the buffer and
 592                    release it. */
 593
 594                 if (is_journal_aborted(journal)) {
 595                         clear_buffer_jbddirty(jh2bh(jh));
 596                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 597                         jbd2_buffer_abort_trigger(jh,
 598                                                   jh->b_frozen_data ?
 599                                                   jh->b_frozen_triggers :
 600                                                   jh->b_triggers);
 601                         jbd2_journal_refile_buffer(journal, jh);
 602                         /* If that was the last one, we need to clean up
 603                          * any descriptor buffers which may have been
 604                          * already allocated, even if we are now
 605                          * aborting. */
 606                         if (!commit_transaction->t_buffers)
 607                                 goto start_journal_io;
 608                         continue;
 609                 }
 610
 611                 /* Make sure we have a descriptor block in which to
 612                    record the metadata buffer. */
 613
 614                 if (!descriptor) {
 615                         J_ASSERT (bufs == 0);
 616
 617                         jbd_debug(4, "JBD2: get descriptor\n");
 618
 619                         descriptor = jbd2_journal_get_descriptor_buffer(journal);
 620                         if (!descriptor) {
 621                                 jbd2_journal_abort(journal, -EIO);
 622                                 continue;
 623                         }
 624
 625                         jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 626                                 (unsigned long long)descriptor->b_blocknr,
 627                                 descriptor->b_data);
 628                         header = (journal_header_t *)descriptor->b_data;
 629                         header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
 630                         header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK);
 631                         header->h_sequence  = cpu_to_be32(commit_transaction->t_tid);
 632
 633                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 634                         space_left = descriptor->b_size -
 635                                                 sizeof(journal_header_t);
 636                         first_tag = 1;
 637                         set_buffer_jwrite(descriptor);
 638                         set_buffer_dirty(descriptor);
 639                         wbuf[bufs++] = descriptor;
 640
 641                         /* Record it so that we can wait for IO
 642                            completion later */
 643                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 644                         jbd2_file_log_bh(&log_bufs, descriptor);
 645                 }
 646
 647                 /* Where is the buffer to be written? */
 648
 649                 err = jbd2_journal_next_log_block(journal, &blocknr);
 650                 /* If the block mapping failed, just abandon the buffer
 651                    and repeat this loop: we'll fall into the
 652                    refile-on-abort condition above. */
 653                 if (err) {
 654                         jbd2_journal_abort(journal, err);
 655                         continue;
 656                 }
 657
 658                 /*
 659                  * start_this_handle() uses t_outstanding_credits to determine
 660                  * the free space in the log, but this counter is changed
 661                  * by jbd2_journal_next_log_block() also.
 662                  */
 663                 atomic_dec(&commit_transaction->t_outstanding_credits);
 664
 665                 /* Bump b_count to prevent truncate from stumbling over
 666                    the shadowed buffer!  @@@ This can go if we ever get
 667                    rid of the shadow pairing of buffers. */
 668                 atomic_inc(&jh2bh(jh)->b_count);
 669
 670                 /*
 671                  * Make a temporary IO buffer with which to write it out
 672                  * (this will requeue the metadata buffer to BJ_Shadow).
 673                  */
 674                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 675                 JBUFFER_TRACE(jh, "ph3: write metadata");
 676                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 677                                                 jh, &wbuf[bufs], blocknr);
 678                 if (flags < 0) {
 679                         jbd2_journal_abort(journal, flags);
 680                         continue;
 681                 }
 682                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 683
 684                 /* Record the new block's tag in the current descriptor
 685                    buffer */
 686
 687                 tag_flag = 0;
 688                 if (flags & 1)
 689                         tag_flag |= JBD2_FLAG_ESCAPE;
 690                 if (!first_tag)
 691                         tag_flag |= JBD2_FLAG_SAME_UUID;
 692
 693                 tag = (journal_block_tag_t *) tagp;
 694                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 695                 tag->t_flags = cpu_to_be16(tag_flag);
 696                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 697                                         commit_transaction->t_tid);
 698                 tagp += tag_bytes;
 699                 space_left -= tag_bytes;
 700                 bufs++;
 701
 702                 if (first_tag) {
 703                         memcpy (tagp, journal->j_uuid, 16);
 704                         tagp += 16;
 705                         space_left -= 16;
 706                         first_tag = 0;
 707                 }
 708
 709                 /* If there's no more to do, or if the descriptor is full,
 710                    let the IO rip! */
 711
 712                 if (bufs == journal->j_wbufsize ||
 713                     commit_transaction->t_buffers == NULL ||
 714                     space_left < tag_bytes + 16 + csum_size) {
 715
 716                         jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 717
 718                         /* Write an end-of-descriptor marker before
 719                            submitting the IOs.  "tag" still points to
 720                            the last tag we set up. */
 721
 722                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 723
 724                         jbd2_descr_block_csum_set(journal, descriptor);
 725 start_journal_io:
 726                         for (i = 0; i < bufs; i++) {
 727                                 struct buffer_head *bh = wbuf[i];
 728                                 /*
 729                                  * Compute checksum.
 730                                  */
 731                                 if (jbd2_has_feature_checksum(journal)) {
 732                                         crc32_sum =
 733                                             jbd2_checksum_data(crc32_sum, bh);
 734                                 }
 735
 736                                 lock_buffer(bh);
 737                                 clear_buffer_dirty(bh);
 738                                 set_buffer_uptodate(bh);
 739                                 bh->b_end_io = journal_end_buffer_io_sync;
 740                                 submit_bh(WRITE_SYNC, bh);
 741                         }
 742                         cond_resched();
 743                         stats.run.rs_blocks_logged += bufs;
 744
 745                         /* Force a new descriptor to be generated next
 746                            time round the loop. */
 747                         descriptor = NULL;
 748                         bufs = 0;
 749                 }
 750         }
 751
 752         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 753         if (err) {
 754                 printk(KERN_WARNING
 755                         "JBD2: Detected IO errors while flushing file data "
 756                        "on %s\n", journal->j_devname);
 757                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 758                         jbd2_journal_abort(journal, err);
 759                 err = 0;
 760         }
 761
 762         /*
 763          * Get current oldest transaction in the log before we issue flush
 764          * to the filesystem device. After the flush we can be sure that
 765          * blocks of all older transactions are checkpointed to persistent
 766          * storage and we will be safe to update journal start in the
 767          * superblock with the numbers we get here.
 768          */
 769         update_tail =
 770                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 771
 772         write_lock(&journal->j_state_lock);
 773         if (update_tail) {
 774                 long freed = first_block - journal->j_tail;
 775
 776                 if (first_block < journal->j_tail)
 777                         freed += journal->j_last - journal->j_first;
 778                 /* Update tail only if we free significant amount of space */
 779                 if (freed < journal->j_maxlen / 4)
 780                         update_tail = 0;
 781         }
 782         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 783         commit_transaction->t_state = T_COMMIT_DFLUSH;
 784         write_unlock(&journal->j_state_lock);
 785
 786         /*
 787          * If the journal is not located on the file system device,
 788          * then we must flush the file system device before we issue
 789          * the commit record
 790          */
 791         if (commit_transaction->t_need_data_flush &&
 792             (journal->j_fs_dev != journal->j_dev) &&
 793             (journal->j_flags & JBD2_BARRIER))
 794                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 795
 796         /* Done it all: now write the commit record asynchronously. */
 797         if (jbd2_has_feature_async_commit(journal)) {
 798                 err = journal_submit_commit_record(journal, commit_transaction,
 799                                                  &cbh, crc32_sum);
 800                 if (err)
 801                         __jbd2_journal_abort_hard(journal);
 802         }
 803
 804         blk_finish_plug(&plug);
 805
 806         /* Lo and behold: we have just managed to send a transaction to
 807            the log.  Before we can commit it, wait for the IO so far to
 808            complete.  Control buffers being written are on the
 809            transaction's t_log_list queue, and metadata buffers are on
 810            the io_bufs list.
 811
 812            Wait for the buffers in reverse order.  That way we are
 813            less likely to be woken up until all IOs have completed, and
 814            so we incur less scheduling load.
 815         */
 816
 817         jbd_debug(3, "JBD2: commit phase 3\n");
 818
 819         while (!list_empty(&io_bufs)) {
 820                 struct buffer_head *bh = list_entry(io_bufs.prev,
 821                                                     struct buffer_head,
 822                                                     b_assoc_buffers);
 823
 824                 wait_on_buffer(bh);
 825                 cond_resched();
 826
 827                 if (unlikely(!buffer_uptodate(bh)))
 828                         err = -EIO;
 829                 jbd2_unfile_log_bh(bh);
 830
 831                 /*
 832                  * The list contains temporary buffer heads created by
 833                  * jbd2_journal_write_metadata_buffer().
 834                  */
 835                 BUFFER_TRACE(bh, "dumping temporary bh");
 836                 __brelse(bh);
 837                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 838                 free_buffer_head(bh);
 839
 840                 /* We also have to refile the corresponding shadowed buffer */
 841                 jh = commit_transaction->t_shadow_list->b_tprev;
 842                 bh = jh2bh(jh);
 843                 clear_buffer_jwrite(bh);
 844                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 845                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 846
 847                 /* The metadata is now released for reuse, but we need
 848                    to remember it against this transaction so that when
 849                    we finally commit, we can do any checkpointing
 850                    required. */
 851                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 852                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 853                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 854                 __brelse(bh);
 855         }
 856
 857         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 858
 859         jbd_debug(3, "JBD2: commit phase 4\n");
 860
 861         /* Here we wait for the revoke record and descriptor record buffers */
 862         while (!list_empty(&log_bufs)) {
 863                 struct buffer_head *bh;
 864
 865                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 866                 wait_on_buffer(bh);
 867                 cond_resched();
 868
 869                 if (unlikely(!buffer_uptodate(bh)))
 870                         err = -EIO;
 871
 872                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 873                 clear_buffer_jwrite(bh);
 874                 jbd2_unfile_log_bh(bh);
 875                 __brelse(bh);           /* One for getblk */
 876                 /* AKPM: bforget here */
 877         }
 878
 879         if (err)
 880                 jbd2_journal_abort(journal, err);
 881
 882         jbd_debug(3, "JBD2: commit phase 5\n");
 883         write_lock(&journal->j_state_lock);
 884         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 885         commit_transaction->t_state = T_COMMIT_JFLUSH;
 886         write_unlock(&journal->j_state_lock);
 887
 888         if (!jbd2_has_feature_async_commit(journal)) {
 889                 err = journal_submit_commit_record(journal, commit_transaction,
 890                                                 &cbh, crc32_sum);
 891                 if (err)
 892                         __jbd2_journal_abort_hard(journal);
 893         }
 894         if (cbh)
 895                 err = journal_wait_on_commit_record(journal, cbh);
 896         if (jbd2_has_feature_async_commit(journal) &&
 897             journal->j_flags & JBD2_BARRIER) {
 898                 blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 899         }
 900
 901         if (err)
 902                 jbd2_journal_abort(journal, err);
 903
 904         /*
 905          * Now disk caches for filesystem device are flushed so we are safe to
 906          * erase checkpointed transactions from the log by updating journal
 907          * superblock.
 908          */
 909         if (update_tail)
 910                 jbd2_update_log_tail(journal, first_tid, first_block);
 911
 912         /* End of a transaction!  Finally, we can do checkpoint
 913            processing: any buffers committed as a result of this
 914            transaction can be removed from any checkpoint list it was on
 915            before. */
 916
 917         jbd_debug(3, "JBD2: commit phase 6\n");
 918
 919         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 920         J_ASSERT(commit_transaction->t_buffers == NULL);
 921         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 922         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 923
 924 restart_loop:
 925         /*
 926          * As there are other places (journal_unmap_buffer()) adding buffers
 927          * to this list we have to be careful and hold the j_list_lock.
 928          */
 929         spin_lock(&journal->j_list_lock);
 930         while (commit_transaction->t_forget) {
 931                 transaction_t *cp_transaction;
 932                 struct buffer_head *bh;
 933                 int try_to_free = 0;
 934
 935                 jh = commit_transaction->t_forget;
 936                 spin_unlock(&journal->j_list_lock);
 937                 bh = jh2bh(jh);
 938                 /*
 939                  * Get a reference so that bh cannot be freed before we are
 940                  * done with it.
 941                  */
 942                 get_bh(bh);
 943                 jbd_lock_bh_state(bh);
 944                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 945
 946                 /*
 947                  * If there is undo-protected committed data against
 948                  * this buffer, then we can remove it now.  If it is a
 949                  * buffer needing such protection, the old frozen_data
 950                  * field now points to a committed version of the
 951                  * buffer, so rotate that field to the new committed
 952                  * data.
 953                  *
 954                  * Otherwise, we can just throw away the frozen data now.
 955                  *
 956                  * We also know that the frozen data has already fired
 957                  * its triggers if they exist, so we can clear that too.
 958                  */
 959                 if (jh->b_committed_data) {
 960                         jbd2_free(jh->b_committed_data, bh->b_size);
 961                         jh->b_committed_data = NULL;
 962                         if (jh->b_frozen_data) {
 963                                 jh->b_committed_data = jh->b_frozen_data;
 964                                 jh->b_frozen_data = NULL;
 965                                 jh->b_frozen_triggers = NULL;
 966                         }
 967                 } else if (jh->b_frozen_data) {
 968                         jbd2_free(jh->b_frozen_data, bh->b_size);
 969                         jh->b_frozen_data = NULL;
 970                         jh->b_frozen_triggers = NULL;
 971                 }
 972
 973                 spin_lock(&journal->j_list_lock);
 974                 cp_transaction = jh->b_cp_transaction;
 975                 if (cp_transaction) {
 976                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 977                         cp_transaction->t_chp_stats.cs_dropped++;
 978                         __jbd2_journal_remove_checkpoint(jh);
 979                 }
 980
 981                 /* Only re-checkpoint the buffer_head if it is marked
 982                  * dirty.  If the buffer was added to the BJ_Forget list
 983                  * by jbd2_journal_forget, it may no longer be dirty and
 984                  * there's no point in keeping a checkpoint record for
 985                  * it. */
 986
 987                 /*
 988                 * A buffer which has been freed while still being journaled by
 989                 * a previous transaction.
 990                 */
 991                 if (buffer_freed(bh)) {
 992                         /*
 993                          * If the running transaction is the one containing
 994                          * "add to orphan" operation (b_next_transaction !=
 995                          * NULL), we have to wait for that transaction to
 996                          * commit before we can really get rid of the buffer.
 997                          * So just clear b_modified to not confuse transaction
 998                          * credit accounting and refile the buffer to
 999                          * BJ_Forget of the running transaction. If the just
1000                          * committed transaction contains "add to orphan"
1001                          * operation, we can completely invalidate the buffer
1002                          * now. We are rather through in that since the
1003                          * buffer may be still accessible when blocksize <
1004                          * pagesize and it is attached to the last partial
1005                          * page.
1006                          */
1007                         jh->b_modified = 0;
1008                         if (!jh->b_next_transaction) {
1009                                 clear_buffer_freed(bh);
1010                                 clear_buffer_jbddirty(bh);
1011                                 clear_buffer_mapped(bh);
1012                                 clear_buffer_new(bh);
1013                                 clear_buffer_req(bh);
1014                                 bh->b_bdev = NULL;
1015                         }
1016                 }
1017
1018                 if (buffer_jbddirty(bh)) {
1019                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1020                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1021                         if (is_journal_aborted(journal))
1022                                 clear_buffer_jbddirty(bh);
1023                 } else {
1024                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1025                         /*
1026                          * The buffer on BJ_Forget list and not jbddirty means
1027                          * it has been freed by this transaction and hence it
1028                          * could not have been reallocated until this
1029                          * transaction has committed. *BUT* it could be
1030                          * reallocated once we have written all the data to
1031                          * disk and before we process the buffer on BJ_Forget
1032                          * list.
1033                          */
1034                         if (!jh->b_next_transaction)
1035                                 try_to_free = 1;
1036                 }
1037                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1038                 __jbd2_journal_refile_buffer(jh);
1039                 jbd_unlock_bh_state(bh);
1040                 if (try_to_free)
1041                         release_buffer_page(bh);        /* Drops bh reference */
1042                 else
1043                         __brelse(bh);
1044                 cond_resched_lock(&journal->j_list_lock);
1045         }
1046         spin_unlock(&journal->j_list_lock);
1047         /*
1048          * This is a bit sleazy.  We use j_list_lock to protect transition
1049          * of a transaction into T_FINISHED state and calling
1050          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1051          * other checkpointing code processing the transaction...
1052          */
1053         write_lock(&journal->j_state_lock);
1054         spin_lock(&journal->j_list_lock);
1055         /*
1056          * Now recheck if some buffers did not get attached to the transaction
1057          * while the lock was dropped...
1058          */
1059         if (commit_transaction->t_forget) {
1060                 spin_unlock(&journal->j_list_lock);
1061                 write_unlock(&journal->j_state_lock);
1062                 goto restart_loop;
1063         }
1064
1065         /* Add the transaction to the checkpoint list
1066          * __journal_remove_checkpoint() can not destroy transaction
1067          * under us because it is not marked as T_FINISHED yet */
1068         if (journal->j_checkpoint_transactions == NULL) {
1069                 journal->j_checkpoint_transactions = commit_transaction;
1070                 commit_transaction->t_cpnext = commit_transaction;
1071                 commit_transaction->t_cpprev = commit_transaction;
1072         } else {
1073                 commit_transaction->t_cpnext =
1074                         journal->j_checkpoint_transactions;
1075                 commit_transaction->t_cpprev =
1076                         commit_transaction->t_cpnext->t_cpprev;
1077                 commit_transaction->t_cpnext->t_cpprev =
1078                         commit_transaction;
1079                 commit_transaction->t_cpprev->t_cpnext =
1080                                 commit_transaction;
1081         }
1082         spin_unlock(&journal->j_list_lock);
1083
1084         /* Done with this transaction! */
1085
1086         jbd_debug(3, "JBD2: commit phase 7\n");
1087
1088         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1089
1090         commit_transaction->t_start = jiffies;
1091         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1092                                               commit_transaction->t_start);
1093
1094         /*
1095          * File the transaction statistics
1096          */
1097         stats.ts_tid = commit_transaction->t_tid;
1098         stats.run.rs_handle_count =
1099                 atomic_read(&commit_transaction->t_handle_count);
1100         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1101                              commit_transaction->t_tid, &stats.run);
1102         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1103
1104         commit_transaction->t_state = T_COMMIT_CALLBACK;
1105         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1106         journal->j_commit_sequence = commit_transaction->t_tid;
1107         journal->j_committing_transaction = NULL;
1108         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1109
1110         /*
1111          * weight the commit time higher than the average time so we don't
1112          * react too strongly to vast changes in the commit time
1113          */
1114         if (likely(journal->j_average_commit_time))
1115                 journal->j_average_commit_time = (commit_time +
1116                                 journal->j_average_commit_time*3) / 4;
1117         else
1118                 journal->j_average_commit_time = commit_time;
1119
1120         write_unlock(&journal->j_state_lock);
1121
1122         if (journal->j_commit_callback)
1123                 journal->j_commit_callback(journal, commit_transaction);
1124
1125         trace_jbd2_end_commit(journal, commit_transaction);
1126         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1127                   journal->j_commit_sequence, journal->j_tail_sequence);
1128
1129         write_lock(&journal->j_state_lock);
1130         spin_lock(&journal->j_list_lock);
1131         commit_transaction->t_state = T_FINISHED;
1132         /* Check if the transaction can be dropped now that we are finished */
1133         if (commit_transaction->t_checkpoint_list == NULL &&
1134             commit_transaction->t_checkpoint_io_list == NULL) {
1135                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1136                 jbd2_journal_free_transaction(commit_transaction);
1137         }
1138         spin_unlock(&journal->j_list_lock);
1139         write_unlock(&journal->j_state_lock);
1140         wake_up(&journal->j_wait_done_commit);
1141
1142         /*
1143          * Calculate overall stats
1144          */
1145         spin_lock(&journal->j_history_lock);
1146         journal->j_stats.ts_tid++;
1147         journal->j_stats.ts_requested += stats.ts_requested;
1148         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1149         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1150         journal->j_stats.run.rs_running += stats.run.rs_running;
1151         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1152         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1153         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1154         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1155         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1156         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1157         spin_unlock(&journal->j_history_lock);
1158 }