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_clear_bit();
  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_COMPAT_FEATURE(journal,
 146                                     JBD2_FEATURE_COMPAT_CHECKSUM)) {
 147                 tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
 148                 tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
 149                 tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
 150         }
 151         jbd2_commit_block_csum_set(journal, bh);
 152
 153         BUFFER_TRACE(bh, "submit commit block");
 154         lock_buffer(bh);
 155         clear_buffer_dirty(bh);
 156         set_buffer_uptodate(bh);
 157         bh->b_end_io = journal_end_buffer_io_sync;
 158
 159         if (journal->j_flags & JBD2_BARRIER &&
 160             !JBD2_HAS_INCOMPAT_FEATURE(journal,
 161                                        JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT))
 162                 ret = submit_bh(WRITE_SYNC | WRITE_FLUSH_FUA, bh);
 163         else
 164                 ret = submit_bh(WRITE_SYNC, bh);
 165
 166         *cbh = bh;
 167         return ret;
 168 }
 169
 170 /*
 171  * This function along with journal_submit_commit_record
 172  * allows to write the commit record asynchronously.
 173  */
 174 static int journal_wait_on_commit_record(journal_t *journal,
 175                                          struct buffer_head *bh)
 176 {
 177         int ret = 0;
 178
 179         clear_buffer_dirty(bh);
 180         wait_on_buffer(bh);
 181
 182         if (unlikely(!buffer_uptodate(bh)))
 183                 ret = -EIO;
 184         put_bh(bh);            /* One for getblk() */
 185
 186         return ret;
 187 }
 188
 189 /*
 190  * write the filemap data using writepage() address_space_operations.
 191  * We don't do block allocation here even for delalloc. We don't
 192  * use writepages() because with dealyed allocation we may be doing
 193  * block allocation in writepages().
 194  */
 195 static int journal_submit_inode_data_buffers(struct address_space *mapping)
 196 {
 197         int ret;
 198         struct writeback_control wbc = {
 199                 .sync_mode =  WB_SYNC_ALL,
 200                 .nr_to_write = mapping->nrpages * 2,
 201                 .range_start = 0,
 202                 .range_end = i_size_read(mapping->host),
 203         };
 204
 205         ret = generic_writepages(mapping, &wbc);
 206         return ret;
 207 }
 208
 209 /*
 210  * Submit all the data buffers of inode associated with the transaction to
 211  * disk.
 212  *
 213  * We are in a committing transaction. Therefore no new inode can be added to
 214  * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
 215  * operate on from being released while we write out pages.
 216  */
 217 static int journal_submit_data_buffers(journal_t *journal,
 218                 transaction_t *commit_transaction)
 219 {
 220         struct jbd2_inode *jinode;
 221         int err, ret = 0;
 222         struct address_space *mapping;
 223
 224         spin_lock(&journal->j_list_lock);
 225         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 226                 mapping = jinode->i_vfs_inode->i_mapping;
 227                 set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 228                 spin_unlock(&journal->j_list_lock);
 229                 /*
 230                  * submit the inode data buffers. We use writepage
 231                  * instead of writepages. Because writepages can do
 232                  * block allocation  with delalloc. We need to write
 233                  * only allocated blocks here.
 234                  */
 235                 trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
 236                 err = journal_submit_inode_data_buffers(mapping);
 237                 if (!ret)
 238                         ret = err;
 239                 spin_lock(&journal->j_list_lock);
 240                 J_ASSERT(jinode->i_transaction == commit_transaction);
 241                 clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 242                 smp_mb__after_clear_bit();
 243                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 244         }
 245         spin_unlock(&journal->j_list_lock);
 246         return ret;
 247 }
 248
 249 /*
 250  * Wait for data submitted for writeout, refile inodes to proper
 251  * transaction if needed.
 252  *
 253  */
 254 static int journal_finish_inode_data_buffers(journal_t *journal,
 255                 transaction_t *commit_transaction)
 256 {
 257         struct jbd2_inode *jinode, *next_i;
 258         int err, ret = 0;
 259
 260         /* For locking, see the comment in journal_submit_data_buffers() */
 261         spin_lock(&journal->j_list_lock);
 262         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 263                 set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 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                 clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 280                 smp_mb__after_clear_bit();
 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_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_64BIT))
 321                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 322 }
 323
 324 static void jbd2_descr_block_csum_set(journal_t *j,
 325                                       struct buffer_head *bh)
 326 {
 327         struct jbd2_journal_block_tail *tail;
 328         __u32 csum;
 329
 330         if (!jbd2_journal_has_csum_v2or3(j))
 331                 return;
 332
 333         tail = (struct jbd2_journal_block_tail *)(bh->b_data + j->j_blocksize -
 334                         sizeof(struct jbd2_journal_block_tail));
 335         tail->t_checksum = 0;
 336         csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 337         tail->t_checksum = cpu_to_be32(csum);
 338 }
 339
 340 static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 341                                     struct buffer_head *bh, __u32 sequence)
 342 {
 343         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 344         struct page *page = bh->b_page;
 345         __u8 *addr;
 346         __u32 csum32;
 347         __be32 seq;
 348
 349         if (!jbd2_journal_has_csum_v2or3(j))
 350                 return;
 351
 352         seq = cpu_to_be32(sequence);
 353         addr = kmap_atomic(page);
 354         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 355         csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 356                              bh->b_size);
 357         kunmap_atomic(addr);
 358
 359         if (JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V3))
 360                 tag3->t_checksum = cpu_to_be32(csum32);
 361         else
 362                 tag->t_checksum = cpu_to_be16(csum32);
 363 }
 364 /*
 365  * jbd2_journal_commit_transaction
 366  *
 367  * The primary function for committing a transaction to the log.  This
 368  * function is called by the journal thread to begin a complete commit.
 369  */
 370 void jbd2_journal_commit_transaction(journal_t *journal)
 371 {
 372         struct transaction_stats_s stats;
 373         transaction_t *commit_transaction;
 374         struct journal_head *jh;
 375         struct buffer_head *descriptor;
 376         struct buffer_head **wbuf = journal->j_wbuf;
 377         int bufs;
 378         int flags;
 379         int err;
 380         unsigned long long blocknr;
 381         ktime_t start_time;
 382         u64 commit_time;
 383         char *tagp = NULL;
 384         journal_header_t *header;
 385         journal_block_tag_t *tag = NULL;
 386         int space_left = 0;
 387         int first_tag = 0;
 388         int tag_flag;
 389         int i;
 390         int tag_bytes = journal_tag_bytes(journal);
 391         struct buffer_head *cbh = NULL; /* For transactional checksums */
 392         __u32 crc32_sum = ~0;
 393         struct blk_plug plug;
 394         /* Tail of the journal */
 395         unsigned long first_block;
 396         tid_t first_tid;
 397         int update_tail;
 398         int csum_size = 0;
 399         LIST_HEAD(io_bufs);
 400         LIST_HEAD(log_bufs);
 401
 402         if (jbd2_journal_has_csum_v2or3(journal))
 403                 csum_size = sizeof(struct jbd2_journal_block_tail);
 404
 405         /*
 406          * First job: lock down the current transaction and wait for
 407          * all outstanding updates to complete.
 408          */
 409
 410         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 411         if (journal->j_flags & JBD2_FLUSHED) {
 412                 jbd_debug(3, "super block updated\n");
 413                 mutex_lock(&journal->j_checkpoint_mutex);
 414                 /*
 415                  * We hold j_checkpoint_mutex so tail cannot change under us.
 416                  * We don't need any special data guarantees for writing sb
 417                  * since journal is empty and it is ok for write to be
 418                  * flushed only with transaction commit.
 419                  */
 420                 jbd2_journal_update_sb_log_tail(journal,
 421                                                 journal->j_tail_sequence,
 422                                                 journal->j_tail,
 423                                                 WRITE_SYNC);
 424                 mutex_unlock(&journal->j_checkpoint_mutex);
 425         } else {
 426                 jbd_debug(3, "superblock not updated\n");
 427         }
 428
 429         J_ASSERT(journal->j_running_transaction != NULL);
 430         J_ASSERT(journal->j_committing_transaction == NULL);
 431
 432         commit_transaction = journal->j_running_transaction;
 433
 434         trace_jbd2_start_commit(journal, commit_transaction);
 435         jbd_debug(1, "JBD2: starting commit of transaction %d\n",
 436                         commit_transaction->t_tid);
 437
 438         write_lock(&journal->j_state_lock);
 439         J_ASSERT(commit_transaction->t_state == T_RUNNING);
 440         commit_transaction->t_state = T_LOCKED;
 441
 442         trace_jbd2_commit_locking(journal, commit_transaction);
 443         stats.run.rs_wait = commit_transaction->t_max_wait;
 444         stats.run.rs_request_delay = 0;
 445         stats.run.rs_locked = jiffies;
 446         if (commit_transaction->t_requested)
 447                 stats.run.rs_request_delay =
 448                         jbd2_time_diff(commit_transaction->t_requested,
 449                                        stats.run.rs_locked);
 450         stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
 451                                               stats.run.rs_locked);
 452
 453         spin_lock(&commit_transaction->t_handle_lock);
 454         while (atomic_read(&commit_transaction->t_updates)) {
 455                 DEFINE_WAIT(wait);
 456
 457                 prepare_to_wait(&journal->j_wait_updates, &wait,
 458                                         TASK_UNINTERRUPTIBLE);
 459                 if (atomic_read(&commit_transaction->t_updates)) {
 460                         spin_unlock(&commit_transaction->t_handle_lock);
 461                         write_unlock(&journal->j_state_lock);
 462                         schedule();
 463                         write_lock(&journal->j_state_lock);
 464                         spin_lock(&commit_transaction->t_handle_lock);
 465                 }
 466                 finish_wait(&journal->j_wait_updates, &wait);
 467         }
 468         spin_unlock(&commit_transaction->t_handle_lock);
 469
 470         J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 471                         journal->j_max_transaction_buffers);
 472
 473         /*
 474          * First thing we are allowed to do is to discard any remaining
 475          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 476          * that there are no such buffers: if a large filesystem
 477          * operation like a truncate needs to split itself over multiple
 478          * transactions, then it may try to do a jbd2_journal_restart() while
 479          * there are still BJ_Reserved buffers outstanding.  These must
 480          * be released cleanly from the current transaction.
 481          *
 482          * In this case, the filesystem must still reserve write access
 483          * again before modifying the buffer in the new transaction, but
 484          * we do not require it to remember exactly which old buffers it
 485          * has reserved.  This is consistent with the existing behaviour
 486          * that multiple jbd2_journal_get_write_access() calls to the same
 487          * buffer are perfectly permissible.
 488          */
 489         while (commit_transaction->t_reserved_list) {
 490                 jh = commit_transaction->t_reserved_list;
 491                 JBUFFER_TRACE(jh, "reserved, unused: refile");
 492                 /*
 493                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 494                  * leave undo-committed data.
 495                  */
 496                 if (jh->b_committed_data) {
 497                         struct buffer_head *bh = jh2bh(jh);
 498
 499                         jbd_lock_bh_state(bh);
 500                         jbd2_free(jh->b_committed_data, bh->b_size);
 501                         jh->b_committed_data = NULL;
 502                         jbd_unlock_bh_state(bh);
 503                 }
 504                 jbd2_journal_refile_buffer(journal, jh);
 505         }
 506
 507         /*
 508          * Now try to drop any written-back buffers from the journal's
 509          * checkpoint lists.  We do this *before* commit because it potentially
 510          * frees some memory
 511          */
 512         spin_lock(&journal->j_list_lock);
 513         __jbd2_journal_clean_checkpoint_list(journal);
 514         spin_unlock(&journal->j_list_lock);
 515
 516         jbd_debug(3, "JBD2: commit phase 1\n");
 517
 518         /*
 519          * Clear revoked flag to reflect there is no revoked buffers
 520          * in the next transaction which is going to be started.
 521          */
 522         jbd2_clear_buffer_revoked_flags(journal);
 523
 524         /*
 525          * Switch to a new revoke table.
 526          */
 527         jbd2_journal_switch_revoke_table(journal);
 528
 529         /*
 530          * Reserved credits cannot be claimed anymore, free them
 531          */
 532         atomic_sub(atomic_read(&journal->j_reserved_credits),
 533                    &commit_transaction->t_outstanding_credits);
 534
 535         trace_jbd2_commit_flushing(journal, commit_transaction);
 536         stats.run.rs_flushing = jiffies;
 537         stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 538                                              stats.run.rs_flushing);
 539
 540         commit_transaction->t_state = T_FLUSH;
 541         journal->j_committing_transaction = commit_transaction;
 542         journal->j_running_transaction = NULL;
 543         start_time = ktime_get();
 544         commit_transaction->t_log_start = journal->j_head;
 545         wake_up(&journal->j_wait_transaction_locked);
 546         write_unlock(&journal->j_state_lock);
 547
 548         jbd_debug(3, "JBD2: commit phase 2a\n");
 549
 550         /*
 551          * Now start flushing things to disk, in the order they appear
 552          * on the transaction lists.  Data blocks go first.
 553          */
 554         err = journal_submit_data_buffers(journal, commit_transaction);
 555         if (err)
 556                 jbd2_journal_abort(journal, err);
 557
 558         blk_start_plug(&plug);
 559         jbd2_journal_write_revoke_records(journal, commit_transaction,
 560                                           &log_bufs, WRITE_SYNC);
 561         blk_finish_plug(&plug);
 562
 563         jbd_debug(3, "JBD2: commit phase 2b\n");
 564
 565         /*
 566          * Way to go: we have now written out all of the data for a
 567          * transaction!  Now comes the tricky part: we need to write out
 568          * metadata.  Loop over the transaction's entire buffer list:
 569          */
 570         write_lock(&journal->j_state_lock);
 571         commit_transaction->t_state = T_COMMIT;
 572         write_unlock(&journal->j_state_lock);
 573
 574         trace_jbd2_commit_logging(journal, commit_transaction);
 575         stats.run.rs_logging = jiffies;
 576         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 577                                                stats.run.rs_logging);
 578         stats.run.rs_blocks =
 579                 atomic_read(&commit_transaction->t_outstanding_credits);
 580         stats.run.rs_blocks_logged = 0;
 581
 582         J_ASSERT(commit_transaction->t_nr_buffers <=
 583                  atomic_read(&commit_transaction->t_outstanding_credits));
 584
 585         err = 0;
 586         bufs = 0;
 587         descriptor = NULL;
 588         blk_start_plug(&plug);
 589         while (commit_transaction->t_buffers) {
 590
 591                 /* Find the next buffer to be journaled... */
 592
 593                 jh = commit_transaction->t_buffers;
 594
 595                 /* If we're in abort mode, we just un-journal the buffer and
 596                    release it. */
 597
 598                 if (is_journal_aborted(journal)) {
 599                         clear_buffer_jbddirty(jh2bh(jh));
 600                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 601                         jbd2_buffer_abort_trigger(jh,
 602                                                   jh->b_frozen_data ?
 603                                                   jh->b_frozen_triggers :
 604                                                   jh->b_triggers);
 605                         jbd2_journal_refile_buffer(journal, jh);
 606                         /* If that was the last one, we need to clean up
 607                          * any descriptor buffers which may have been
 608                          * already allocated, even if we are now
 609                          * aborting. */
 610                         if (!commit_transaction->t_buffers)
 611                                 goto start_journal_io;
 612                         continue;
 613                 }
 614
 615                 /* Make sure we have a descriptor block in which to
 616                    record the metadata buffer. */
 617
 618                 if (!descriptor) {
 619                         J_ASSERT (bufs == 0);
 620
 621                         jbd_debug(4, "JBD2: get descriptor\n");
 622
 623                         descriptor = jbd2_journal_get_descriptor_buffer(journal);
 624                         if (!descriptor) {
 625                                 jbd2_journal_abort(journal, -EIO);
 626                                 continue;
 627                         }
 628
 629                         jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 630                                 (unsigned long long)descriptor->b_blocknr,
 631                                 descriptor->b_data);
 632                         header = (journal_header_t *)descriptor->b_data;
 633                         header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
 634                         header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK);
 635                         header->h_sequence  = cpu_to_be32(commit_transaction->t_tid);
 636
 637                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 638                         space_left = descriptor->b_size -
 639                                                 sizeof(journal_header_t);
 640                         first_tag = 1;
 641                         set_buffer_jwrite(descriptor);
 642                         set_buffer_dirty(descriptor);
 643                         wbuf[bufs++] = descriptor;
 644
 645                         /* Record it so that we can wait for IO
 646                            completion later */
 647                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 648                         jbd2_file_log_bh(&log_bufs, descriptor);
 649                 }
 650
 651                 /* Where is the buffer to be written? */
 652
 653                 err = jbd2_journal_next_log_block(journal, &blocknr);
 654                 /* If the block mapping failed, just abandon the buffer
 655                    and repeat this loop: we'll fall into the
 656                    refile-on-abort condition above. */
 657                 if (err) {
 658                         jbd2_journal_abort(journal, err);
 659                         continue;
 660                 }
 661
 662                 /*
 663                  * start_this_handle() uses t_outstanding_credits to determine
 664                  * the free space in the log, but this counter is changed
 665                  * by jbd2_journal_next_log_block() also.
 666                  */
 667                 atomic_dec(&commit_transaction->t_outstanding_credits);
 668
 669                 /* Bump b_count to prevent truncate from stumbling over
 670                    the shadowed buffer!  @@@ This can go if we ever get
 671                    rid of the shadow pairing of buffers. */
 672                 atomic_inc(&jh2bh(jh)->b_count);
 673
 674                 /*
 675                  * Make a temporary IO buffer with which to write it out
 676                  * (this will requeue the metadata buffer to BJ_Shadow).
 677                  */
 678                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 679                 JBUFFER_TRACE(jh, "ph3: write metadata");
 680                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 681                                                 jh, &wbuf[bufs], blocknr);
 682                 if (flags < 0) {
 683                         jbd2_journal_abort(journal, flags);
 684                         continue;
 685                 }
 686                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 687
 688                 /* Record the new block's tag in the current descriptor
 689                    buffer */
 690
 691                 tag_flag = 0;
 692                 if (flags & 1)
 693                         tag_flag |= JBD2_FLAG_ESCAPE;
 694                 if (!first_tag)
 695                         tag_flag |= JBD2_FLAG_SAME_UUID;
 696
 697                 tag = (journal_block_tag_t *) tagp;
 698                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 699                 tag->t_flags = cpu_to_be16(tag_flag);
 700                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 701                                         commit_transaction->t_tid);
 702                 tagp += tag_bytes;
 703                 space_left -= tag_bytes;
 704                 bufs++;
 705
 706                 if (first_tag) {
 707                         memcpy (tagp, journal->j_uuid, 16);
 708                         tagp += 16;
 709                         space_left -= 16;
 710                         first_tag = 0;
 711                 }
 712
 713                 /* If there's no more to do, or if the descriptor is full,
 714                    let the IO rip! */
 715
 716                 if (bufs == journal->j_wbufsize ||
 717                     commit_transaction->t_buffers == NULL ||
 718                     space_left < tag_bytes + 16 + csum_size) {
 719
 720                         jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 721
 722                         /* Write an end-of-descriptor marker before
 723                            submitting the IOs.  "tag" still points to
 724                            the last tag we set up. */
 725
 726                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 727
 728                         jbd2_descr_block_csum_set(journal, descriptor);
 729 start_journal_io:
 730                         for (i = 0; i < bufs; i++) {
 731                                 struct buffer_head *bh = wbuf[i];
 732                                 /*
 733                                  * Compute checksum.
 734                                  */
 735                                 if (JBD2_HAS_COMPAT_FEATURE(journal,
 736                                         JBD2_FEATURE_COMPAT_CHECKSUM)) {
 737                                         crc32_sum =
 738                                             jbd2_checksum_data(crc32_sum, bh);
 739                                 }
 740
 741                                 lock_buffer(bh);
 742                                 clear_buffer_dirty(bh);
 743                                 set_buffer_uptodate(bh);
 744                                 bh->b_end_io = journal_end_buffer_io_sync;
 745                                 submit_bh(WRITE_SYNC, bh);
 746                         }
 747                         cond_resched();
 748                         stats.run.rs_blocks_logged += bufs;
 749
 750                         /* Force a new descriptor to be generated next
 751                            time round the loop. */
 752                         descriptor = NULL;
 753                         bufs = 0;
 754                 }
 755         }
 756
 757         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 758         if (err) {
 759                 printk(KERN_WARNING
 760                         "JBD2: Detected IO errors while flushing file data "
 761                        "on %s\n", journal->j_devname);
 762                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 763                         jbd2_journal_abort(journal, err);
 764                 err = 0;
 765         }
 766
 767         /*
 768          * Get current oldest transaction in the log before we issue flush
 769          * to the filesystem device. After the flush we can be sure that
 770          * blocks of all older transactions are checkpointed to persistent
 771          * storage and we will be safe to update journal start in the
 772          * superblock with the numbers we get here.
 773          */
 774         update_tail =
 775                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 776
 777         write_lock(&journal->j_state_lock);
 778         if (update_tail) {
 779                 long freed = first_block - journal->j_tail;
 780
 781                 if (first_block < journal->j_tail)
 782                         freed += journal->j_last - journal->j_first;
 783                 /* Update tail only if we free significant amount of space */
 784                 if (freed < journal->j_maxlen / 4)
 785                         update_tail = 0;
 786         }
 787         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 788         commit_transaction->t_state = T_COMMIT_DFLUSH;
 789         write_unlock(&journal->j_state_lock);
 790
 791         /*
 792          * If the journal is not located on the file system device,
 793          * then we must flush the file system device before we issue
 794          * the commit record
 795          */
 796         if (commit_transaction->t_need_data_flush &&
 797             (journal->j_fs_dev != journal->j_dev) &&
 798             (journal->j_flags & JBD2_BARRIER))
 799                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 800
 801         /* Done it all: now write the commit record asynchronously. */
 802         if (JBD2_HAS_INCOMPAT_FEATURE(journal,
 803                                       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 804                 err = journal_submit_commit_record(journal, commit_transaction,
 805                                                  &cbh, crc32_sum);
 806                 if (err)
 807                         __jbd2_journal_abort_hard(journal);
 808         }
 809
 810         blk_finish_plug(&plug);
 811
 812         /* Lo and behold: we have just managed to send a transaction to
 813            the log.  Before we can commit it, wait for the IO so far to
 814            complete.  Control buffers being written are on the
 815            transaction's t_log_list queue, and metadata buffers are on
 816            the io_bufs list.
 817
 818            Wait for the buffers in reverse order.  That way we are
 819            less likely to be woken up until all IOs have completed, and
 820            so we incur less scheduling load.
 821         */
 822
 823         jbd_debug(3, "JBD2: commit phase 3\n");
 824
 825         while (!list_empty(&io_bufs)) {
 826                 struct buffer_head *bh = list_entry(io_bufs.prev,
 827                                                     struct buffer_head,
 828                                                     b_assoc_buffers);
 829
 830                 wait_on_buffer(bh);
 831                 cond_resched();
 832
 833                 if (unlikely(!buffer_uptodate(bh)))
 834                         err = -EIO;
 835                 jbd2_unfile_log_bh(bh);
 836
 837                 /*
 838                  * The list contains temporary buffer heads created by
 839                  * jbd2_journal_write_metadata_buffer().
 840                  */
 841                 BUFFER_TRACE(bh, "dumping temporary bh");
 842                 __brelse(bh);
 843                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 844                 free_buffer_head(bh);
 845
 846                 /* We also have to refile the corresponding shadowed buffer */
 847                 jh = commit_transaction->t_shadow_list->b_tprev;
 848                 bh = jh2bh(jh);
 849                 clear_buffer_jwrite(bh);
 850                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 851                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 852
 853                 /* The metadata is now released for reuse, but we need
 854                    to remember it against this transaction so that when
 855                    we finally commit, we can do any checkpointing
 856                    required. */
 857                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 858                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 859                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 860                 __brelse(bh);
 861         }
 862
 863         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 864
 865         jbd_debug(3, "JBD2: commit phase 4\n");
 866
 867         /* Here we wait for the revoke record and descriptor record buffers */
 868         while (!list_empty(&log_bufs)) {
 869                 struct buffer_head *bh;
 870
 871                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 872                 wait_on_buffer(bh);
 873                 cond_resched();
 874
 875                 if (unlikely(!buffer_uptodate(bh)))
 876                         err = -EIO;
 877
 878                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 879                 clear_buffer_jwrite(bh);
 880                 jbd2_unfile_log_bh(bh);
 881                 __brelse(bh);           /* One for getblk */
 882                 /* AKPM: bforget here */
 883         }
 884
 885         if (err)
 886                 jbd2_journal_abort(journal, err);
 887
 888         jbd_debug(3, "JBD2: commit phase 5\n");
 889         write_lock(&journal->j_state_lock);
 890         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 891         commit_transaction->t_state = T_COMMIT_JFLUSH;
 892         write_unlock(&journal->j_state_lock);
 893
 894         if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
 895                                        JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 896                 err = journal_submit_commit_record(journal, commit_transaction,
 897                                                 &cbh, crc32_sum);
 898                 if (err)
 899                         __jbd2_journal_abort_hard(journal);
 900         }
 901         if (cbh)
 902                 err = journal_wait_on_commit_record(journal, cbh);
 903         if (JBD2_HAS_INCOMPAT_FEATURE(journal,
 904                                       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) &&
 905             journal->j_flags & JBD2_BARRIER) {
 906                 blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 907         }
 908
 909         if (err)
 910                 jbd2_journal_abort(journal, err);
 911
 912         /*
 913          * Now disk caches for filesystem device are flushed so we are safe to
 914          * erase checkpointed transactions from the log by updating journal
 915          * superblock.
 916          */
 917         if (update_tail)
 918                 jbd2_update_log_tail(journal, first_tid, first_block);
 919
 920         /* End of a transaction!  Finally, we can do checkpoint
 921            processing: any buffers committed as a result of this
 922            transaction can be removed from any checkpoint list it was on
 923            before. */
 924
 925         jbd_debug(3, "JBD2: commit phase 6\n");
 926
 927         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 928         J_ASSERT(commit_transaction->t_buffers == NULL);
 929         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 930         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 931
 932 restart_loop:
 933         /*
 934          * As there are other places (journal_unmap_buffer()) adding buffers
 935          * to this list we have to be careful and hold the j_list_lock.
 936          */
 937         spin_lock(&journal->j_list_lock);
 938         while (commit_transaction->t_forget) {
 939                 transaction_t *cp_transaction;
 940                 struct buffer_head *bh;
 941                 int try_to_free = 0;
 942
 943                 jh = commit_transaction->t_forget;
 944                 spin_unlock(&journal->j_list_lock);
 945                 bh = jh2bh(jh);
 946                 /*
 947                  * Get a reference so that bh cannot be freed before we are
 948                  * done with it.
 949                  */
 950                 get_bh(bh);
 951                 jbd_lock_bh_state(bh);
 952                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 953
 954                 /*
 955                  * If there is undo-protected committed data against
 956                  * this buffer, then we can remove it now.  If it is a
 957                  * buffer needing such protection, the old frozen_data
 958                  * field now points to a committed version of the
 959                  * buffer, so rotate that field to the new committed
 960                  * data.
 961                  *
 962                  * Otherwise, we can just throw away the frozen data now.
 963                  *
 964                  * We also know that the frozen data has already fired
 965                  * its triggers if they exist, so we can clear that too.
 966                  */
 967                 if (jh->b_committed_data) {
 968                         jbd2_free(jh->b_committed_data, bh->b_size);
 969                         jh->b_committed_data = NULL;
 970                         if (jh->b_frozen_data) {
 971                                 jh->b_committed_data = jh->b_frozen_data;
 972                                 jh->b_frozen_data = NULL;
 973                                 jh->b_frozen_triggers = NULL;
 974                         }
 975                 } else if (jh->b_frozen_data) {
 976                         jbd2_free(jh->b_frozen_data, bh->b_size);
 977                         jh->b_frozen_data = NULL;
 978                         jh->b_frozen_triggers = NULL;
 979                 }
 980
 981                 spin_lock(&journal->j_list_lock);
 982                 cp_transaction = jh->b_cp_transaction;
 983                 if (cp_transaction) {
 984                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 985                         cp_transaction->t_chp_stats.cs_dropped++;
 986                         __jbd2_journal_remove_checkpoint(jh);
 987                 }
 988
 989                 /* Only re-checkpoint the buffer_head if it is marked
 990                  * dirty.  If the buffer was added to the BJ_Forget list
 991                  * by jbd2_journal_forget, it may no longer be dirty and
 992                  * there's no point in keeping a checkpoint record for
 993                  * it. */
 994
 995                 /*
 996                 * A buffer which has been freed while still being journaled by
 997                 * a previous transaction.
 998                 */
 999                 if (buffer_freed(bh)) {
1000                         /*
1001                          * If the running transaction is the one containing
1002                          * "add to orphan" operation (b_next_transaction !=
1003                          * NULL), we have to wait for that transaction to
1004                          * commit before we can really get rid of the buffer.
1005                          * So just clear b_modified to not confuse transaction
1006                          * credit accounting and refile the buffer to
1007                          * BJ_Forget of the running transaction. If the just
1008                          * committed transaction contains "add to orphan"
1009                          * operation, we can completely invalidate the buffer
1010                          * now. We are rather through in that since the
1011                          * buffer may be still accessible when blocksize <
1012                          * pagesize and it is attached to the last partial
1013                          * page.
1014                          */
1015                         jh->b_modified = 0;
1016                         if (!jh->b_next_transaction) {
1017                                 clear_buffer_freed(bh);
1018                                 clear_buffer_jbddirty(bh);
1019                                 clear_buffer_mapped(bh);
1020                                 clear_buffer_new(bh);
1021                                 clear_buffer_req(bh);
1022                                 bh->b_bdev = NULL;
1023                         }
1024                 }
1025
1026                 if (buffer_jbddirty(bh)) {
1027                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1028                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1029                         if (is_journal_aborted(journal))
1030                                 clear_buffer_jbddirty(bh);
1031                 } else {
1032                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1033                         /*
1034                          * The buffer on BJ_Forget list and not jbddirty means
1035                          * it has been freed by this transaction and hence it
1036                          * could not have been reallocated until this
1037                          * transaction has committed. *BUT* it could be
1038                          * reallocated once we have written all the data to
1039                          * disk and before we process the buffer on BJ_Forget
1040                          * list.
1041                          */
1042                         if (!jh->b_next_transaction)
1043                                 try_to_free = 1;
1044                 }
1045                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1046                 __jbd2_journal_refile_buffer(jh);
1047                 jbd_unlock_bh_state(bh);
1048                 if (try_to_free)
1049                         release_buffer_page(bh);        /* Drops bh reference */
1050                 else
1051                         __brelse(bh);
1052                 cond_resched_lock(&journal->j_list_lock);
1053         }
1054         spin_unlock(&journal->j_list_lock);
1055         /*
1056          * This is a bit sleazy.  We use j_list_lock to protect transition
1057          * of a transaction into T_FINISHED state and calling
1058          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1059          * other checkpointing code processing the transaction...
1060          */
1061         write_lock(&journal->j_state_lock);
1062         spin_lock(&journal->j_list_lock);
1063         /*
1064          * Now recheck if some buffers did not get attached to the transaction
1065          * while the lock was dropped...
1066          */
1067         if (commit_transaction->t_forget) {
1068                 spin_unlock(&journal->j_list_lock);
1069                 write_unlock(&journal->j_state_lock);
1070                 goto restart_loop;
1071         }
1072
1073         /* Done with this transaction! */
1074
1075         jbd_debug(3, "JBD2: commit phase 7\n");
1076
1077         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1078
1079         commit_transaction->t_start = jiffies;
1080         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1081                                               commit_transaction->t_start);
1082
1083         /*
1084          * File the transaction statistics
1085          */
1086         stats.ts_tid = commit_transaction->t_tid;
1087         stats.run.rs_handle_count =
1088                 atomic_read(&commit_transaction->t_handle_count);
1089         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1090                              commit_transaction->t_tid, &stats.run);
1091
1092         /*
1093          * Calculate overall stats
1094          */
1095         spin_lock(&journal->j_history_lock);
1096         journal->j_stats.ts_tid++;
1097         if (commit_transaction->t_requested)
1098                 journal->j_stats.ts_requested++;
1099         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1100         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1101         journal->j_stats.run.rs_running += stats.run.rs_running;
1102         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1103         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1104         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1105         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1106         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1107         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1108         spin_unlock(&journal->j_history_lock);
1109
1110         commit_transaction->t_state = T_COMMIT_CALLBACK;
1111         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1112         journal->j_commit_sequence = commit_transaction->t_tid;
1113         journal->j_committing_transaction = NULL;
1114         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1115
1116         /*
1117          * weight the commit time higher than the average time so we don't
1118          * react too strongly to vast changes in the commit time
1119          */
1120         if (likely(journal->j_average_commit_time))
1121                 journal->j_average_commit_time = (commit_time +
1122                                 journal->j_average_commit_time*3) / 4;
1123         else
1124                 journal->j_average_commit_time = commit_time;
1125
1126         write_unlock(&journal->j_state_lock);
1127
1128         if (journal->j_checkpoint_transactions == NULL) {
1129                 journal->j_checkpoint_transactions = commit_transaction;
1130                 commit_transaction->t_cpnext = commit_transaction;
1131                 commit_transaction->t_cpprev = commit_transaction;
1132         } else {
1133                 commit_transaction->t_cpnext =
1134                         journal->j_checkpoint_transactions;
1135                 commit_transaction->t_cpprev =
1136                         commit_transaction->t_cpnext->t_cpprev;
1137                 commit_transaction->t_cpnext->t_cpprev =
1138                         commit_transaction;
1139                 commit_transaction->t_cpprev->t_cpnext =
1140                                 commit_transaction;
1141         }
1142         spin_unlock(&journal->j_list_lock);
1143         /* Drop all spin_locks because commit_callback may be block.
1144          * __journal_remove_checkpoint() can not destroy transaction
1145          * under us because it is not marked as T_FINISHED yet */
1146         if (journal->j_commit_callback)
1147                 journal->j_commit_callback(journal, commit_transaction);
1148
1149         trace_jbd2_end_commit(journal, commit_transaction);
1150         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1151                   journal->j_commit_sequence, journal->j_tail_sequence);
1152
1153         write_lock(&journal->j_state_lock);
1154         spin_lock(&journal->j_list_lock);
1155         commit_transaction->t_state = T_FINISHED;
1156         /* Recheck checkpoint lists after j_list_lock was dropped */
1157         if (commit_transaction->t_checkpoint_list == NULL &&
1158             commit_transaction->t_checkpoint_io_list == NULL) {
1159                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1160                 jbd2_journal_free_transaction(commit_transaction);
1161         }
1162         spin_unlock(&journal->j_list_lock);
1163         write_unlock(&journal->j_state_lock);
1164         wake_up(&journal->j_wait_done_commit);
1165 }