fs/jbd2/commit.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * linux/fs/jbd2/commit.c
   4  *
   5  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
   6  *
   7  * Copyright 1998 Red Hat corp --- All Rights Reserved
   8  *
   9  * Journal commit routines for the generic filesystem journaling code;
  10  * part of the ext2fs journaling system.
  11  */
  12
  13 #include <linux/time.h>
  14 #include <linux/fs.h>
  15 #include <linux/jbd2.h>
  16 #include <linux/errno.h>
  17 #include <linux/slab.h>
  18 #include <linux/mm.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/crc32.h>
  22 #include <linux/writeback.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/bio.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/bitops.h>
  27 #include <trace/events/jbd2.h>
  28
  29 /*
  30  * IO end handler for temporary buffer_heads handling writes to the journal.
  31  */
  32 static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
  33 {
  34         struct buffer_head *orig_bh = bh->b_private;
  35
  36         BUFFER_TRACE(bh, "");
  37         if (uptodate)
  38                 set_buffer_uptodate(bh);
  39         else
  40                 clear_buffer_uptodate(bh);
  41         if (orig_bh) {
  42                 clear_bit_unlock(BH_Shadow, &orig_bh->b_state);
  43                 smp_mb__after_atomic();
  44                 wake_up_bit(&orig_bh->b_state, BH_Shadow);
  45         }
  46         unlock_buffer(bh);
  47 }
  48
  49 /*
  50  * When an ext4 file is truncated, it is possible that some pages are not
  51  * successfully freed, because they are attached to a committing transaction.
  52  * After the transaction commits, these pages are left on the LRU, with no
  53  * ->mapping, and with attached buffers.  These pages are trivially reclaimable
  54  * by the VM, but their apparent absence upsets the VM accounting, and it makes
  55  * the numbers in /proc/meminfo look odd.
  56  *
  57  * So here, we have a buffer which has just come off the forget list.  Look to
  58  * see if we can strip all buffers from the backing page.
  59  *
  60  * Called under lock_journal(), and possibly under journal_datalist_lock.  The
  61  * caller provided us with a ref against the buffer, and we drop that here.
  62  */
  63 static void release_buffer_page(struct buffer_head *bh)
  64 {
  65         struct folio *folio;
  66
  67         if (buffer_dirty(bh))
  68                 goto nope;
  69         if (atomic_read(&bh->b_count) != 1)
  70                 goto nope;
  71         folio = bh->b_folio;
  72         if (folio->mapping)
  73                 goto nope;
  74
  75         /* OK, it's a truncated page */
  76         if (!folio_trylock(folio))
  77                 goto nope;
  78
  79         folio_get(folio);
  80         __brelse(bh);
  81         try_to_free_buffers(folio);
  82         folio_unlock(folio);
  83         folio_put(folio);
  84         return;
  85
  86 nope:
  87         __brelse(bh);
  88 }
  89
  90 static void jbd2_commit_block_csum_set(journal_t *j, struct buffer_head *bh)
  91 {
  92         struct commit_header *h;
  93         __u32 csum;
  94
  95         if (!jbd2_journal_has_csum_v2or3(j))
  96                 return;
  97
  98         h = (struct commit_header *)(bh->b_data);
  99         h->h_chksum_type = 0;
 100         h->h_chksum_size = 0;
 101         h->h_chksum[0] = 0;
 102         csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 103         h->h_chksum[0] = cpu_to_be32(csum);
 104 }
 105
 106 /*
 107  * Done it all: now submit the commit record.  We should have
 108  * cleaned up our previous buffers by now, so if we are in abort
 109  * mode we can now just skip the rest of the journal write
 110  * entirely.
 111  *
 112  * Returns 1 if the journal needs to be aborted or 0 on success
 113  */
 114 static int journal_submit_commit_record(journal_t *journal,
 115                                         transaction_t *commit_transaction,
 116                                         struct buffer_head **cbh,
 117                                         __u32 crc32_sum)
 118 {
 119         struct commit_header *tmp;
 120         struct buffer_head *bh;
 121         struct timespec64 now;
 122         blk_opf_t write_flags = REQ_OP_WRITE | REQ_SYNC;
 123
 124         *cbh = NULL;
 125
 126         if (is_journal_aborted(journal))
 127                 return 0;
 128
 129         bh = jbd2_journal_get_descriptor_buffer(commit_transaction,
 130                                                 JBD2_COMMIT_BLOCK);
 131         if (!bh)
 132                 return 1;
 133
 134         tmp = (struct commit_header *)bh->b_data;
 135         ktime_get_coarse_real_ts64(&now);
 136         tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
 137         tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
 138
 139         if (jbd2_has_feature_checksum(journal)) {
 140                 tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
 141                 tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
 142                 tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
 143         }
 144         jbd2_commit_block_csum_set(journal, bh);
 145
 146         BUFFER_TRACE(bh, "submit commit block");
 147         lock_buffer(bh);
 148         clear_buffer_dirty(bh);
 149         set_buffer_uptodate(bh);
 150         bh->b_end_io = journal_end_buffer_io_sync;
 151
 152         if (journal->j_flags & JBD2_BARRIER &&
 153             !jbd2_has_feature_async_commit(journal))
 154                 write_flags |= REQ_PREFLUSH | REQ_FUA;
 155
 156         submit_bh(write_flags, bh);
 157         *cbh = bh;
 158         return 0;
 159 }
 160
 161 /*
 162  * This function along with journal_submit_commit_record
 163  * allows to write the commit record asynchronously.
 164  */
 165 static int journal_wait_on_commit_record(journal_t *journal,
 166                                          struct buffer_head *bh)
 167 {
 168         int ret = 0;
 169
 170         clear_buffer_dirty(bh);
 171         wait_on_buffer(bh);
 172
 173         if (unlikely(!buffer_uptodate(bh)))
 174                 ret = -EIO;
 175         put_bh(bh);            /* One for getblk() */
 176
 177         return ret;
 178 }
 179
 180 /* Send all the data buffers related to an inode */
 181 int jbd2_submit_inode_data(journal_t *journal, struct jbd2_inode *jinode)
 182 {
 183         if (!jinode || !(jinode->i_flags & JI_WRITE_DATA))
 184                 return 0;
 185
 186         trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
 187         return journal->j_submit_inode_data_buffers(jinode);
 188
 189 }
 190 EXPORT_SYMBOL(jbd2_submit_inode_data);
 191
 192 int jbd2_wait_inode_data(journal_t *journal, struct jbd2_inode *jinode)
 193 {
 194         if (!jinode || !(jinode->i_flags & JI_WAIT_DATA) ||
 195                 !jinode->i_vfs_inode || !jinode->i_vfs_inode->i_mapping)
 196                 return 0;
 197         return filemap_fdatawait_range_keep_errors(
 198                 jinode->i_vfs_inode->i_mapping, jinode->i_dirty_start,
 199                 jinode->i_dirty_end);
 200 }
 201 EXPORT_SYMBOL(jbd2_wait_inode_data);
 202
 203 /*
 204  * Submit all the data buffers of inode associated with the transaction to
 205  * disk.
 206  *
 207  * We are in a committing transaction. Therefore no new inode can be added to
 208  * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
 209  * operate on from being released while we write out pages.
 210  */
 211 static int journal_submit_data_buffers(journal_t *journal,
 212                 transaction_t *commit_transaction)
 213 {
 214         struct jbd2_inode *jinode;
 215         int err, ret = 0;
 216
 217         spin_lock(&journal->j_list_lock);
 218         list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 219                 if (!(jinode->i_flags & JI_WRITE_DATA))
 220                         continue;
 221                 jinode->i_flags |= JI_COMMIT_RUNNING;
 222                 spin_unlock(&journal->j_list_lock);
 223                 /* submit the inode data buffers. */
 224                 trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
 225                 if (journal->j_submit_inode_data_buffers) {
 226                         err = journal->j_submit_inode_data_buffers(jinode);
 227                         if (!ret)
 228                                 ret = err;
 229                 }
 230                 spin_lock(&journal->j_list_lock);
 231                 J_ASSERT(jinode->i_transaction == commit_transaction);
 232                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 233                 smp_mb();
 234                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 235         }
 236         spin_unlock(&journal->j_list_lock);
 237         return ret;
 238 }
 239
 240 int jbd2_journal_finish_inode_data_buffers(struct jbd2_inode *jinode)
 241 {
 242         struct address_space *mapping = jinode->i_vfs_inode->i_mapping;
 243
 244         return filemap_fdatawait_range_keep_errors(mapping,
 245                                                    jinode->i_dirty_start,
 246                                                    jinode->i_dirty_end);
 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                 if (!(jinode->i_flags & JI_WAIT_DATA))
 264                         continue;
 265                 jinode->i_flags |= JI_COMMIT_RUNNING;
 266                 spin_unlock(&journal->j_list_lock);
 267                 /* wait for the inode data buffers writeout. */
 268                 if (journal->j_finish_inode_data_buffers) {
 269                         err = journal->j_finish_inode_data_buffers(jinode);
 270                         if (!ret)
 271                                 ret = err;
 272                 }
 273                 spin_lock(&journal->j_list_lock);
 274                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 275                 smp_mb();
 276                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 277         }
 278
 279         /* Now refile inode to proper lists */
 280         list_for_each_entry_safe(jinode, next_i,
 281                                  &commit_transaction->t_inode_list, i_list) {
 282                 list_del(&jinode->i_list);
 283                 if (jinode->i_next_transaction) {
 284                         jinode->i_transaction = jinode->i_next_transaction;
 285                         jinode->i_next_transaction = NULL;
 286                         list_add(&jinode->i_list,
 287                                 &jinode->i_transaction->t_inode_list);
 288                 } else {
 289                         jinode->i_transaction = NULL;
 290                         jinode->i_dirty_start = 0;
 291                         jinode->i_dirty_end = 0;
 292                 }
 293         }
 294         spin_unlock(&journal->j_list_lock);
 295
 296         return ret;
 297 }
 298
 299 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 300 {
 301         char *addr;
 302         __u32 checksum;
 303
 304         addr = kmap_local_folio(bh->b_folio, bh_offset(bh));
 305         checksum = crc32_be(crc32_sum, addr, bh->b_size);
 306         kunmap_local(addr);
 307
 308         return checksum;
 309 }
 310
 311 static void write_tag_block(journal_t *j, journal_block_tag_t *tag,
 312                                    unsigned long long block)
 313 {
 314         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
 315         if (jbd2_has_feature_64bit(j))
 316                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 317 }
 318
 319 static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 320                                     struct buffer_head *bh, __u32 sequence)
 321 {
 322         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 323         __u8 *addr;
 324         __u32 csum32;
 325         __be32 seq;
 326
 327         if (!jbd2_journal_has_csum_v2or3(j))
 328                 return;
 329
 330         seq = cpu_to_be32(sequence);
 331         addr = kmap_local_folio(bh->b_folio, bh_offset(bh));
 332         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 333         csum32 = jbd2_chksum(j, csum32, addr, bh->b_size);
 334         kunmap_local(addr);
 335
 336         if (jbd2_has_feature_csum3(j))
 337                 tag3->t_checksum = cpu_to_be32(csum32);
 338         else
 339                 tag->t_checksum = cpu_to_be16(csum32);
 340 }
 341 /*
 342  * jbd2_journal_commit_transaction
 343  *
 344  * The primary function for committing a transaction to the log.  This
 345  * function is called by the journal thread to begin a complete commit.
 346  */
 347 void jbd2_journal_commit_transaction(journal_t *journal)
 348 {
 349         struct transaction_stats_s stats;
 350         transaction_t *commit_transaction;
 351         struct journal_head *jh;
 352         struct buffer_head *descriptor;
 353         struct buffer_head **wbuf = journal->j_wbuf;
 354         int bufs;
 355         int flags;
 356         int err;
 357         unsigned long long blocknr;
 358         ktime_t start_time;
 359         u64 commit_time;
 360         char *tagp = NULL;
 361         journal_block_tag_t *tag = NULL;
 362         int space_left = 0;
 363         int first_tag = 0;
 364         int tag_flag;
 365         int i;
 366         int tag_bytes = journal_tag_bytes(journal);
 367         struct buffer_head *cbh = NULL; /* For transactional checksums */
 368         __u32 crc32_sum = ~0;
 369         struct blk_plug plug;
 370         /* Tail of the journal */
 371         unsigned long first_block;
 372         tid_t first_tid;
 373         int update_tail;
 374         int csum_size = 0;
 375         LIST_HEAD(io_bufs);
 376         LIST_HEAD(log_bufs);
 377
 378         if (jbd2_journal_has_csum_v2or3(journal))
 379                 csum_size = sizeof(struct jbd2_journal_block_tail);
 380
 381         /*
 382          * First job: lock down the current transaction and wait for
 383          * all outstanding updates to complete.
 384          */
 385
 386         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 387         if (journal->j_flags & JBD2_FLUSHED) {
 388                 jbd2_debug(3, "super block updated\n");
 389                 mutex_lock_io(&journal->j_checkpoint_mutex);
 390                 /*
 391                  * We hold j_checkpoint_mutex so tail cannot change under us.
 392                  * We don't need any special data guarantees for writing sb
 393                  * since journal is empty and it is ok for write to be
 394                  * flushed only with transaction commit.
 395                  */
 396                 jbd2_journal_update_sb_log_tail(journal,
 397                                                 journal->j_tail_sequence,
 398                                                 journal->j_tail,
 399                                                 REQ_SYNC);
 400                 mutex_unlock(&journal->j_checkpoint_mutex);
 401         } else {
 402                 jbd2_debug(3, "superblock not updated\n");
 403         }
 404
 405         J_ASSERT(journal->j_running_transaction != NULL);
 406         J_ASSERT(journal->j_committing_transaction == NULL);
 407
 408         write_lock(&journal->j_state_lock);
 409         journal->j_flags |= JBD2_FULL_COMMIT_ONGOING;
 410         while (journal->j_flags & JBD2_FAST_COMMIT_ONGOING) {
 411                 DEFINE_WAIT(wait);
 412
 413                 prepare_to_wait(&journal->j_fc_wait, &wait,
 414                                 TASK_UNINTERRUPTIBLE);
 415                 write_unlock(&journal->j_state_lock);
 416                 schedule();
 417                 write_lock(&journal->j_state_lock);
 418                 finish_wait(&journal->j_fc_wait, &wait);
 419                 /*
 420                  * TODO: by blocking fast commits here, we are increasing
 421                  * fsync() latency slightly. Strictly speaking, we don't need
 422                  * to block fast commits until the transaction enters T_FLUSH
 423                  * state. So an optimization is possible where we block new fast
 424                  * commits here and wait for existing ones to complete
 425                  * just before we enter T_FLUSH. That way, the existing fast
 426                  * commits and this full commit can proceed parallely.
 427                  */
 428         }
 429         write_unlock(&journal->j_state_lock);
 430
 431         commit_transaction = journal->j_running_transaction;
 432
 433         trace_jbd2_start_commit(journal, commit_transaction);
 434         jbd2_debug(1, "JBD2: starting commit of transaction %d\n",
 435                         commit_transaction->t_tid);
 436
 437         write_lock(&journal->j_state_lock);
 438         journal->j_fc_off = 0;
 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         // waits for any t_updates to finish
 454         jbd2_journal_wait_updates(journal);
 455
 456         commit_transaction->t_state = T_SWITCH;
 457
 458         J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 459                         journal->j_max_transaction_buffers);
 460
 461         /*
 462          * First thing we are allowed to do is to discard any remaining
 463          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 464          * that there are no such buffers: if a large filesystem
 465          * operation like a truncate needs to split itself over multiple
 466          * transactions, then it may try to do a jbd2_journal_restart() while
 467          * there are still BJ_Reserved buffers outstanding.  These must
 468          * be released cleanly from the current transaction.
 469          *
 470          * In this case, the filesystem must still reserve write access
 471          * again before modifying the buffer in the new transaction, but
 472          * we do not require it to remember exactly which old buffers it
 473          * has reserved.  This is consistent with the existing behaviour
 474          * that multiple jbd2_journal_get_write_access() calls to the same
 475          * buffer are perfectly permissible.
 476          * We use journal->j_state_lock here to serialize processing of
 477          * t_reserved_list with eviction of buffers from journal_unmap_buffer().
 478          */
 479         while (commit_transaction->t_reserved_list) {
 480                 jh = commit_transaction->t_reserved_list;
 481                 JBUFFER_TRACE(jh, "reserved, unused: refile");
 482                 /*
 483                  * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 484                  * leave undo-committed data.
 485                  */
 486                 if (jh->b_committed_data) {
 487                         struct buffer_head *bh = jh2bh(jh);
 488
 489                         spin_lock(&jh->b_state_lock);
 490                         jbd2_free(jh->b_committed_data, bh->b_size);
 491                         jh->b_committed_data = NULL;
 492                         spin_unlock(&jh->b_state_lock);
 493                 }
 494                 jbd2_journal_refile_buffer(journal, jh);
 495         }
 496
 497         write_unlock(&journal->j_state_lock);
 498         /*
 499          * Now try to drop any written-back buffers from the journal's
 500          * checkpoint lists.  We do this *before* commit because it potentially
 501          * frees some memory
 502          */
 503         spin_lock(&journal->j_list_lock);
 504         __jbd2_journal_clean_checkpoint_list(journal, false);
 505         spin_unlock(&journal->j_list_lock);
 506
 507         jbd2_debug(3, "JBD2: commit phase 1\n");
 508
 509         /*
 510          * Clear revoked flag to reflect there is no revoked buffers
 511          * in the next transaction which is going to be started.
 512          */
 513         jbd2_clear_buffer_revoked_flags(journal);
 514
 515         /*
 516          * Switch to a new revoke table.
 517          */
 518         jbd2_journal_switch_revoke_table(journal);
 519
 520         write_lock(&journal->j_state_lock);
 521         /*
 522          * Reserved credits cannot be claimed anymore, free them
 523          */
 524         atomic_sub(atomic_read(&journal->j_reserved_credits),
 525                    &commit_transaction->t_outstanding_credits);
 526
 527         trace_jbd2_commit_flushing(journal, commit_transaction);
 528         stats.run.rs_flushing = jiffies;
 529         stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 530                                              stats.run.rs_flushing);
 531
 532         commit_transaction->t_state = T_FLUSH;
 533         journal->j_committing_transaction = commit_transaction;
 534         journal->j_running_transaction = NULL;
 535         start_time = ktime_get();
 536         commit_transaction->t_log_start = journal->j_head;
 537         wake_up_all(&journal->j_wait_transaction_locked);
 538         write_unlock(&journal->j_state_lock);
 539
 540         jbd2_debug(3, "JBD2: commit phase 2a\n");
 541
 542         /*
 543          * Now start flushing things to disk, in the order they appear
 544          * on the transaction lists.  Data blocks go first.
 545          */
 546         err = journal_submit_data_buffers(journal, commit_transaction);
 547         if (err)
 548                 jbd2_journal_abort(journal, err);
 549
 550         blk_start_plug(&plug);
 551         jbd2_journal_write_revoke_records(commit_transaction, &log_bufs);
 552
 553         jbd2_debug(3, "JBD2: commit phase 2b\n");
 554
 555         /*
 556          * Way to go: we have now written out all of the data for a
 557          * transaction!  Now comes the tricky part: we need to write out
 558          * metadata.  Loop over the transaction's entire buffer list:
 559          */
 560         write_lock(&journal->j_state_lock);
 561         commit_transaction->t_state = T_COMMIT;
 562         write_unlock(&journal->j_state_lock);
 563
 564         trace_jbd2_commit_logging(journal, commit_transaction);
 565         stats.run.rs_logging = jiffies;
 566         stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 567                                                stats.run.rs_logging);
 568         stats.run.rs_blocks = commit_transaction->t_nr_buffers;
 569         stats.run.rs_blocks_logged = 0;
 570
 571         J_ASSERT(commit_transaction->t_nr_buffers <=
 572                  atomic_read(&commit_transaction->t_outstanding_credits));
 573
 574         err = 0;
 575         bufs = 0;
 576         descriptor = NULL;
 577         while (commit_transaction->t_buffers) {
 578
 579                 /* Find the next buffer to be journaled... */
 580
 581                 jh = commit_transaction->t_buffers;
 582
 583                 /* If we're in abort mode, we just un-journal the buffer and
 584                    release it. */
 585
 586                 if (is_journal_aborted(journal)) {
 587                         clear_buffer_jbddirty(jh2bh(jh));
 588                         JBUFFER_TRACE(jh, "journal is aborting: refile");
 589                         jbd2_buffer_abort_trigger(jh,
 590                                                   jh->b_frozen_data ?
 591                                                   jh->b_frozen_triggers :
 592                                                   jh->b_triggers);
 593                         jbd2_journal_refile_buffer(journal, jh);
 594                         /* If that was the last one, we need to clean up
 595                          * any descriptor buffers which may have been
 596                          * already allocated, even if we are now
 597                          * aborting. */
 598                         if (!commit_transaction->t_buffers)
 599                                 goto start_journal_io;
 600                         continue;
 601                 }
 602
 603                 /* Make sure we have a descriptor block in which to
 604                    record the metadata buffer. */
 605
 606                 if (!descriptor) {
 607                         J_ASSERT (bufs == 0);
 608
 609                         jbd2_debug(4, "JBD2: get descriptor\n");
 610
 611                         descriptor = jbd2_journal_get_descriptor_buffer(
 612                                                         commit_transaction,
 613                                                         JBD2_DESCRIPTOR_BLOCK);
 614                         if (!descriptor) {
 615                                 jbd2_journal_abort(journal, -EIO);
 616                                 continue;
 617                         }
 618
 619                         jbd2_debug(4, "JBD2: got buffer %llu (%p)\n",
 620                                 (unsigned long long)descriptor->b_blocknr,
 621                                 descriptor->b_data);
 622                         tagp = &descriptor->b_data[sizeof(journal_header_t)];
 623                         space_left = descriptor->b_size -
 624                                                 sizeof(journal_header_t);
 625                         first_tag = 1;
 626                         set_buffer_jwrite(descriptor);
 627                         set_buffer_dirty(descriptor);
 628                         wbuf[bufs++] = descriptor;
 629
 630                         /* Record it so that we can wait for IO
 631                            completion later */
 632                         BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 633                         jbd2_file_log_bh(&log_bufs, descriptor);
 634                 }
 635
 636                 /* Where is the buffer to be written? */
 637
 638                 err = jbd2_journal_next_log_block(journal, &blocknr);
 639                 /* If the block mapping failed, just abandon the buffer
 640                    and repeat this loop: we'll fall into the
 641                    refile-on-abort condition above. */
 642                 if (err) {
 643                         jbd2_journal_abort(journal, err);
 644                         continue;
 645                 }
 646
 647                 /*
 648                  * start_this_handle() uses t_outstanding_credits to determine
 649                  * the free space in the log.
 650                  */
 651                 atomic_dec(&commit_transaction->t_outstanding_credits);
 652
 653                 /* Bump b_count to prevent truncate from stumbling over
 654                    the shadowed buffer!  @@@ This can go if we ever get
 655                    rid of the shadow pairing of buffers. */
 656                 atomic_inc(&jh2bh(jh)->b_count);
 657
 658                 /*
 659                  * Make a temporary IO buffer with which to write it out
 660                  * (this will requeue the metadata buffer to BJ_Shadow).
 661                  */
 662                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 663                 JBUFFER_TRACE(jh, "ph3: write metadata");
 664                 flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 665                                                 jh, &wbuf[bufs], blocknr);
 666                 if (flags < 0) {
 667                         jbd2_journal_abort(journal, flags);
 668                         continue;
 669                 }
 670                 jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 671
 672                 /* Record the new block's tag in the current descriptor
 673                    buffer */
 674
 675                 tag_flag = 0;
 676                 if (flags & 1)
 677                         tag_flag |= JBD2_FLAG_ESCAPE;
 678                 if (!first_tag)
 679                         tag_flag |= JBD2_FLAG_SAME_UUID;
 680
 681                 tag = (journal_block_tag_t *) tagp;
 682                 write_tag_block(journal, tag, jh2bh(jh)->b_blocknr);
 683                 tag->t_flags = cpu_to_be16(tag_flag);
 684                 jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 685                                         commit_transaction->t_tid);
 686                 tagp += tag_bytes;
 687                 space_left -= tag_bytes;
 688                 bufs++;
 689
 690                 if (first_tag) {
 691                         memcpy (tagp, journal->j_uuid, 16);
 692                         tagp += 16;
 693                         space_left -= 16;
 694                         first_tag = 0;
 695                 }
 696
 697                 /* If there's no more to do, or if the descriptor is full,
 698                    let the IO rip! */
 699
 700                 if (bufs == journal->j_wbufsize ||
 701                     commit_transaction->t_buffers == NULL ||
 702                     space_left < tag_bytes + 16 + csum_size) {
 703
 704                         jbd2_debug(4, "JBD2: Submit %d IOs\n", bufs);
 705
 706                         /* Write an end-of-descriptor marker before
 707                            submitting the IOs.  "tag" still points to
 708                            the last tag we set up. */
 709
 710                         tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 711 start_journal_io:
 712                         if (descriptor)
 713                                 jbd2_descriptor_block_csum_set(journal,
 714                                                         descriptor);
 715
 716                         for (i = 0; i < bufs; i++) {
 717                                 struct buffer_head *bh = wbuf[i];
 718                                 /*
 719                                  * Compute checksum.
 720                                  */
 721                                 if (jbd2_has_feature_checksum(journal)) {
 722                                         crc32_sum =
 723                                             jbd2_checksum_data(crc32_sum, bh);
 724                                 }
 725
 726                                 lock_buffer(bh);
 727                                 clear_buffer_dirty(bh);
 728                                 set_buffer_uptodate(bh);
 729                                 bh->b_end_io = journal_end_buffer_io_sync;
 730                                 submit_bh(REQ_OP_WRITE | REQ_SYNC, bh);
 731                         }
 732                         cond_resched();
 733
 734                         /* Force a new descriptor to be generated next
 735                            time round the loop. */
 736                         descriptor = NULL;
 737                         bufs = 0;
 738                 }
 739         }
 740
 741         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 742         if (err) {
 743                 printk(KERN_WARNING
 744                         "JBD2: Detected IO errors while flushing file data "
 745                        "on %s\n", journal->j_devname);
 746                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 747                         jbd2_journal_abort(journal, err);
 748                 err = 0;
 749         }
 750
 751         /*
 752          * Get current oldest transaction in the log before we issue flush
 753          * to the filesystem device. After the flush we can be sure that
 754          * blocks of all older transactions are checkpointed to persistent
 755          * storage and we will be safe to update journal start in the
 756          * superblock with the numbers we get here.
 757          */
 758         update_tail =
 759                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 760
 761         write_lock(&journal->j_state_lock);
 762         if (update_tail) {
 763                 long freed = first_block - journal->j_tail;
 764
 765                 if (first_block < journal->j_tail)
 766                         freed += journal->j_last - journal->j_first;
 767                 /* Update tail only if we free significant amount of space */
 768                 if (freed < jbd2_journal_get_max_txn_bufs(journal))
 769                         update_tail = 0;
 770         }
 771         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 772         commit_transaction->t_state = T_COMMIT_DFLUSH;
 773         write_unlock(&journal->j_state_lock);
 774
 775         /*
 776          * If the journal is not located on the file system device,
 777          * then we must flush the file system device before we issue
 778          * the commit record
 779          */
 780         if (commit_transaction->t_need_data_flush &&
 781             (journal->j_fs_dev != journal->j_dev) &&
 782             (journal->j_flags & JBD2_BARRIER))
 783                 blkdev_issue_flush(journal->j_fs_dev);
 784
 785         /* Done it all: now write the commit record asynchronously. */
 786         if (jbd2_has_feature_async_commit(journal)) {
 787                 err = journal_submit_commit_record(journal, commit_transaction,
 788                                                  &cbh, crc32_sum);
 789                 if (err)
 790                         jbd2_journal_abort(journal, err);
 791         }
 792
 793         blk_finish_plug(&plug);
 794
 795         /* Lo and behold: we have just managed to send a transaction to
 796            the log.  Before we can commit it, wait for the IO so far to
 797            complete.  Control buffers being written are on the
 798            transaction's t_log_list queue, and metadata buffers are on
 799            the io_bufs list.
 800
 801            Wait for the buffers in reverse order.  That way we are
 802            less likely to be woken up until all IOs have completed, and
 803            so we incur less scheduling load.
 804         */
 805
 806         jbd2_debug(3, "JBD2: commit phase 3\n");
 807
 808         while (!list_empty(&io_bufs)) {
 809                 struct buffer_head *bh = list_entry(io_bufs.prev,
 810                                                     struct buffer_head,
 811                                                     b_assoc_buffers);
 812
 813                 wait_on_buffer(bh);
 814                 cond_resched();
 815
 816                 if (unlikely(!buffer_uptodate(bh)))
 817                         err = -EIO;
 818                 jbd2_unfile_log_bh(bh);
 819                 stats.run.rs_blocks_logged++;
 820
 821                 /*
 822                  * The list contains temporary buffer heads created by
 823                  * jbd2_journal_write_metadata_buffer().
 824                  */
 825                 BUFFER_TRACE(bh, "dumping temporary bh");
 826                 __brelse(bh);
 827                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 828                 free_buffer_head(bh);
 829
 830                 /* We also have to refile the corresponding shadowed buffer */
 831                 jh = commit_transaction->t_shadow_list->b_tprev;
 832                 bh = jh2bh(jh);
 833                 clear_buffer_jwrite(bh);
 834                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 835                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 836
 837                 /* The metadata is now released for reuse, but we need
 838                    to remember it against this transaction so that when
 839                    we finally commit, we can do any checkpointing
 840                    required. */
 841                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 842                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 843                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 844                 __brelse(bh);
 845         }
 846
 847         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 848
 849         jbd2_debug(3, "JBD2: commit phase 4\n");
 850
 851         /* Here we wait for the revoke record and descriptor record buffers */
 852         while (!list_empty(&log_bufs)) {
 853                 struct buffer_head *bh;
 854
 855                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 856                 wait_on_buffer(bh);
 857                 cond_resched();
 858
 859                 if (unlikely(!buffer_uptodate(bh)))
 860                         err = -EIO;
 861
 862                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 863                 clear_buffer_jwrite(bh);
 864                 jbd2_unfile_log_bh(bh);
 865                 stats.run.rs_blocks_logged++;
 866                 __brelse(bh);           /* One for getblk */
 867                 /* AKPM: bforget here */
 868         }
 869
 870         if (err)
 871                 jbd2_journal_abort(journal, err);
 872
 873         jbd2_debug(3, "JBD2: commit phase 5\n");
 874         write_lock(&journal->j_state_lock);
 875         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 876         commit_transaction->t_state = T_COMMIT_JFLUSH;
 877         write_unlock(&journal->j_state_lock);
 878
 879         if (!jbd2_has_feature_async_commit(journal)) {
 880                 err = journal_submit_commit_record(journal, commit_transaction,
 881                                                 &cbh, crc32_sum);
 882                 if (err)
 883                         jbd2_journal_abort(journal, err);
 884         }
 885         if (cbh)
 886                 err = journal_wait_on_commit_record(journal, cbh);
 887         stats.run.rs_blocks_logged++;
 888         if (jbd2_has_feature_async_commit(journal) &&
 889             journal->j_flags & JBD2_BARRIER) {
 890                 blkdev_issue_flush(journal->j_dev);
 891         }
 892
 893         if (err)
 894                 jbd2_journal_abort(journal, err);
 895
 896         WARN_ON_ONCE(
 897                 atomic_read(&commit_transaction->t_outstanding_credits) < 0);
 898
 899         /*
 900          * Now disk caches for filesystem device are flushed so we are safe to
 901          * erase checkpointed transactions from the log by updating journal
 902          * superblock.
 903          */
 904         if (update_tail)
 905                 jbd2_update_log_tail(journal, first_tid, first_block);
 906
 907         /* End of a transaction!  Finally, we can do checkpoint
 908            processing: any buffers committed as a result of this
 909            transaction can be removed from any checkpoint list it was on
 910            before. */
 911
 912         jbd2_debug(3, "JBD2: commit phase 6\n");
 913
 914         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 915         J_ASSERT(commit_transaction->t_buffers == NULL);
 916         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 917         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 918
 919 restart_loop:
 920         /*
 921          * As there are other places (journal_unmap_buffer()) adding buffers
 922          * to this list we have to be careful and hold the j_list_lock.
 923          */
 924         spin_lock(&journal->j_list_lock);
 925         while (commit_transaction->t_forget) {
 926                 transaction_t *cp_transaction;
 927                 struct buffer_head *bh;
 928                 int try_to_free = 0;
 929                 bool drop_ref;
 930
 931                 jh = commit_transaction->t_forget;
 932                 spin_unlock(&journal->j_list_lock);
 933                 bh = jh2bh(jh);
 934                 /*
 935                  * Get a reference so that bh cannot be freed before we are
 936                  * done with it.
 937                  */
 938                 get_bh(bh);
 939                 spin_lock(&jh->b_state_lock);
 940                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 941
 942                 /*
 943                  * If there is undo-protected committed data against
 944                  * this buffer, then we can remove it now.  If it is a
 945                  * buffer needing such protection, the old frozen_data
 946                  * field now points to a committed version of the
 947                  * buffer, so rotate that field to the new committed
 948                  * data.
 949                  *
 950                  * Otherwise, we can just throw away the frozen data now.
 951                  *
 952                  * We also know that the frozen data has already fired
 953                  * its triggers if they exist, so we can clear that too.
 954                  */
 955                 if (jh->b_committed_data) {
 956                         jbd2_free(jh->b_committed_data, bh->b_size);
 957                         jh->b_committed_data = NULL;
 958                         if (jh->b_frozen_data) {
 959                                 jh->b_committed_data = jh->b_frozen_data;
 960                                 jh->b_frozen_data = NULL;
 961                                 jh->b_frozen_triggers = NULL;
 962                         }
 963                 } else if (jh->b_frozen_data) {
 964                         jbd2_free(jh->b_frozen_data, bh->b_size);
 965                         jh->b_frozen_data = NULL;
 966                         jh->b_frozen_triggers = NULL;
 967                 }
 968
 969                 spin_lock(&journal->j_list_lock);
 970                 cp_transaction = jh->b_cp_transaction;
 971                 if (cp_transaction) {
 972                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 973                         cp_transaction->t_chp_stats.cs_dropped++;
 974                         __jbd2_journal_remove_checkpoint(jh);
 975                 }
 976
 977                 /* Only re-checkpoint the buffer_head if it is marked
 978                  * dirty.  If the buffer was added to the BJ_Forget list
 979                  * by jbd2_journal_forget, it may no longer be dirty and
 980                  * there's no point in keeping a checkpoint record for
 981                  * it. */
 982
 983                 /*
 984                  * A buffer which has been freed while still being journaled
 985                  * by a previous transaction, refile the buffer to BJ_Forget of
 986                  * the running transaction. If the just committed transaction
 987                  * contains "add to orphan" operation, we can completely
 988                  * invalidate the buffer now. We are rather through in that
 989                  * since the buffer may be still accessible when blocksize <
 990                  * pagesize and it is attached to the last partial page.
 991                  */
 992                 if (buffer_freed(bh) && !jh->b_next_transaction) {
 993                         struct address_space *mapping;
 994
 995                         clear_buffer_freed(bh);
 996                         clear_buffer_jbddirty(bh);
 997
 998                         /*
 999                          * Block device buffers need to stay mapped all the
1000                          * time, so it is enough to clear buffer_jbddirty and
1001                          * buffer_freed bits. For the file mapping buffers (i.e.
1002                          * journalled data) we need to unmap buffer and clear
1003                          * more bits. We also need to be careful about the check
1004                          * because the data page mapping can get cleared under
1005                          * our hands. Note that if mapping == NULL, we don't
1006                          * need to make buffer unmapped because the page is
1007                          * already detached from the mapping and buffers cannot
1008                          * get reused.
1009                          */
1010                         mapping = READ_ONCE(bh->b_folio->mapping);
1011                         if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {
1012                                 clear_buffer_mapped(bh);
1013                                 clear_buffer_new(bh);
1014                                 clear_buffer_req(bh);
1015                                 bh->b_bdev = NULL;
1016                         }
1017                 }
1018
1019                 if (buffer_jbddirty(bh)) {
1020                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1021                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1022                         if (is_journal_aborted(journal))
1023                                 clear_buffer_jbddirty(bh);
1024                 } else {
1025                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1026                         /*
1027                          * The buffer on BJ_Forget list and not jbddirty means
1028                          * it has been freed by this transaction and hence it
1029                          * could not have been reallocated until this
1030                          * transaction has committed. *BUT* it could be
1031                          * reallocated once we have written all the data to
1032                          * disk and before we process the buffer on BJ_Forget
1033                          * list.
1034                          */
1035                         if (!jh->b_next_transaction)
1036                                 try_to_free = 1;
1037                 }
1038                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1039                 drop_ref = __jbd2_journal_refile_buffer(jh);
1040                 spin_unlock(&jh->b_state_lock);
1041                 if (drop_ref)
1042                         jbd2_journal_put_journal_head(jh);
1043                 if (try_to_free)
1044                         release_buffer_page(bh);        /* Drops bh reference */
1045                 else
1046                         __brelse(bh);
1047                 cond_resched_lock(&journal->j_list_lock);
1048         }
1049         spin_unlock(&journal->j_list_lock);
1050         /*
1051          * This is a bit sleazy.  We use j_list_lock to protect transition
1052          * of a transaction into T_FINISHED state and calling
1053          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1054          * other checkpointing code processing the transaction...
1055          */
1056         write_lock(&journal->j_state_lock);
1057         spin_lock(&journal->j_list_lock);
1058         /*
1059          * Now recheck if some buffers did not get attached to the transaction
1060          * while the lock was dropped...
1061          */
1062         if (commit_transaction->t_forget) {
1063                 spin_unlock(&journal->j_list_lock);
1064                 write_unlock(&journal->j_state_lock);
1065                 goto restart_loop;
1066         }
1067
1068         /* Add the transaction to the checkpoint list
1069          * __journal_remove_checkpoint() can not destroy transaction
1070          * under us because it is not marked as T_FINISHED yet */
1071         if (journal->j_checkpoint_transactions == NULL) {
1072                 journal->j_checkpoint_transactions = commit_transaction;
1073                 commit_transaction->t_cpnext = commit_transaction;
1074                 commit_transaction->t_cpprev = commit_transaction;
1075         } else {
1076                 commit_transaction->t_cpnext =
1077                         journal->j_checkpoint_transactions;
1078                 commit_transaction->t_cpprev =
1079                         commit_transaction->t_cpnext->t_cpprev;
1080                 commit_transaction->t_cpnext->t_cpprev =
1081                         commit_transaction;
1082                 commit_transaction->t_cpprev->t_cpnext =
1083                                 commit_transaction;
1084         }
1085         spin_unlock(&journal->j_list_lock);
1086
1087         /* Done with this transaction! */
1088
1089         jbd2_debug(3, "JBD2: commit phase 7\n");
1090
1091         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1092
1093         commit_transaction->t_start = jiffies;
1094         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1095                                               commit_transaction->t_start);
1096
1097         /*
1098          * File the transaction statistics
1099          */
1100         stats.ts_tid = commit_transaction->t_tid;
1101         stats.run.rs_handle_count =
1102                 atomic_read(&commit_transaction->t_handle_count);
1103         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1104                              commit_transaction->t_tid, &stats.run);
1105         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1106
1107         commit_transaction->t_state = T_COMMIT_CALLBACK;
1108         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1109         journal->j_commit_sequence = commit_transaction->t_tid;
1110         journal->j_committing_transaction = NULL;
1111         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1112
1113         /*
1114          * weight the commit time higher than the average time so we don't
1115          * react too strongly to vast changes in the commit time
1116          */
1117         if (likely(journal->j_average_commit_time))
1118                 journal->j_average_commit_time = (commit_time +
1119                                 journal->j_average_commit_time*3) / 4;
1120         else
1121                 journal->j_average_commit_time = commit_time;
1122
1123         write_unlock(&journal->j_state_lock);
1124
1125         if (journal->j_commit_callback)
1126                 journal->j_commit_callback(journal, commit_transaction);
1127         if (journal->j_fc_cleanup_callback)
1128                 journal->j_fc_cleanup_callback(journal, 1, commit_transaction->t_tid);
1129
1130         trace_jbd2_end_commit(journal, commit_transaction);
1131         jbd2_debug(1, "JBD2: commit %d complete, head %d\n",
1132                   journal->j_commit_sequence, journal->j_tail_sequence);
1133
1134         write_lock(&journal->j_state_lock);
1135         journal->j_flags &= ~JBD2_FULL_COMMIT_ONGOING;
1136         journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
1137         spin_lock(&journal->j_list_lock);
1138         commit_transaction->t_state = T_FINISHED;
1139         /* Check if the transaction can be dropped now that we are finished */
1140         if (commit_transaction->t_checkpoint_list == NULL) {
1141                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1142                 jbd2_journal_free_transaction(commit_transaction);
1143         }
1144         spin_unlock(&journal->j_list_lock);
1145         write_unlock(&journal->j_state_lock);
1146         wake_up(&journal->j_wait_done_commit);
1147         wake_up(&journal->j_fc_wait);
1148
1149         /*
1150          * Calculate overall stats
1151          */
1152         spin_lock(&journal->j_history_lock);
1153         journal->j_stats.ts_tid++;
1154         journal->j_stats.ts_requested += stats.ts_requested;
1155         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1156         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1157         journal->j_stats.run.rs_running += stats.run.rs_running;
1158         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1159         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1160         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1161         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1162         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1163         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1164         spin_unlock(&journal->j_history_lock);
1165 }