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 | JBD2_JOURNAL_REQ_FLAGS;
 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                 cond_resched();
 274                 spin_lock(&journal->j_list_lock);
 275                 jinode->i_flags &= ~JI_COMMIT_RUNNING;
 276                 smp_mb();
 277                 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 278         }
 279
 280         /* Now refile inode to proper lists */
 281         list_for_each_entry_safe(jinode, next_i,
 282                                  &commit_transaction->t_inode_list, i_list) {
 283                 list_del(&jinode->i_list);
 284                 if (jinode->i_next_transaction) {
 285                         jinode->i_transaction = jinode->i_next_transaction;
 286                         jinode->i_next_transaction = NULL;
 287                         list_add(&jinode->i_list,
 288                                 &jinode->i_transaction->t_inode_list);
 289                 } else {
 290                         jinode->i_transaction = NULL;
 291                         jinode->i_dirty_start = 0;
 292                         jinode->i_dirty_end = 0;
 293                 }
 294         }
 295         spin_unlock(&journal->j_list_lock);
 296
 297         return ret;
 298 }
 299
 300 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 301 {
 302         char *addr;
 303         __u32 checksum;
 304
 305         addr = kmap_local_folio(bh->b_folio, bh_offset(bh));
 306         checksum = crc32_be(crc32_sum, addr, bh->b_size);
 307         kunmap_local(addr);
 308
 309         return checksum;
 310 }
 311
 312 static void write_tag_block(journal_t *j, journal_block_tag_t *tag,
 313                                    unsigned long long block)
 314 {
 315         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
 316         if (jbd2_has_feature_64bit(j))
 317                 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 318 }
 319
 320 static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 321                                     struct buffer_head *bh, __u32 sequence)
 322 {
 323         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 324         __u8 *addr;
 325         __u32 csum32;
 326         __be32 seq;
 327
 328         if (!jbd2_journal_has_csum_v2or3(j))
 329                 return;
 330
 331         seq = cpu_to_be32(sequence);
 332         addr = kmap_local_folio(bh->b_folio, bh_offset(bh));
 333         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 334         csum32 = jbd2_chksum(j, csum32, addr, bh->b_size);
 335         kunmap_local(addr);
 336
 337         if (jbd2_has_feature_csum3(j))
 338                 tag3->t_checksum = cpu_to_be32(csum32);
 339         else
 340                 tag->t_checksum = cpu_to_be16(csum32);
 341 }
 342 /*
 343  * jbd2_journal_commit_transaction
 344  *
 345  * The primary function for committing a transaction to the log.  This
 346  * function is called by the journal thread to begin a complete commit.
 347  */
 348 void jbd2_journal_commit_transaction(journal_t *journal)
 349 {
 350         struct transaction_stats_s stats;
 351         transaction_t *commit_transaction;
 352         struct journal_head *jh;
 353         struct buffer_head *descriptor;
 354         struct buffer_head **wbuf = journal->j_wbuf;
 355         int bufs;
 356         int flags;
 357         int err;
 358         unsigned long long blocknr;
 359         ktime_t start_time;
 360         u64 commit_time;
 361         char *tagp = NULL;
 362         journal_block_tag_t *tag = NULL;
 363         int space_left = 0;
 364         int first_tag = 0;
 365         int tag_flag;
 366         int i;
 367         int tag_bytes = journal_tag_bytes(journal);
 368         struct buffer_head *cbh = NULL; /* For transactional checksums */
 369         __u32 crc32_sum = ~0;
 370         struct blk_plug plug;
 371         /* Tail of the journal */
 372         unsigned long first_block;
 373         tid_t first_tid;
 374         int update_tail;
 375         int csum_size = 0;
 376         LIST_HEAD(io_bufs);
 377         LIST_HEAD(log_bufs);
 378
 379         if (jbd2_journal_has_csum_v2or3(journal))
 380                 csum_size = sizeof(struct jbd2_journal_block_tail);
 381
 382         /*
 383          * First job: lock down the current transaction and wait for
 384          * all outstanding updates to complete.
 385          */
 386
 387         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 388         if (journal->j_flags & JBD2_FLUSHED) {
 389                 jbd2_debug(3, "super block updated\n");
 390                 mutex_lock_io(&journal->j_checkpoint_mutex);
 391                 /*
 392                  * We hold j_checkpoint_mutex so tail cannot change under us.
 393                  * We don't need any special data guarantees for writing sb
 394                  * since journal is empty and it is ok for write to be
 395                  * flushed only with transaction commit.
 396                  */
 397                 jbd2_journal_update_sb_log_tail(journal,
 398                                                 journal->j_tail_sequence,
 399                                                 journal->j_tail, 0);
 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                                 /*
 720                                  * Compute checksum.
 721                                  */
 722                                 if (jbd2_has_feature_checksum(journal)) {
 723                                         crc32_sum =
 724                                             jbd2_checksum_data(crc32_sum, bh);
 725                                 }
 726
 727                                 lock_buffer(bh);
 728                                 clear_buffer_dirty(bh);
 729                                 set_buffer_uptodate(bh);
 730                                 bh->b_end_io = journal_end_buffer_io_sync;
 731                                 submit_bh(REQ_OP_WRITE | JBD2_JOURNAL_REQ_FLAGS,
 732                                           bh);
 733                         }
 734                         cond_resched();
 735
 736                         /* Force a new descriptor to be generated next
 737                            time round the loop. */
 738                         descriptor = NULL;
 739                         bufs = 0;
 740                 }
 741         }
 742
 743         err = journal_finish_inode_data_buffers(journal, commit_transaction);
 744         if (err) {
 745                 printk(KERN_WARNING
 746                         "JBD2: Detected IO errors while flushing file data "
 747                        "on %s\n", journal->j_devname);
 748                 if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 749                         jbd2_journal_abort(journal, err);
 750                 err = 0;
 751         }
 752
 753         /*
 754          * Get current oldest transaction in the log before we issue flush
 755          * to the filesystem device. After the flush we can be sure that
 756          * blocks of all older transactions are checkpointed to persistent
 757          * storage and we will be safe to update journal start in the
 758          * superblock with the numbers we get here.
 759          */
 760         update_tail =
 761                 jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 762
 763         write_lock(&journal->j_state_lock);
 764         if (update_tail) {
 765                 long freed = first_block - journal->j_tail;
 766
 767                 if (first_block < journal->j_tail)
 768                         freed += journal->j_last - journal->j_first;
 769                 /* Update tail only if we free significant amount of space */
 770                 if (freed < jbd2_journal_get_max_txn_bufs(journal))
 771                         update_tail = 0;
 772         }
 773         J_ASSERT(commit_transaction->t_state == T_COMMIT);
 774         commit_transaction->t_state = T_COMMIT_DFLUSH;
 775         write_unlock(&journal->j_state_lock);
 776
 777         /*
 778          * If the journal is not located on the file system device,
 779          * then we must flush the file system device before we issue
 780          * the commit record
 781          */
 782         if (commit_transaction->t_need_data_flush &&
 783             (journal->j_fs_dev != journal->j_dev) &&
 784             (journal->j_flags & JBD2_BARRIER))
 785                 blkdev_issue_flush(journal->j_fs_dev);
 786
 787         /* Done it all: now write the commit record asynchronously. */
 788         if (jbd2_has_feature_async_commit(journal)) {
 789                 err = journal_submit_commit_record(journal, commit_transaction,
 790                                                  &cbh, crc32_sum);
 791                 if (err)
 792                         jbd2_journal_abort(journal, err);
 793         }
 794
 795         blk_finish_plug(&plug);
 796
 797         /* Lo and behold: we have just managed to send a transaction to
 798            the log.  Before we can commit it, wait for the IO so far to
 799            complete.  Control buffers being written are on the
 800            transaction's t_log_list queue, and metadata buffers are on
 801            the io_bufs list.
 802
 803            Wait for the buffers in reverse order.  That way we are
 804            less likely to be woken up until all IOs have completed, and
 805            so we incur less scheduling load.
 806         */
 807
 808         jbd2_debug(3, "JBD2: commit phase 3\n");
 809
 810         while (!list_empty(&io_bufs)) {
 811                 struct buffer_head *bh = list_entry(io_bufs.prev,
 812                                                     struct buffer_head,
 813                                                     b_assoc_buffers);
 814
 815                 wait_on_buffer(bh);
 816                 cond_resched();
 817
 818                 if (unlikely(!buffer_uptodate(bh)))
 819                         err = -EIO;
 820                 jbd2_unfile_log_bh(bh);
 821                 stats.run.rs_blocks_logged++;
 822
 823                 /*
 824                  * The list contains temporary buffer heads created by
 825                  * jbd2_journal_write_metadata_buffer().
 826                  */
 827                 BUFFER_TRACE(bh, "dumping temporary bh");
 828                 __brelse(bh);
 829                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 830                 free_buffer_head(bh);
 831
 832                 /* We also have to refile the corresponding shadowed buffer */
 833                 jh = commit_transaction->t_shadow_list->b_tprev;
 834                 bh = jh2bh(jh);
 835                 clear_buffer_jwrite(bh);
 836                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
 837                 J_ASSERT_BH(bh, !buffer_shadow(bh));
 838
 839                 /* The metadata is now released for reuse, but we need
 840                    to remember it against this transaction so that when
 841                    we finally commit, we can do any checkpointing
 842                    required. */
 843                 JBUFFER_TRACE(jh, "file as BJ_Forget");
 844                 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 845                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
 846                 __brelse(bh);
 847         }
 848
 849         J_ASSERT (commit_transaction->t_shadow_list == NULL);
 850
 851         jbd2_debug(3, "JBD2: commit phase 4\n");
 852
 853         /* Here we wait for the revoke record and descriptor record buffers */
 854         while (!list_empty(&log_bufs)) {
 855                 struct buffer_head *bh;
 856
 857                 bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 858                 wait_on_buffer(bh);
 859                 cond_resched();
 860
 861                 if (unlikely(!buffer_uptodate(bh)))
 862                         err = -EIO;
 863
 864                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 865                 clear_buffer_jwrite(bh);
 866                 jbd2_unfile_log_bh(bh);
 867                 stats.run.rs_blocks_logged++;
 868                 __brelse(bh);           /* One for getblk */
 869                 /* AKPM: bforget here */
 870         }
 871
 872         if (err)
 873                 jbd2_journal_abort(journal, err);
 874
 875         jbd2_debug(3, "JBD2: commit phase 5\n");
 876         write_lock(&journal->j_state_lock);
 877         J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 878         commit_transaction->t_state = T_COMMIT_JFLUSH;
 879         write_unlock(&journal->j_state_lock);
 880
 881         if (!jbd2_has_feature_async_commit(journal)) {
 882                 err = journal_submit_commit_record(journal, commit_transaction,
 883                                                 &cbh, crc32_sum);
 884                 if (err)
 885                         jbd2_journal_abort(journal, err);
 886         }
 887         if (cbh)
 888                 err = journal_wait_on_commit_record(journal, cbh);
 889         stats.run.rs_blocks_logged++;
 890         if (jbd2_has_feature_async_commit(journal) &&
 891             journal->j_flags & JBD2_BARRIER) {
 892                 blkdev_issue_flush(journal->j_dev);
 893         }
 894
 895         if (err)
 896                 jbd2_journal_abort(journal, err);
 897
 898         WARN_ON_ONCE(
 899                 atomic_read(&commit_transaction->t_outstanding_credits) < 0);
 900
 901         /*
 902          * Now disk caches for filesystem device are flushed so we are safe to
 903          * erase checkpointed transactions from the log by updating journal
 904          * superblock.
 905          */
 906         if (update_tail)
 907                 jbd2_update_log_tail(journal, first_tid, first_block);
 908
 909         /* End of a transaction!  Finally, we can do checkpoint
 910            processing: any buffers committed as a result of this
 911            transaction can be removed from any checkpoint list it was on
 912            before. */
 913
 914         jbd2_debug(3, "JBD2: commit phase 6\n");
 915
 916         J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 917         J_ASSERT(commit_transaction->t_buffers == NULL);
 918         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 919         J_ASSERT(commit_transaction->t_shadow_list == NULL);
 920
 921 restart_loop:
 922         /*
 923          * As there are other places (journal_unmap_buffer()) adding buffers
 924          * to this list we have to be careful and hold the j_list_lock.
 925          */
 926         spin_lock(&journal->j_list_lock);
 927         while (commit_transaction->t_forget) {
 928                 transaction_t *cp_transaction;
 929                 struct buffer_head *bh;
 930                 int try_to_free = 0;
 931                 bool drop_ref;
 932
 933                 jh = commit_transaction->t_forget;
 934                 spin_unlock(&journal->j_list_lock);
 935                 bh = jh2bh(jh);
 936                 /*
 937                  * Get a reference so that bh cannot be freed before we are
 938                  * done with it.
 939                  */
 940                 get_bh(bh);
 941                 spin_lock(&jh->b_state_lock);
 942                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 943
 944                 /*
 945                  * If there is undo-protected committed data against
 946                  * this buffer, then we can remove it now.  If it is a
 947                  * buffer needing such protection, the old frozen_data
 948                  * field now points to a committed version of the
 949                  * buffer, so rotate that field to the new committed
 950                  * data.
 951                  *
 952                  * Otherwise, we can just throw away the frozen data now.
 953                  *
 954                  * We also know that the frozen data has already fired
 955                  * its triggers if they exist, so we can clear that too.
 956                  */
 957                 if (jh->b_committed_data) {
 958                         jbd2_free(jh->b_committed_data, bh->b_size);
 959                         jh->b_committed_data = NULL;
 960                         if (jh->b_frozen_data) {
 961                                 jh->b_committed_data = jh->b_frozen_data;
 962                                 jh->b_frozen_data = NULL;
 963                                 jh->b_frozen_triggers = NULL;
 964                         }
 965                 } else if (jh->b_frozen_data) {
 966                         jbd2_free(jh->b_frozen_data, bh->b_size);
 967                         jh->b_frozen_data = NULL;
 968                         jh->b_frozen_triggers = NULL;
 969                 }
 970
 971                 spin_lock(&journal->j_list_lock);
 972                 cp_transaction = jh->b_cp_transaction;
 973                 if (cp_transaction) {
 974                         JBUFFER_TRACE(jh, "remove from old cp transaction");
 975                         cp_transaction->t_chp_stats.cs_dropped++;
 976                         __jbd2_journal_remove_checkpoint(jh);
 977                 }
 978
 979                 /* Only re-checkpoint the buffer_head if it is marked
 980                  * dirty.  If the buffer was added to the BJ_Forget list
 981                  * by jbd2_journal_forget, it may no longer be dirty and
 982                  * there's no point in keeping a checkpoint record for
 983                  * it. */
 984
 985                 /*
 986                  * A buffer which has been freed while still being journaled
 987                  * by a previous transaction, refile the buffer to BJ_Forget of
 988                  * the running transaction. If the just committed transaction
 989                  * contains "add to orphan" operation, we can completely
 990                  * invalidate the buffer now. We are rather through in that
 991                  * since the buffer may be still accessible when blocksize <
 992                  * pagesize and it is attached to the last partial page.
 993                  */
 994                 if (buffer_freed(bh) && !jh->b_next_transaction) {
 995                         struct address_space *mapping;
 996
 997                         clear_buffer_freed(bh);
 998                         clear_buffer_jbddirty(bh);
 999
1000                         /*
1001                          * Block device buffers need to stay mapped all the
1002                          * time, so it is enough to clear buffer_jbddirty and
1003                          * buffer_freed bits. For the file mapping buffers (i.e.
1004                          * journalled data) we need to unmap buffer and clear
1005                          * more bits. We also need to be careful about the check
1006                          * because the data page mapping can get cleared under
1007                          * our hands. Note that if mapping == NULL, we don't
1008                          * need to make buffer unmapped because the page is
1009                          * already detached from the mapping and buffers cannot
1010                          * get reused.
1011                          */
1012                         mapping = READ_ONCE(bh->b_folio->mapping);
1013                         if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {
1014                                 clear_buffer_mapped(bh);
1015                                 clear_buffer_new(bh);
1016                                 clear_buffer_req(bh);
1017                                 bh->b_bdev = NULL;
1018                         }
1019                 }
1020
1021                 if (buffer_jbddirty(bh)) {
1022                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
1023                         __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1024                         if (is_journal_aborted(journal))
1025                                 clear_buffer_jbddirty(bh);
1026                 } else {
1027                         J_ASSERT_BH(bh, !buffer_dirty(bh));
1028                         /*
1029                          * The buffer on BJ_Forget list and not jbddirty means
1030                          * it has been freed by this transaction and hence it
1031                          * could not have been reallocated until this
1032                          * transaction has committed. *BUT* it could be
1033                          * reallocated once we have written all the data to
1034                          * disk and before we process the buffer on BJ_Forget
1035                          * list.
1036                          */
1037                         if (!jh->b_next_transaction)
1038                                 try_to_free = 1;
1039                 }
1040                 JBUFFER_TRACE(jh, "refile or unfile buffer");
1041                 drop_ref = __jbd2_journal_refile_buffer(jh);
1042                 spin_unlock(&jh->b_state_lock);
1043                 if (drop_ref)
1044                         jbd2_journal_put_journal_head(jh);
1045                 if (try_to_free)
1046                         release_buffer_page(bh);        /* Drops bh reference */
1047                 else
1048                         __brelse(bh);
1049                 cond_resched_lock(&journal->j_list_lock);
1050         }
1051         spin_unlock(&journal->j_list_lock);
1052         /*
1053          * This is a bit sleazy.  We use j_list_lock to protect transition
1054          * of a transaction into T_FINISHED state and calling
1055          * __jbd2_journal_drop_transaction(). Otherwise we could race with
1056          * other checkpointing code processing the transaction...
1057          */
1058         write_lock(&journal->j_state_lock);
1059         spin_lock(&journal->j_list_lock);
1060         /*
1061          * Now recheck if some buffers did not get attached to the transaction
1062          * while the lock was dropped...
1063          */
1064         if (commit_transaction->t_forget) {
1065                 spin_unlock(&journal->j_list_lock);
1066                 write_unlock(&journal->j_state_lock);
1067                 goto restart_loop;
1068         }
1069
1070         /* Add the transaction to the checkpoint list
1071          * __journal_remove_checkpoint() can not destroy transaction
1072          * under us because it is not marked as T_FINISHED yet */
1073         if (journal->j_checkpoint_transactions == NULL) {
1074                 journal->j_checkpoint_transactions = commit_transaction;
1075                 commit_transaction->t_cpnext = commit_transaction;
1076                 commit_transaction->t_cpprev = commit_transaction;
1077         } else {
1078                 commit_transaction->t_cpnext =
1079                         journal->j_checkpoint_transactions;
1080                 commit_transaction->t_cpprev =
1081                         commit_transaction->t_cpnext->t_cpprev;
1082                 commit_transaction->t_cpnext->t_cpprev =
1083                         commit_transaction;
1084                 commit_transaction->t_cpprev->t_cpnext =
1085                                 commit_transaction;
1086         }
1087         spin_unlock(&journal->j_list_lock);
1088
1089         /* Done with this transaction! */
1090
1091         jbd2_debug(3, "JBD2: commit phase 7\n");
1092
1093         J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1094
1095         commit_transaction->t_start = jiffies;
1096         stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1097                                               commit_transaction->t_start);
1098
1099         /*
1100          * File the transaction statistics
1101          */
1102         stats.ts_tid = commit_transaction->t_tid;
1103         stats.run.rs_handle_count =
1104                 atomic_read(&commit_transaction->t_handle_count);
1105         trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1106                              commit_transaction->t_tid, &stats.run);
1107         stats.ts_requested = (commit_transaction->t_requested) ? 1 : 0;
1108
1109         commit_transaction->t_state = T_COMMIT_CALLBACK;
1110         J_ASSERT(commit_transaction == journal->j_committing_transaction);
1111         journal->j_commit_sequence = commit_transaction->t_tid;
1112         journal->j_committing_transaction = NULL;
1113         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1114
1115         /*
1116          * weight the commit time higher than the average time so we don't
1117          * react too strongly to vast changes in the commit time
1118          */
1119         if (likely(journal->j_average_commit_time))
1120                 journal->j_average_commit_time = (commit_time +
1121                                 journal->j_average_commit_time*3) / 4;
1122         else
1123                 journal->j_average_commit_time = commit_time;
1124
1125         write_unlock(&journal->j_state_lock);
1126
1127         if (journal->j_commit_callback)
1128                 journal->j_commit_callback(journal, commit_transaction);
1129         if (journal->j_fc_cleanup_callback)
1130                 journal->j_fc_cleanup_callback(journal, 1, commit_transaction->t_tid);
1131
1132         trace_jbd2_end_commit(journal, commit_transaction);
1133         jbd2_debug(1, "JBD2: commit %d complete, head %d\n",
1134                   journal->j_commit_sequence, journal->j_tail_sequence);
1135
1136         write_lock(&journal->j_state_lock);
1137         journal->j_flags &= ~JBD2_FULL_COMMIT_ONGOING;
1138         journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
1139         spin_lock(&journal->j_list_lock);
1140         commit_transaction->t_state = T_FINISHED;
1141         /* Check if the transaction can be dropped now that we are finished */
1142         if (commit_transaction->t_checkpoint_list == NULL) {
1143                 __jbd2_journal_drop_transaction(journal, commit_transaction);
1144                 jbd2_journal_free_transaction(commit_transaction);
1145         }
1146         spin_unlock(&journal->j_list_lock);
1147         write_unlock(&journal->j_state_lock);
1148         wake_up(&journal->j_wait_done_commit);
1149         wake_up(&journal->j_fc_wait);
1150
1151         /*
1152          * Calculate overall stats
1153          */
1154         spin_lock(&journal->j_history_lock);
1155         journal->j_stats.ts_tid++;
1156         journal->j_stats.ts_requested += stats.ts_requested;
1157         journal->j_stats.run.rs_wait += stats.run.rs_wait;
1158         journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1159         journal->j_stats.run.rs_running += stats.run.rs_running;
1160         journal->j_stats.run.rs_locked += stats.run.rs_locked;
1161         journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1162         journal->j_stats.run.rs_logging += stats.run.rs_logging;
1163         journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1164         journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1165         journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1166         spin_unlock(&journal->j_history_lock);
1167 }