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jbd2: ensure abort the journal if detect IO error when writing original buffer back

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Although we merged c044f3d836 ("jbd2: abort journal if free a async
write error metadata buffer"), there is a race between
jbd2_journal_try_to_free_buffers() and jbd2_journal_destroy(), so the
jbd2_log_do_checkpoint() may still fail to detect the buffer write
io error flag which may lead to filesystem inconsistency.

jbd2_journal_try_to_free_buffers()     ext4_put_super()
                                        jbd2_journal_destroy()
  __jbd2_journal_remove_checkpoint()
  detect buffer write error              jbd2_log_do_checkpoint()
                                         jbd2_cleanup_journal_tail()
                                           <--- lead to inconsistency
  jbd2_journal_abort()

Fix this issue by introducing a new atomic flag which only have one
JBD2_CHECKPOINT_IO_ERROR bit now, and set it in
__jbd2_journal_remove_checkpoint() when freeing a checkpoint buffer
which has write_io_error flag. Then jbd2_journal_destroy() will detect
this mark and abort the journal to prevent updating log tail.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210610112440.3438139-3-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi 2021-06-10 19:24:34 +08:00 committed by Theodore Ts'o
parent 1866cba842
commit fcf37549ae
3 changed files with 37 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
fs/jbd2/checkpoint.c
View file

@ -564,6 +564,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
struct transaction_chp_stats_s *stats;
transaction_t *transaction;
journal_t *journal;
struct buffer_head *bh = jh2bh(jh);
JBUFFER_TRACE(jh, "entry");
@ -575,6 +576,17 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
journal = transaction->t_journal;
JBUFFER_TRACE(jh, "removing from transaction");
/*
* If we have failed to write the buffer out to disk, the filesystem
* may become inconsistent. We cannot abort the journal here since
* we hold j_list_lock and we have to be careful about races with
* jbd2_journal_destroy(). So mark the writeback IO error in the
* journal here and we abort the journal later from a better context.
*/
if (buffer_write_io_error(bh))
set_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags);
__buffer_unlink(jh);
jh->b_cp_transaction = NULL;
jbd2_journal_put_journal_head(jh);

14
fs/jbd2/journal.c
View file

@ -1610,6 +1610,10 @@ int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
if (is_journal_aborted(journal))
return -EIO;
if (test_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags)) {
jbd2_journal_abort(journal, -EIO);
return -EIO;
}
BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
@ -2091,6 +2095,16 @@ int jbd2_journal_destroy(journal_t *journal)
J_ASSERT(journal->j_checkpoint_transactions == NULL);
spin_unlock(&journal->j_list_lock);
/*
* OK, all checkpoint transactions have been checked, now check the
* write out io error flag and abort the journal if some buffer failed
* to write back to the original location, otherwise the filesystem
* may become inconsistent.
*/
if (!is_journal_aborted(journal) &&
test_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags))
jbd2_journal_abort(journal, -EIO);
if (journal->j_sb_buffer) {
if (!is_journal_aborted(journal)) {
mutex_lock_io(&journal->j_checkpoint_mutex);

11
include/linux/jbd2.h
View file

@ -779,6 +779,11 @@ struct journal_s
*/
unsigned long j_flags;
/**
* @j_atomic_flags: Atomic journaling state flags.
*/
unsigned long j_atomic_flags;
/**
* @j_errno:
*
@ -1375,6 +1380,12 @@ JBD2_FEATURE_INCOMPAT_FUNCS(fast_commit, FAST_COMMIT)
#define JBD2_JOURNAL_FLUSH_VALID (JBD2_JOURNAL_FLUSH_DISCARD | \
JBD2_JOURNAL_FLUSH_ZEROOUT)
/*
* Journal atomic flag definitions
*/
#define JBD2_CHECKPOINT_IO_ERROR 0x001 /* Detect io error while writing
* buffer back to disk */
/*
* Function declarations for the journaling transaction and buffer
* management