Commit fcf37549 authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

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



Although we merged c044f3d8 ("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: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210610112440.3438139-3-yi.zhang@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 1866cba8

fs/jbd2/checkpoint.c

+12 −0
Original line number Diff line number Diff line
@@ -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);

fs/jbd2/journal.c

+14 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/jbd2.h

+11 −0
Original line number Diff line number Diff line
@@ -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