Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 47/76] jbd2: fix FS corruption possibility in jbd2_journal_destroy() on umount path | Date | Sun, 10 Apr 2016 11:36:55 -0700 |
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3.14-stable review patch. If anyone has any objections, please let me know.
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From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
commit c0a2ad9b50dd80eeccd73d9ff962234590d5ec93 upstream.
On umount path, jbd2_journal_destroy() writes latest transaction ID (->j_tail_sequence) to be used at next mount.
The bug is that ->j_tail_sequence is not holding latest transaction ID in some cases. So, at next mount, there is chance to conflict with remaining (not overwritten yet) transactions.
mount (id=10) write transaction (id=11) write transaction (id=12) umount (id=10) <= the bug doesn't write latest ID
mount (id=10) write transaction (id=11) crash
mount [recovery process] transaction (id=11) transaction (id=12) <= valid transaction ID, but old commit must not replay
Like above, this bug become the cause of recovery failure, or FS corruption.
So why ->j_tail_sequence doesn't point latest ID?
Because if checkpoint transactions was reclaimed by memory pressure (i.e. bdev_try_to_free_page()), then ->j_tail_sequence is not updated. (And another case is, __jbd2_journal_clean_checkpoint_list() is called with empty transaction.)
So in above cases, ->j_tail_sequence is not pointing latest transaction ID at umount path. Plus, REQ_FLUSH for checkpoint is not done too.
So, to fix this problem with minimum changes, this patch updates ->j_tail_sequence, and issue REQ_FLUSH. (With more complex changes, some optimizations would be possible to avoid unnecessary REQ_FLUSH for example though.)
BTW,
journal->j_tail_sequence = ++journal->j_transaction_sequence;
Increment of ->j_transaction_sequence seems to be unnecessary, but ext3 does this.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/jbd2/journal.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
--- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1423,11 +1423,12 @@ out: /** * jbd2_mark_journal_empty() - Mark on disk journal as empty. * @journal: The journal to update. + * @write_op: With which operation should we write the journal sb * * Update a journal's dynamic superblock fields to show that journal is empty. * Write updated superblock to disk waiting for IO to complete. */ -static void jbd2_mark_journal_empty(journal_t *journal) +static void jbd2_mark_journal_empty(journal_t *journal, int write_op) { journal_superblock_t *sb = journal->j_superblock; @@ -1445,7 +1446,7 @@ static void jbd2_mark_journal_empty(jour sb->s_start = cpu_to_be32(0); read_unlock(&journal->j_state_lock); - jbd2_write_superblock(journal, WRITE_FUA); + jbd2_write_superblock(journal, write_op); /* Log is no longer empty */ write_lock(&journal->j_state_lock); @@ -1730,7 +1731,13 @@ int jbd2_journal_destroy(journal_t *jour if (journal->j_sb_buffer) { if (!is_journal_aborted(journal)) { mutex_lock(&journal->j_checkpoint_mutex); - jbd2_mark_journal_empty(journal); + + write_lock(&journal->j_state_lock); + journal->j_tail_sequence = + ++journal->j_transaction_sequence; + write_unlock(&journal->j_state_lock); + + jbd2_mark_journal_empty(journal, WRITE_FLUSH_FUA); mutex_unlock(&journal->j_checkpoint_mutex); } else err = -EIO; @@ -1991,7 +1998,7 @@ int jbd2_journal_flush(journal_t *journa * the magic code for a fully-recovered superblock. Any future * commits of data to the journal will restore the current * s_start value. */ - jbd2_mark_journal_empty(journal); + jbd2_mark_journal_empty(journal, WRITE_FUA); mutex_unlock(&journal->j_checkpoint_mutex); write_lock(&journal->j_state_lock); J_ASSERT(!journal->j_running_transaction); @@ -2037,7 +2044,7 @@ int jbd2_journal_wipe(journal_t *journal if (write) { /* Lock to make assertions happy... */ mutex_lock(&journal->j_checkpoint_mutex); - jbd2_mark_journal_empty(journal); + jbd2_mark_journal_empty(journal, WRITE_FUA); mutex_unlock(&journal->j_checkpoint_mutex); }
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