diff options
| author | Ted Ts'o <tytso@mit.edu> | 2011-04-30 13:17:11 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-06-23 15:28:34 -0700 |
| commit | 46ee272bfb5eb7bdc7f950d770b698e37e4a15a1 (patch) | |
| tree | ce7b2fd8652cad05aca7e2a4ba240a50992dbe7c | |
| parent | d60d3e608149ff8c88070c97f86970d0c1033e5c (diff) | |
jbd: fix fsync() tid wraparound bug
commit d9b01934d56a96d9f4ae2d6204d4ea78a36f5f36 upstream.
If an application program does not make any changes to the indirect
blocks or extent tree, i_datasync_tid will not get updated. If there
are enough commits (i.e., 2**31) such that tid_geq()'s calculations
wrap, and there isn't a currently active transaction at the time of
the fdatasync() call, this can end up triggering a BUG_ON in
fs/jbd/commit.c:
J_ASSERT(journal->j_running_transaction != NULL);
It's pretty rare that this can happen, since it requires the use of
fdatasync() plus *very* frequent and excessive use of fsync(). But
with the right workload, it can.
We fix this by replacing the use of tid_geq() with an equality test,
since there's only one valid transaction id that is valid for us to
start: namely, the currently running transaction (if it exists).
Reported-by: Martin_Zielinski@McAfee.com
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/jbd/journal.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c index bd224eec9b07..45905ff762c9 100644 --- a/fs/jbd/journal.c +++ b/fs/jbd/journal.c @@ -435,9 +435,12 @@ int __log_space_left(journal_t *journal) int __log_start_commit(journal_t *journal, tid_t target) { /* - * Are we already doing a recent enough commit? + * The only transaction we can possibly wait upon is the + * currently running transaction (if it exists). Otherwise, + * the target tid must be an old one. */ - if (!tid_geq(journal->j_commit_request, target)) { + if (journal->j_running_transaction && + journal->j_running_transaction->t_tid == target) { /* * We want a new commit: OK, mark the request and wakup the * commit thread. We do _not_ do the commit ourselves. @@ -449,7 +452,14 @@ int __log_start_commit(journal_t *journal, tid_t target) journal->j_commit_sequence); wake_up(&journal->j_wait_commit); return 1; - } + } else if (!tid_geq(journal->j_commit_request, target)) + /* This should never happen, but if it does, preserve + the evidence before kjournald goes into a loop and + increments j_commit_sequence beyond all recognition. */ + WARN_ONCE(1, "jbd: bad log_start_commit: %u %u %u %u\n", + journal->j_commit_request, journal->j_commit_sequence, + target, journal->j_running_transaction ? + journal->j_running_transaction->t_tid : 0); return 0; } |