mirror of
https://github.com/FEX-Emu/linux.git
synced 2024-12-17 06:17:35 +00:00
jbd: fix fsync() tid wraparound bug
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). CC: stable@kernel.org Reported-by: Martin_Zielinski@McAfee.com Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
parent
86c4f6d855
commit
d9b01934d5
@ -437,9 +437,12 @@ 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 wakeup the
|
||||
* commit thread. We do _not_ do the commit ourselves.
|
||||
@ -451,7 +454,14 @@ 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;
|
||||
}
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user