2.6.32-longterm review patch. If anyone has any objections, please let us know.
------------------ From: Ted Ts'o <[email protected]> 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: [email protected] Signed-off-by: "Theodore Ts'o" <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/jbd/journal.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- 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 *journa 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; } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
