ext4: disable synchronous transaction batching if max_batch_time==0

commit 5dd214248f94d430d70e9230bda72f2654ac88a8 upstream.

The mount manpage says of the max_batch_time option,

	This optimization can be turned off entirely
	by setting max_batch_time to 0.

But the code doesn't do that.  So fix the code to do
that.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 3.2: option parsing looks different]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e32ee5c..6581ee7 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1663,8 +1663,6 @@ static int parse_options(char *options, struct super_block *sb,
                                return 0;
                        if (option < 0)
                                return 0;
-                       if (option == 0)
-                               option = EXT4_DEF_MAX_BATCH_TIME;
                        sbi->s_max_batch_time = option;
                        break;
                case Opt_min_batch_time:

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 18ea4d9..86dc68a 100644 (file)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1388,9 +1388,12 @@ int jbd2_journal_stop(handle_t *handle)
         * to perform a synchronous write.  We do this to detect the
         * case where a single process is doing a stream of sync
         * writes.  No point in waiting for joiners in that case.
+        *
+        * Setting max_batch_time to 0 disables this completely.
         */
        pid = current->pid;
-       if (handle->h_sync && journal->j_last_sync_writer != pid) {
+       if (handle->h_sync && journal->j_last_sync_writer != pid &&
+           journal->j_max_batch_time) {
                u64 commit_time, trans_time;
 
                journal->j_last_sync_writer = pid;