[PATCH 3.2 27/94] ext4: disable synchronous transaction batching if max_batch_time==0

From: Ben Hutchings
Date: Mon Aug 04 2014 - 12:56:57 EST


3.2.62-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Eric Sandeen <sandeen@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
[bwh: Backported to 3.2: option parsing looks different]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/ext4/super.c | 2 --
fs/jbd2/transaction.c | 5 ++++-
2 files changed, 4 insertions(+), 3 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1663,8 +1663,6 @@ static int parse_options(char *options,
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:
--- 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;

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