| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Mon, 17 Feb 2014 17:30:03 +0100 |
| Subject: fs: jbd2: pull your plug when waiting for space |
| |
| Two cps in parallel managed to stall the the ext4 fs. It seems that |
| journal code is either waiting for locks or sleeping waiting for |
| something to happen. This seems similar to what Mike observed on ext3, |
| here is his description: |
| |
| |With an -rt kernel, and a heavy sync IO load, tasks can jam |
| |up on journal locks without unplugging, which can lead to |
| |terminal IO starvation. Unplug and schedule when waiting |
| |for space. |
| |
| |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| fs/jbd2/checkpoint.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/fs/jbd2/checkpoint.c |
| +++ b/fs/jbd2/checkpoint.c |
| @@ -116,6 +116,8 @@ void __jbd2_log_wait_for_space(journal_t |
| nblocks = jbd2_space_needed(journal); |
| while (jbd2_log_space_left(journal) < nblocks) { |
| write_unlock(&journal->j_state_lock); |
| + if (current->plug) |
| + io_schedule(); |
| mutex_lock(&journal->j_checkpoint_mutex); |
| |
| /* |
