From 4b386fb672a366ec2fe2929da01caf71dde172d0 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Mon, 17 Feb 2014 17:30:03 +0100 Subject: [PATCH 202/365] 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 --- fs/jbd2/checkpoint.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c index addb0784dd1c..bd8ab9c28869 100644 --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -116,6 +116,8 @@ void __jbd2_log_wait_for_space(journal_t *journal) 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); /* -- 2.28.0