From a2d139c0d9fe7fbcbc35877fdfb707729a231439 Mon Sep 17 00:00:00 2001
From: Gang He <ghe@suse.com>
Date: Wed, 23 Sep 2020 18:27:56 +0800
Subject: [PATCH] ocfs2: give applications more IO opportunities during fstrim
Patch-mainline: Never, workaround to lock handoff problem
References: bsc#1175228
When we discard unused blocks on a mounted ocfs2 filesystem, fstrim
lock/unlock global bitmap meta-file repeatedly. we should let fstrim
thread take a break between unlock and lock, this will give the upper
applications more IO opportunities, then these applications are not
blocked for too long at writing files.
Mutex lock handoff is not implemented in old kernels, this patch is
a solution in this situation.
Signed-off-by: Gang He <ghe@suse.com>
---
fs/ocfs2/alloc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 4c1b90442d6f..113f07c2453d 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -17,6 +17,7 @@
#include <linux/quotaops.h>
#include <linux/blkdev.h>
#include <linux/sched/signal.h>
+#include <linux/delay.h>
#include <cluster/masklog.h>
@@ -7654,8 +7655,11 @@ int ocfs2_trim_mainbm(struct super_block *sb, struct fstrim_range *range)
* main_bm related locks for avoiding the current IO starve, then go to
* trim the next group
*/
- if (ret >= 0 && group <= last_group)
+ if (ret >= 0 && group <= last_group) {
+ /* Take a break for avoiding write IO starvation */
+ usleep_range(5000, 6000);
goto next_group;
+ }
out:
range->len = trimmed * sb->s_blocksize;
return ret;
--
2.21.0