[3.13.y.z extended stable] Patch "quota: missing lock in dqcache_shrink_scan()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    quota: missing lock in dqcache_shrink_scan()

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 3069e57332886020c571339904e20f1affcaab0c Mon Sep 17 00:00:00 2001
From: Niu Yawei <yawei.niu at gmail.com>
Date: Wed, 4 Jun 2014 12:22:13 +0800
Subject: quota: missing lock in dqcache_shrink_scan()

commit d68aab6b8f572406aa93b45ef6483934dd3b54a6 upstream.

Commit 1ab6c4997e04 (fs: convert fs shrinkers to new scan/count API)
accidentally removed locking from quota shrinker. Fix it -
dqcache_shrink_scan() should use dq_list_lock to protect the
scan on free_dquots list.

Fixes: 1ab6c4997e04a00c50c6d786c2f046adc0d1f5de
Signed-off-by: Niu Yawei <yawei.niu at intel.com>
Signed-off-by: Jan Kara <jack at suse.cz>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/quota/dquot.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index cfc8dcc..ce87c90 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -702,6 +702,7 @@ dqcache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 	struct dquot *dquot;
 	unsigned long freed = 0;

+	spin_lock(&dq_list_lock);
 	head = free_dquots.prev;
 	while (head != &free_dquots && sc->nr_to_scan) {
 		dquot = list_entry(head, struct dquot, dq_free);
@@ -713,6 +714,7 @@ dqcache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 		freed++;
 		head = free_dquots.prev;
 	}
+	spin_unlock(&dq_list_lock);
 	return freed;
 }

--
1.9.1