From: Niu Yawei <yawei.niu@gmail.com>
Date: Wed, 4 Jun 2014 04:22:13 +0000 (+0800)
Subject: quota: missing lock in dqcache_shrink_scan()
X-Git-Tag: v3.15.7~84
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9b018d7a75a3cd933b01e22c8e722b5d2435520d;p=thirdparty%2Fkernel%2Fstable.git

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@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 9cd5f63715c0e..7f30bdc57d13b 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;
 }