[PATCH 3.15 026/109] quota: missing lock in dqcache_shrink_scan()

Greg Kroah-Hartman
2014-07-26T19:37:58Z

From: Niu Yawei <yawei.niu@gmail.com>

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>

---
fs/quota/dquot.c | 2 ++
1 file changed, 2 insertions(+)

--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -702,6 +702,7 @@ dqcache_shrink_scan(struct shrinker *shr
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 *shr
freed++;
head = free_dquots.prev;
}
+ spin_unlock(&dq_list_lock);
return freed;
}