quota: protect Q_GETFMT by dqonoff_mutex

dqptr_sem will go away. Protect Q_GETFMT quotactl by
dqonoff_mutex instead. This is also enough to make sure
quota info will not go away while we are looking at it.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index ff3f0b3cfdb3..75621649dbd7 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -79,13 +79,13 @@ static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
 {
         __u32 fmt;
 
-        down_read(&sb_dqopt(sb)->dqptr_sem);
+        mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
         if (!sb_has_quota_active(sb, type)) {
-                up_read(&sb_dqopt(sb)->dqptr_sem);
+                mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
                 return -ESRCH;
         }
         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
-        up_read(&sb_dqopt(sb)->dqptr_sem);
+        mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
         if (copy_to_user(addr, &fmt, sizeof(fmt)))
                 return -EFAULT;
         return 0;