reiserfs: Protect reiserfs_quota_on() with write lock

In reiserfs_quota_on() we do quite some work - for example unpacking
tail of a quota file. Thus we have to hold write lock until a moment
we call back into the quota code.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 5372980ec458..e59d6ddcc69f 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -2216,8 +2216,11 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
         struct reiserfs_transaction_handle th;
         int opt = type == USRQUOTA ? REISERFS_USRQUOTA : REISERFS_GRPQUOTA;
 
-        if (!(REISERFS_SB(sb)->s_mount_opt & (1 << opt)))
-                return -EINVAL;
+        reiserfs_write_lock(sb);
+        if (!(REISERFS_SB(sb)->s_mount_opt & (1 << opt))) {
+                err = -EINVAL;
+                goto out;
+        }
 
         /* Quotafile not on the same filesystem? */
         if (path->dentry->d_sb != sb) {
@@ -2259,8 +2262,10 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
                 if (err)
                         goto out;
         }
-        err = dquot_quota_on(sb, type, format_id, path);
+        reiserfs_write_unlock(sb);
+        return dquot_quota_on(sb, type, format_id, path);
 out:
+        reiserfs_write_unlock(sb);
         return err;
 }