ext4: fix oops in ext4_quota_off()

If quota is not enabled when ext4_quota_off() is called, we must not
dereference quota file inode since it is NULL.  Check properly for
this.

This fixes a bug in commit 21f976975cbe (ext4: remove unnecessary
[cm]time update of quota file), which was merged for 2.6.39-rc3.

Reported-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index fc827bb2a69b..268935118251 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4681,6 +4681,9 @@ static int ext4_quota_off(struct super_block *sb, int type)
         if (test_opt(sb, DELALLOC))
                 sync_filesystem(sb);
 
+        if (!inode)
+                goto out;
+
         /* Update modification times of quota files when userspace can
          * start looking at them */
         handle = ext4_journal_start(inode, 1);