[57/70] ext4: fix oops in ext4_quota_off()

[Greg KH <gregkh@suse.de>]

2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Amir Goldstein <amir73il@gmail.com>

commit 0b26859027ce0005ef89520af20351360e51ad76 upstream.

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>
Cc: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/ext4/super.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4635,6 +4635,9 @@ static int ext4_quota_off(struct super_b
 	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);