ext3: fix hang on umount with quotas when journal is aborted

Call dquot_drop() from ext3_dquot_drop() even if we fail to start a
transaction.  Otherwise we never get to dropping references to quota
structures from the inode and umount will hang indefinitely.  Thanks to
Payphone LIOU for spotting the problem.
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Payphone LIOU <lioupayphone@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ext3/super.c

@@ -2639,8 +2639,14 @@ static int ext3_dquot_drop(struct inode *inode)
 
 	/* We may delete quota structure so we need to reserve enough blocks */
 	handle = ext3_journal_start(inode, 2*EXT3_QUOTA_DEL_BLOCKS(inode->i_sb));
-	if (IS_ERR(handle))
+	if (IS_ERR(handle)) {
+		/*
+		 * We call dquot_drop() anyway to at least release references
+		 * to quota structures so that umount does not hang.
+		 */
+		dquot_drop(inode);
 		return PTR_ERR(handle);
+	}
 	ret = dquot_drop(inode);
 	err = ext3_journal_stop(handle);
 	if (!ret)