ext4: fix ext4_da_write_begin error path

ext4_da_write_begin needs to call journal_stop before returning,
if the page allocation fails.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Acked-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -2280,8 +2280,11 @@ static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
 	}
 
 	page = __grab_cache_page(mapping, index);
-	if (!page)
-		return -ENOMEM;
+	if (!page) {
+		ext4_journal_stop(handle);
+		ret = -ENOMEM;
+		goto out;
+	}
 	*pagep = page;
 
 	ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,