ext4: check ext4_journal_get_write_access() errors

Check ext4_journal_get_write_access() errors.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: adilger@clusterfs.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mingming Cao <cmm@us.ibm.com>

fs/ext4/namei.c

@@ -57,10 +57,15 @@ static struct buffer_head *ext4_append(handle_t *handle,
 
 	*block = inode->i_size >> inode->i_sb->s_blocksize_bits;
 
-	if ((bh = ext4_bread(handle, inode, *block, 1, err))) {
+	bh = ext4_bread(handle, inode, *block, 1, err);
+	if (bh) {
 		inode->i_size += inode->i_sb->s_blocksize;
 		EXT4_I(inode)->i_disksize = inode->i_size;
-		ext4_journal_get_write_access(handle,bh);
+		*err = ext4_journal_get_write_access(handle, bh);
+		if (*err) {
+			brelse(bh);
+			bh = NULL;
+		}
 	}
 	return bh;
 }