Ext2: free memory allocated and forget buffer head when io error happens

Add a necessary check when an io error happens.
If io error happens,free the memory allocated and forget
buffer head.
Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext2/inode.c

@@ -495,6 +495,10 @@ static int ext2_alloc_branch(struct inode *inode,
 		 * parent to disk.
 		 */
 		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
+		if (unlikely(!bh)) {
+			err = -ENOMEM;
+			goto failed;
+		}
 		branch[n].bh = bh;
 		lock_buffer(bh);
 		memset(bh->b_data, 0, blocksize);
@@ -523,6 +527,14 @@ static int ext2_alloc_branch(struct inode *inode,
 	}
 	*blks = num;
 	return err;
+
+failed:
+	for (i = 1; i < n; i++)
+		bforget(branch[i].bh);
+	for (i = 0; i < indirect_blks; i++)
+		ext2_free_blocks(inode, new_blocks[i], 1);
+	ext2_free_blocks(inode, new_blocks[i], num);
+	return err;
 }
 
 /**