Btrfs: check return value of kmalloc()

The check on the return value of kmalloc() is added to some places.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/extent-tree.c

@@ -8059,6 +8059,10 @@ static noinline int relocate_one_extent(struct btrfs_root *extent_root,
 				u64 group_start = group->key.objectid;
 				new_extents = kmalloc(sizeof(*new_extents),
 						      GFP_NOFS);
+				if (!new_extents) {
+					ret = -ENOMEM;
+					goto out;
+				}
 				nr_extents = 1;
 				ret = get_new_locations(reloc_inode,
 							extent_key,