Btrfs: Fix space checking during fs resize

Fix out-of-space checking, addressing a warning and potential resource
leak when resizing the filesystem down while allocating blocks.
Signed-off-by: NDaniel J Blueman <daniel@quora.org>
Reviewed-by: NJosef Bacik <josef@redhat.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

fs/btrfs/relocation.c

@@ -3813,7 +3813,7 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 
 		ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
 		if (ret < 0) {
-			if (ret != -EAGAIN) {
+			if (ret != -ENOSPC) {
 				err = ret;
 				WARN_ON(1);
 				break;