btrfs: send: use vmalloc only as fallback for clone_roots

Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/send.c

@@ -6053,11 +6053,14 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 
 	alloc_size = sizeof(struct clone_root) * (arg->clone_sources_count + 1);
 
+	sctx->clone_roots = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN);
+	if (!sctx->clone_roots) {
 		sctx->clone_roots = vzalloc(alloc_size);
 		if (!sctx->clone_roots) {
 			ret = -ENOMEM;
 			goto out;
 		}
+	}
 
 	alloc_size = arg->clone_sources_count * sizeof(*arg->clone_sources);
 
@@ -6227,7 +6230,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 		if (sctx->send_filp)
 			fput(sctx->send_filp);
 
-		vfree(sctx->clone_roots);
+		kvfree(sctx->clone_roots);
 		kvfree(sctx->send_buf);
 		kvfree(sctx->read_buf);