btrfs: switch to btrfs_create_{clone,snapshot}()

src/lxc/bdev/bdev.c

@@ -96,8 +96,8 @@ static const struct bdev_ops btrfs_ops = {
     .clone_paths = &btrfs_clonepaths,
     .destroy = &btrfs_destroy,
     .create = &btrfs_create,
-    .create_clone = NULL,
-    .create_snapshot = NULL,
+    .create_clone = &btrfs_create_clone,
+    .create_snapshot = &btrfs_create_snapshot,
     .can_snapshot = true,
     .can_backup = true,
 };
@@ -415,6 +415,8 @@ struct bdev *bdev_copy(struct lxc_container *c0, const char *cname,
 		bdevtype = "dir";
 	else if (!bdevtype)
 		bdevtype = orig->type;
+
+	/* get new bdev type */
 	new = bdev_get(bdevtype);
 	if (!new) {
 		ERROR("no such block device type: %s",
@@ -424,17 +426,24 @@ struct bdev *bdev_copy(struct lxc_container *c0, const char *cname,
 	}
 	TRACE("Detected \"%s\" storage driver", new->type);
 
-	if (bdevtype && !strcmp(orig->type, "btrfs") &&
-	    !strcmp(new->type, "btrfs"))
-		snap = 1;
-
+	/* create new paths */
 	if (new->ops->clone_paths(orig, new, oldname, cname, oldpath, lxcpath,
 				  snap, newsize, c0->lxc_conf) < 0) {
 		ERROR("Failed getting pathnames for clone of \"%s\"", src);
 		goto err;
 	}
 
-	/* If the storage driver is "btrfs" then the we will create snapshot. */
+	if (!strcmp(orig->type, "btrfs") && !strcmp(new->type, "btrfs")) {
+		bool bret = false;
+		if (snap || btrfs_same_fs(orig->dest, new->dest) == 0)
+			bret = new->ops->create_snapshot(c0->lxc_conf, orig, new);
+		else
+			bret = new->ops->create_clone(c0->lxc_conf, orig, new, 0);
+		if (!bret)
+			return NULL;
+		return new;
+	}
+
 	if (strcmp(bdevtype, "btrfs")) {
 		if (!strcmp(new->type, "overlay") ||
 		    !strcmp(new->type, "overlayfs"))

src/lxc/bdev/lxcbtrfs.c

@@ -372,7 +372,6 @@ int btrfs_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
 		     const char *lxcpath, int snap, uint64_t newsize,
 		     struct lxc_conf *conf)
 {
-	int ret;
 	char *src;
 
 	if (!orig->dest || !orig->src)
@@ -393,7 +392,7 @@ int btrfs_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
 		ERROR("Failed to create new rootfs path");
 		return -1;
 	}
-	TRACE("Created new rootfs path \"%s\"", new->src);
+	TRACE("Constructed new rootfs path \"%s\"", new->src);
 
 	src = lxc_storage_get_path(new->src, "btrfs");
 	new->dest = strdup(src);
@@ -411,39 +410,95 @@ int btrfs_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
 		}
 	}
 
-	if (snap) {
-		struct rsync_data_char sdata;
-		if (!am_unpriv()) {
-			ret = btrfs_snapshot(orig->dest, new->dest);
-			if (ret < 0) {
-				SYSERROR("Failed to create btrfs snapshot "
-					 "\"%s\" from \"%s\"",
-					 new->dest, orig->dest);
-				return -1;
-			}
-			TRACE("Created btrfs snapshot \"%s\" from \"%s\"",
-			      new->dest, orig->dest);
-			return 0;
-		}
+	return 0;
+}
 
-		sdata.dest = new->dest;
-		sdata.src = orig->dest;
-		return userns_exec_1(conf, btrfs_snapshot_wrapper, &sdata,
-				     "btrfs_snapshot_wrapper");
-	}
+bool btrfs_create_clone(struct lxc_conf *conf, struct bdev *orig,
+			struct bdev *new, uint64_t newsize)
+{
+	int pid, ret;
+	struct rsync_data data;
 
 	ret = rmdir(new->dest);
-	if (ret < 0 && errno != ENOENT) {
-		SYSERROR("Failed to remove directory \"%s\"", new->dest);
-		return -1;
-	}
+	if (ret < 0 && errno != ENOENT)
+		return false;
 
 	ret = btrfs_subvolume_create(new->dest);
-	if (ret < 0)
+	if (ret < 0) {
 		SYSERROR("Failed to create btrfs subvolume \"%s\"", new->dest);
+		return false;
+	}
+
+	/* rsync contents */
+	pid = fork();
+	if (pid < 0) {
+		SYSERROR("fork");
+		return false;
+	}
+
+	if (pid > 0) {
+		int ret = wait_for_pid(pid);
+		bdev_put(orig);
+		if (ret < 0) {
+			bdev_put(new);
+			return false;
+		}
+		return true;
+	}
+
+	data.orig = orig;
+	data.new = new;
+
+	if (am_unpriv())
+		ret = userns_exec_1(conf, rsync_rootfs_wrapper, &data,
+				    "rsync_rootfs_wrapper");
 	else
-		TRACE("Created btrfs subvolume \"%s\"", new->dest);
-	return ret;
+		ret = rsync_rootfs(&data);
+	if (ret < 0) {
+		ERROR("Failed to rsync");
+		return false;
+	}
+
+	TRACE("Created btrfs subvolume \"%s\"", new->dest);
+	return true;
+}
+
+bool btrfs_create_snapshot(struct lxc_conf *conf, struct bdev *orig,
+			   struct bdev *new)
+{
+	int ret;
+
+	ret = rmdir(new->dest);
+	if (ret < 0 && errno != ENOENT)
+		return false;
+
+	if (am_unpriv()) {
+		struct rsync_data_char args;
+
+		args.src = orig->dest;
+		args.dest = new->dest;
+
+		ret = userns_exec_1(conf, btrfs_snapshot_wrapper, &args,
+				"btrfs_snapshot_wrapper");
+		if (ret < 0) {
+			ERROR("Failed to run \"btrfs_snapshot_wrapper\"");
+			return false;
+		}
+
+		TRACE("Created btrfs snapshot \"%s\" from \"%s\"", new->dest,
+		      orig->dest);
+		return true;
+	}
+
+	ret = btrfs_snapshot(orig->dest, new->dest);
+	if (ret < 0) {
+		SYSERROR("Failed to create btrfs snapshot \"%s\" from \"%s\"",
+			 new->dest, orig->dest);
+		return false;
+	}
+
+	TRACE("Created btrfs snapshot \"%s\" from \"%s\"", new->dest, orig->dest);
+	return true;
 }
 
 static int btrfs_do_destroy_subvol(const char *path)

src/lxc/bdev/lxcbtrfs.h

@@ -413,5 +413,9 @@ bool btrfs_try_remove_subvol(const char *path);
 int btrfs_same_fs(const char *orig, const char *new);
 int btrfs_snapshot(const char *orig, const char *new);
 int btrfs_snapshot_wrapper(void *data);
+bool btrfs_create_clone(struct lxc_conf *conf, struct bdev *orig,
+			struct bdev *new, uint64_t newsize);
+bool btrfs_create_snapshot(struct lxc_conf *conf, struct bdev *orig,
+			   struct bdev *new);
 
 #endif // __LXC_BTRFS_H