storage: make storage_init() smart and simplify

src/lxc/conf.c

@@ -1204,7 +1204,7 @@ static int lxc_setup_rootfs(struct lxc_conf *conf)
 		return -1;
 	}
 
-	bdev = storage_init(conf, rootfs->path, rootfs->mount, rootfs->options);
+	bdev = storage_init(conf);
 	if (!bdev) {
 		ERROR("Failed to mount rootfs \"%s\" onto \"%s\" with options \"%s\".",
 		      rootfs->path, rootfs->mount,

src/lxc/lxccontainer.c

@@ -1250,7 +1250,7 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool need_
 			exit(1);
 		}
 
-		bdev = storage_init(c->lxc_conf, c->lxc_conf->rootfs.path, c->lxc_conf->rootfs.mount, NULL);
+		bdev = storage_init(c->lxc_conf);
 		if (!bdev) {
 			ERROR("Error opening rootfs");
 			exit(1);
@@ -3326,7 +3326,7 @@ static int clone_update_rootfs(struct clone_update_data *data)
 
 	if (unshare(CLONE_NEWNS) < 0)
 		return -1;
-	bdev = storage_init(c->lxc_conf, c->lxc_conf->rootfs.path, c->lxc_conf->rootfs.mount, NULL);
+	bdev = storage_init(c->lxc_conf);
 	if (!bdev)
 		return -1;
 	if (strcmp(bdev->type, "dir") != 0) {
@@ -3657,7 +3657,7 @@ static bool do_lxcapi_rename(struct lxc_container *c, const char *newname)
 		ERROR("Renaming a container with snapshots is not supported");
 		return false;
 	}
-	bdev = storage_init(c->lxc_conf, c->lxc_conf->rootfs.path, c->lxc_conf->rootfs.mount, NULL);
+	bdev = storage_init(c->lxc_conf);
 	if (!bdev) {
 		ERROR("Failed to find original backing store type");
 		return false;
@@ -4007,8 +4007,7 @@ static bool do_lxcapi_snapshot_restore(struct lxc_container *c, const char *snap
 		return false;
 	}
 
-	bdev = storage_init(c->lxc_conf, c->lxc_conf->rootfs.path,
-			    c->lxc_conf->rootfs.mount, NULL);
+	bdev = storage_init(c->lxc_conf);
 	if (!bdev) {
 		ERROR("Failed to find original backing store type");
 		return false;

src/lxc/storage/storage.c

@@ -213,7 +213,7 @@ static const struct lxc_storage_type bdevs[] = {
 
 static const size_t numbdevs = sizeof(bdevs) / sizeof(struct lxc_storage_type);
 
-static const struct lxc_storage_type *get_storage_by_name(const char *name,
+static const struct lxc_storage_type *get_storage_by_name(const char *path,
 							  const char *type)
 {
 	int ret;
@@ -222,7 +222,7 @@ static const struct lxc_storage_type *get_storage_by_name(const char *name,
 	if (type)
 		cmplen = strlen(type);
 	else
-		cmplen = strcspn(name, ":");
+		cmplen = strcspn(path, ":");
 	if (cmplen == 0)
 		return NULL;
 
@@ -230,7 +230,7 @@ static const struct lxc_storage_type *get_storage_by_name(const char *name,
 		if (type)
 			ret = strncmp(bdevs[i].name, type, cmplen);
 		else
-			ret = strncmp(bdevs[i].name, name, cmplen);
+			ret = strncmp(bdevs[i].name, path, cmplen);
 		if (ret == 0)
 			break;
 	}
@@ -242,18 +242,19 @@ static const struct lxc_storage_type *get_storage_by_name(const char *name,
 	return &bdevs[i];
 }
 
-const struct lxc_storage_type *storage_query(struct lxc_conf *conf,
-					     const char *src)
+static const struct lxc_storage_type *storage_query(struct lxc_conf *conf)
 {
 	size_t i;
 	const struct lxc_storage_type *bdev;
+	const char *path = conf->rootfs.path;
+	const char *type = conf->rootfs.bdev_type;
 
-	bdev = get_storage_by_name(src, conf->rootfs.bdev_type);
+	bdev = get_storage_by_name(path, type);
 	if (bdev)
 		return bdev;
 
 	for (i = 0; i < numbdevs; i++)
-		if (bdevs[i].ops->detect(src))
+		if (bdevs[i].ops->detect(path))
 			break;
 
 	if (i == numbdevs)
@@ -316,9 +317,10 @@ static struct lxc_storage *do_storage_create(const char *dest, const char *type,
 
 bool storage_can_backup(struct lxc_conf *conf)
 {
-	struct lxc_storage *bdev = storage_init(conf, NULL, NULL, NULL);
 	bool ret;
+	struct lxc_storage *bdev;
 
+	bdev = storage_init(conf);
 	if (!bdev)
 		return false;
 
@@ -361,7 +363,7 @@ struct lxc_storage *storage_copy(struct lxc_container *c, const char *cname,
 		return NULL;
 	}
 
-	orig = storage_init(c->lxc_conf, src, NULL, NULL);
+	orig = storage_init(c->lxc_conf);
 	if (!orig) {
 		ERROR("Failed to detect storage driver for \"%s\"", src);
 		return NULL;
@@ -597,32 +599,32 @@ bool storage_destroy(struct lxc_conf *conf)
 	struct lxc_storage *r;
 	bool ret = false;
 
-	r = storage_init(conf, conf->rootfs.path, conf->rootfs.mount, NULL);
+	r = storage_init(conf);
 	if (!r)
 		return ret;
 
-	if (r->ops->destroy(r) == 0)
+	ret = r->ops->destroy(r);
+	if (ret == 0)
 		ret = true;
 
 	storage_put(r);
 	return ret;
 }
 
-struct lxc_storage *storage_init(struct lxc_conf *conf, const char *src,
-				 const char *dst, const char *mntopts)
+struct lxc_storage *storage_init(struct lxc_conf *conf)
 {
 	struct lxc_storage *bdev;
 	const struct lxc_storage_type *q;
+	const char *src = conf->rootfs.path;
+	const char *dst = conf->rootfs.mount;
+	const char *mntopts = conf->rootfs.options;
 
 	BUILD_BUG_ON(LXC_STORAGE_INTERNAL_OVERLAY_RESTORE <= LXC_CLONE_MAXFLAGS);
 
 	if (!src)
-		src = conf->rootfs.path;
-
-	if (!src)
 		return NULL;
 
-	q = storage_query(conf, src);
+	q = storage_query(conf);
 	if (!q)
 		return NULL;
 
@@ -631,18 +633,23 @@ struct lxc_storage *storage_init(struct lxc_conf *conf, const char *src,
 		return NULL;
 
 	memset(bdev, 0, sizeof(struct lxc_storage));
+
 	bdev->ops = q->ops;
 	bdev->type = q->name;
+
 	if (mntopts)
 		bdev->mntopts = strdup(mntopts);
+
 	if (src)
 		bdev->src = strdup(src);
+
 	if (dst)
 		bdev->dest = strdup(dst);
+
 	if (strcmp(bdev->type, "nbd") == 0)
 		bdev->nbd_idx = conf->nbd_idx;
 
-	if (!strcmp(bdev->type, "aufs"))
+	if (strcmp(bdev->type, "aufs") == 0)
 		WARN("The \"aufs\" driver will is deprecated and will soon be "
 		     "removed. For similar functionality see the \"overlay\" "
 		     "storage driver");
@@ -659,7 +666,7 @@ bool storage_is_dir(struct lxc_conf *conf)
 	if (type)
 		return (strcmp(type, "dir") == 0);
 
-	orig = storage_init(conf, conf->lxc_rootfs.path, NULL, NULL);
+	orig = storage_init(conf);
 	if (!orig)
 		return bret;
 
@@ -692,7 +699,7 @@ bool rootfs_is_blockdev(struct lxc_conf *conf)
 	if (ret == 0 && S_ISBLK(st.st_mode))
 		return true;
 
-	q = storage_query(conf, conf->rootfs.path);
+	q = storage_query(conf);
 	if (!q)
 		return false;
 

src/lxc/storage/storage.h

@@ -124,18 +124,7 @@ struct lxc_storage {
 extern bool storage_is_dir(struct lxc_conf *conf);
 extern bool storage_can_backup(struct lxc_conf *conf);
 
-/* Instantiate a lxc_storage object. The src is used to determine which blockdev
- * type this should be. The dst and data are optional, and will be used in case
- * of mount/umount.
- *
- * The source will be "dir:/var/lib/lxc/c1" or "lvm:/dev/lxc/c1". For other
- * backing stores, this will allow additional options. In particular,
- * "overlayfs:/var/lib/lxc/canonical/rootfs:/var/lib/lxc/c1/delta" will mean use
- * /var/lib/lxc/canonical/rootfs as lower dir, and /var/lib/lxc/c1/delta as the
- * upper, writeable layer.
- */
-extern struct lxc_storage *storage_init(struct lxc_conf *conf, const char *src,
-					const char *dst, const char *data);
+extern struct lxc_storage *storage_init(struct lxc_conf *conf);
 
 extern struct lxc_storage *storage_copy(struct lxc_container *c0,
 					const char *cname, const char *lxcpath,