rbd: define image specification structure

Group the fields that uniquely specify an rbd image into a new
reference-counted rbd_spec structure.  This structure will be used
to describe the desired image when mapping an image, and when
probing parent images in layered rbd devices.  Replace the set of
fields in the rbd device structure with a pointer to a dynamically
allocated rbd_spec.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -112,6 +112,27 @@ struct rbd_image_header {
 	u64 obj_version;
 };
 
+/*
+ * An rbd image specification.
+ *
+ * The tuple (pool_id, image_id, snap_id) is sufficient to uniquely
+ * identify an image.
+ */
+struct rbd_spec {
+	u64		pool_id;
+	char		*pool_name;
+
+	char		*image_id;
+	size_t		image_id_len;
+	char		*image_name;
+	size_t		image_name_len;
+
+	u64		snap_id;
+	char		*snap_name;
+
+	struct kref	kref;
+};
+
 struct rbd_options {
 	bool	read_only;
 };
@@ -189,16 +210,9 @@ struct rbd_device {
 
 	struct rbd_image_header	header;
 	bool                    exists;
-	char			*image_id;
-	size_t			image_id_len;
-	char			*image_name;
-	size_t			image_name_len;
-	char			*header_name;
-	char			*pool_name;
-	u64			pool_id;
+	struct rbd_spec		*spec;
 
-	char                    *snap_name;
-	u64                     snap_id;
+	char			*header_name;
 
 	struct ceph_osd_event   *watch_event;
 	struct ceph_osd_request *watch_request;
@@ -654,7 +668,7 @@ static int snap_by_name(struct rbd_device *rbd_dev, const char *snap_name)
 
 	list_for_each_entry(snap, &rbd_dev->snaps, node) {
 		if (!strcmp(snap_name, snap->name)) {
-			rbd_dev->snap_id = snap->id;
+			rbd_dev->spec->snap_id = snap->id;
 			rbd_dev->mapping.size = snap->size;
 			rbd_dev->mapping.features = snap->features;
 
@@ -669,14 +683,14 @@ static int rbd_dev_set_mapping(struct rbd_device *rbd_dev)
 {
 	int ret;
 
-	if (!memcmp(rbd_dev->snap_name, RBD_SNAP_HEAD_NAME,
+	if (!memcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME,
 		    sizeof (RBD_SNAP_HEAD_NAME))) {
-		rbd_dev->snap_id = CEPH_NOSNAP;
+		rbd_dev->spec->snap_id = CEPH_NOSNAP;
 		rbd_dev->mapping.size = rbd_dev->header.image_size;
 		rbd_dev->mapping.features = rbd_dev->header.features;
 		ret = 0;
 	} else {
-		ret = snap_by_name(rbd_dev, rbd_dev->snap_name);
+		ret = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
 		if (ret < 0)
 			goto done;
 		rbd_dev->mapping.read_only = true;
@@ -1096,7 +1110,7 @@ static int rbd_do_request(struct request *rq,
 	layout->fl_stripe_unit = cpu_to_le32(1 << RBD_MAX_OBJ_ORDER);
 	layout->fl_stripe_count = cpu_to_le32(1);
 	layout->fl_object_size = cpu_to_le32(1 << RBD_MAX_OBJ_ORDER);
-	layout->fl_pg_pool = cpu_to_le32((int) rbd_dev->pool_id);
+	layout->fl_pg_pool = cpu_to_le32((int) rbd_dev->spec->pool_id);
 	ret = ceph_calc_raw_layout(osdc, layout, snapid, ofs, &len, &bno,
 				   req, ops);
 	rbd_assert(ret == 0);
@@ -1261,7 +1275,7 @@ static int rbd_do_op(struct request *rq,
 		opcode = CEPH_OSD_OP_READ;
 		flags = CEPH_OSD_FLAG_READ;
 		snapc = NULL;
-		snapid = rbd_dev->snap_id;
+		snapid = rbd_dev->spec->snap_id;
 		payload_len = 0;
 	}
 
@@ -1545,7 +1559,7 @@ static void rbd_rq_fn(struct request_queue *q)
 		down_read(&rbd_dev->header_rwsem);
 
 		if (!rbd_dev->exists) {
-			rbd_assert(rbd_dev->snap_id != CEPH_NOSNAP);
+			rbd_assert(rbd_dev->spec->snap_id != CEPH_NOSNAP);
 			up_read(&rbd_dev->header_rwsem);
 			dout("request for non-existent snapshot");
 			spin_lock_irq(q->queue_lock);
@@ -1726,13 +1740,13 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev, u64 *version)
 			ret = -ENXIO;
 			pr_warning("short header read for image %s"
 					" (want %zd got %d)\n",
-				rbd_dev->image_name, size, ret);
+				rbd_dev->spec->image_name, size, ret);
 			goto out_err;
 		}
 		if (!rbd_dev_ondisk_valid(ondisk)) {
 			ret = -ENXIO;
 			pr_warning("invalid header for image %s\n",
-				rbd_dev->image_name);
+				rbd_dev->spec->image_name);
 			goto out_err;
 		}
 
@@ -1783,7 +1797,7 @@ static void rbd_update_mapping_size(struct rbd_device *rbd_dev)
 {
 	sector_t size;
 
-	if (rbd_dev->snap_id != CEPH_NOSNAP)
+	if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
 		return;
 
 	size = (sector_t) rbd_dev->header.image_size / SECTOR_SIZE;
@@ -1957,7 +1971,7 @@ static ssize_t rbd_pool_show(struct device *dev,
 {
 	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-	return sprintf(buf, "%s\n", rbd_dev->pool_name);
+	return sprintf(buf, "%s\n", rbd_dev->spec->pool_name);
 }
 
 static ssize_t rbd_pool_id_show(struct device *dev,
@@ -1965,7 +1979,8 @@ static ssize_t rbd_pool_id_show(struct device *dev,
 {
 	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-	return sprintf(buf, "%llu\n", (unsigned long long) rbd_dev->pool_id);
+	return sprintf(buf, "%llu\n",
+		(unsigned long long) rbd_dev->spec->pool_id);
 }
 
 static ssize_t rbd_name_show(struct device *dev,
@@ -1973,7 +1988,7 @@ static ssize_t rbd_name_show(struct device *dev,
 {
 	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-	return sprintf(buf, "%s\n", rbd_dev->image_name);
+	return sprintf(buf, "%s\n", rbd_dev->spec->image_name);
 }
 
 static ssize_t rbd_image_id_show(struct device *dev,
@@ -1981,7 +1996,7 @@ static ssize_t rbd_image_id_show(struct device *dev,
 {
 	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-	return sprintf(buf, "%s\n", rbd_dev->image_id);
+	return sprintf(buf, "%s\n", rbd_dev->spec->image_id);
 }
 
 /*
@@ -1994,7 +2009,7 @@ static ssize_t rbd_snap_show(struct device *dev,
 {
 	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-	return sprintf(buf, "%s\n", rbd_dev->snap_name);
+	return sprintf(buf, "%s\n", rbd_dev->spec->snap_name);
 }
 
 static ssize_t rbd_image_refresh(struct device *dev,
@@ -2547,11 +2562,12 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
 
 			/* Existing snapshot not in the new snap context */
 
-			if (rbd_dev->snap_id == snap->id)
+			if (rbd_dev->spec->snap_id == snap->id)
 				rbd_dev->exists = false;
 			rbd_remove_snap_dev(snap);
 			dout("%ssnap id %llu has been removed\n",
-				rbd_dev->snap_id == snap->id ?  "mapped " : "",
+				rbd_dev->spec->snap_id == snap->id ?
+							"mapped " : "",
 				(unsigned long long) snap->id);
 
 			/* Done with this list entry; advance */
@@ -2869,16 +2885,17 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
 	if (!*options)
 		goto out_err;	/* Missing options */
 
-	rbd_dev->pool_name = dup_token(&buf, NULL);
-	if (!rbd_dev->pool_name)
+	rbd_dev->spec->pool_name = dup_token(&buf, NULL);
+	if (!rbd_dev->spec->pool_name)
 		goto out_mem;
-	if (!*rbd_dev->pool_name)
+	if (!*rbd_dev->spec->pool_name)
 		goto out_err;	/* Missing pool name */
 
-	rbd_dev->image_name = dup_token(&buf, &rbd_dev->image_name_len);
-	if (!rbd_dev->image_name)
+	rbd_dev->spec->image_name =
+		dup_token(&buf, &rbd_dev->spec->image_name_len);
+	if (!rbd_dev->spec->image_name)
 		goto out_mem;
-	if (!*rbd_dev->image_name)
+	if (!*rbd_dev->spec->image_name)
 		goto out_err;	/* Missing image name */
 
 	/*
@@ -2893,11 +2910,11 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
 		ret = -ENAMETOOLONG;
 		goto out_err;
 	}
-	rbd_dev->snap_name = kmalloc(len + 1, GFP_KERNEL);
-	if (!rbd_dev->snap_name)
+	rbd_dev->spec->snap_name = kmalloc(len + 1, GFP_KERNEL);
+	if (!rbd_dev->spec->snap_name)
 		goto out_mem;
-	memcpy(rbd_dev->snap_name, buf, len);
-	*(rbd_dev->snap_name + len) = '\0';
+	memcpy(rbd_dev->spec->snap_name, buf, len);
+	*(rbd_dev->spec->snap_name + len) = '\0';
 
 	/* Initialize all rbd options to the defaults */
 
@@ -2921,11 +2938,11 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
 out_mem:
 	ret = -ENOMEM;
 out_err:
-	kfree(rbd_dev->image_name);
-	rbd_dev->image_name = NULL;
-	rbd_dev->image_name_len = 0;
-	kfree(rbd_dev->pool_name);
-	rbd_dev->pool_name = NULL;
+	kfree(rbd_dev->spec->image_name);
+	rbd_dev->spec->image_name = NULL;
+	rbd_dev->spec->image_name_len = 0;
+	kfree(rbd_dev->spec->pool_name);
+	rbd_dev->spec->pool_name = NULL;
 	kfree(options);
 
 	return ret;
@@ -2957,11 +2974,11 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
 	 * First, see if the format 2 image id file exists, and if
 	 * so, get the image's persistent id from it.
 	 */
-	size = sizeof (RBD_ID_PREFIX) + rbd_dev->image_name_len;
+	size = sizeof (RBD_ID_PREFIX) + rbd_dev->spec->image_name_len;
 	object_name = kmalloc(size, GFP_NOIO);
 	if (!object_name)
 		return -ENOMEM;
-	sprintf(object_name, "%s%s", RBD_ID_PREFIX, rbd_dev->image_name);
+	sprintf(object_name, "%s%s", RBD_ID_PREFIX, rbd_dev->spec->image_name);
 	dout("rbd id object name is %s\n", object_name);
 
 	/* Response will be an encoded string, which includes a length */
@@ -2984,15 +3001,15 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
 	ret = 0;    /* rbd_req_sync_exec() can return positive */
 
 	p = response;
-	rbd_dev->image_id = ceph_extract_encoded_string(&p,
+	rbd_dev->spec->image_id = ceph_extract_encoded_string(&p,
 						p + RBD_IMAGE_ID_LEN_MAX,
-						&rbd_dev->image_id_len,
+						&rbd_dev->spec->image_id_len,
 						GFP_NOIO);
-	if (IS_ERR(rbd_dev->image_id)) {
-		ret = PTR_ERR(rbd_dev->image_id);
-		rbd_dev->image_id = NULL;
+	if (IS_ERR(rbd_dev->spec->image_id)) {
+		ret = PTR_ERR(rbd_dev->spec->image_id);
+		rbd_dev->spec->image_id = NULL;
 	} else {
-		dout("image_id is %s\n", rbd_dev->image_id);
+		dout("image_id is %s\n", rbd_dev->spec->image_id);
 	}
 out:
 	kfree(response);
@@ -3008,20 +3025,21 @@ static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
 
 	/* Version 1 images have no id; empty string is used */
 
-	rbd_dev->image_id = kstrdup("", GFP_KERNEL);
-	if (!rbd_dev->image_id)
+	rbd_dev->spec->image_id = kstrdup("", GFP_KERNEL);
+	if (!rbd_dev->spec->image_id)
 		return -ENOMEM;
-	rbd_dev->image_id_len = 0;
+	rbd_dev->spec->image_id_len = 0;
 
 	/* Record the header object name for this rbd image. */
 
-	size = rbd_dev->image_name_len + sizeof (RBD_SUFFIX);
+	size = rbd_dev->spec->image_name_len + sizeof (RBD_SUFFIX);
 	rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
 	if (!rbd_dev->header_name) {
 		ret = -ENOMEM;
 		goto out_err;
 	}
-	sprintf(rbd_dev->header_name, "%s%s", rbd_dev->image_name, RBD_SUFFIX);
+	sprintf(rbd_dev->header_name, "%s%s",
+		rbd_dev->spec->image_name, RBD_SUFFIX);
 
 	/* Populate rbd image metadata */
 
@@ -3038,8 +3056,8 @@ static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
 out_err:
 	kfree(rbd_dev->header_name);
 	rbd_dev->header_name = NULL;
-	kfree(rbd_dev->image_id);
-	rbd_dev->image_id = NULL;
+	kfree(rbd_dev->spec->image_id);
+	rbd_dev->spec->image_id = NULL;
 
 	return ret;
 }
@@ -3054,12 +3072,12 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
 	 * Image id was filled in by the caller.  Record the header
 	 * object name for this rbd image.
 	 */
-	size = sizeof (RBD_HEADER_PREFIX) + rbd_dev->image_id_len;
+	size = sizeof (RBD_HEADER_PREFIX) + rbd_dev->spec->image_id_len;
 	rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
 	if (!rbd_dev->header_name)
 		return -ENOMEM;
 	sprintf(rbd_dev->header_name, "%s%s",
-			RBD_HEADER_PREFIX, rbd_dev->image_id);
+			RBD_HEADER_PREFIX, rbd_dev->spec->image_id);
 
 	/* Get the size and object order for the image */
 
@@ -3147,6 +3165,9 @@ static ssize_t rbd_add(struct bus_type *bus,
 	rbd_dev = kzalloc(sizeof(*rbd_dev), GFP_KERNEL);
 	if (!rbd_dev)
 		return -ENOMEM;
+	rbd_dev->spec = kzalloc(sizeof (*rbd_dev->spec), GFP_KERNEL);
+	if (!rbd_dev->spec)
+		goto err_out_mem;
 
 	/* static rbd_device initialization */
 	spin_lock_init(&rbd_dev->lock);
@@ -3167,10 +3188,10 @@ static ssize_t rbd_add(struct bus_type *bus,
 
 	/* pick the pool */
 	osdc = &rbd_dev->rbd_client->client->osdc;
-	rc = ceph_pg_poolid_by_name(osdc->osdmap, rbd_dev->pool_name);
+	rc = ceph_pg_poolid_by_name(osdc->osdmap, rbd_dev->spec->pool_name);
 	if (rc < 0)
 		goto err_out_client;
-	rbd_dev->pool_id = (u64) rc;
+	rbd_dev->spec->pool_id = (u64) rc;
 
 	rc = rbd_dev_probe(rbd_dev);
 	if (rc < 0)
@@ -3257,15 +3278,16 @@ err_out_probe:
 err_out_client:
 	kfree(rbd_dev->header_name);
 	rbd_put_client(rbd_dev);
-	kfree(rbd_dev->image_id);
+	kfree(rbd_dev->spec->image_id);
 err_out_args:
 	if (ceph_opts)
 		ceph_destroy_options(ceph_opts);
-	kfree(rbd_dev->snap_name);
-	kfree(rbd_dev->image_name);
-	kfree(rbd_dev->pool_name);
+	kfree(rbd_dev->spec->snap_name);
+	kfree(rbd_dev->spec->image_name);
+	kfree(rbd_dev->spec->pool_name);
 	kfree(rbd_opts);
 err_out_mem:
+	kfree(rbd_dev->spec);
 	kfree(rbd_dev);
 
 	dout("Error adding device %s\n", buf);
@@ -3314,11 +3336,11 @@ static void rbd_dev_release(struct device *dev)
 	rbd_header_free(&rbd_dev->header);
 
 	/* done with the id, and with the rbd_dev */
-	kfree(rbd_dev->snap_name);
-	kfree(rbd_dev->image_id);
+	kfree(rbd_dev->spec->snap_name);
+	kfree(rbd_dev->spec->image_id);
 	kfree(rbd_dev->header_name);
-	kfree(rbd_dev->pool_name);
-	kfree(rbd_dev->image_name);
+	kfree(rbd_dev->spec->pool_name);
+	kfree(rbd_dev->spec->image_name);
 	rbd_dev_id_put(rbd_dev);
 	kfree(rbd_dev);