Commit 589d30e0 authored by Alex Elder's avatar Alex Elder
Browse files

rbd: define rbd_dev_image_id() 



New format 2 rbd images are permanently identified by a unique image
id.  Each rbd image also has a name, but the name can be changed.
A format 2 rbd image will have an object--whose name is based on the
image name--which maps an image's name to its image id.

Create a new function rbd_dev_image_id() that checks for the
existence of the image id object, and if it's found, records the
image id in the rbd_device structure.

Create a new rbd device attribute (/sys/bus/rbd/<num>/image_id) that
makes this information available.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 3bb59ad5

Documentation/ABI/testing/sysfs-bus-rbd

+5 −0
Original line number Diff line number Diff line
@@ -33,6 +33,11 @@ name 


	The name of the rbd image.



image_id



	The unique id for the rbd image.  (For rbd image format 1

	this is empty.)



pool



	The name of the storage pool where this rbd image resides.

drivers/block/rbd.c

+100 −0
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ 


#define RBD_SNAP_HEAD_NAME	"-"



#define	RBD_IMAGE_ID_LEN_MAX	64



/*

 * An RBD device name will be "rbd#", where the "rbd" comes from

 * RBD_DRV_NAME above, and # is a unique integer identifier.
@@ -173,6 +175,8 @@ struct rbd_device { 
	spinlock_t		lock;		/* queue lock */



	struct rbd_image_header	header;

	char			*image_id;

	size_t			image_id_len;

	char			*image_name;

	size_t			image_name_len;

	char			*header_name;
@@ -1987,6 +1991,14 @@ static ssize_t rbd_name_show(struct device *dev, 
	return sprintf(buf, "%s\n", rbd_dev->image_name);

}



static ssize_t rbd_image_id_show(struct device *dev,

			     struct device_attribute *attr, char *buf)

{

	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);



	return sprintf(buf, "%s\n", rbd_dev->image_id);

}



static ssize_t rbd_snap_show(struct device *dev,

			     struct device_attribute *attr,

			     char *buf)
@@ -2015,6 +2027,7 @@ static DEVICE_ATTR(client_id, S_IRUGO, rbd_client_id_show, NULL); 
static DEVICE_ATTR(pool, S_IRUGO, rbd_pool_show, NULL);

static DEVICE_ATTR(pool_id, S_IRUGO, rbd_pool_id_show, NULL);

static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, NULL);

static DEVICE_ATTR(image_id, S_IRUGO, rbd_image_id_show, NULL);

static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh);

static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL);

static DEVICE_ATTR(create_snap, S_IWUSR, NULL, rbd_snap_add);
@@ -2026,6 +2039,7 @@ static struct attribute *rbd_attrs[] = { 
	&dev_attr_pool.attr,

	&dev_attr_pool_id.attr,

	&dev_attr_name.attr,

	&dev_attr_image_id.attr,

	&dev_attr_current_snap.attr,

	&dev_attr_refresh.attr,

	&dev_attr_create_snap.attr,
@@ -2553,6 +2567,75 @@ out_err: 
	return err_ptr;

}



/*

 * An rbd format 2 image has a unique identifier, distinct from the

 * name given to it by the user.  Internally, that identifier is

 * what's used to specify the names of objects related to the image.

 *

 * A special "rbd id" object is used to map an rbd image name to its

 * id.  If that object doesn't exist, then there is no v2 rbd image

 * with the supplied name.

 *

 * This function will record the given rbd_dev's image_id field if

 * it can be determined, and in that case will return 0.  If any

 * errors occur a negative errno will be returned and the rbd_dev's

 * image_id field will be unchanged (and should be NULL).

 */

static int rbd_dev_image_id(struct rbd_device *rbd_dev)

{

	int ret;

	size_t size;

	char *object_name;

	void *response;

	void *p;



	/*

	 * 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;

	object_name = kmalloc(size, GFP_NOIO);

	if (!object_name)

		return -ENOMEM;

	sprintf(object_name, "%s%s", RBD_ID_PREFIX, rbd_dev->image_name);

	dout("rbd id object name is %s\n", object_name);



	/* Response will be an encoded string, which includes a length */



	size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX;

	response = kzalloc(size, GFP_NOIO);

	if (!response) {

		ret = -ENOMEM;

		goto out;

	}



	ret = rbd_req_sync_exec(rbd_dev, object_name,

				"rbd", "get_id",

				NULL, 0,

				response, RBD_IMAGE_ID_LEN_MAX,

				CEPH_OSD_FLAG_READ, NULL);

	dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);

	if (ret < 0)

		goto out;



	p = response;

	rbd_dev->image_id = ceph_extract_encoded_string(&p,

						p + RBD_IMAGE_ID_LEN_MAX,

						&rbd_dev->image_id_len,

						GFP_NOIO);

	if (IS_ERR(rbd_dev->image_id)) {

		ret = PTR_ERR(rbd_dev->image_id);

		rbd_dev->image_id = NULL;

	} else {

		dout("image_id is %s\n", rbd_dev->image_id);

	}

out:

	kfree(response);

	kfree(object_name);



	return ret;

}



static ssize_t rbd_add(struct bus_type *bus,

		       const char *buf,

		       size_t count)
@@ -2600,6 +2683,21 @@ static ssize_t rbd_add(struct bus_type *bus, 
		goto err_out_client;

	rbd_dev->pool_id = rc;



	rc = rbd_dev_image_id(rbd_dev);

	if (!rc) {

		rc = -ENOTSUPP;	/* Not actually supporting format 2 yet */

		goto err_out_client;

	}



	/* Version 1 images have no id; empty string is used */



	rbd_dev->image_id = kstrdup("", GFP_KERNEL);

	if (!rbd_dev->image_id) {

		rc = -ENOMEM;

		goto err_out_client;

	}

	rbd_dev->image_id_len = 0;



	/* Create the name of the header object */



	rbd_dev->header_name = kmalloc(rbd_dev->image_name_len
@@ -2691,6 +2789,7 @@ err_out_header: 
err_out_client:

	kfree(rbd_dev->header_name);

	rbd_put_client(rbd_dev);

	kfree(rbd_dev->image_id);

err_out_args:

	kfree(rbd_dev->mapping.snap_name);

	kfree(rbd_dev->image_name);
@@ -2746,6 +2845,7 @@ static void rbd_dev_release(struct device *dev) 


	/* done with the id, and with the rbd_dev */

	kfree(rbd_dev->mapping.snap_name);

	kfree(rbd_dev->image_id);

	kfree(rbd_dev->header_name);

	kfree(rbd_dev->pool_name);

	kfree(rbd_dev->image_name);

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