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Commit 86b00e0d authored by Alex Elder's avatar Alex Elder
Browse files

rbd: get parent spec for version 2 images 



Add support for getting the the information identifying the parent
image for rbd images that have them.  The child image holds a
reference to its parent image specification structure.  Create a new
entry "parent" in /sys/bus/rbd/image/N/ to report the identifying
information for the parent image, if any.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent a92ffdf8

Documentation/ABI/testing/sysfs-bus-rbd

+4 −0
Original line number Diff line number Diff line
@@ -70,6 +70,10 @@ snap_* 


	A directory per each snapshot



parent



	Information identifying the pool, image, and snapshot id for

	the parent image in a layered rbd image (format 2 only).



Entries under /sys/bus/rbd/devices/<dev-id>/snap_<snap-name>

-------------------------------------------------------------

drivers/block/rbd.c

+131 −0
Original line number Diff line number Diff line
@@ -217,6 +217,9 @@ struct rbd_device { 
	struct ceph_osd_event   *watch_event;

	struct ceph_osd_request *watch_request;



	struct rbd_spec		*parent_spec;

	u64			parent_overlap;



	/* protects updating the header */

	struct rw_semaphore     header_rwsem;
@@ -2009,6 +2012,49 @@ static ssize_t rbd_snap_show(struct device *dev, 
	return sprintf(buf, "%s\n", rbd_dev->spec->snap_name);

}



/*

 * For an rbd v2 image, shows the pool id, image id, and snapshot id

 * for the parent image.  If there is no parent, simply shows

 * "(no parent image)".

 */

static ssize_t rbd_parent_show(struct device *dev,

			     struct device_attribute *attr,

			     char *buf)

{

	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	struct rbd_spec *spec = rbd_dev->parent_spec;

	int count;

	char *bufp = buf;



	if (!spec)

		return sprintf(buf, "(no parent image)\n");



	count = sprintf(bufp, "pool_id %llu\npool_name %s\n",

			(unsigned long long) spec->pool_id, spec->pool_name);

	if (count < 0)

		return count;

	bufp += count;



	count = sprintf(bufp, "image_id %s\nimage_name %s\n", spec->image_id,

			spec->image_name ? spec->image_name : "(unknown)");

	if (count < 0)

		return count;

	bufp += count;



	count = sprintf(bufp, "snap_id %llu\nsnap_name %s\n",

			(unsigned long long) spec->snap_id, spec->snap_name);

	if (count < 0)

		return count;

	bufp += count;



	count = sprintf(bufp, "overlap %llu\n", rbd_dev->parent_overlap);

	if (count < 0)

		return count;

	bufp += count;



	return (ssize_t) (bufp - buf);

}



static ssize_t rbd_image_refresh(struct device *dev,

				 struct device_attribute *attr,

				 const char *buf,
@@ -2032,6 +2078,7 @@ 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(parent, S_IRUGO, rbd_parent_show, NULL);



static struct attribute *rbd_attrs[] = {

	&dev_attr_size.attr,
@@ -2043,6 +2090,7 @@ static struct attribute *rbd_attrs[] = { 
	&dev_attr_name.attr,

	&dev_attr_image_id.attr,

	&dev_attr_current_snap.attr,

	&dev_attr_parent.attr,

	&dev_attr_refresh.attr,

	NULL

};
@@ -2192,6 +2240,7 @@ struct rbd_device *rbd_dev_create(struct rbd_client *rbdc, 


static void rbd_dev_destroy(struct rbd_device *rbd_dev)

{

	rbd_spec_put(rbd_dev->parent_spec);

	kfree(rbd_dev->header_name);

	rbd_put_client(rbd_dev->rbd_client);

	rbd_spec_put(rbd_dev->spec);
@@ -2400,6 +2449,71 @@ static int rbd_dev_v2_features(struct rbd_device *rbd_dev) 
						&rbd_dev->header.features);

}



static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)

{

	struct rbd_spec *parent_spec;

	size_t size;

	void *reply_buf = NULL;

	__le64 snapid;

	void *p;

	void *end;

	char *image_id;

	u64 overlap;

	size_t len = 0;

	int ret;



	parent_spec = rbd_spec_alloc();

	if (!parent_spec)

		return -ENOMEM;



	size = sizeof (__le64) +				/* pool_id */

		sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX +	/* image_id */

		sizeof (__le64) +				/* snap_id */

		sizeof (__le64);				/* overlap */

	reply_buf = kmalloc(size, GFP_KERNEL);

	if (!reply_buf) {

		ret = -ENOMEM;

		goto out_err;

	}



	snapid = cpu_to_le64(CEPH_NOSNAP);

	ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,

				"rbd", "get_parent",

				(char *) &snapid, sizeof (snapid),

				(char *) reply_buf, size,

				CEPH_OSD_FLAG_READ, NULL);

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

	if (ret < 0)

		goto out_err;



	ret = -ERANGE;

	p = reply_buf;

	end = (char *) reply_buf + size;

	ceph_decode_64_safe(&p, end, parent_spec->pool_id, out_err);

	if (parent_spec->pool_id == CEPH_NOPOOL)

		goto out;	/* No parent?  No problem. */



	image_id = ceph_extract_encoded_string(&p, end, &len, GFP_KERNEL);

	if (IS_ERR(image_id)) {

		ret = PTR_ERR(image_id);

		goto out_err;

	}

	parent_spec->image_id = image_id;

	ceph_decode_64_safe(&p, end, parent_spec->snap_id, out_err);

	ceph_decode_64_safe(&p, end, overlap, out_err);



	rbd_dev->parent_overlap = overlap;

	rbd_dev->parent_spec = parent_spec;

	parent_spec = NULL;	/* rbd_dev now owns this */

out:

	ret = 0;

out_err:

	kfree(reply_buf);

	rbd_spec_put(parent_spec);



	return ret;

}



static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver)

{

	size_t size;
@@ -3154,6 +3268,12 @@ static int rbd_dev_v1_probe(struct rbd_device *rbd_dev) 
	ret = rbd_read_header(rbd_dev, &rbd_dev->header);

	if (ret < 0)

		goto out_err;



	/* Version 1 images have no parent (no layering) */



	rbd_dev->parent_spec = NULL;

	rbd_dev->parent_overlap = 0;



	rbd_dev->image_format = 1;



	dout("discovered version 1 image, header name is %s\n",
@@ -3205,6 +3325,14 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev) 
	if (ret < 0)

		goto out_err;



	/* If the image supports layering, get the parent info */



	if (rbd_dev->header.features & RBD_FEATURE_LAYERING) {

		ret = rbd_dev_v2_parent_info(rbd_dev);

		if (ret < 0)

			goto out_err;

	}



	/* crypto and compression type aren't (yet) supported for v2 images */



	rbd_dev->header.crypt_type = 0;
@@ -3224,6 +3352,9 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev) 


	return 0;

out_err:

	rbd_dev->parent_overlap = 0;

	rbd_spec_put(rbd_dev->parent_spec);

	rbd_dev->parent_spec = NULL;

	kfree(rbd_dev->header_name);

	rbd_dev->header_name = NULL;

	kfree(rbd_dev->header.object_prefix);

include/linux/ceph/rados.h

+2 −0
Original line number Diff line number Diff line
@@ -87,6 +87,8 @@ struct ceph_pg { 
 *

 *  lpgp_num -- as above.

 */

#define CEPH_NOPOOL  ((__u64) (-1))  /* pool id not defined */



#define CEPH_PG_TYPE_REP     1

#define CEPH_PG_TYPE_RAID4   2

#define CEPH_PG_POOL_VERSION 2