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Commit 2ad3d716 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

rbd: define rbd_snap_size() and rbd_snap_features() 



This patch defines a handful of new functions that will allow
us to get rid of the rbd device structure's list of snapshots.

Define rbd_snap_id_by_name() to look up a snapshot id given its
name.  This is efficient for format 1 images but not for format 2.
Fortunately it only gets called at mapping time so it's not that
critical.

Use rbd_snap_id_by_name() to find out the id for a snapshot getting
mapped, and pass that id to new functions rbd_snap_size() and
rbd_snap_features() to look up information about a given snapshot's
size and feature mask given its snapshot id.  All this gets done
in rbd_dev_mapping_set().

As a result, snap_by_name() is no longer needed, so get rid of it.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 54cac61f

drivers/block/rbd.c

+129 −23
Original line number Diff line number Diff line
@@ -435,6 +435,11 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev); 
static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev);

static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,

					u64 snap_id);

static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,

				u8 *order, u64 *snap_size);

static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,

		u64 *snap_features);

static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name);



static int rbd_open(struct block_device *bdev, fmode_t mode)

{
@@ -840,7 +845,8 @@ static u32 rbd_dev_snap_index(struct rbd_device *rbd_dev, u64 snap_id) 
	return BAD_SNAP_INDEX;

}



static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev, u64 snap_id)

static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev,

					u64 snap_id)

{

	u32 which;
@@ -863,35 +869,85 @@ static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id) 
	return rbd_dev_v2_snap_name(rbd_dev, snap_id);

}



static struct rbd_snap *snap_by_name(struct rbd_device *rbd_dev,

					const char *snap_name)

static int rbd_snap_size(struct rbd_device *rbd_dev, u64 snap_id,

				u64 *snap_size)

{

	struct rbd_snap *snap;

	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));

	if (snap_id == CEPH_NOSNAP) {

		*snap_size = rbd_dev->header.image_size;

	} else if (rbd_dev->image_format == 1) {

		u32 which;



	list_for_each_entry(snap, &rbd_dev->snaps, node)

		if (!strcmp(snap_name, snap->name))

			return snap;

		which = rbd_dev_snap_index(rbd_dev, snap_id);

		if (which == BAD_SNAP_INDEX)

			return -ENOENT;



	return NULL;

		*snap_size = rbd_dev->header.snap_sizes[which];

	} else {

		u64 size = 0;

		int ret;



		ret = _rbd_dev_v2_snap_size(rbd_dev, snap_id, NULL, &size);

		if (ret)

			return ret;



		*snap_size = size;

	}

	return 0;

}



static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)

static int rbd_snap_features(struct rbd_device *rbd_dev, u64 snap_id,

			u64 *snap_features)

{

	if (!memcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME,

		    sizeof (RBD_SNAP_HEAD_NAME))) {

		rbd_dev->mapping.size = rbd_dev->header.image_size;

		rbd_dev->mapping.features = rbd_dev->header.features;

	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));

	if (snap_id == CEPH_NOSNAP) {

		*snap_features = rbd_dev->header.features;

	} else if (rbd_dev->image_format == 1) {

		*snap_features = 0;	/* No features for format 1 */

	} else {

		struct rbd_snap *snap;

		u64 features = 0;

		int ret;



		snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);

		if (!snap)

		ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, &features);

		if (ret)

			return ret;



		*snap_features = features;

	}

	return 0;

}



static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)

{

	const char *snap_name = rbd_dev->spec->snap_name;

	u64 snap_id;

	u64 size = 0;

	u64 features = 0;

	int ret;



	if (strcmp(snap_name, RBD_SNAP_HEAD_NAME)) {

		snap_id = rbd_snap_id_by_name(rbd_dev, snap_name);

		if (snap_id == CEPH_NOSNAP)

			return -ENOENT;

		rbd_dev->mapping.size = snap->size;

		rbd_dev->mapping.features = snap->features;

		rbd_dev->mapping.read_only = true;

	} else {

		snap_id = CEPH_NOSNAP;

	}



	ret = rbd_snap_size(rbd_dev, snap_id, &size);

	if (ret)

		return ret;

	ret = rbd_snap_features(rbd_dev, snap_id, &features);

	if (ret)

		return ret;



	rbd_dev->mapping.size = size;

	rbd_dev->mapping.features = features;



	/* If we are mapping a snapshot it must be marked read-only */



	if (snap_id != CEPH_NOSNAP)

		rbd_dev->mapping.read_only = true;



	return 0;

}
@@ -3766,6 +3822,56 @@ out: 
	return image_name;

}



static u64 rbd_v1_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)

{

	struct ceph_snap_context *snapc = rbd_dev->header.snapc;

	const char *snap_name;

	u32 which = 0;



	/* Skip over names until we find the one we are looking for */



	snap_name = rbd_dev->header.snap_names;

	while (which < snapc->num_snaps) {

		if (!strcmp(name, snap_name))

			return snapc->snaps[which];

		snap_name += strlen(snap_name) + 1;

		which++;

	}

	return CEPH_NOSNAP;

}



static u64 rbd_v2_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)

{

	struct ceph_snap_context *snapc = rbd_dev->header.snapc;

	u32 which;

	bool found = false;

	u64 snap_id;



	for (which = 0; !found && which < snapc->num_snaps; which++) {

		const char *snap_name;



		snap_id = snapc->snaps[which];

		snap_name = rbd_dev_v2_snap_name(rbd_dev, snap_id);

		if (IS_ERR(snap_name))

			break;

		found = !strcmp(name, snap_name);

		kfree(snap_name);

	}

	return found ? snap_id : CEPH_NOSNAP;

}



/*

 * Assumes name is never RBD_SNAP_HEAD_NAME; returns CEPH_NOSNAP if

 * no snapshot by that name is found, or if an error occurs.

 */

static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)

{

	if (rbd_dev->image_format == 1)

		return rbd_v1_snap_id_by_name(rbd_dev, name);



	return rbd_v2_snap_id_by_name(rbd_dev, name);

}



/*

 * When an rbd image has a parent image, it is identified by the

 * pool, image, and snapshot ids (not names).  This function fills
@@ -3797,12 +3903,12 @@ static int rbd_dev_spec_update(struct rbd_device *rbd_dev) 
	 */

	if (spec->pool_name) {

		if (strcmp(spec->snap_name, RBD_SNAP_HEAD_NAME)) {

			struct rbd_snap *snap;

			u64 snap_id;



			snap = snap_by_name(rbd_dev, spec->snap_name);

			if (!snap)

			snap_id = rbd_snap_id_by_name(rbd_dev, spec->snap_name);

			if (snap_id == CEPH_NOSNAP)

				return -ENOENT;

			spec->snap_id = snap->id;

			spec->snap_id = snap_id;

		} else {

			spec->snap_id = CEPH_NOSNAP;

		}