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rbd: define rbd_snap_size() and rbd_snap_features()

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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: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-04-30 00:44:33 -05:00 committed by Sage Weil
parent 54cac61fb6
commit 2ad3d7167e
1 changed files with 129 additions and 23 deletions
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152
drivers/block/rbd.c
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@ -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_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
u64 *snap_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 {
u64 features = 0;
int ret;
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)
{
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;
} else {
struct rbd_snap *snap;
const char *snap_name = rbd_dev->spec->snap_name;
u64 snap_id;
u64 size = 0;
u64 features = 0;
int ret;
snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
if (!snap)
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;
}