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@xxxxxxxxxxx>
---
drivers/block/rbd.c | 152
+++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 129 insertions(+), 23 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b1e1d12..67fd866d 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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;
+
+ ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, &features);
+ if (ret)
+ return ret;
+
+ *snap_features = features;
+ }
+ return 0;
+}
- snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
- if (!snap)
+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;
}
--
1.7.9.5
--
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