rbd: encapsulate code that gets snapshot info
Create a function that encapsulates looking up the name, size and
features related to a given snapshot, which is indicated by its
index in an rbd device's snapshot context array of snapshot ids.
This interface will be used to hide differences between the format 1
and format 2 images.
At the moment this (looking up the name anyway) is slightly less
efficient than what's done currently, but we may be able to optimize
this a bit later on by cacheing the last lookup if it proves to be a
problem.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 463f8b2..366a3a1 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2102,6 +2102,25 @@
return ERR_PTR(ret);
}
+static char *rbd_dev_v1_snap_info(struct rbd_device *rbd_dev, u32 which,
+ u64 *snap_size, u64 *snap_features)
+{
+ char *snap_name;
+
+ rbd_assert(which < rbd_dev->header.snapc->num_snaps);
+
+ *snap_size = rbd_dev->header.snap_sizes[which];
+ *snap_features = 0; /* No features for v1 */
+
+ /* Skip over names until we find the one we are looking for */
+
+ snap_name = rbd_dev->header.snap_names;
+ while (which--)
+ snap_name += strlen(snap_name) + 1;
+
+ return snap_name;
+}
+
/*
* Scan the rbd device's current snapshot list and compare it to the
* newly-received snapshot context. Remove any existing snapshots
@@ -2118,7 +2137,6 @@
{
struct ceph_snap_context *snapc = rbd_dev->header.snapc;
const u32 snap_count = snapc->num_snaps;
- char *snap_name = rbd_dev->header.snap_names;
struct list_head *head = &rbd_dev->snaps;
struct list_head *links = head->next;
u32 index = 0;
@@ -2127,6 +2145,9 @@
while (index < snap_count || links != head) {
u64 snap_id;
struct rbd_snap *snap;
+ char *snap_name;
+ u64 snap_size = 0;
+ u64 snap_features = 0;
snap_id = index < snap_count ? snapc->snaps[index]
: CEPH_NOSNAP;
@@ -2153,16 +2174,20 @@
continue;
}
+ snap_name = rbd_dev_v1_snap_info(rbd_dev, index,
+ &snap_size, &snap_features);
+ if (IS_ERR(snap_name))
+ return PTR_ERR(snap_name);
+
dout("entry %u: snap_id = %llu\n", (unsigned int) snap_count,
(unsigned long long) snap_id);
if (!snap || (snap_id != CEPH_NOSNAP && snap->id < snap_id)) {
- struct rbd_image_header *header = &rbd_dev->header;
struct rbd_snap *new_snap;
/* We haven't seen this snapshot before */
new_snap = __rbd_add_snap_dev(rbd_dev, snap_name,
- snap_id, header->snap_sizes[index], 0);
+ snap_id, snap_size, snap_features);
if (IS_ERR(new_snap)) {
int err = PTR_ERR(new_snap);
@@ -2183,9 +2208,9 @@
dout(" already present\n");
- rbd_assert(snap->size ==
- rbd_dev->header.snap_sizes[index]);
+ rbd_assert(snap->size == snap_size);
rbd_assert(!strcmp(snap->name, snap_name));
+ rbd_assert(snap->features == snap_features);
/* Done with this list entry; advance */
@@ -2195,7 +2220,6 @@
/* Advance to the next entry in the snapshot context */
index++;
- snap_name += strlen(snap_name) + 1;
}
dout("%s: done\n", __func__);