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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>
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@ -2102,6 +2102,25 @@ err:
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return ERR_PTR(ret);
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}
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static char *rbd_dev_v1_snap_info(struct rbd_device *rbd_dev, u32 which,
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u64 *snap_size, u64 *snap_features)
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{
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char *snap_name;
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rbd_assert(which < rbd_dev->header.snapc->num_snaps);
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*snap_size = rbd_dev->header.snap_sizes[which];
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*snap_features = 0; /* No features for v1 */
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/* Skip over names until we find the one we are looking for */
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snap_name = rbd_dev->header.snap_names;
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while (which--)
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snap_name += strlen(snap_name) + 1;
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return snap_name;
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}
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/*
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* Scan the rbd device's current snapshot list and compare it to the
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* newly-received snapshot context. Remove any existing snapshots
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@ -2118,7 +2137,6 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
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{
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struct ceph_snap_context *snapc = rbd_dev->header.snapc;
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const u32 snap_count = snapc->num_snaps;
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char *snap_name = rbd_dev->header.snap_names;
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struct list_head *head = &rbd_dev->snaps;
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struct list_head *links = head->next;
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u32 index = 0;
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@ -2127,6 +2145,9 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
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while (index < snap_count || links != head) {
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u64 snap_id;
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struct rbd_snap *snap;
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char *snap_name;
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u64 snap_size = 0;
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u64 snap_features = 0;
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snap_id = index < snap_count ? snapc->snaps[index]
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: CEPH_NOSNAP;
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@ -2153,16 +2174,20 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
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continue;
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}
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snap_name = rbd_dev_v1_snap_info(rbd_dev, index,
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&snap_size, &snap_features);
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if (IS_ERR(snap_name))
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return PTR_ERR(snap_name);
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dout("entry %u: snap_id = %llu\n", (unsigned int) snap_count,
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(unsigned long long) snap_id);
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if (!snap || (snap_id != CEPH_NOSNAP && snap->id < snap_id)) {
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struct rbd_image_header *header = &rbd_dev->header;
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struct rbd_snap *new_snap;
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/* We haven't seen this snapshot before */
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new_snap = __rbd_add_snap_dev(rbd_dev, snap_name,
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snap_id, header->snap_sizes[index], 0);
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snap_id, snap_size, snap_features);
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if (IS_ERR(new_snap)) {
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int err = PTR_ERR(new_snap);
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@ -2183,9 +2208,9 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
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dout(" already present\n");
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rbd_assert(snap->size ==
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rbd_dev->header.snap_sizes[index]);
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rbd_assert(snap->size == snap_size);
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rbd_assert(!strcmp(snap->name, snap_name));
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rbd_assert(snap->features == snap_features);
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/* Done with this list entry; advance */
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@ -2195,7 +2220,6 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
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/* Advance to the next entry in the snapshot context */
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index++;
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snap_name += strlen(snap_name) + 1;
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}
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dout("%s: done\n", __func__);
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