/*
* lv_cache_create
* @pool
* @origin
*
* Given a cache_pool and an origin, link the two and create a
* cached LV.
*
* Returns: cache LV on success, NULL on failure
*/
struct logical_volume *lv_cache_create(struct logical_volume *pool,
struct logical_volume *origin)
{
const struct segment_type *segtype;
struct cmd_context *cmd = pool->vg->cmd;
struct logical_volume *cache_lv;
struct lv_segment *seg;
if (!lv_is_cache_pool(pool)) {
log_error(INTERNAL_ERROR
"%s is not a cache_pool LV", pool->name);
return NULL;
}
if (!dm_list_empty(&pool->segs_using_this_lv)) {
seg = get_only_segment_using_this_lv(pool);
log_error("%s is already in use by %s",
pool->name, seg ? seg->lv->name : "another LV");
return NULL;
}
if (lv_is_cache_type(origin)) {
/*
* FIXME: We can layer caches, insert_layer_for_lv() would
* have to do a better job renaming the LVs in the stack
* first so that there isn't a name collision with <name>_corig.
* The origin under the origin would become *_corig_corig
* before renaming the origin above to *_corig.
*/
log_error(INTERNAL_ERROR
"The origin, %s, cannot be of cache type",
origin->name);
return NULL;
}
if (!(segtype = get_segtype_from_string(cmd, "cache")))
return_NULL;
cache_lv = origin;
if (!(origin = insert_layer_for_lv(cmd, cache_lv, CACHE, "_corig")))
return_NULL;
seg = first_seg(cache_lv);
seg->segtype = segtype;
if (!attach_pool_lv(seg, pool, NULL, NULL))
return_NULL;
return cache_lv;
}
/* Check if given LV is usable as snapshot origin LV */
int validate_snapshot_origin(const struct logical_volume *origin_lv)
{
const char *err = NULL; /* For error string */
if (lv_is_cow(origin_lv))
err = "snapshots";
else if (lv_is_locked(origin_lv))
err = "locked volumes";
else if (lv_is_pvmove(origin_lv))
err = "pvmoved volumes";
else if (!lv_is_visible(origin_lv))
err = "hidden volumes";
else if (lv_is_merging_origin(origin_lv))
err = "an origin that has a merging snapshot";
else if (lv_is_cache_type(origin_lv) && !lv_is_cache(origin_lv))
err = "cache type volumes";
else if (lv_is_thin_type(origin_lv) && !lv_is_thin_volume(origin_lv))
err = "thin pool type volumes";
else if (lv_is_mirror_type(origin_lv)) {
if (!lv_is_mirror(origin_lv))
err = "mirror subvolumes";
else {
log_warn("WARNING: Snapshots of mirrors can deadlock under rare device failures.");
log_warn("WARNING: Consider using the raid1 mirror type to avoid this.");
log_warn("WARNING: See global/mirror_segtype_default in lvm.conf.");
}
} else if (lv_is_raid_type(origin_lv) && !lv_is_raid(origin_lv))
err = "raid subvolumes";
if (err) {
log_error("Snapshots of %s are not supported.", err);
return 0;
}
if (vg_is_clustered(origin_lv->vg) && lv_is_active(origin_lv) &&
!lv_is_active_exclusive_locally(origin_lv)) {
log_error("Snapshot origin must be active exclusively.");
return 0;
}
return 1;
}
