cache: support cached origin for snapshot

Enable  'lvcreate/lvconvert -s' for cached LV.
and supported operations:

Create a snapshot of cached LV

Split/Join snapshot LV to cached origin LV.

diff --git a/WHATS_NEW b/WHATS_NEW
index ab113aea7304228cc74ac510a9e5134bed2070f5..fa8f5c3cf80604fb9235418560810f6e15c2c292 100644 (file)
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.169 - 
 =====================================
+  Enable usage of cached volumes as snapshot origin LV.
   Fix displayed lv name when splitting snapshot (2.02.146).
   Warn about command not making metadata backup just once per command.
   Enable usage of cached volume as thin volume's external origin.

diff --git a/lib/metadata/cache_manip.c b/lib/metadata/cache_manip.c
index 12b10547caae4ee832982fe2ef279b77eab9a290..404b1af79a151e03d6c70a0eb669304ae1ea8537 100644 (file)
--- a/lib/metadata/cache_manip.c
+++ b/lib/metadata/cache_manip.c
@@ -322,7 +322,7 @@ int validate_lv_cache_create_origin(const struct logical_volume *origin_lv)
        if (lv_is_cache_type(origin_lv) ||
            lv_is_mirror_type(origin_lv) ||
            lv_is_thin_volume(origin_lv) || lv_is_thin_pool_metadata(origin_lv) ||
-           lv_is_origin(origin_lv) || lv_is_merging_origin(origin_lv) ||
+           lv_is_merging_origin(origin_lv) ||
            lv_is_cow(origin_lv) || lv_is_merging_cow(origin_lv) ||
            lv_is_virtual(origin_lv)) {
                log_error("Cache is not supported with %s segment type of the original logical volume %s.",

diff --git a/lib/metadata/lv_manip.c b/lib/metadata/lv_manip.c
index 92a6d449fa187d93037477f008f1babcf69f3217..3862f110c75d2795d003e28165ddfd2b79990c63 100644 (file)
--- a/lib/metadata/lv_manip.c
+++ b/lib/metadata/lv_manip.c
@@ -7428,7 +7428,7 @@ static struct logical_volume *_lv_create_an_lv(struct volume_group *vg,
                                return NULL;
                        }
 
-                       if (lv_is_cache_type(origin_lv)) {
+                       if (lv_is_cache_type(origin_lv) && !lv_is_cache(origin_lv)) {
                                log_error("Snapshots of cache type volume %s "
                                          "is not supported.", display_lvname(origin_lv));
                                return NULL;

diff --git a/tools/lvconvert.c b/tools/lvconvert.c
index 41039954bcc879d5e9015a99cbb85a3b747fca32..0f0f0addb9d76018cc4fb5e656bcd250ddc38581 100644 (file)
--- a/tools/lvconvert.c
+++ b/tools/lvconvert.c
@@ -2336,7 +2336,7 @@ static int _lvconvert_snapshot(struct cmd_context *cmd,
                return_0;
 
        if (lv_is_locked(org) ||
-           lv_is_cache_type(org) ||
+           (lv_is_cache_type(org) && !lv_is_cache(org)) ||
            lv_is_thin_type(org) ||
            lv_is_pvmove(org) ||
            lv_is_mirrored(org) ||
@@ -3770,6 +3770,16 @@ static int _convert_cache_volume_thin_pool(struct cmd_context *cmd, struct logic
        return 1;
 }
 
+/*
+ * Convert/Recombine  cacheLV to be an origin for snapshot
+ * lvconvert --type snapshot cacheLV snapshotLV
+ */
+static int _convert_cache_volume_snapshot(struct cmd_context *cmd, struct logical_volume *lv,
+                                         struct lvconvert_params *lp)
+{
+       return _lvconvert_snapshot(cmd, lv, lp);
+}
+
 /*
  * Split a cache volume from a cache pool LV.
  * lvconvert --splitcache LV
@@ -4311,6 +4321,10 @@ static int _convert_cache_volume(struct cmd_context *cmd, struct logical_volume
            arg_is_set(cmd, thinpool_ARG))
                return _convert_cache_volume_thin_pool(cmd, lv, lp);
 
+       if (!strcmp(lp->type_str, SEG_TYPE_NAME_SNAPSHOT) ||
+           arg_is_set(cmd, snapshot_ARG))
+               return _convert_cache_volume_snapshot(cmd, lv, lp);
+
        /* The --thinpool alternative for --type thin-pool is not preferred, so not shown. */
 
        log_error("Operation not permitted on cache LV %s.", display_lvname(lv));