lvcreate: improve --chunksize support for cached volume.

Support parsing --chunksize option also when converting.
Now user can use cache pool created with i.e. 32K chunksize,
while in caching user can select 512K blocks.
Tool is supposed to validate cache metadata size is big enough
to support such chunk size. Otherwise error is shown.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.153 - 
 ==================================
+  Support --chunksize option also when caching LV when possible.
   Add function to check for target presence and version via 1 ioctl.
 
 Version 2.02.152 - 30th April 2016

lib/metadata/lv_manip.c

@@ -7166,9 +7166,17 @@ static struct logical_volume *_lv_create_an_lv(struct volume_group *vg,
 			return NULL;
 		}
 
+		if (seg_is_cache(lp)) {
+			/* validate metadata size */
+			if (!validate_lv_cache_chunk_size(pool_lv, lp->chunk_size))
+				return_0;
+
+			first_seg(pool_lv)->chunk_size = lp->chunk_size;
+		}
+
 		/* Validate volume size to to aling on chunk for small extents */
 		/* Cache chunk size is always set */
-		size = seg_is_cache(lp) ? lp->chunk_size : first_seg(pool_lv)->chunk_size;
+		size = first_seg(pool_lv)->chunk_size;
 		if (size > vg->extent_size) {
 			/* Align extents on chunk boundary size */
 			size = ((uint64_t)vg->extent_size * lp->extents + size - 1) /
@@ -7427,27 +7435,15 @@ static struct logical_volume *_lv_create_an_lv(struct volume_group *vg,
 	/* Unlock memory if possible */
 	memlock_unlock(vg->cmd);
 
-	if (lv_is_cache_pool(lv) || lv_is_cache(lv)) {
+	if (lv_is_cache_pool(lv)) {
-		if (!cache_set_mode(first_seg(lv), lp->cache_mode)) {
+		if (!cache_set_params(first_seg(lv),
+				      lp->cache_mode,
+				      lp->policy_name,
+				      lp->policy_settings,
+				      lp->chunk_size)) {
 			stack;
 			goto revert_new_lv;
 		}
-
-		if (!cache_set_policy(first_seg(lv), lp->policy_name, lp->policy_settings)) {
-			stack;
-			goto revert_new_lv;
-		}
-
-		pool_lv = pool_lv ? : lv;
-		if (lp->chunk_size) {
-			first_seg(pool_lv)->chunk_size = lp->chunk_size;
-			/* TODO: some calc_policy solution for cache ? */
-			if (!recalculate_pool_chunk_size_with_dev_hints(pool_lv, lp->passed_args,
-									THIN_CHUNK_SIZE_CALC_METHOD_GENERIC)) {
-				stack;
-				goto revert_new_lv;
-			}
-		}
 	} else if (lv_is_raid(lv)) {
 		first_seg(lv)->min_recovery_rate = lp->min_recovery_rate;
 		first_seg(lv)->max_recovery_rate = lp->max_recovery_rate;
@@ -7649,10 +7645,11 @@ static struct logical_volume *_lv_create_an_lv(struct volume_group *vg,
 		}
 		lv = tmp_lv;
 
-		if (!cache_set_mode(first_seg(lv), lp->cache_mode))
+		if (!cache_set_params(first_seg(lv),
-			return_NULL; /* revert? */
+				      lp->cache_mode,
-
+				      lp->policy_name,
-		if (!cache_set_policy(first_seg(lv), lp->policy_name, lp->policy_settings))
+				      lp->policy_settings,
+				      (lp->passed_args & PASS_ARG_CHUNK_SIZE) ? lp->chunk_size : 0))
 			return_NULL; /* revert? */
 
 		cache_check_for_warns(first_seg(lv));

man/lvcreate.8.in

@@ -260,6 +260,8 @@ and the default value is 4KiB.
 .br
 For cache pools the value must a multiple of 32KiB
 between 32KiB and 1GiB. The default is 64KiB.
+When the size is specified with volume caching, it may not be smaller
+then cache pool creation chunk size was.
 .br
 For thin pools the value must be a multiple of 64KiB
 between 64KiB and 1GiB.