thin: preserve chunksize with lvconvert

When repairing thin pool or swapping thin pool metadata,
preserve  chunk_size property and avoid to be automatically changed
later in the code to better match thin pool metadata size.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.116 - 
 ====================================
+  Preserve chunk size with repair and metadata swap of a thin pool.
   Fix raid --splitmirror 1 functionality (2.02.112).
   Fix tree preload to handle splitting raid images.
   Do not support unpartitioned DASD devices.

test/shell/lvconvert-repair-thin.sh

@@ -24,7 +24,9 @@ aux have_thin 1 0 0 || skip
 aux prepare_vg 4
 
 # Create LV
-lvcreate -T -L20 -V10 -n $lv1 $vg/pool  "$dev1" "$dev2"
+# TODO: investigate problem with --zero n and my repairable damage trick
+#lvcreate -T -L20 -V10 -n $lv1 $vg/pool --discards ignore --zero n --chunksize 128 "$dev1" "$dev2"
+lvcreate -T -L20 -V10 -n $lv1 $vg/pool --chunksize 128 --discards ignore "$dev1" "$dev2"
 lvcreate -T -V10 -n $lv2 $vg/pool
 
 mkfs.ext2 "$DM_DEV_DIR/$vg/$lv1"
@@ -71,6 +73,11 @@ lvchange -an $vg
 # Swap repaired metadata back
 lvconvert -y -f --poolmetadata $vg/fixed --thinpool $vg/pool
 
+# Check pool still preserves its original settings
+check lv_field $vg/pool chunksize "128.00k"
+check lv_field $vg/pool discards "ignore"
+check lv_field $vg/pool zero "zero"
+
 # Activate pool - this should now work
 vgchange -ay $vg
 

tools/lvconvert.c

@@ -2956,6 +2956,7 @@ static int _lvconvert_pool(struct cmd_context *cmd,
 			return 0;
 		}
 
+		lp->passed_args |= PASS_ARG_CHUNK_SIZE | PASS_ARG_DISCARDS | PASS_ARG_ZERO;
 		seg = first_seg(pool_lv);
 
 		/* Normally do NOT change chunk size when swapping */