File bug-1172566_cachevol-use-cachepool-code-for-metadata-size.patch of Package lvm2.25911

By heming.zhao@suse.com
this patch is based on upstream commit
```
commit c08704cee7e34a96fdaa453faf900683283e8691
Author: David Teigland <teigland@redhat.com>
Date:   Mon Oct 21 12:13:33 2019 -0500

    cachevol: use cachepool code for metadata size
    
    Based on a more detailed calculation, but because of
    extent size rounding, the final result is about the
    same.
```

diff -Nupr a/lib/metadata/cache_manip.c b/lib/metadata/cache_manip.c
--- a/lib/metadata/cache_manip.c	2020-06-12 09:04:17.474637002 +0800
+++ b/lib/metadata/cache_manip.c	2020-06-12 09:04:28.914578582 +0800
@@ -184,12 +184,16 @@ void cache_check_for_warns(const struct
  */
 static uint64_t _cache_min_metadata_size(uint64_t data_size, uint32_t chunk_size)
 {
-	uint64_t min_meta_size;
-
-	min_meta_size = data_size / chunk_size;		/* nr_chunks */
-	min_meta_size *= (DM_BYTES_PER_BLOCK + DM_MAX_HINT_WIDTH + DM_HINT_OVERHEAD_PER_BLOCK);
-	min_meta_size = (min_meta_size + (SECTOR_SIZE - 1)) >> SECTOR_SHIFT;	/* in sectors */
-	min_meta_size += DM_TRANSACTION_OVERHEAD * (1024 >> SECTOR_SHIFT);
+	/* Used space for mapping and hints for each cached chunk in bytes
+	 * (matching thin-tools cache_metadata_size.cc) */
+	const uint64_t chunk_overhead = (DM_BYTES_PER_BLOCK + DM_MAX_HINT_WIDTH + DM_HINT_OVERHEAD_PER_BLOCK);
+	const uint64_t transaction_overhead = DM_TRANSACTION_OVERHEAD * 1024; /* 4MiB */
+
+	/* Number of cache chunks we have in caching volume */
+	uint64_t nr_chunks = data_size / chunk_size;
+	/* Minimal size of metadata volume converted back to sectors */
+	uint64_t min_meta_size = (transaction_overhead + nr_chunks * chunk_overhead +
+			(SECTOR_SIZE - 1)) >> SECTOR_SHIFT;
 
 	return min_meta_size;
 }
@@ -1242,14 +1246,7 @@ int cache_vol_set_params(struct cmd_cont
 	}
 
 	if (!meta_size) {
-		if (pool_lv->size < (128 * ONE_MB_S))
-			meta_size = 16 * ONE_MB_S;
-
-		else if (pool_lv->size < ONE_GB_S)
-			meta_size = 32 * ONE_MB_S;
-
-		else if (pool_lv->size < (128 * ONE_GB_S))
-			meta_size = 64 * ONE_MB_S;
+		meta_size = _cache_min_metadata_size(pool_lv->size, chunk_size);
 
 		if (meta_size > (pool_lv->size / 2))
 			meta_size = pool_lv->size / 2;