From: Li Chen <[email protected]>

The on-media cache_info index used sizeof(struct) instead of the
4K metadata stride, so gc_percent updates from dmsetup message
were written between slots and lost after reboot. Use
PCACHE_CACHE_INFO_SIZE in get_cache_info_addr() and align
info_index with the slot returned by pcache_meta_find_latest().

Signed-off-by: Li Chen <[email protected]>
---
 drivers/md/dm-pcache/cache.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-pcache/cache.c b/drivers/md/dm-pcache/cache.c
index 698697a7a73c..6d5001548628 100644
--- a/drivers/md/dm-pcache/cache.c
+++ b/drivers/md/dm-pcache/cache.c
@@ -8,9 +8,11 @@
 
 struct kmem_cache *key_cache;
 
-static inline struct pcache_cache_info *get_cache_info_addr(struct 
pcache_cache *cache)
+static inline struct pcache_cache_info *
+get_cache_info_addr(struct pcache_cache *cache)
 {
-       return cache->cache_info_addr + cache->info_index;
+       return (struct pcache_cache_info *)((char *)cache->cache_info_addr +
+                                               (size_t)cache->info_index * 
PCACHE_CACHE_INFO_SIZE);
 }
 
 static void cache_info_write(struct pcache_cache *cache)
@@ -40,7 +42,12 @@ static int cache_info_init(struct pcache_cache *cache, 
struct pcache_cache_optio
        if (IS_ERR(cache_info_addr))
                return PTR_ERR(cache_info_addr);
 
-       if (cache_info_addr) {
+    if (cache_info_addr) {
+               int index = ((char *)cache_info_addr - (char 
*)cache->cache_info_addr) /
+                               PCACHE_CACHE_INFO_SIZE;
+
+               cache->info_index = (index + 1) % PCACHE_META_INDEX_MAX;
+
                if (opts->data_crc !=
                                (cache->cache_info.flags & 
PCACHE_CACHE_FLAGS_DATA_CRC)) {
                        pcache_dev_err(pcache, "invalid option for data_crc: 
%s, expected: %s",
-- 
2.51.0


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