dm cache: cache shrinking support

[platform/adaptation/renesas_rcar/renesas_kernel.git] / drivers / md / dm-cache-target.c

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 655994f..183dfc9 100644 (file)
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2502,26 +2502,71 @@ static int load_discard(void *context, sector_t discard_block_size,
        return 0;
 }
 
+static dm_cblock_t get_cache_dev_size(struct cache *cache)
+{
+       sector_t size = get_dev_size(cache->cache_dev);
+       (void) sector_div(size, cache->sectors_per_block);
+       return to_cblock(size);
+}
+
+static bool can_resize(struct cache *cache, dm_cblock_t new_size)
+{
+       if (from_cblock(new_size) > from_cblock(cache->cache_size))
+               return true;
+
+       /*
+        * We can't drop a dirty block when shrinking the cache.
+        */
+       while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
+               new_size = to_cblock(from_cblock(new_size) + 1);
+               if (is_dirty(cache, new_size)) {
+                       DMERR("unable to shrink cache; cache block %llu is dirty",
+                             (unsigned long long) from_cblock(new_size));
+                       return false;
+               }
+       }
+
+       return true;
+}
+
+static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
+{
+       int r;
+
+       r = dm_cache_resize(cache->cmd, cache->cache_size);
+       if (r) {
+               DMERR("could not resize cache metadata");
+               return r;
+       }
+
+       cache->cache_size = new_size;
+
+       return 0;
+}
+
 static int cache_preresume(struct dm_target *ti)
 {
        int r = 0;
        struct cache *cache = ti->private;
-       sector_t actual_cache_size = get_dev_size(cache->cache_dev);
-       (void) sector_div(actual_cache_size, cache->sectors_per_block);
+       dm_cblock_t csize = get_cache_dev_size(cache);
 
        /*
         * Check to see if the cache has resized.
         */
-       if (from_cblock(cache->cache_size) != actual_cache_size || !cache->sized) {
-               cache->cache_size = to_cblock(actual_cache_size);
-
-               r = dm_cache_resize(cache->cmd, cache->cache_size);
-               if (r) {
-                       DMERR("could not resize cache metadata");
+       if (!cache->sized) {
+               r = resize_cache_dev(cache, csize);
+               if (r)
                        return r;
-               }
 
                cache->sized = true;
+
+       } else if (csize != cache->cache_size) {
+               if (!can_resize(cache, csize))
+                       return -EINVAL;
+
+               r = resize_cache_dev(cache, csize);
+               if (r)
+                       return r;
        }
 
        if (!cache->loaded_mappings) {