diff options
author | Joe Thornber <ejt@redhat.com> | 2013-10-31 13:55:49 -0400 |
---|---|---|
committer | Mike Snitzer <snitzer@redhat.com> | 2013-11-11 11:37:45 -0500 |
commit | f494a9c6b1b6dd9a9f21bbb75d9210d478eeb498 (patch) | |
tree | e57197b7d38e7c6b2d718681fd70540ccc9a831e /drivers/md/dm-cache-target.c | |
parent | c9d28d5d09a0fd5f02f1321c8e18ff7d9f92270b (diff) |
dm cache: cache shrinking support
Allow a cache to shrink if the blocks being removed from the cache are
not dirty.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-cache-target.c')
-rw-r--r-- | drivers/md/dm-cache-target.c | 63 |
1 files changed, 54 insertions, 9 deletions
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 655994fdf30..183dfc9db29 100644 --- 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) { |