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| author | Ming-Hung Tsai <mtsai@redhat.com> | 2024-10-22 15:13:39 +0800 |
|---|---|---|
| committer | Mikulas Patocka <mpatocka@redhat.com> | 2024-11-04 17:39:31 +0100 |
| commit | f484697e619a83ecc370443a34746379ad99d204 (patch) | |
| tree | 63bdf5b8de9075c414540643ef739b61a51e09fd /drivers | |
| parent | 792227719725497ce10a8039803bec13f89f8910 (diff) | |
| download | linux-f484697e619a83ecc370443a34746379ad99d204.tar.gz linux-f484697e619a83ecc370443a34746379ad99d204.tar.bz2 linux-f484697e619a83ecc370443a34746379ad99d204.zip | |
dm cache: optimize dirty bit checking with find_next_bit when resizing
When shrinking the fast device, dm-cache iteratively searches for a
dirty bit among the cache blocks to be dropped, which is less efficient.
Use find_next_bit instead, as it is twice as fast as the iterative
approach with test_bit.
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Fixes: f494a9c6b1b6 ("dm cache: cache shrinking support")
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Joe Thornber <thornber@redhat.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/md/dm-cache-target.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 1fcd8c5c220e..fa8ef2c32af8 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2911,14 +2911,14 @@ static bool can_resize(struct cache *cache, dm_cblock_t new_size) /* * We can't drop a dirty block when shrinking the cache. */ - while (from_cblock(new_size) < from_cblock(cache->cache_size)) { - if (is_dirty(cache, new_size)) { - DMERR("%s: unable to shrink cache; cache block %llu is dirty", - cache_device_name(cache), - (unsigned long long) from_cblock(new_size)); - return false; - } - new_size = to_cblock(from_cblock(new_size) + 1); + new_size = to_cblock(find_next_bit(cache->dirty_bitset, + from_cblock(cache->cache_size), + from_cblock(new_size))); + if (new_size != cache->cache_size) { + DMERR("%s: unable to shrink cache; cache block %llu is dirty", + cache_device_name(cache), + (unsigned long long) from_cblock(new_size)); + return false; } return true; |