# \[PATCH\] bcache: fix wrong BITMASK offset value for BDEV\_CACHE\_MODE - From: Lin Feng \ - Date: 2021-07-20 10:43:04 - List: linux-bcache - Page: https://ratatoskr.run/linux-bcache/2021/07/1452259 - Thread: https://ratatoskr.run/linux-bcache/2021/07/1452259/t.md ```text Original codes: BITMASK(CACHE_SYNC, struct cache_sb, flags, 0, 1); BITMASK(CACHE_DISCARD, struct cache_sb, flags, 1, 1); BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3); ... BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4); Should BDEV_CACHE_MODE bits start from bit-nr 5(2+3) else it overlaps with previous defined bit chunks, since we have 4 types of cache modes, BDEV_CACHE_MODE will overwrite CACHE_SYNC and CACHE_DISCARD bits. This bug stays there since first upstream version of bcache, don't know why it lives so long, or am i missing something, please point me out if I'm wrong, thanks! Signed-off-by: Lin Feng --- include/uapi/linux/bcache.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h index cf7399f03b71..dccd89756451 100644 --- a/include/uapi/linux/bcache.h +++ b/include/uapi/linux/bcache.h @@ -288,7 +288,7 @@ BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3); #define CACHE_REPLACEMENT_FIFO 1U #define CACHE_REPLACEMENT_RANDOM 2U -BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4); +BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 5, 4); #define CACHE_MODE_WRITETHROUGH 0U #define CACHE_MODE_WRITEBACK 1U #define CACHE_MODE_WRITEAROUND 2U -- 2.31.1 ```