From 4c1ccd0896d6a45f2159280d957afd441a7aeaba Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 25 Jul 2020 20:00:29 +0800 Subject: [PATCH] bcache: struct cache_sb is only for in-memory super block now We have struct cache_sb_disk for on-disk super block already, it is unnecessary to keep the in-memory super block format exactly mapping to the on-disk struct layout. This patch adds code comments to notice that struct cache_sb is not exactly mapping to cache_sb_disk, and removes the useless member csum and pad[5]. Although struct cache_sb does not belong to uapi, but there are still some on-disk format related macros reference it and it is unncessary to get rid of such dependency now. So struct cache_sb will continue to stay in include/uapi/linux/bache.h for now. Signed-off-by: Coly Li Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe --- include/uapi/linux/bcache.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h index 47df2db..0ef984e 100644 --- a/include/uapi/linux/bcache.h +++ b/include/uapi/linux/bcache.h @@ -215,8 +215,13 @@ struct cache_sb_disk { __le64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */ }; +/* + * This is for in-memory bcache super block. + * NOTE: cache_sb is NOT exactly mapping to cache_sb_disk, the member + * size, ordering and even whole struct size may be different + * from cache_sb_disk. + */ struct cache_sb { - __u64 csum; __u64 offset; /* sector where this sb was written */ __u64 version; @@ -236,8 +241,6 @@ struct cache_sb { __u64 feature_incompat; __u64 feature_ro_compat; - __u64 pad[5]; - union { struct { /* Cache devices */ @@ -245,7 +248,6 @@ struct cache_sb { __u16 block_size; /* sectors */ __u16 bucket_size; /* sectors */ - __u16 nr_in_set; __u16 nr_this_dev; }; -- 2.7.4