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bcache: struct cache_sb is only for in-memory super block now

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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 <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Coly Li
2020-07-25 20:00:29 +08:00
committed by Jens Axboe
parent 198efa35c5
commit 4c1ccd0896
1 changed files with 6 additions and 4 deletions
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10
include/uapi/linux/bcache.h
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@@ -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;
};