On 8/15/20 6:10 AM, Coly Li wrote:

struct cache_sb does not exactly map to cache_sb_disk, it is only for
in-memory super block and dosn't belong to uapi bcache.h.

This patch moves the struct cache_sb definition and other depending
macros and inline routines from include/uapi/linux/bcache.h to
drivers/md/bcache/bcache.h, this is the proper location to have them.

And that I'm not sure of.
The 'uapi' directory is there to hold the user-visible kernel API.
So the real question is whether the bcache superblock is or should be 
part of the user API or not.
Hence an alternative way would be to detail out the entire superblock in
include/uapi/linux/bcache.h, and remove the definitions from
drivers/md/bcache/bcache.h.

There doesn't seem to be a consistent policy here; some things like MD 
have their superblock in the uapi directory, others like btrfs only have 
the ioctl definitions there.

I'm somewhat in favour of having the superblock definition as part of 
the uapi, as this would make writing external tools like blkid easier.
But then the ultimate decision is yours.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
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