bcache: move uapi header bcache.h to bcache code directory

The header file include/uapi/linux/bcache.h is not really a user space
API heaer. This file defines the ondisk format of bcache internal meta
data but no one includes it from user space, bcache-tools has its own
copy of this header with minor modification.

Therefore, this patch moves include/uapi/linux/bcache.h to bcache code
directory as drivers/md/bcache/bcache_ondisk.h.

Suggested-by: Arnd Bergmann <[e-mail]>
Suggested-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Coly Li <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

drivers/md/bcache/bcache.h

···
 
 #define pr_fmt(fmt) "bcache: %s() " fmt, __func__
 
-#include <linux/bcache.h>
 #include <linux/bio.h>
 #include <linux/kobject.h>
 #include <linux/list.h>
···
 #include <linux/workqueue.h>
 #include <linux/kthread.h>
 
+#include "bcache_ondisk.h"
 #include "bset.h"
 #include "util.h"
 #include "closure.h"

drivers/md/bcache/bset.h

···
 #ifndef _BCACHE_BSET_H
 #define _BCACHE_BSET_H
 
-#include <linux/bcache.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 
+#include "bcache_ondisk.h"
 #include "util.h" /* for time_stats */
 
 /*

drivers/md/bcache/features.c

···
  * Copyright 2020 Coly Li <[e-mail]>
  *
  */
-#include <linux/bcache.h>
+#include "bcache_ondisk.h"
 #include "bcache.h"
 #include "features.h"
 

drivers/md/bcache/features.h

···
 #ifndef _BCACHE_FEATURES_H
 #define _BCACHE_FEATURES_H
 
-#include <linux/bcache.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
+
+#include "bcache_ondisk.h"
 
 #define BCH_FEATURE_COMPAT		0
 #define BCH_FEATURE_RO_COMPAT		1