Merge tag 'for-5.6/drivers-2020-01-27' of git://git.kernel.dk/linux-block

Pull block driver updates from Jens Axboe:
 "Like the core side, not a lot of changes here, just two main items:

   - Series of patches (via Coly) with fixes for bcache (Coly,
     Christoph)

   - MD pull request from Song"

* tag 'for-5.6/drivers-2020-01-27' of git://git.kernel.dk/linux-block: (31 commits)
  bcache: reap from tail of c->btree_cache in bch_mca_scan()
  bcache: reap c->btree_cache_freeable from the tail in bch_mca_scan()
  bcache: remove member accessed from struct btree
  bcache: print written and keys in trace_bcache_btree_write
  bcache: avoid unnecessary btree nodes flushing in btree_flush_write()
  bcache: add code comments for state->pool in __btree_sort()
  lib: crc64: include <linux/crc64.h> for 'crc64_be'
  bcache: use read_cache_page_gfp to read the superblock
  bcache: store a pointer to the on-disk sb in the cache and cached_dev structures
  bcache: return a pointer to the on-disk sb from read_super
  bcache: transfer the sb_page reference to register_{bdev,cache}
  bcache: fix use-after-free in register_bcache()
  bcache: properly initialize 'path' and 'err' in register_bcache()
  bcache: rework error unwinding in register_bcache
  bcache: use a separate data structure for the on-disk super block
  bcache: cached_dev_free needs to put the sb page
  md/raid1: introduce wait_for_serialization
  md/raid1: use bucket based mechanism for IO serialization
  md: introduce a new struct for IO serialization
  md: don't destroy serial_info_pool if serialize_policy is true
  ...

include/uapi/linux/bcache.h

@@ -148,6 +148,7 @@ static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)
 #define BCACHE_SB_MAX_VERSION		4
 
 #define SB_SECTOR			8
+#define SB_OFFSET			(SB_SECTOR << SECTOR_SHIFT)
 #define SB_SIZE				4096
 #define SB_LABEL_SIZE			32
 #define SB_JOURNAL_BUCKETS		256U
@@ -156,6 +157,57 @@ static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)
 
 #define BDEV_DATA_START_DEFAULT		16	/* sectors */
 
+struct cache_sb_disk {
+	__le64			csum;
+	__le64			offset;	/* sector where this sb was written */
+	__le64			version;
+
+	__u8			magic[16];
+
+	__u8			uuid[16];
+	union {
+		__u8		set_uuid[16];
+		__le64		set_magic;
+	};
+	__u8			label[SB_LABEL_SIZE];
+
+	__le64			flags;
+	__le64			seq;
+	__le64			pad[8];
+
+	union {
+	struct {
+		/* Cache devices */
+		__le64		nbuckets;	/* device size */
+
+		__le16		block_size;	/* sectors */
+		__le16		bucket_size;	/* sectors */
+
+		__le16		nr_in_set;
+		__le16		nr_this_dev;
+	};
+	struct {
+		/* Backing devices */
+		__le64		data_offset;
+
+		/*
+		 * block_size from the cache device section is still used by
+		 * backing devices, so don't add anything here until we fix
+		 * things to not need it for backing devices anymore
+		 */
+	};
+	};
+
+	__le32			last_mount;	/* time overflow in y2106 */
+
+	__le16			first_bucket;
+	union {
+		__le16		njournal_buckets;
+		__le16		keys;
+	};
+	__le64			d[SB_JOURNAL_BUCKETS];	/* journal buckets */
+};
+
 struct cache_sb {
 	__u64			csum;
 	__u64			offset;	/* sector where this sb was written */