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linux-next/include/uapi/linux/bcache.h
Christoph Hellwig 6321bef028 bcache: use read_cache_page_gfp to read the superblock 
Avoid a pointless dependency on buffer heads in bcache by simply open
coding reading a single page.  Also add a SB_OFFSET define for the
byte offset of the superblock instead of using magic numbers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-01-23 11:40:01 -07:00

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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _LINUX_BCACHE_H
#define _LINUX_BCACHE_H
/*
* Bcache on disk data structures
*/
#include <linux/types.h>
#define BITMASK(name, type, field, offset, size) \
static inline __u64 name(const type *k) \
{ return (k->field >> offset) & ~(~0ULL << size); } \
\
static inline void SET_##name(type *k, __u64 v) \
{ \
k->field &= ~(~(~0ULL << size) << offset); \
k->field |= (v & ~(~0ULL << size)) << offset; \
}
/* Btree keys - all units are in sectors */
struct bkey {
__u64 high;
__u64 low;
__u64 ptr[];
};
#define KEY_FIELD(name, field, offset, size) \
BITMASK(name, struct bkey, field, offset, size)
#define PTR_FIELD(name, offset, size) \
static inline __u64 name(const struct bkey *k, unsigned int i) \
{ return (k->ptr[i] >> offset) & ~(~0ULL << size); } \
\
static inline void SET_##name(struct bkey *k, unsigned int i, __u64 v) \
{ \
k->ptr[i] &= ~(~(~0ULL << size) << offset); \
k->ptr[i] |= (v & ~(~0ULL << size)) << offset; \
}
#define KEY_SIZE_BITS 16
#define KEY_MAX_U64S 8
KEY_FIELD(KEY_PTRS, high, 60, 3)
KEY_FIELD(HEADER_SIZE, high, 58, 2)
KEY_FIELD(KEY_CSUM, high, 56, 2)
KEY_FIELD(KEY_PINNED, high, 55, 1)
KEY_FIELD(KEY_DIRTY, high, 36, 1)
KEY_FIELD(KEY_SIZE, high, 20, KEY_SIZE_BITS)
KEY_FIELD(KEY_INODE, high, 0, 20)
/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
static inline __u64 KEY_OFFSET(const struct bkey *k)
{
return k->low;
}
static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
{
k->low = v;
}
/*
* The high bit being set is a relic from when we used it to do binary
* searches - it told you where a key started. It's not used anymore,
* and can probably be safely dropped.
*/
#define KEY(inode, offset, size) \
((struct bkey) { \
.high = (1ULL << 63) | ((__u64) (size) << 20) | (inode), \
.low = (offset) \
})
#define ZERO_KEY KEY(0, 0, 0)
#define MAX_KEY_INODE (~(~0 << 20))
#define MAX_KEY_OFFSET (~0ULL >> 1)
#define MAX_KEY KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
#define KEY_START(k) (KEY_OFFSET(k) - KEY_SIZE(k))
#define START_KEY(k) KEY(KEY_INODE(k), KEY_START(k), 0)
#define PTR_DEV_BITS 12
PTR_FIELD(PTR_DEV, 51, PTR_DEV_BITS)
PTR_FIELD(PTR_OFFSET, 8, 43)
PTR_FIELD(PTR_GEN, 0, 8)
#define PTR_CHECK_DEV ((1 << PTR_DEV_BITS) - 1)
#define MAKE_PTR(gen, offset, dev) \
((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
/* Bkey utility code */
static inline unsigned long bkey_u64s(const struct bkey *k)
{
return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
}
static inline unsigned long bkey_bytes(const struct bkey *k)
{
return bkey_u64s(k) * sizeof(__u64);
}
#define bkey_copy(_dest, _src) memcpy(_dest, _src, bkey_bytes(_src))
static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
{
SET_KEY_INODE(dest, KEY_INODE(src));
SET_KEY_OFFSET(dest, KEY_OFFSET(src));
}
static inline struct bkey *bkey_next(const struct bkey *k)
{
__u64 *d = (void *) k;
return (struct bkey *) (d + bkey_u64s(k));
}
static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)
{
__u64 *d = (void *) k;
return (struct bkey *) (d + nr_keys);
}
/* Enough for a key with 6 pointers */
#define BKEY_PAD 8
#define BKEY_PADDED(key) \
union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
/* Superblock */
/* Version 0: Cache device
* Version 1: Backing device
* Version 2: Seed pointer into btree node checksum
* Version 3: Cache device with new UUID format
* Version 4: Backing device with data offset
*/
#define BCACHE_SB_VERSION_CDEV 0
#define BCACHE_SB_VERSION_BDEV 1
#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
#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
/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
#define MAX_CACHES_PER_SET 8
#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 */
__u64 version;
__u8 magic[16];
__u8 uuid[16];
union {
__u8 set_uuid[16];
__u64 set_magic;
};
__u8 label[SB_LABEL_SIZE];
__u64 flags;
__u64 seq;
__u64 pad[8];
union {
struct {
/* Cache devices */
__u64 nbuckets; /* device size */
__u16 block_size; /* sectors */
__u16 bucket_size; /* sectors */
__u16 nr_in_set;
__u16 nr_this_dev;
};
struct {
/* Backing devices */
__u64 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
*/
};
};
__u32 last_mount; /* time overflow in y2106 */
__u16 first_bucket;
union {
__u16 njournal_buckets;
__u16 keys;
};
__u64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
};
static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
{
return sb->version == BCACHE_SB_VERSION_BDEV
|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
}
BITMASK(CACHE_SYNC, struct cache_sb, flags, 0, 1);
BITMASK(CACHE_DISCARD, struct cache_sb, flags, 1, 1);
BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3);
#define CACHE_REPLACEMENT_LRU 0U
#define CACHE_REPLACEMENT_FIFO 1U
#define CACHE_REPLACEMENT_RANDOM 2U
BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4);
#define CACHE_MODE_WRITETHROUGH 0U
#define CACHE_MODE_WRITEBACK 1U
#define CACHE_MODE_WRITEAROUND 2U
#define CACHE_MODE_NONE 3U
BITMASK(BDEV_STATE, struct cache_sb, flags, 61, 2);
#define BDEV_STATE_NONE 0U
#define BDEV_STATE_CLEAN 1U
#define BDEV_STATE_DIRTY 2U
#define BDEV_STATE_STALE 3U
/*
* Magic numbers
*
* The various other data structures have their own magic numbers, which are
* xored with the first part of the cache set's UUID
*/
#define JSET_MAGIC 0x245235c1a3625032ULL
#define PSET_MAGIC 0x6750e15f87337f91ULL
#define BSET_MAGIC 0x90135c78b99e07f5ULL
static inline __u64 jset_magic(struct cache_sb *sb)
{
return sb->set_magic ^ JSET_MAGIC;
}
static inline __u64 pset_magic(struct cache_sb *sb)
{
return sb->set_magic ^ PSET_MAGIC;
}
static inline __u64 bset_magic(struct cache_sb *sb)
{
return sb->set_magic ^ BSET_MAGIC;
}
/*
* Journal
*
* On disk format for a journal entry:
* seq is monotonically increasing; every journal entry has its own unique
* sequence number.
*
* last_seq is the oldest journal entry that still has keys the btree hasn't
* flushed to disk yet.
*
* version is for on disk format changes.
*/
#define BCACHE_JSET_VERSION_UUIDv1 1
#define BCACHE_JSET_VERSION_UUID 1 /* Always latest UUID format */
#define BCACHE_JSET_VERSION 1
struct jset {
__u64 csum;
__u64 magic;
__u64 seq;
__u32 version;
__u32 keys;
__u64 last_seq;
BKEY_PADDED(uuid_bucket);
BKEY_PADDED(btree_root);
__u16 btree_level;
__u16 pad[3];
__u64 prio_bucket[MAX_CACHES_PER_SET];
union {
struct bkey start[0];
__u64 d[0];
};
};
/* Bucket prios/gens */
struct prio_set {
__u64 csum;
__u64 magic;
__u64 seq;
__u32 version;
__u32 pad;
__u64 next_bucket;
struct bucket_disk {
__u16 prio;
__u8 gen;
} __attribute((packed)) data[];
};
/* UUIDS - per backing device/flash only volume metadata */
struct uuid_entry {
union {
struct {
__u8 uuid[16];
__u8 label[32];
__u32 first_reg; /* time overflow in y2106 */
__u32 last_reg;
__u32 invalidated;
__u32 flags;
/* Size of flash only volumes */
__u64 sectors;
};
__u8 pad[128];
};
};
BITMASK(UUID_FLASH_ONLY, struct uuid_entry, flags, 0, 1);
/* Btree nodes */
/* Version 1: Seed pointer into btree node checksum
*/
#define BCACHE_BSET_CSUM 1
#define BCACHE_BSET_VERSION 1
/*
* Btree nodes
*
* On disk a btree node is a list/log of these; within each set the keys are
* sorted
*/
struct bset {
__u64 csum;
__u64 magic;
__u64 seq;
__u32 version;
__u32 keys;
union {
struct bkey start[0];
__u64 d[0];
};
};
/* OBSOLETE */
/* UUIDS - per backing device/flash only volume metadata */
struct uuid_entry_v0 {
__u8 uuid[16];
__u8 label[32];
__u32 first_reg;
__u32 last_reg;
__u32 invalidated;
__u32 pad;
};
#endif /* _LINUX_BCACHE_H */
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