1#ifndef _LINUX_BCACHE_H
2#define _LINUX_BCACHE_H
3
4/*
5 * Bcache on disk data structures
6 */
7
8#include <asm/types.h>
9
10#define BITMASK(name, type, field, offset, size)		\
11static inline __u64 name(const type *k)				\
12{ return (k->field >> offset) & ~(~0ULL << size); }		\
13								\
14static inline void SET_##name(type *k, __u64 v)			\
15{								\
16	k->field &= ~(~(~0ULL << size) << offset);		\
17	k->field |= (v & ~(~0ULL << size)) << offset;		\
18}
19
20/* Btree keys - all units are in sectors */
21
22struct bkey {
23	__u64	high;
24	__u64	low;
25	__u64	ptr[];
26};
27
28#define KEY_FIELD(name, field, offset, size)				\
29	BITMASK(name, struct bkey, field, offset, size)
30
31#define PTR_FIELD(name, offset, size)					\
32static inline __u64 name(const struct bkey *k, unsigned i)		\
33{ return (k->ptr[i] >> offset) & ~(~0ULL << size); }			\
34									\
35static inline void SET_##name(struct bkey *k, unsigned i, __u64 v)	\
36{									\
37	k->ptr[i] &= ~(~(~0ULL << size) << offset);			\
38	k->ptr[i] |= (v & ~(~0ULL << size)) << offset;			\
39}
40
41#define KEY_SIZE_BITS		16
42#define KEY_MAX_U64S		8
43
44KEY_FIELD(KEY_PTRS,	high, 60, 3)
45KEY_FIELD(HEADER_SIZE,	high, 58, 2)
46KEY_FIELD(KEY_CSUM,	high, 56, 2)
47KEY_FIELD(KEY_PINNED,	high, 55, 1)
48KEY_FIELD(KEY_DIRTY,	high, 36, 1)
49
50KEY_FIELD(KEY_SIZE,	high, 20, KEY_SIZE_BITS)
51KEY_FIELD(KEY_INODE,	high, 0,  20)
52
53/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
54
55static inline __u64 KEY_OFFSET(const struct bkey *k)
56{
57	return k->low;
58}
59
60static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
61{
62	k->low = v;
63}
64
65/*
66 * The high bit being set is a relic from when we used it to do binary
67 * searches - it told you where a key started. It's not used anymore,
68 * and can probably be safely dropped.
69 */
70#define KEY(inode, offset, size)					\
71((struct bkey) {							\
72	.high = (1ULL << 63) | ((__u64) (size) << 20) | (inode),	\
73	.low = (offset)							\
74})
75
76#define ZERO_KEY			KEY(0, 0, 0)
77
78#define MAX_KEY_INODE			(~(~0 << 20))
79#define MAX_KEY_OFFSET			(~0ULL >> 1)
80#define MAX_KEY				KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
81
82#define KEY_START(k)			(KEY_OFFSET(k) - KEY_SIZE(k))
83#define START_KEY(k)			KEY(KEY_INODE(k), KEY_START(k), 0)
84
85#define PTR_DEV_BITS			12
86
87PTR_FIELD(PTR_DEV,			51, PTR_DEV_BITS)
88PTR_FIELD(PTR_OFFSET,			8,  43)
89PTR_FIELD(PTR_GEN,			0,  8)
90
91#define PTR_CHECK_DEV			((1 << PTR_DEV_BITS) - 1)
92
93#define PTR(gen, offset, dev)						\
94	((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
95
96/* Bkey utility code */
97
98static inline unsigned long bkey_u64s(const struct bkey *k)
99{
100	return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
101}
102
103static inline unsigned long bkey_bytes(const struct bkey *k)
104{
105	return bkey_u64s(k) * sizeof(__u64);
106}
107
108#define bkey_copy(_dest, _src)	memcpy(_dest, _src, bkey_bytes(_src))
109
110static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
111{
112	SET_KEY_INODE(dest, KEY_INODE(src));
113	SET_KEY_OFFSET(dest, KEY_OFFSET(src));
114}
115
116static inline struct bkey *bkey_next(const struct bkey *k)
117{
118	__u64 *d = (void *) k;
119	return (struct bkey *) (d + bkey_u64s(k));
120}
121
122static inline struct bkey *bkey_idx(const struct bkey *k, unsigned nr_keys)
123{
124	__u64 *d = (void *) k;
125	return (struct bkey *) (d + nr_keys);
126}
127/* Enough for a key with 6 pointers */
128#define BKEY_PAD		8
129
130#define BKEY_PADDED(key)					\
131	union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
132
133/* Superblock */
134
135/* Version 0: Cache device
136 * Version 1: Backing device
137 * Version 2: Seed pointer into btree node checksum
138 * Version 3: Cache device with new UUID format
139 * Version 4: Backing device with data offset
140 */
141#define BCACHE_SB_VERSION_CDEV		0
142#define BCACHE_SB_VERSION_BDEV		1
143#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
144#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
145#define BCACHE_SB_MAX_VERSION		4
146
147#define SB_SECTOR			8
148#define SB_SIZE				4096
149#define SB_LABEL_SIZE			32
150#define SB_JOURNAL_BUCKETS		256U
151/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
152#define MAX_CACHES_PER_SET		8
153
154#define BDEV_DATA_START_DEFAULT		16	/* sectors */
155
156struct cache_sb {
157	__u64			csum;
158	__u64			offset;	/* sector where this sb was written */
159	__u64			version;
160
161	__u8			magic[16];
162
163	__u8			uuid[16];
164	union {
165		__u8		set_uuid[16];
166		__u64		set_magic;
167	};
168	__u8			label[SB_LABEL_SIZE];
169
170	__u64			flags;
171	__u64			seq;
172	__u64			pad[8];
173
174	union {
175	struct {
176		/* Cache devices */
177		__u64		nbuckets;	/* device size */
178
179		__u16		block_size;	/* sectors */
180		__u16		bucket_size;	/* sectors */
181
182		__u16		nr_in_set;
183		__u16		nr_this_dev;
184	};
185	struct {
186		/* Backing devices */
187		__u64		data_offset;
188
189		/*
190		 * block_size from the cache device section is still used by
191		 * backing devices, so don't add anything here until we fix
192		 * things to not need it for backing devices anymore
193		 */
194	};
195	};
196
197	__u32			last_mount;	/* time_t */
198
199	__u16			first_bucket;
200	union {
201		__u16		njournal_buckets;
202		__u16		keys;
203	};
204	__u64			d[SB_JOURNAL_BUCKETS];	/* journal buckets */
205};
206
207static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
208{
209	return sb->version == BCACHE_SB_VERSION_BDEV
210		|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
211}
212
213BITMASK(CACHE_SYNC,			struct cache_sb, flags, 0, 1);
214BITMASK(CACHE_DISCARD,			struct cache_sb, flags, 1, 1);
215BITMASK(CACHE_REPLACEMENT,		struct cache_sb, flags, 2, 3);
216#define CACHE_REPLACEMENT_LRU		0U
217#define CACHE_REPLACEMENT_FIFO		1U
218#define CACHE_REPLACEMENT_RANDOM	2U
219
220BITMASK(BDEV_CACHE_MODE,		struct cache_sb, flags, 0, 4);
221#define CACHE_MODE_WRITETHROUGH		0U
222#define CACHE_MODE_WRITEBACK		1U
223#define CACHE_MODE_WRITEAROUND		2U
224#define CACHE_MODE_NONE			3U
225BITMASK(BDEV_STATE,			struct cache_sb, flags, 61, 2);
226#define BDEV_STATE_NONE			0U
227#define BDEV_STATE_CLEAN		1U
228#define BDEV_STATE_DIRTY		2U
229#define BDEV_STATE_STALE		3U
230
231/*
232 * Magic numbers
233 *
234 * The various other data structures have their own magic numbers, which are
235 * xored with the first part of the cache set's UUID
236 */
237
238#define JSET_MAGIC			0x245235c1a3625032ULL
239#define PSET_MAGIC			0x6750e15f87337f91ULL
240#define BSET_MAGIC			0x90135c78b99e07f5ULL
241
242static inline __u64 jset_magic(struct cache_sb *sb)
243{
244	return sb->set_magic ^ JSET_MAGIC;
245}
246
247static inline __u64 pset_magic(struct cache_sb *sb)
248{
249	return sb->set_magic ^ PSET_MAGIC;
250}
251
252static inline __u64 bset_magic(struct cache_sb *sb)
253{
254	return sb->set_magic ^ BSET_MAGIC;
255}
256
257/*
258 * Journal
259 *
260 * On disk format for a journal entry:
261 * seq is monotonically increasing; every journal entry has its own unique
262 * sequence number.
263 *
264 * last_seq is the oldest journal entry that still has keys the btree hasn't
265 * flushed to disk yet.
266 *
267 * version is for on disk format changes.
268 */
269
270#define BCACHE_JSET_VERSION_UUIDv1	1
271#define BCACHE_JSET_VERSION_UUID	1	/* Always latest UUID format */
272#define BCACHE_JSET_VERSION		1
273
274struct jset {
275	__u64			csum;
276	__u64			magic;
277	__u64			seq;
278	__u32			version;
279	__u32			keys;
280
281	__u64			last_seq;
282
283	BKEY_PADDED(uuid_bucket);
284	BKEY_PADDED(btree_root);
285	__u16			btree_level;
286	__u16			pad[3];
287
288	__u64			prio_bucket[MAX_CACHES_PER_SET];
289
290	union {
291		struct bkey	start[0];
292		__u64		d[0];
293	};
294};
295
296/* Bucket prios/gens */
297
298struct prio_set {
299	__u64			csum;
300	__u64			magic;
301	__u64			seq;
302	__u32			version;
303	__u32			pad;
304
305	__u64			next_bucket;
306
307	struct bucket_disk {
308		__u16		prio;
309		__u8		gen;
310	} __attribute((packed)) data[];
311};
312
313/* UUIDS - per backing device/flash only volume metadata */
314
315struct uuid_entry {
316	union {
317		struct {
318			__u8	uuid[16];
319			__u8	label[32];
320			__u32	first_reg;
321			__u32	last_reg;
322			__u32	invalidated;
323
324			__u32	flags;
325			/* Size of flash only volumes */
326			__u64	sectors;
327		};
328
329		__u8		pad[128];
330	};
331};
332
333BITMASK(UUID_FLASH_ONLY,	struct uuid_entry, flags, 0, 1);
334
335/* Btree nodes */
336
337/* Version 1: Seed pointer into btree node checksum
338 */
339#define BCACHE_BSET_CSUM		1
340#define BCACHE_BSET_VERSION		1
341
342/*
343 * Btree nodes
344 *
345 * On disk a btree node is a list/log of these; within each set the keys are
346 * sorted
347 */
348struct bset {
349	__u64			csum;
350	__u64			magic;
351	__u64			seq;
352	__u32			version;
353	__u32			keys;
354
355	union {
356		struct bkey	start[0];
357		__u64		d[0];
358	};
359};
360
361/* OBSOLETE */
362
363/* UUIDS - per backing device/flash only volume metadata */
364
365struct uuid_entry_v0 {
366	__u8		uuid[16];
367	__u8		label[32];
368	__u32		first_reg;
369	__u32		last_reg;
370	__u32		invalidated;
371	__u32		pad;
372};
373
374#endif /* _LINUX_BCACHE_H */
375