1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2#ifndef _LINUX_BCACHE_H
3#define _LINUX_BCACHE_H
4
5/*
6 * Bcache on disk data structures
7 */
8
9#include <linux/types.h>
10
11#define BITMASK(name, type, field, offset, size) \
12static inline __u64 name(const type *k) \
13{ return (k->field >> offset) & ~(~0ULL << size); } \
14 \
15static inline void SET_##name(type *k, __u64 v) \
16{ \
17 k->field &= ~(~(~0ULL << size) << offset); \
18 k->field |= (v & ~(~0ULL << size)) << offset; \
19}
20
21/* Btree keys - all units are in sectors */
22
23struct bkey {
24 __u64 high;
25 __u64 low;
26 __u64 ptr[];
27};
28
29#define KEY_FIELD(name, field, offset, size) \
30 BITMASK(name, struct bkey, field, offset, size)
31
32#define PTR_FIELD(name, offset, size) \
33static inline __u64 name(const struct bkey *k, unsigned int i) \
34{ return (k->ptr[i] >> offset) & ~(~0ULL << size); } \
35 \
36static inline void SET_##name(struct bkey *k, unsigned int i, __u64 v) \
37{ \
38 k->ptr[i] &= ~(~(~0ULL << size) << offset); \
39 k->ptr[i] |= (v & ~(~0ULL << size)) << offset; \
40}
41
42#define KEY_SIZE_BITS 16
43#define KEY_MAX_U64S 8
44
45KEY_FIELD(KEY_PTRS, high, 60, 3)
46KEY_FIELD(__PAD0, high, 58, 2)
47KEY_FIELD(KEY_CSUM, high, 56, 2)
48KEY_FIELD(__PAD1, high, 55, 1)
49KEY_FIELD(KEY_DIRTY, high, 36, 1)
50
51KEY_FIELD(KEY_SIZE, high, 20, KEY_SIZE_BITS)
52KEY_FIELD(KEY_INODE, high, 0, 20)
53
54/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
55
56static inline __u64 KEY_OFFSET(const struct bkey *k)
57{
58 return k->low;
59}
60
61static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
62{
63 k->low = v;
64}
65
66/*
67 * The high bit being set is a relic from when we used it to do binary
68 * searches - it told you where a key started. It's not used anymore,
69 * and can probably be safely dropped.
70 */
71#define KEY(inode, offset, size) \
72((struct bkey) { \
73 .high = (1ULL << 63) | ((__u64) (size) << 20) | (inode), \
74 .low = (offset) \
75})
76
77#define ZERO_KEY KEY(0, 0, 0)
78
79#define MAX_KEY_INODE (~(~0 << 20))
80#define MAX_KEY_OFFSET (~0ULL >> 1)
81#define MAX_KEY KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
82
83#define KEY_START(k) (KEY_OFFSET(k) - KEY_SIZE(k))
84#define START_KEY(k) KEY(KEY_INODE(k), KEY_START(k), 0)
85
86#define PTR_DEV_BITS 12
87
88PTR_FIELD(PTR_DEV, 51, PTR_DEV_BITS)
89PTR_FIELD(PTR_OFFSET, 8, 43)
90PTR_FIELD(PTR_GEN, 0, 8)
91
92#define PTR_CHECK_DEV ((1 << PTR_DEV_BITS) - 1)
93
94#define MAKE_PTR(gen, offset, dev) \
95 ((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
96
97/* Bkey utility code */
98
99static inline unsigned long bkey_u64s(const struct bkey *k)
100{
101 return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
102}
103
104static inline unsigned long bkey_bytes(const struct bkey *k)
105{
106 return bkey_u64s(k) * sizeof(__u64);
107}
108
109#define bkey_copy(_dest, _src) unsafe_memcpy(_dest, _src, bkey_bytes(_src), \
110 /* bkey is always padded */)
111
112static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
113{
114 SET_KEY_INODE(k: dest, v: KEY_INODE(k: src));
115 SET_KEY_OFFSET(k: dest, v: KEY_OFFSET(k: src));
116}
117
118static inline struct bkey *bkey_next(const struct bkey *k)
119{
120 __u64 *d = (void *) k;
121
122 return (struct bkey *) (d + bkey_u64s(k));
123}
124
125static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)
126{
127 __u64 *d = (void *) k;
128
129 return (struct bkey *) (d + nr_keys);
130}
131/* Enough for a key with 6 pointers */
132#define BKEY_PAD 8
133
134#define BKEY_PADDED(key) \
135 union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
136
137/* Superblock */
138
139/* Version 0: Cache device
140 * Version 1: Backing device
141 * Version 2: Seed pointer into btree node checksum
142 * Version 3: Cache device with new UUID format
143 * Version 4: Backing device with data offset
144 */
145#define BCACHE_SB_VERSION_CDEV 0
146#define BCACHE_SB_VERSION_BDEV 1
147#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
148#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
149#define BCACHE_SB_VERSION_CDEV_WITH_FEATURES 5
150#define BCACHE_SB_VERSION_BDEV_WITH_FEATURES 6
151#define BCACHE_SB_MAX_VERSION 6
152
153#define SB_SECTOR 8
154#define SB_OFFSET (SB_SECTOR << SECTOR_SHIFT)
155#define SB_SIZE 4096
156#define SB_LABEL_SIZE 32
157#define SB_JOURNAL_BUCKETS 256U
158/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
159#define MAX_CACHES_PER_SET 8
160
161#define BDEV_DATA_START_DEFAULT 16 /* sectors */
162
163struct cache_sb_disk {
164 __le64 csum;
165 __le64 offset; /* sector where this sb was written */
166 __le64 version;
167
168 __u8 magic[16];
169
170 __u8 uuid[16];
171 union {
172 __u8 set_uuid[16];
173 __le64 set_magic;
174 };
175 __u8 label[SB_LABEL_SIZE];
176
177 __le64 flags;
178 __le64 seq;
179
180 __le64 feature_compat;
181 __le64 feature_incompat;
182 __le64 feature_ro_compat;
183
184 __le64 pad[5];
185
186 union {
187 struct {
188 /* Cache devices */
189 __le64 nbuckets; /* device size */
190
191 __le16 block_size; /* sectors */
192 __le16 bucket_size; /* sectors */
193
194 __le16 nr_in_set;
195 __le16 nr_this_dev;
196 };
197 struct {
198 /* Backing devices */
199 __le64 data_offset;
200
201 /*
202 * block_size from the cache device section is still used by
203 * backing devices, so don't add anything here until we fix
204 * things to not need it for backing devices anymore
205 */
206 };
207 };
208
209 __le32 last_mount; /* time overflow in y2106 */
210
211 __le16 first_bucket;
212 union {
213 __le16 njournal_buckets;
214 __le16 keys;
215 };
216 __le64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
217 __le16 obso_bucket_size_hi; /* obsoleted */
218};
219
220/*
221 * This is for in-memory bcache super block.
222 * NOTE: cache_sb is NOT exactly mapping to cache_sb_disk, the member
223 * size, ordering and even whole struct size may be different
224 * from cache_sb_disk.
225 */
226struct cache_sb {
227 __u64 offset; /* sector where this sb was written */
228 __u64 version;
229
230 __u8 magic[16];
231
232 __u8 uuid[16];
233 union {
234 __u8 set_uuid[16];
235 __u64 set_magic;
236 };
237 __u8 label[SB_LABEL_SIZE];
238
239 __u64 flags;
240 __u64 seq;
241
242 __u64 feature_compat;
243 __u64 feature_incompat;
244 __u64 feature_ro_compat;
245
246 union {
247 struct {
248 /* Cache devices */
249 __u64 nbuckets; /* device size */
250
251 __u16 block_size; /* sectors */
252 __u16 nr_in_set;
253 __u16 nr_this_dev;
254 __u32 bucket_size; /* sectors */
255 };
256 struct {
257 /* Backing devices */
258 __u64 data_offset;
259
260 /*
261 * block_size from the cache device section is still used by
262 * backing devices, so don't add anything here until we fix
263 * things to not need it for backing devices anymore
264 */
265 };
266 };
267
268 __u32 last_mount; /* time overflow in y2106 */
269
270 __u16 first_bucket;
271 union {
272 __u16 njournal_buckets;
273 __u16 keys;
274 };
275 __u64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
276};
277
278static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
279{
280 return sb->version == BCACHE_SB_VERSION_BDEV
281 || sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET
282 || sb->version == BCACHE_SB_VERSION_BDEV_WITH_FEATURES;
283}
284
285BITMASK(CACHE_SYNC, struct cache_sb, flags, 0, 1);
286BITMASK(CACHE_DISCARD, struct cache_sb, flags, 1, 1);
287BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3);
288#define CACHE_REPLACEMENT_LRU 0U
289#define CACHE_REPLACEMENT_FIFO 1U
290#define CACHE_REPLACEMENT_RANDOM 2U
291
292BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4);
293#define CACHE_MODE_WRITETHROUGH 0U
294#define CACHE_MODE_WRITEBACK 1U
295#define CACHE_MODE_WRITEAROUND 2U
296#define CACHE_MODE_NONE 3U
297BITMASK(BDEV_STATE, struct cache_sb, flags, 61, 2);
298#define BDEV_STATE_NONE 0U
299#define BDEV_STATE_CLEAN 1U
300#define BDEV_STATE_DIRTY 2U
301#define BDEV_STATE_STALE 3U
302
303/*
304 * Magic numbers
305 *
306 * The various other data structures have their own magic numbers, which are
307 * xored with the first part of the cache set's UUID
308 */
309
310#define JSET_MAGIC 0x245235c1a3625032ULL
311#define PSET_MAGIC 0x6750e15f87337f91ULL
312#define BSET_MAGIC 0x90135c78b99e07f5ULL
313
314static inline __u64 jset_magic(struct cache_sb *sb)
315{
316 return sb->set_magic ^ JSET_MAGIC;
317}
318
319static inline __u64 pset_magic(struct cache_sb *sb)
320{
321 return sb->set_magic ^ PSET_MAGIC;
322}
323
324static inline __u64 bset_magic(struct cache_sb *sb)
325{
326 return sb->set_magic ^ BSET_MAGIC;
327}
328
329/*
330 * Journal
331 *
332 * On disk format for a journal entry:
333 * seq is monotonically increasing; every journal entry has its own unique
334 * sequence number.
335 *
336 * last_seq is the oldest journal entry that still has keys the btree hasn't
337 * flushed to disk yet.
338 *
339 * version is for on disk format changes.
340 */
341
342#define BCACHE_JSET_VERSION_UUIDv1 1
343#define BCACHE_JSET_VERSION_UUID 1 /* Always latest UUID format */
344#define BCACHE_JSET_VERSION 1
345
346struct jset {
347 __u64 csum;
348 __u64 magic;
349 __u64 seq;
350 __u32 version;
351 __u32 keys;
352
353 __u64 last_seq;
354
355 BKEY_PADDED(uuid_bucket);
356 BKEY_PADDED(btree_root);
357 __u16 btree_level;
358 __u16 pad[3];
359
360 __u64 prio_bucket[MAX_CACHES_PER_SET];
361
362 union {
363 DECLARE_FLEX_ARRAY(struct bkey, start);
364 DECLARE_FLEX_ARRAY(__u64, d);
365 };
366};
367
368/* Bucket prios/gens */
369
370struct prio_set {
371 __u64 csum;
372 __u64 magic;
373 __u64 seq;
374 __u32 version;
375 __u32 pad;
376
377 __u64 next_bucket;
378
379 struct bucket_disk {
380 __u16 prio;
381 __u8 gen;
382 } __attribute((packed)) data[];
383};
384
385/* UUIDS - per backing device/flash only volume metadata */
386
387struct uuid_entry {
388 union {
389 struct {
390 __u8 uuid[16];
391 __u8 label[32];
392 __u32 first_reg; /* time overflow in y2106 */
393 __u32 last_reg;
394 __u32 invalidated;
395
396 __u32 flags;
397 /* Size of flash only volumes */
398 __u64 sectors;
399 };
400
401 __u8 pad[128];
402 };
403};
404
405BITMASK(UUID_FLASH_ONLY, struct uuid_entry, flags, 0, 1);
406
407/* Btree nodes */
408
409/* Version 1: Seed pointer into btree node checksum
410 */
411#define BCACHE_BSET_CSUM 1
412#define BCACHE_BSET_VERSION 1
413
414/*
415 * Btree nodes
416 *
417 * On disk a btree node is a list/log of these; within each set the keys are
418 * sorted
419 */
420struct bset {
421 __u64 csum;
422 __u64 magic;
423 __u64 seq;
424 __u32 version;
425 __u32 keys;
426
427 union {
428 DECLARE_FLEX_ARRAY(struct bkey, start);
429 DECLARE_FLEX_ARRAY(__u64, d);
430 };
431};
432
433/* OBSOLETE */
434
435/* UUIDS - per backing device/flash only volume metadata */
436
437struct uuid_entry_v0 {
438 __u8 uuid[16];
439 __u8 label[32];
440 __u32 first_reg;
441 __u32 last_reg;
442 __u32 invalidated;
443 __u32 pad;
444};
445
446#endif /* _LINUX_BCACHE_H */
447

source code of linux/drivers/md/bcache/bcache_ondisk.h