1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _BCACHEFS_STR_HASH_H
3#define _BCACHEFS_STR_HASH_H
4
5#include "btree_iter.h"
6#include "btree_update.h"
7#include "checksum.h"
8#include "error.h"
9#include "inode.h"
10#include "siphash.h"
11#include "subvolume.h"
12#include "super.h"
13
14#include <linux/crc32c.h>
15#include <crypto/hash.h>
16#include <crypto/sha2.h>
17
18typedef unsigned __bitwise bch_str_hash_flags_t;
19
20enum bch_str_hash_flags {
21	__BCH_HASH_SET_MUST_CREATE,
22	__BCH_HASH_SET_MUST_REPLACE,
23};
24
25#define BCH_HASH_SET_MUST_CREATE	(__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_CREATE)
26#define BCH_HASH_SET_MUST_REPLACE	(__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_REPLACE)
27
28static inline enum bch_str_hash_type
29bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
30{
31	switch (opt) {
32	case BCH_STR_HASH_OPT_crc32c:
33		return BCH_STR_HASH_crc32c;
34	case BCH_STR_HASH_OPT_crc64:
35		return BCH_STR_HASH_crc64;
36	case BCH_STR_HASH_OPT_siphash:
37		return c->sb.features & (1ULL << BCH_FEATURE_new_siphash)
38			? BCH_STR_HASH_siphash
39			: BCH_STR_HASH_siphash_old;
40	default:
41	     BUG();
42	}
43}
44
45struct bch_hash_info {
46	u8			type;
47	/*
48	 * For crc32 or crc64 string hashes the first key value of
49	 * the siphash_key (k0) is used as the key.
50	 */
51	SIPHASH_KEY	siphash_key;
52};
53
54static inline struct bch_hash_info
55bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
56{
57	/* XXX ick */
58	struct bch_hash_info info = {
59		.type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
60			~(~0U << INODE_STR_HASH_BITS),
61		.siphash_key = { .k0 = bi->bi_hash_seed }
62	};
63
64	if (unlikely(info.type == BCH_STR_HASH_siphash_old)) {
65		SHASH_DESC_ON_STACK(desc, c->sha256);
66		u8 digest[SHA256_DIGEST_SIZE];
67
68		desc->tfm = c->sha256;
69
70		crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
71				    sizeof(bi->bi_hash_seed), digest);
72		memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
73	}
74
75	return info;
76}
77
78struct bch_str_hash_ctx {
79	union {
80		u32		crc32c;
81		u64		crc64;
82		SIPHASH_CTX	siphash;
83	};
84};
85
86static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
87				     const struct bch_hash_info *info)
88{
89	switch (info->type) {
90	case BCH_STR_HASH_crc32c:
91		ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
92				     sizeof(info->siphash_key.k0));
93		break;
94	case BCH_STR_HASH_crc64:
95		ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
96				      sizeof(info->siphash_key.k0));
97		break;
98	case BCH_STR_HASH_siphash_old:
99	case BCH_STR_HASH_siphash:
100		SipHash24_Init(&ctx->siphash, &info->siphash_key);
101		break;
102	default:
103		BUG();
104	}
105}
106
107static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
108				       const struct bch_hash_info *info,
109				       const void *data, size_t len)
110{
111	switch (info->type) {
112	case BCH_STR_HASH_crc32c:
113		ctx->crc32c = crc32c(ctx->crc32c, data, len);
114		break;
115	case BCH_STR_HASH_crc64:
116		ctx->crc64 = crc64_be(ctx->crc64, data, len);
117		break;
118	case BCH_STR_HASH_siphash_old:
119	case BCH_STR_HASH_siphash:
120		SipHash24_Update(&ctx->siphash, data, len);
121		break;
122	default:
123		BUG();
124	}
125}
126
127static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
128				   const struct bch_hash_info *info)
129{
130	switch (info->type) {
131	case BCH_STR_HASH_crc32c:
132		return ctx->crc32c;
133	case BCH_STR_HASH_crc64:
134		return ctx->crc64 >> 1;
135	case BCH_STR_HASH_siphash_old:
136	case BCH_STR_HASH_siphash:
137		return SipHash24_End(&ctx->siphash) >> 1;
138	default:
139		BUG();
140	}
141}
142
143struct bch_hash_desc {
144	enum btree_id	btree_id;
145	u8		key_type;
146
147	u64		(*hash_key)(const struct bch_hash_info *, const void *);
148	u64		(*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
149	bool		(*cmp_key)(struct bkey_s_c, const void *);
150	bool		(*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
151	bool		(*is_visible)(subvol_inum inum, struct bkey_s_c);
152};
153
154static inline bool is_visible_key(struct bch_hash_desc desc, subvol_inum inum, struct bkey_s_c k)
155{
156	return k.k->type == desc.key_type &&
157		(!desc.is_visible ||
158		 !inum.inum ||
159		 desc.is_visible(inum, k));
160}
161
162static __always_inline int
163bch2_hash_lookup_in_snapshot(struct btree_trans *trans,
164		 struct btree_iter *iter,
165		 const struct bch_hash_desc desc,
166		 const struct bch_hash_info *info,
167		 subvol_inum inum, const void *key,
168		 unsigned flags, u32 snapshot)
169{
170	struct bkey_s_c k;
171	int ret;
172
173	for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
174			   SPOS(inum.inum, desc.hash_key(info, key), snapshot),
175			   POS(inum.inum, U64_MAX),
176			   BTREE_ITER_SLOTS|flags, k, ret) {
177		if (is_visible_key(desc, inum, k)) {
178			if (!desc.cmp_key(k, key))
179				return 0;
180		} else if (k.k->type == KEY_TYPE_hash_whiteout) {
181			;
182		} else {
183			/* hole, not found */
184			break;
185		}
186	}
187	bch2_trans_iter_exit(trans, iter);
188
189	return ret ?: -BCH_ERR_ENOENT_str_hash_lookup;
190}
191
192static __always_inline int
193bch2_hash_lookup(struct btree_trans *trans,
194		 struct btree_iter *iter,
195		 const struct bch_hash_desc desc,
196		 const struct bch_hash_info *info,
197		 subvol_inum inum, const void *key,
198		 unsigned flags)
199{
200	u32 snapshot;
201	return  bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot) ?:
202		bch2_hash_lookup_in_snapshot(trans, iter, desc, info, inum, key, flags, snapshot);
203}
204
205static __always_inline int
206bch2_hash_hole(struct btree_trans *trans,
207	       struct btree_iter *iter,
208	       const struct bch_hash_desc desc,
209	       const struct bch_hash_info *info,
210	       subvol_inum inum, const void *key)
211{
212	struct bkey_s_c k;
213	u32 snapshot;
214	int ret;
215
216	ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
217	if (ret)
218		return ret;
219
220	for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
221			   SPOS(inum.inum, desc.hash_key(info, key), snapshot),
222			   POS(inum.inum, U64_MAX),
223			   BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret)
224		if (!is_visible_key(desc, inum, k))
225			return 0;
226	bch2_trans_iter_exit(trans, iter);
227
228	return ret ?: -BCH_ERR_ENOSPC_str_hash_create;
229}
230
231static __always_inline
232int bch2_hash_needs_whiteout(struct btree_trans *trans,
233			     const struct bch_hash_desc desc,
234			     const struct bch_hash_info *info,
235			     struct btree_iter *start)
236{
237	struct btree_iter iter;
238	struct bkey_s_c k;
239	int ret;
240
241	bch2_trans_copy_iter(&iter, start);
242
243	bch2_btree_iter_advance(&iter);
244
245	for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) {
246		if (k.k->type != desc.key_type &&
247		    k.k->type != KEY_TYPE_hash_whiteout)
248			break;
249
250		if (k.k->type == desc.key_type &&
251		    desc.hash_bkey(info, k) <= start->pos.offset) {
252			ret = 1;
253			break;
254		}
255	}
256
257	bch2_trans_iter_exit(trans, &iter);
258	return ret;
259}
260
261static __always_inline
262int bch2_hash_set_in_snapshot(struct btree_trans *trans,
263			   const struct bch_hash_desc desc,
264			   const struct bch_hash_info *info,
265			   subvol_inum inum, u32 snapshot,
266			   struct bkey_i *insert,
267			   bch_str_hash_flags_t str_hash_flags,
268			   int update_flags)
269{
270	struct btree_iter iter, slot = { NULL };
271	struct bkey_s_c k;
272	bool found = false;
273	int ret;
274
275	for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
276			   SPOS(insert->k.p.inode,
277				desc.hash_bkey(info, bkey_i_to_s_c(insert)),
278				snapshot),
279			   POS(insert->k.p.inode, U64_MAX),
280			   BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
281		if (is_visible_key(desc, inum, k)) {
282			if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
283				goto found;
284
285			/* hash collision: */
286			continue;
287		}
288
289		if (!slot.path &&
290		    !(str_hash_flags & BCH_HASH_SET_MUST_REPLACE))
291			bch2_trans_copy_iter(&slot, &iter);
292
293		if (k.k->type != KEY_TYPE_hash_whiteout)
294			goto not_found;
295	}
296
297	if (!ret)
298		ret = -BCH_ERR_ENOSPC_str_hash_create;
299out:
300	bch2_trans_iter_exit(trans, &slot);
301	bch2_trans_iter_exit(trans, &iter);
302
303	return ret;
304found:
305	found = true;
306not_found:
307
308	if (!found && (str_hash_flags & BCH_HASH_SET_MUST_REPLACE)) {
309		ret = -BCH_ERR_ENOENT_str_hash_set_must_replace;
310	} else if (found && (str_hash_flags & BCH_HASH_SET_MUST_CREATE)) {
311		ret = -EEXIST;
312	} else {
313		if (!found && slot.path)
314			swap(iter, slot);
315
316		insert->k.p = iter.pos;
317		ret = bch2_trans_update(trans, &iter, insert, update_flags);
318	}
319
320	goto out;
321}
322
323static __always_inline
324int bch2_hash_set(struct btree_trans *trans,
325		  const struct bch_hash_desc desc,
326		  const struct bch_hash_info *info,
327		  subvol_inum inum,
328		  struct bkey_i *insert,
329		  bch_str_hash_flags_t str_hash_flags)
330{
331	insert->k.p.inode = inum.inum;
332
333	u32 snapshot;
334	return  bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot) ?:
335		bch2_hash_set_in_snapshot(trans, desc, info, inum,
336					  snapshot, insert, str_hash_flags, 0);
337}
338
339static __always_inline
340int bch2_hash_delete_at(struct btree_trans *trans,
341			const struct bch_hash_desc desc,
342			const struct bch_hash_info *info,
343			struct btree_iter *iter,
344			unsigned update_flags)
345{
346	struct bkey_i *delete;
347	int ret;
348
349	delete = bch2_trans_kmalloc(trans, sizeof(*delete));
350	ret = PTR_ERR_OR_ZERO(delete);
351	if (ret)
352		return ret;
353
354	ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
355	if (ret < 0)
356		return ret;
357
358	bkey_init(&delete->k);
359	delete->k.p = iter->pos;
360	delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;
361
362	return bch2_trans_update(trans, iter, delete, update_flags);
363}
364
365static __always_inline
366int bch2_hash_delete(struct btree_trans *trans,
367		     const struct bch_hash_desc desc,
368		     const struct bch_hash_info *info,
369		     subvol_inum inum, const void *key)
370{
371	struct btree_iter iter;
372	int ret;
373
374	ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
375				BTREE_ITER_INTENT);
376	if (ret)
377		return ret;
378
379	ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
380	bch2_trans_iter_exit(trans, &iter);
381	return ret;
382}
383
384#endif /* _BCACHEFS_STR_HASH_H */
385