1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright 2022 Red Hat, Inc.
4  */
5 
6 #include <linux/bio.h>
7 #include <linux/blk-crypto.h>
8 #include <linux/blk-integrity.h>
9 
10 #include "dm-core.h"
11 
dm_bvec_iter_rewind(const struct bio_vec * bv,struct bvec_iter * iter,unsigned int bytes)12 static inline bool dm_bvec_iter_rewind(const struct bio_vec *bv,
13 				       struct bvec_iter *iter,
14 				       unsigned int bytes)
15 {
16 	int idx;
17 
18 	iter->bi_size += bytes;
19 	if (bytes <= iter->bi_bvec_done) {
20 		iter->bi_bvec_done -= bytes;
21 		return true;
22 	}
23 
24 	bytes -= iter->bi_bvec_done;
25 	idx = iter->bi_idx - 1;
26 
27 	while (idx >= 0 && bytes && bytes > bv[idx].bv_len) {
28 		bytes -= bv[idx].bv_len;
29 		idx--;
30 	}
31 
32 	if (WARN_ONCE(idx < 0 && bytes,
33 		      "Attempted to rewind iter beyond bvec's boundaries\n")) {
34 		iter->bi_size -= bytes;
35 		iter->bi_bvec_done = 0;
36 		iter->bi_idx = 0;
37 		return false;
38 	}
39 
40 	iter->bi_idx = idx;
41 	iter->bi_bvec_done = bv[idx].bv_len - bytes;
42 	return true;
43 }
44 
45 #if defined(CONFIG_BLK_DEV_INTEGRITY)
46 
47 /**
48  * dm_bio_integrity_rewind - Rewind integrity vector
49  * @bio:	bio whose integrity vector to update
50  * @bytes_done:	number of data bytes to rewind
51  *
52  * Description: This function calculates how many integrity bytes the
53  * number of completed data bytes correspond to and rewind the
54  * integrity vector accordingly.
55  */
dm_bio_integrity_rewind(struct bio * bio,unsigned int bytes_done)56 static void dm_bio_integrity_rewind(struct bio *bio, unsigned int bytes_done)
57 {
58 	struct bio_integrity_payload *bip = bio_integrity(bio);
59 	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
60 	unsigned int bytes = bio_integrity_bytes(bi, bytes_done >> 9);
61 
62 	bip->bip_iter.bi_sector -= bio_integrity_intervals(bi, bytes_done >> 9);
63 	dm_bvec_iter_rewind(bip->bip_vec, &bip->bip_iter, bytes);
64 }
65 
66 #else /* CONFIG_BLK_DEV_INTEGRITY */
67 
dm_bio_integrity_rewind(struct bio * bio,unsigned int bytes_done)68 static inline void dm_bio_integrity_rewind(struct bio *bio,
69 					   unsigned int bytes_done)
70 {
71 }
72 
73 #endif
74 
75 #if defined(CONFIG_BLK_INLINE_ENCRYPTION)
76 
77 /* Decrements @dun by @dec, treating @dun as a multi-limb integer. */
dm_bio_crypt_dun_decrement(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],unsigned int dec)78 static void dm_bio_crypt_dun_decrement(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
79 				       unsigned int dec)
80 {
81 	int i;
82 
83 	for (i = 0; dec && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
84 		u64 prev = dun[i];
85 
86 		dun[i] -= dec;
87 		if (dun[i] > prev)
88 			dec = 1;
89 		else
90 			dec = 0;
91 	}
92 }
93 
dm_bio_crypt_rewind(struct bio * bio,unsigned int bytes)94 static void dm_bio_crypt_rewind(struct bio *bio, unsigned int bytes)
95 {
96 	struct bio_crypt_ctx *bc = bio->bi_crypt_context;
97 
98 	dm_bio_crypt_dun_decrement(bc->bc_dun,
99 				   bytes >> bc->bc_key->data_unit_size_bits);
100 }
101 
102 #else /* CONFIG_BLK_INLINE_ENCRYPTION */
103 
dm_bio_crypt_rewind(struct bio * bio,unsigned int bytes)104 static inline void dm_bio_crypt_rewind(struct bio *bio, unsigned int bytes)
105 {
106 }
107 
108 #endif
109 
dm_bio_rewind_iter(const struct bio * bio,struct bvec_iter * iter,unsigned int bytes)110 static inline void dm_bio_rewind_iter(const struct bio *bio,
111 				      struct bvec_iter *iter, unsigned int bytes)
112 {
113 	iter->bi_sector -= bytes >> 9;
114 
115 	/* No advance means no rewind */
116 	if (bio_no_advance_iter(bio))
117 		iter->bi_size += bytes;
118 	else
119 		dm_bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
120 }
121 
122 /**
123  * dm_bio_rewind - update ->bi_iter of @bio by rewinding @bytes.
124  * @bio: bio to rewind
125  * @bytes: how many bytes to rewind
126  *
127  * WARNING:
128  * Caller must ensure that @bio has a fixed end sector, to allow
129  * rewinding from end of bio and restoring its original position.
130  * Caller is also responsibile for restoring bio's size.
131  */
dm_bio_rewind(struct bio * bio,unsigned int bytes)132 static void dm_bio_rewind(struct bio *bio, unsigned int bytes)
133 {
134 	if (bio_integrity(bio))
135 		dm_bio_integrity_rewind(bio, bytes);
136 
137 	if (bio_has_crypt_ctx(bio))
138 		dm_bio_crypt_rewind(bio, bytes);
139 
140 	dm_bio_rewind_iter(bio, &bio->bi_iter, bytes);
141 }
142 
dm_io_rewind(struct dm_io * io,struct bio_set * bs)143 void dm_io_rewind(struct dm_io *io, struct bio_set *bs)
144 {
145 	struct bio *orig = io->orig_bio;
146 	struct bio *new_orig = bio_alloc_clone(orig->bi_bdev, orig,
147 					       GFP_NOIO, bs);
148 	/*
149 	 * dm_bio_rewind can restore to previous position since the
150 	 * end sector is fixed for original bio, but we still need
151 	 * to restore bio's size manually (using io->sectors).
152 	 */
153 	dm_bio_rewind(new_orig, ((io->sector_offset << 9) -
154 				 orig->bi_iter.bi_size));
155 	bio_trim(new_orig, 0, io->sectors);
156 
157 	bio_chain(new_orig, orig);
158 	/*
159 	 * __bi_remaining was increased (by dm_split_and_process_bio),
160 	 * so must drop the one added in bio_chain.
161 	 */
162 	atomic_dec(&orig->__bi_remaining);
163 	io->orig_bio = new_orig;
164 }
165