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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * Functions related to mapping data to requests | |
4 | */ | |
5 | #include <linux/kernel.h> | |
6 | #include <linux/sched/task_stack.h> | |
7 | #include <linux/module.h> | |
8 | #include <linux/bio.h> | |
9 | #include <linux/blkdev.h> | |
10 | #include <linux/uio.h> | |
11 | ||
12 | #include "blk.h" | |
13 | ||
14 | /* | |
15 | * Append a bio to a passthrough request. Only works if the bio can be merged | |
16 | * into the request based on the driver constraints. | |
17 | */ | |
18 | int blk_rq_append_bio(struct request *rq, struct bio **bio) | |
19 | { | |
20 | struct bio *orig_bio = *bio; | |
21 | ||
22 | blk_queue_bounce(rq->q, bio); | |
23 | ||
24 | if (!rq->bio) { | |
25 | blk_rq_bio_prep(rq->q, rq, *bio); | |
26 | } else { | |
27 | if (!ll_back_merge_fn(rq->q, rq, *bio)) { | |
28 | if (orig_bio != *bio) { | |
29 | bio_put(*bio); | |
30 | *bio = orig_bio; | |
31 | } | |
32 | return -EINVAL; | |
33 | } | |
34 | ||
35 | rq->biotail->bi_next = *bio; | |
36 | rq->biotail = *bio; | |
37 | rq->__data_len += (*bio)->bi_iter.bi_size; | |
38 | } | |
39 | ||
40 | return 0; | |
41 | } | |
42 | EXPORT_SYMBOL(blk_rq_append_bio); | |
43 | ||
44 | static int __blk_rq_unmap_user(struct bio *bio) | |
45 | { | |
46 | int ret = 0; | |
47 | ||
48 | if (bio) { | |
49 | if (bio_flagged(bio, BIO_USER_MAPPED)) | |
50 | bio_unmap_user(bio); | |
51 | else | |
52 | ret = bio_uncopy_user(bio); | |
53 | } | |
54 | ||
55 | return ret; | |
56 | } | |
57 | ||
58 | static int __blk_rq_map_user_iov(struct request *rq, | |
59 | struct rq_map_data *map_data, struct iov_iter *iter, | |
60 | gfp_t gfp_mask, bool copy) | |
61 | { | |
62 | struct request_queue *q = rq->q; | |
63 | struct bio *bio, *orig_bio; | |
64 | int ret; | |
65 | ||
66 | if (copy) | |
67 | bio = bio_copy_user_iov(q, map_data, iter, gfp_mask); | |
68 | else | |
69 | bio = bio_map_user_iov(q, iter, gfp_mask); | |
70 | ||
71 | if (IS_ERR(bio)) | |
72 | return PTR_ERR(bio); | |
73 | ||
74 | bio->bi_opf &= ~REQ_OP_MASK; | |
75 | bio->bi_opf |= req_op(rq); | |
76 | ||
77 | orig_bio = bio; | |
78 | ||
79 | /* | |
80 | * We link the bounce buffer in and could have to traverse it | |
81 | * later so we have to get a ref to prevent it from being freed | |
82 | */ | |
83 | ret = blk_rq_append_bio(rq, &bio); | |
84 | if (ret) { | |
85 | __blk_rq_unmap_user(orig_bio); | |
86 | return ret; | |
87 | } | |
88 | bio_get(bio); | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | /** | |
94 | * blk_rq_map_user_iov - map user data to a request, for passthrough requests | |
95 | * @q: request queue where request should be inserted | |
96 | * @rq: request to map data to | |
97 | * @map_data: pointer to the rq_map_data holding pages (if necessary) | |
98 | * @iter: iovec iterator | |
99 | * @gfp_mask: memory allocation flags | |
100 | * | |
101 | * Description: | |
102 | * Data will be mapped directly for zero copy I/O, if possible. Otherwise | |
103 | * a kernel bounce buffer is used. | |
104 | * | |
105 | * A matching blk_rq_unmap_user() must be issued at the end of I/O, while | |
106 | * still in process context. | |
107 | * | |
108 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() | |
109 | * before being submitted to the device, as pages mapped may be out of | |
110 | * reach. It's the callers responsibility to make sure this happens. The | |
111 | * original bio must be passed back in to blk_rq_unmap_user() for proper | |
112 | * unmapping. | |
113 | */ | |
114 | int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, | |
115 | struct rq_map_data *map_data, | |
116 | const struct iov_iter *iter, gfp_t gfp_mask) | |
117 | { | |
118 | bool copy = false; | |
119 | unsigned long align = q->dma_pad_mask | queue_dma_alignment(q); | |
120 | struct bio *bio = NULL; | |
121 | struct iov_iter i; | |
122 | int ret = -EINVAL; | |
123 | ||
124 | if (!iter_is_iovec(iter)) | |
125 | goto fail; | |
126 | ||
127 | if (map_data) | |
128 | copy = true; | |
129 | else if (iov_iter_alignment(iter) & align) | |
130 | copy = true; | |
131 | else if (queue_virt_boundary(q)) | |
132 | copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter); | |
133 | ||
134 | i = *iter; | |
135 | do { | |
136 | ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy); | |
137 | if (ret) | |
138 | goto unmap_rq; | |
139 | if (!bio) | |
140 | bio = rq->bio; | |
141 | } while (iov_iter_count(&i)); | |
142 | ||
143 | if (!bio_flagged(bio, BIO_USER_MAPPED)) | |
144 | rq->rq_flags |= RQF_COPY_USER; | |
145 | return 0; | |
146 | ||
147 | unmap_rq: | |
148 | __blk_rq_unmap_user(bio); | |
149 | fail: | |
150 | rq->bio = NULL; | |
151 | return ret; | |
152 | } | |
153 | EXPORT_SYMBOL(blk_rq_map_user_iov); | |
154 | ||
155 | int blk_rq_map_user(struct request_queue *q, struct request *rq, | |
156 | struct rq_map_data *map_data, void __user *ubuf, | |
157 | unsigned long len, gfp_t gfp_mask) | |
158 | { | |
159 | struct iovec iov; | |
160 | struct iov_iter i; | |
161 | int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i); | |
162 | ||
163 | if (unlikely(ret < 0)) | |
164 | return ret; | |
165 | ||
166 | return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask); | |
167 | } | |
168 | EXPORT_SYMBOL(blk_rq_map_user); | |
169 | ||
170 | /** | |
171 | * blk_rq_unmap_user - unmap a request with user data | |
172 | * @bio: start of bio list | |
173 | * | |
174 | * Description: | |
175 | * Unmap a rq previously mapped by blk_rq_map_user(). The caller must | |
176 | * supply the original rq->bio from the blk_rq_map_user() return, since | |
177 | * the I/O completion may have changed rq->bio. | |
178 | */ | |
179 | int blk_rq_unmap_user(struct bio *bio) | |
180 | { | |
181 | struct bio *mapped_bio; | |
182 | int ret = 0, ret2; | |
183 | ||
184 | while (bio) { | |
185 | mapped_bio = bio; | |
186 | if (unlikely(bio_flagged(bio, BIO_BOUNCED))) | |
187 | mapped_bio = bio->bi_private; | |
188 | ||
189 | ret2 = __blk_rq_unmap_user(mapped_bio); | |
190 | if (ret2 && !ret) | |
191 | ret = ret2; | |
192 | ||
193 | mapped_bio = bio; | |
194 | bio = bio->bi_next; | |
195 | bio_put(mapped_bio); | |
196 | } | |
197 | ||
198 | return ret; | |
199 | } | |
200 | EXPORT_SYMBOL(blk_rq_unmap_user); | |
201 | ||
202 | /** | |
203 | * blk_rq_map_kern - map kernel data to a request, for passthrough requests | |
204 | * @q: request queue where request should be inserted | |
205 | * @rq: request to fill | |
206 | * @kbuf: the kernel buffer | |
207 | * @len: length of user data | |
208 | * @gfp_mask: memory allocation flags | |
209 | * | |
210 | * Description: | |
211 | * Data will be mapped directly if possible. Otherwise a bounce | |
212 | * buffer is used. Can be called multiple times to append multiple | |
213 | * buffers. | |
214 | */ | |
215 | int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, | |
216 | unsigned int len, gfp_t gfp_mask) | |
217 | { | |
218 | int reading = rq_data_dir(rq) == READ; | |
219 | unsigned long addr = (unsigned long) kbuf; | |
220 | int do_copy = 0; | |
221 | struct bio *bio, *orig_bio; | |
222 | int ret; | |
223 | ||
224 | if (len > (queue_max_hw_sectors(q) << 9)) | |
225 | return -EINVAL; | |
226 | if (!len || !kbuf) | |
227 | return -EINVAL; | |
228 | ||
229 | do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf); | |
230 | if (do_copy) | |
231 | bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); | |
232 | else | |
233 | bio = bio_map_kern(q, kbuf, len, gfp_mask); | |
234 | ||
235 | if (IS_ERR(bio)) | |
236 | return PTR_ERR(bio); | |
237 | ||
238 | bio->bi_opf &= ~REQ_OP_MASK; | |
239 | bio->bi_opf |= req_op(rq); | |
240 | ||
241 | if (do_copy) | |
242 | rq->rq_flags |= RQF_COPY_USER; | |
243 | ||
244 | orig_bio = bio; | |
245 | ret = blk_rq_append_bio(rq, &bio); | |
246 | if (unlikely(ret)) { | |
247 | /* request is too big */ | |
248 | bio_put(orig_bio); | |
249 | return ret; | |
250 | } | |
251 | ||
252 | return 0; | |
253 | } | |
254 | EXPORT_SYMBOL(blk_rq_map_kern); |