1 /*
2 * Functions related to mapping data to requests
3 */
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/bio.h>
7 #include <linux/blkdev.h>
8 #include <scsi/sg.h> /* for struct sg_iovec */
9
10 #include "blk.h"
11
blk_rq_append_bio(struct request_queue * q,struct request * rq,struct bio * bio)12 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
13 struct bio *bio)
14 {
15 if (!rq->bio)
16 blk_rq_bio_prep(q, rq, bio);
17 else if (!ll_back_merge_fn(q, rq, bio))
18 return -EINVAL;
19 else {
20 rq->biotail->bi_next = bio;
21 rq->biotail = bio;
22
23 rq->data_len += bio->bi_size;
24 }
25 return 0;
26 }
27 EXPORT_SYMBOL(blk_rq_append_bio);
28
__blk_rq_unmap_user(struct bio * bio)29 static int __blk_rq_unmap_user(struct bio *bio)
30 {
31 int ret = 0;
32
33 if (bio) {
34 if (bio_flagged(bio, BIO_USER_MAPPED))
35 bio_unmap_user(bio);
36 else
37 ret = bio_uncopy_user(bio);
38 }
39
40 return ret;
41 }
42
__blk_rq_map_user(struct request_queue * q,struct request * rq,struct rq_map_data * map_data,void __user * ubuf,unsigned int len,gfp_t gfp_mask)43 static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
44 struct rq_map_data *map_data, void __user *ubuf,
45 unsigned int len, gfp_t gfp_mask)
46 {
47 unsigned long uaddr;
48 struct bio *bio, *orig_bio;
49 int reading, ret;
50
51 reading = rq_data_dir(rq) == READ;
52
53 /*
54 * if alignment requirement is satisfied, map in user pages for
55 * direct dma. else, set up kernel bounce buffers
56 */
57 uaddr = (unsigned long) ubuf;
58 if (blk_rq_aligned(q, ubuf, len) && !map_data)
59 bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
60 else
61 bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);
62
63 if (IS_ERR(bio))
64 return PTR_ERR(bio);
65
66 if (map_data && map_data->null_mapped)
67 bio->bi_flags |= (1 << BIO_NULL_MAPPED);
68
69 orig_bio = bio;
70 blk_queue_bounce(q, &bio);
71
72 /*
73 * We link the bounce buffer in and could have to traverse it
74 * later so we have to get a ref to prevent it from being freed
75 */
76 bio_get(bio);
77
78 ret = blk_rq_append_bio(q, rq, bio);
79 if (!ret)
80 return bio->bi_size;
81
82 /* if it was boucned we must call the end io function */
83 bio_endio(bio, 0);
84 __blk_rq_unmap_user(orig_bio);
85 bio_put(bio);
86 return ret;
87 }
88
89 /**
90 * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage
91 * @q: request queue where request should be inserted
92 * @rq: request structure to fill
93 * @map_data: pointer to the rq_map_data holding pages (if necessary)
94 * @ubuf: the user buffer
95 * @len: length of user data
96 * @gfp_mask: memory allocation flags
97 *
98 * Description:
99 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
100 * a kernel bounce buffer is used.
101 *
102 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
103 * still in process context.
104 *
105 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
106 * before being submitted to the device, as pages mapped may be out of
107 * reach. It's the callers responsibility to make sure this happens. The
108 * original bio must be passed back in to blk_rq_unmap_user() for proper
109 * unmapping.
110 */
blk_rq_map_user(struct request_queue * q,struct request * rq,struct rq_map_data * map_data,void __user * ubuf,unsigned long len,gfp_t gfp_mask)111 int blk_rq_map_user(struct request_queue *q, struct request *rq,
112 struct rq_map_data *map_data, void __user *ubuf,
113 unsigned long len, gfp_t gfp_mask)
114 {
115 unsigned long bytes_read = 0;
116 struct bio *bio = NULL;
117 int ret;
118
119 if (len > (q->max_hw_sectors << 9))
120 return -EINVAL;
121 if (!len)
122 return -EINVAL;
123
124 if (!ubuf && (!map_data || !map_data->null_mapped))
125 return -EINVAL;
126
127 while (bytes_read != len) {
128 unsigned long map_len, end, start;
129
130 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
131 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
132 >> PAGE_SHIFT;
133 start = (unsigned long)ubuf >> PAGE_SHIFT;
134
135 /*
136 * A bad offset could cause us to require BIO_MAX_PAGES + 1
137 * pages. If this happens we just lower the requested
138 * mapping len by a page so that we can fit
139 */
140 if (end - start > BIO_MAX_PAGES)
141 map_len -= PAGE_SIZE;
142
143 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
144 gfp_mask);
145 if (ret < 0)
146 goto unmap_rq;
147 if (!bio)
148 bio = rq->bio;
149 bytes_read += ret;
150 ubuf += ret;
151
152 if (map_data)
153 map_data->offset += ret;
154 }
155
156 if (!bio_flagged(bio, BIO_USER_MAPPED))
157 rq->cmd_flags |= REQ_COPY_USER;
158
159 rq->buffer = rq->data = NULL;
160 return 0;
161 unmap_rq:
162 blk_rq_unmap_user(bio);
163 rq->bio = NULL;
164 return ret;
165 }
166 EXPORT_SYMBOL(blk_rq_map_user);
167
168 /**
169 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
170 * @q: request queue where request should be inserted
171 * @rq: request to map data to
172 * @map_data: pointer to the rq_map_data holding pages (if necessary)
173 * @iov: pointer to the iovec
174 * @iov_count: number of elements in the iovec
175 * @len: I/O byte count
176 * @gfp_mask: memory allocation flags
177 *
178 * Description:
179 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
180 * a kernel bounce buffer is used.
181 *
182 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
183 * still in process context.
184 *
185 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
186 * before being submitted to the device, as pages mapped may be out of
187 * reach. It's the callers responsibility to make sure this happens. The
188 * original bio must be passed back in to blk_rq_unmap_user() for proper
189 * unmapping.
190 */
blk_rq_map_user_iov(struct request_queue * q,struct request * rq,struct rq_map_data * map_data,struct sg_iovec * iov,int iov_count,unsigned int len,gfp_t gfp_mask)191 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
192 struct rq_map_data *map_data, struct sg_iovec *iov,
193 int iov_count, unsigned int len, gfp_t gfp_mask)
194 {
195 struct bio *bio;
196 int i, read = rq_data_dir(rq) == READ;
197 int unaligned = 0;
198
199 if (!iov || iov_count <= 0)
200 return -EINVAL;
201
202 for (i = 0; i < iov_count; i++) {
203 unsigned long uaddr = (unsigned long)iov[i].iov_base;
204
205 if (uaddr & queue_dma_alignment(q)) {
206 unaligned = 1;
207 break;
208 }
209 }
210
211 if (unaligned || (q->dma_pad_mask & len) || map_data)
212 bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
213 gfp_mask);
214 else
215 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
216
217 if (IS_ERR(bio))
218 return PTR_ERR(bio);
219
220 if (bio->bi_size != len) {
221 /*
222 * Grab an extra reference to this bio, as bio_unmap_user()
223 * expects to be able to drop it twice as it happens on the
224 * normal IO completion path
225 */
226 bio_get(bio);
227 bio_endio(bio, 0);
228 __blk_rq_unmap_user(bio);
229 return -EINVAL;
230 }
231
232 if (!bio_flagged(bio, BIO_USER_MAPPED))
233 rq->cmd_flags |= REQ_COPY_USER;
234
235 blk_queue_bounce(q, &bio);
236 bio_get(bio);
237 blk_rq_bio_prep(q, rq, bio);
238 rq->buffer = rq->data = NULL;
239 return 0;
240 }
241 EXPORT_SYMBOL(blk_rq_map_user_iov);
242
243 /**
244 * blk_rq_unmap_user - unmap a request with user data
245 * @bio: start of bio list
246 *
247 * Description:
248 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
249 * supply the original rq->bio from the blk_rq_map_user() return, since
250 * the I/O completion may have changed rq->bio.
251 */
blk_rq_unmap_user(struct bio * bio)252 int blk_rq_unmap_user(struct bio *bio)
253 {
254 struct bio *mapped_bio;
255 int ret = 0, ret2;
256
257 while (bio) {
258 mapped_bio = bio;
259 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
260 mapped_bio = bio->bi_private;
261
262 ret2 = __blk_rq_unmap_user(mapped_bio);
263 if (ret2 && !ret)
264 ret = ret2;
265
266 mapped_bio = bio;
267 bio = bio->bi_next;
268 bio_put(mapped_bio);
269 }
270
271 return ret;
272 }
273 EXPORT_SYMBOL(blk_rq_unmap_user);
274
275 /**
276 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
277 * @q: request queue where request should be inserted
278 * @rq: request to fill
279 * @kbuf: the kernel buffer
280 * @len: length of user data
281 * @gfp_mask: memory allocation flags
282 *
283 * Description:
284 * Data will be mapped directly if possible. Otherwise a bounce
285 * buffer is used.
286 */
blk_rq_map_kern(struct request_queue * q,struct request * rq,void * kbuf,unsigned int len,gfp_t gfp_mask)287 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
288 unsigned int len, gfp_t gfp_mask)
289 {
290 int reading = rq_data_dir(rq) == READ;
291 int do_copy = 0;
292 struct bio *bio;
293
294 if (len > (q->max_hw_sectors << 9))
295 return -EINVAL;
296 if (!len || !kbuf)
297 return -EINVAL;
298
299 do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf);
300 if (do_copy)
301 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
302 else
303 bio = bio_map_kern(q, kbuf, len, gfp_mask);
304
305 if (IS_ERR(bio))
306 return PTR_ERR(bio);
307
308 if (rq_data_dir(rq) == WRITE)
309 bio->bi_rw |= (1 << BIO_RW);
310
311 if (do_copy)
312 rq->cmd_flags |= REQ_COPY_USER;
313
314 blk_rq_bio_prep(q, rq, bio);
315 blk_queue_bounce(q, &rq->bio);
316 rq->buffer = rq->data = NULL;
317 return 0;
318 }
319 EXPORT_SYMBOL(blk_rq_map_kern);
320