projects/linux·blob v3.6 · refs

331 lines · 8.2 KiB

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
12int 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
28static int __blk_rq_unmap_user(struct bio *bio)
29{
30 int ret = 0;
31
32 if (bio) {
33 if (bio_flagged(bio, BIO_USER_MAPPED))
34 bio_unmap_user(bio);
35 else
36 ret = bio_uncopy_user(bio);
37 }
38
39 return ret;
40}
41
42static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
43 struct rq_map_data *map_data, void __user *ubuf,
44 unsigned int len, gfp_t gfp_mask)
45{
46 unsigned long uaddr;
47 struct bio *bio, *orig_bio;
48 int reading, ret;
49
50 reading = rq_data_dir(rq) == READ;
51
52 /*
53 * if alignment requirement is satisfied, map in user pages for
54 * direct dma. else, set up kernel bounce buffers
55 */
56 uaddr = (unsigned long) ubuf;
57 if (blk_rq_aligned(q, uaddr, len) && !map_data)
58 bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
59 else
60 bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);
61
62 if (IS_ERR(bio))
63 return PTR_ERR(bio);
64
65 if (map_data && map_data->null_mapped)
66 bio->bi_flags |= (1 << BIO_NULL_MAPPED);
67
68 orig_bio = bio;
69 blk_queue_bounce(q, &bio);
70
71 /*
72 * We link the bounce buffer in and could have to traverse it
73 * later so we have to get a ref to prevent it from being freed
74 */
75 bio_get(bio);
76
77 ret = blk_rq_append_bio(q, rq, bio);
78 if (!ret)
79 return bio->bi_size;
80
81 /* if it was boucned we must call the end io function */
82 bio_endio(bio, 0);
83 __blk_rq_unmap_user(orig_bio);
84 bio_put(bio);
85 return ret;
86}
87
88/**
89 * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage
90 * @q: request queue where request should be inserted
91 * @rq: request structure to fill
92 * @map_data: pointer to the rq_map_data holding pages (if necessary)
93 * @ubuf: the user buffer
94 * @len: length of user data
95 * @gfp_mask: memory allocation flags
96 *
97 * Description:
98 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
99 * a kernel bounce buffer is used.
100 *
101 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
102 * still in process context.
103 *
104 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
105 * before being submitted to the device, as pages mapped may be out of
106 * reach. It's the callers responsibility to make sure this happens. The
107 * original bio must be passed back in to blk_rq_unmap_user() for proper
108 * unmapping.
109 */
110int blk_rq_map_user(struct request_queue *q, struct request *rq,
111 struct rq_map_data *map_data, void __user *ubuf,
112 unsigned long len, gfp_t gfp_mask)
113{
114 unsigned long bytes_read = 0;
115 struct bio *bio = NULL;
116 int ret;
117
118 if (len > (queue_max_hw_sectors(q) << 9))
119 return -EINVAL;
120 if (!len)
121 return -EINVAL;
122
123 if (!ubuf && (!map_data || !map_data->null_mapped))
124 return -EINVAL;
125
126 while (bytes_read != len) {
127 unsigned long map_len, end, start;
128
129 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
130 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
131 >> PAGE_SHIFT;
132 start = (unsigned long)ubuf >> PAGE_SHIFT;
133
134 /*
135 * A bad offset could cause us to require BIO_MAX_PAGES + 1
136 * pages. If this happens we just lower the requested
137 * mapping len by a page so that we can fit
138 */
139 if (end - start > BIO_MAX_PAGES)
140 map_len -= PAGE_SIZE;
141
142 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
143 gfp_mask);
144 if (ret < 0)
145 goto unmap_rq;
146 if (!bio)
147 bio = rq->bio;
148 bytes_read += ret;
149 ubuf += ret;
150
151 if (map_data)
152 map_data->offset += ret;
153 }
154
155 if (!bio_flagged(bio, BIO_USER_MAPPED))
156 rq->cmd_flags |= REQ_COPY_USER;
157
158 rq->buffer = NULL;
159 return 0;
160unmap_rq:
161 blk_rq_unmap_user(bio);
162 rq->bio = NULL;
163 return ret;
164}
165EXPORT_SYMBOL(blk_rq_map_user);
166
167/**
168 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
169 * @q: request queue where request should be inserted
170 * @rq: request to map data to
171 * @map_data: pointer to the rq_map_data holding pages (if necessary)
172 * @iov: pointer to the iovec
173 * @iov_count: number of elements in the iovec
174 * @len: I/O byte count
175 * @gfp_mask: memory allocation flags
176 *
177 * Description:
178 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
179 * a kernel bounce buffer is used.
180 *
181 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
182 * still in process context.
183 *
184 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
185 * before being submitted to the device, as pages mapped may be out of
186 * reach. It's the callers responsibility to make sure this happens. The
187 * original bio must be passed back in to blk_rq_unmap_user() for proper
188 * unmapping.
189 */
190int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
191 struct rq_map_data *map_data, struct sg_iovec *iov,
192 int iov_count, unsigned int len, gfp_t gfp_mask)
193{
194 struct bio *bio;
195 int i, read = rq_data_dir(rq) == READ;
196 int unaligned = 0;
197
198 if (!iov || iov_count <= 0)
199 return -EINVAL;
200
201 for (i = 0; i < iov_count; i++) {
202 unsigned long uaddr = (unsigned long)iov[i].iov_base;
203
204 if (!iov[i].iov_len)
205 return -EINVAL;
206
207 /*
208 * Keep going so we check length of all segments
209 */
210 if (uaddr & queue_dma_alignment(q))
211 unaligned = 1;
212 }
213
214 if (unaligned || (q->dma_pad_mask & len) || map_data)
215 bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
216 gfp_mask);
217 else
218 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
219
220 if (IS_ERR(bio))
221 return PTR_ERR(bio);
222
223 if (bio->bi_size != len) {
224 /*
225 * Grab an extra reference to this bio, as bio_unmap_user()
226 * expects to be able to drop it twice as it happens on the
227 * normal IO completion path
228 */
229 bio_get(bio);
230 bio_endio(bio, 0);
231 __blk_rq_unmap_user(bio);
232 return -EINVAL;
233 }
234
235 if (!bio_flagged(bio, BIO_USER_MAPPED))
236 rq->cmd_flags |= REQ_COPY_USER;
237
238 blk_queue_bounce(q, &bio);
239 bio_get(bio);
240 blk_rq_bio_prep(q, rq, bio);
241 rq->buffer = NULL;
242 return 0;
243}
244EXPORT_SYMBOL(blk_rq_map_user_iov);
245
246/**
247 * blk_rq_unmap_user - unmap a request with user data
248 * @bio: start of bio list
249 *
250 * Description:
251 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
252 * supply the original rq->bio from the blk_rq_map_user() return, since
253 * the I/O completion may have changed rq->bio.
254 */
255int blk_rq_unmap_user(struct bio *bio)
256{
257 struct bio *mapped_bio;
258 int ret = 0, ret2;
259
260 while (bio) {
261 mapped_bio = bio;
262 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
263 mapped_bio = bio->bi_private;
264
265 ret2 = __blk_rq_unmap_user(mapped_bio);
266 if (ret2 && !ret)
267 ret = ret2;
268
269 mapped_bio = bio;
270 bio = bio->bi_next;
271 bio_put(mapped_bio);
272 }
273
274 return ret;
275}
276EXPORT_SYMBOL(blk_rq_unmap_user);
277
278/**
279 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
280 * @q: request queue where request should be inserted
281 * @rq: request to fill
282 * @kbuf: the kernel buffer
283 * @len: length of user data
284 * @gfp_mask: memory allocation flags
285 *
286 * Description:
287 * Data will be mapped directly if possible. Otherwise a bounce
288 * buffer is used. Can be called multple times to append multple
289 * buffers.
290 */
291int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
292 unsigned int len, gfp_t gfp_mask)
293{
294 int reading = rq_data_dir(rq) == READ;
295 unsigned long addr = (unsigned long) kbuf;
296 int do_copy = 0;
297 struct bio *bio;
298 int ret;
299
300 if (len > (queue_max_hw_sectors(q) << 9))
301 return -EINVAL;
302 if (!len || !kbuf)
303 return -EINVAL;
304
305 do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
306 if (do_copy)
307 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
308 else
309 bio = bio_map_kern(q, kbuf, len, gfp_mask);
310
311 if (IS_ERR(bio))
312 return PTR_ERR(bio);
313
314 if (!reading)
315 bio->bi_rw |= REQ_WRITE;
316
317 if (do_copy)
318 rq->cmd_flags |= REQ_COPY_USER;
319
320 ret = blk_rq_append_bio(q, rq, bio);
321 if (unlikely(ret)) {
322 /* request is too big */
323 bio_put(bio);
324 return ret;
325 }
326
327 blk_queue_bounce(q, &rq->bio);
328 rq->buffer = NULL;
329 return 0;
330}
331EXPORT_SYMBOL(blk_rq_map_kern);