blob: 955d75c1a58fd634e3f168ec8d091c4c9e93a965 [file] [log] [blame]
Jens Axboe86db1e22008-01-29 14:53:40 +01001/*
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
9#include "blk.h"
10
11int blk_rq_append_bio(struct request_queue *q, struct request *rq,
12 struct bio *bio)
13{
14 if (!rq->bio)
15 blk_rq_bio_prep(q, rq, bio);
16 else if (!ll_back_merge_fn(q, rq, bio))
17 return -EINVAL;
18 else {
19 rq->biotail->bi_next = bio;
20 rq->biotail = bio;
21
22 rq->data_len += bio->bi_size;
23 }
24 return 0;
25}
26EXPORT_SYMBOL(blk_rq_append_bio);
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 void __user *ubuf, unsigned int len)
44{
45 unsigned long uaddr;
46 struct bio *bio, *orig_bio;
47 int reading, ret;
48
49 reading = rq_data_dir(rq) == READ;
50
51 /*
52 * if alignment requirement is satisfied, map in user pages for
53 * direct dma. else, set up kernel bounce buffers
54 */
55 uaddr = (unsigned long) ubuf;
Jens Axboe6728cb02008-01-31 13:03:55 +010056 if (!(uaddr & queue_dma_alignment(q)) &&
57 !(len & queue_dma_alignment(q)))
Jens Axboe86db1e22008-01-29 14:53:40 +010058 bio = bio_map_user(q, NULL, uaddr, len, reading);
59 else
60 bio = bio_copy_user(q, uaddr, len, reading);
61
62 if (IS_ERR(bio))
63 return PTR_ERR(bio);
64
65 orig_bio = bio;
66 blk_queue_bounce(q, &bio);
67
68 /*
69 * We link the bounce buffer in and could have to traverse it
70 * later so we have to get a ref to prevent it from being freed
71 */
72 bio_get(bio);
73
74 ret = blk_rq_append_bio(q, rq, bio);
75 if (!ret)
76 return bio->bi_size;
77
78 /* if it was boucned we must call the end io function */
79 bio_endio(bio, 0);
80 __blk_rq_unmap_user(orig_bio);
81 bio_put(bio);
82 return ret;
83}
84
85/**
86 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
87 * @q: request queue where request should be inserted
88 * @rq: request structure to fill
89 * @ubuf: the user buffer
90 * @len: length of user data
91 *
92 * Description:
93 * Data will be mapped directly for zero copy io, if possible. Otherwise
94 * a kernel bounce buffer is used.
95 *
96 * A matching blk_rq_unmap_user() must be issued at the end of io, while
97 * still in process context.
98 *
99 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
100 * before being submitted to the device, as pages mapped may be out of
101 * reach. It's the callers responsibility to make sure this happens. The
102 * original bio must be passed back in to blk_rq_unmap_user() for proper
103 * unmapping.
104 */
105int blk_rq_map_user(struct request_queue *q, struct request *rq,
106 void __user *ubuf, unsigned long len)
107{
108 unsigned long bytes_read = 0;
109 struct bio *bio = NULL;
110 int ret;
111
112 if (len > (q->max_hw_sectors << 9))
113 return -EINVAL;
114 if (!len || !ubuf)
115 return -EINVAL;
116
117 while (bytes_read != len) {
118 unsigned long map_len, end, start;
119
120 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
121 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
122 >> PAGE_SHIFT;
123 start = (unsigned long)ubuf >> PAGE_SHIFT;
124
125 /*
126 * A bad offset could cause us to require BIO_MAX_PAGES + 1
127 * pages. If this happens we just lower the requested
128 * mapping len by a page so that we can fit
129 */
130 if (end - start > BIO_MAX_PAGES)
131 map_len -= PAGE_SIZE;
132
133 ret = __blk_rq_map_user(q, rq, ubuf, map_len);
134 if (ret < 0)
135 goto unmap_rq;
136 if (!bio)
137 bio = rq->bio;
138 bytes_read += ret;
139 ubuf += ret;
140 }
141
142 rq->buffer = rq->data = NULL;
143 return 0;
144unmap_rq:
145 blk_rq_unmap_user(bio);
146 return ret;
147}
Jens Axboe86db1e22008-01-29 14:53:40 +0100148EXPORT_SYMBOL(blk_rq_map_user);
149
150/**
151 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
152 * @q: request queue where request should be inserted
153 * @rq: request to map data to
154 * @iov: pointer to the iovec
155 * @iov_count: number of elements in the iovec
156 * @len: I/O byte count
157 *
158 * Description:
159 * Data will be mapped directly for zero copy io, if possible. Otherwise
160 * a kernel bounce buffer is used.
161 *
162 * A matching blk_rq_unmap_user() must be issued at the end of io, while
163 * still in process context.
164 *
165 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
166 * before being submitted to the device, as pages mapped may be out of
167 * reach. It's the callers responsibility to make sure this happens. The
168 * original bio must be passed back in to blk_rq_unmap_user() for proper
169 * unmapping.
170 */
171int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
172 struct sg_iovec *iov, int iov_count, unsigned int len)
173{
174 struct bio *bio;
175
176 if (!iov || iov_count <= 0)
177 return -EINVAL;
178
179 /* we don't allow misaligned data like bio_map_user() does. If the
180 * user is using sg, they're expected to know the alignment constraints
181 * and respect them accordingly */
Jens Axboe6728cb02008-01-31 13:03:55 +0100182 bio = bio_map_user_iov(q, NULL, iov, iov_count,
183 rq_data_dir(rq) == READ);
Jens Axboe86db1e22008-01-29 14:53:40 +0100184 if (IS_ERR(bio))
185 return PTR_ERR(bio);
186
187 if (bio->bi_size != len) {
188 bio_endio(bio, 0);
189 bio_unmap_user(bio);
190 return -EINVAL;
191 }
192
193 bio_get(bio);
194 blk_rq_bio_prep(q, rq, bio);
195 rq->buffer = rq->data = NULL;
196 return 0;
197}
Jens Axboe86db1e22008-01-29 14:53:40 +0100198EXPORT_SYMBOL(blk_rq_map_user_iov);
199
200/**
201 * blk_rq_unmap_user - unmap a request with user data
202 * @bio: start of bio list
203 *
204 * Description:
205 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
206 * supply the original rq->bio from the blk_rq_map_user() return, since
207 * the io completion may have changed rq->bio.
208 */
209int blk_rq_unmap_user(struct bio *bio)
210{
211 struct bio *mapped_bio;
212 int ret = 0, ret2;
213
214 while (bio) {
215 mapped_bio = bio;
216 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
217 mapped_bio = bio->bi_private;
218
219 ret2 = __blk_rq_unmap_user(mapped_bio);
220 if (ret2 && !ret)
221 ret = ret2;
222
223 mapped_bio = bio;
224 bio = bio->bi_next;
225 bio_put(mapped_bio);
226 }
227
228 return ret;
229}
Jens Axboe86db1e22008-01-29 14:53:40 +0100230EXPORT_SYMBOL(blk_rq_unmap_user);
231
232/**
233 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
234 * @q: request queue where request should be inserted
235 * @rq: request to fill
236 * @kbuf: the kernel buffer
237 * @len: length of user data
238 * @gfp_mask: memory allocation flags
239 */
240int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
241 unsigned int len, gfp_t gfp_mask)
242{
243 struct bio *bio;
244
245 if (len > (q->max_hw_sectors << 9))
246 return -EINVAL;
247 if (!len || !kbuf)
248 return -EINVAL;
249
250 bio = bio_map_kern(q, kbuf, len, gfp_mask);
251 if (IS_ERR(bio))
252 return PTR_ERR(bio);
253
254 if (rq_data_dir(rq) == WRITE)
255 bio->bi_rw |= (1 << BIO_RW);
256
257 blk_rq_bio_prep(q, rq, bio);
258 blk_queue_bounce(q, &rq->bio);
259 rq->buffer = rq->data = NULL;
260 return 0;
261}
Jens Axboe86db1e22008-01-29 14:53:40 +0100262EXPORT_SYMBOL(blk_rq_map_kern);