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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>
FUJITA Tomonoriafdc1a72008-04-11 12:56:51 +02008#include <scsi/sg.h> /* for struct sg_iovec */
Jens Axboe86db1e22008-01-29 14:53:40 +01009
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}
27EXPORT_SYMBOL(blk_rq_append_bio);
28
29static 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
43static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
44 void __user *ubuf, unsigned int len)
45{
46 unsigned long uaddr;
Tejun Heoe3790c72008-03-04 11:18:17 +010047 unsigned int alignment;
Jens Axboe86db1e22008-01-29 14:53:40 +010048 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;
Tejun Heoe3790c72008-03-04 11:18:17 +010058 alignment = queue_dma_alignment(q) | q->dma_pad_mask;
59 if (!(uaddr & alignment) && !(len & alignment))
Jens Axboe86db1e22008-01-29 14:53:40 +010060 bio = bio_map_user(q, NULL, uaddr, len, reading);
61 else
62 bio = bio_copy_user(q, uaddr, len, reading);
63
64 if (IS_ERR(bio))
65 return PTR_ERR(bio);
66
67 orig_bio = bio;
68 blk_queue_bounce(q, &bio);
69
70 /*
71 * We link the bounce buffer in and could have to traverse it
72 * later so we have to get a ref to prevent it from being freed
73 */
74 bio_get(bio);
75
76 ret = blk_rq_append_bio(q, rq, bio);
77 if (!ret)
78 return bio->bi_size;
79
80 /* if it was boucned we must call the end io function */
81 bio_endio(bio, 0);
82 __blk_rq_unmap_user(orig_bio);
83 bio_put(bio);
84 return ret;
85}
86
87/**
88 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
89 * @q: request queue where request should be inserted
90 * @rq: request structure to fill
91 * @ubuf: the user buffer
92 * @len: length of user data
93 *
94 * Description:
95 * Data will be mapped directly for zero copy io, if possible. Otherwise
96 * a kernel bounce buffer is used.
97 *
98 * A matching blk_rq_unmap_user() must be issued at the end of io, while
99 * still in process context.
100 *
101 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
102 * before being submitted to the device, as pages mapped may be out of
103 * reach. It's the callers responsibility to make sure this happens. The
104 * original bio must be passed back in to blk_rq_unmap_user() for proper
105 * unmapping.
106 */
107int blk_rq_map_user(struct request_queue *q, struct request *rq,
108 void __user *ubuf, unsigned long len)
109{
110 unsigned long bytes_read = 0;
111 struct bio *bio = NULL;
112 int ret;
113
114 if (len > (q->max_hw_sectors << 9))
115 return -EINVAL;
116 if (!len || !ubuf)
117 return -EINVAL;
118
119 while (bytes_read != len) {
120 unsigned long map_len, end, start;
121
122 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
123 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
124 >> PAGE_SHIFT;
125 start = (unsigned long)ubuf >> PAGE_SHIFT;
126
127 /*
128 * A bad offset could cause us to require BIO_MAX_PAGES + 1
129 * pages. If this happens we just lower the requested
130 * mapping len by a page so that we can fit
131 */
132 if (end - start > BIO_MAX_PAGES)
133 map_len -= PAGE_SIZE;
134
135 ret = __blk_rq_map_user(q, rq, ubuf, map_len);
136 if (ret < 0)
137 goto unmap_rq;
138 if (!bio)
139 bio = rq->bio;
140 bytes_read += ret;
141 ubuf += ret;
142 }
143
FUJITA Tomonorif18573a2008-04-11 12:56:52 +0200144 if (!bio_flagged(bio, BIO_USER_MAPPED))
145 rq->cmd_flags |= REQ_COPY_USER;
Tejun Heo40b01b92008-02-19 11:35:38 +0100146
Jens Axboe86db1e22008-01-29 14:53:40 +0100147 rq->buffer = rq->data = NULL;
148 return 0;
149unmap_rq:
150 blk_rq_unmap_user(bio);
Jens Axboe84e9e032008-02-18 13:51:56 +0100151 rq->bio = NULL;
Jens Axboe86db1e22008-01-29 14:53:40 +0100152 return ret;
153}
Jens Axboe86db1e22008-01-29 14:53:40 +0100154EXPORT_SYMBOL(blk_rq_map_user);
155
156/**
157 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
158 * @q: request queue where request should be inserted
159 * @rq: request to map data to
160 * @iov: pointer to the iovec
161 * @iov_count: number of elements in the iovec
162 * @len: I/O byte count
163 *
164 * Description:
165 * Data will be mapped directly for zero copy io, if possible. Otherwise
166 * a kernel bounce buffer is used.
167 *
168 * A matching blk_rq_unmap_user() must be issued at the end of io, while
169 * still in process context.
170 *
171 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
172 * before being submitted to the device, as pages mapped may be out of
173 * reach. It's the callers responsibility to make sure this happens. The
174 * original bio must be passed back in to blk_rq_unmap_user() for proper
175 * unmapping.
176 */
177int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
178 struct sg_iovec *iov, int iov_count, unsigned int len)
179{
180 struct bio *bio;
FUJITA Tomonoriafdc1a72008-04-11 12:56:51 +0200181 int i, read = rq_data_dir(rq) == READ;
182 int unaligned = 0;
Jens Axboe86db1e22008-01-29 14:53:40 +0100183
184 if (!iov || iov_count <= 0)
185 return -EINVAL;
186
FUJITA Tomonoriafdc1a72008-04-11 12:56:51 +0200187 for (i = 0; i < iov_count; i++) {
188 unsigned long uaddr = (unsigned long)iov[i].iov_base;
189
190 if (uaddr & queue_dma_alignment(q)) {
191 unaligned = 1;
192 break;
193 }
194 }
195
196 if (unaligned || (q->dma_pad_mask & len))
197 bio = bio_copy_user_iov(q, iov, iov_count, read);
198 else
199 bio = bio_map_user_iov(q, NULL, iov, iov_count, read);
200
Jens Axboe86db1e22008-01-29 14:53:40 +0100201 if (IS_ERR(bio))
202 return PTR_ERR(bio);
203
204 if (bio->bi_size != len) {
205 bio_endio(bio, 0);
206 bio_unmap_user(bio);
207 return -EINVAL;
208 }
209
FUJITA Tomonorif18573a2008-04-11 12:56:52 +0200210 if (!bio_flagged(bio, BIO_USER_MAPPED))
211 rq->cmd_flags |= REQ_COPY_USER;
212
FUJITA Tomonori07359fc2008-06-26 19:39:23 +0200213 blk_queue_bounce(q, &bio);
Jens Axboe86db1e22008-01-29 14:53:40 +0100214 bio_get(bio);
215 blk_rq_bio_prep(q, rq, bio);
216 rq->buffer = rq->data = NULL;
217 return 0;
218}
Jens Axboe86db1e22008-01-29 14:53:40 +0100219
220/**
221 * blk_rq_unmap_user - unmap a request with user data
222 * @bio: start of bio list
223 *
224 * Description:
225 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
226 * supply the original rq->bio from the blk_rq_map_user() return, since
227 * the io completion may have changed rq->bio.
228 */
229int blk_rq_unmap_user(struct bio *bio)
230{
231 struct bio *mapped_bio;
232 int ret = 0, ret2;
233
234 while (bio) {
235 mapped_bio = bio;
236 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
237 mapped_bio = bio->bi_private;
238
239 ret2 = __blk_rq_unmap_user(mapped_bio);
240 if (ret2 && !ret)
241 ret = ret2;
242
243 mapped_bio = bio;
244 bio = bio->bi_next;
245 bio_put(mapped_bio);
246 }
247
248 return ret;
249}
Jens Axboe86db1e22008-01-29 14:53:40 +0100250EXPORT_SYMBOL(blk_rq_unmap_user);
251
252/**
253 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
254 * @q: request queue where request should be inserted
255 * @rq: request to fill
256 * @kbuf: the kernel buffer
257 * @len: length of user data
258 * @gfp_mask: memory allocation flags
FUJITA Tomonori68154e92008-04-25 12:47:50 +0200259 *
260 * Description:
261 * Data will be mapped directly if possible. Otherwise a bounce
262 * buffer is used.
Jens Axboe86db1e22008-01-29 14:53:40 +0100263 */
264int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
265 unsigned int len, gfp_t gfp_mask)
266{
FUJITA Tomonori68154e92008-04-25 12:47:50 +0200267 unsigned long kaddr;
268 unsigned int alignment;
269 int reading = rq_data_dir(rq) == READ;
270 int do_copy = 0;
Jens Axboe86db1e22008-01-29 14:53:40 +0100271 struct bio *bio;
272
273 if (len > (q->max_hw_sectors << 9))
274 return -EINVAL;
275 if (!len || !kbuf)
276 return -EINVAL;
277
FUJITA Tomonori68154e92008-04-25 12:47:50 +0200278 kaddr = (unsigned long)kbuf;
279 alignment = queue_dma_alignment(q) | q->dma_pad_mask;
FUJITA Tomonoria76eef92008-07-25 19:44:39 -0700280 do_copy = ((kaddr & alignment) || (len & alignment) ||
281 object_is_on_stack(kbuf));
FUJITA Tomonori30c00ed2008-07-04 09:31:11 +0200282
FUJITA Tomonori68154e92008-04-25 12:47:50 +0200283 if (do_copy)
284 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
285 else
286 bio = bio_map_kern(q, kbuf, len, gfp_mask);
287
Jens Axboe86db1e22008-01-29 14:53:40 +0100288 if (IS_ERR(bio))
289 return PTR_ERR(bio);
290
291 if (rq_data_dir(rq) == WRITE)
292 bio->bi_rw |= (1 << BIO_RW);
293
FUJITA Tomonori68154e92008-04-25 12:47:50 +0200294 if (do_copy)
295 rq->cmd_flags |= REQ_COPY_USER;
296
Jens Axboe86db1e22008-01-29 14:53:40 +0100297 blk_rq_bio_prep(q, rq, bio);
298 blk_queue_bounce(q, &rq->bio);
299 rq->buffer = rq->data = NULL;
300 return 0;
301}
Jens Axboe86db1e22008-01-29 14:53:40 +0100302EXPORT_SYMBOL(blk_rq_map_kern);