2 * Functions related to mapping data to requests
4 #include <linux/kernel.h>
5 #include <linux/module.h>
7 #include <linux/blkdev.h>
8 #include <scsi/sg.h> /* for struct sg_iovec */
12 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
16 blk_rq_bio_prep(q, rq, bio);
17 else if (!ll_back_merge_fn(q, rq, bio))
20 rq->biotail->bi_next = bio;
23 rq->data_len += bio->bi_size;
27 EXPORT_SYMBOL(blk_rq_append_bio);
29 static int __blk_rq_unmap_user(struct bio *bio)
34 if (bio_flagged(bio, BIO_USER_MAPPED))
37 ret = bio_uncopy_user(bio);
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)
48 unsigned int alignment;
49 struct bio *bio, *orig_bio;
52 reading = rq_data_dir(rq) == READ;
55 * if alignment requirement is satisfied, map in user pages for
56 * direct dma. else, set up kernel bounce buffers
58 uaddr = (unsigned long) ubuf;
59 alignment = queue_dma_alignment(q) | q->dma_pad_mask;
60 if (!(uaddr & alignment) && !(len & alignment) && !map_data)
61 bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
63 bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);
69 blk_queue_bounce(q, &bio);
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
77 ret = blk_rq_append_bio(q, rq, bio);
81 /* if it was boucned we must call the end io function */
83 __blk_rq_unmap_user(orig_bio);
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
98 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
99 * a kernel bounce buffer is used.
101 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
102 * still in process context.
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
110 int 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)
114 unsigned long bytes_read = 0;
115 struct bio *bio = NULL;
118 if (len > (q->max_hw_sectors << 9))
123 while (bytes_read != len) {
124 unsigned long map_len, end, start;
126 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
127 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
129 start = (unsigned long)ubuf >> PAGE_SHIFT;
132 * A bad offset could cause us to require BIO_MAX_PAGES + 1
133 * pages. If this happens we just lower the requested
134 * mapping len by a page so that we can fit
136 if (end - start > BIO_MAX_PAGES)
137 map_len -= PAGE_SIZE;
139 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
149 if (!bio_flagged(bio, BIO_USER_MAPPED))
150 rq->cmd_flags |= REQ_COPY_USER;
152 rq->buffer = rq->data = NULL;
155 blk_rq_unmap_user(bio);
159 EXPORT_SYMBOL(blk_rq_map_user);
162 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
163 * @q: request queue where request should be inserted
164 * @rq: request to map data to
165 * @map_data: pointer to the rq_map_data holding pages (if necessary)
166 * @iov: pointer to the iovec
167 * @iov_count: number of elements in the iovec
168 * @len: I/O byte count
169 * @gfp_mask: memory allocation flags
172 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
173 * a kernel bounce buffer is used.
175 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
176 * still in process context.
178 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
179 * before being submitted to the device, as pages mapped may be out of
180 * reach. It's the callers responsibility to make sure this happens. The
181 * original bio must be passed back in to blk_rq_unmap_user() for proper
184 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
185 struct rq_map_data *map_data, struct sg_iovec *iov,
186 int iov_count, unsigned int len, gfp_t gfp_mask)
189 int i, read = rq_data_dir(rq) == READ;
192 if (!iov || iov_count <= 0)
195 for (i = 0; i < iov_count; i++) {
196 unsigned long uaddr = (unsigned long)iov[i].iov_base;
198 if (uaddr & queue_dma_alignment(q)) {
204 if (unaligned || (q->dma_pad_mask & len) || map_data)
205 bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
208 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
213 if (bio->bi_size != len) {
219 if (!bio_flagged(bio, BIO_USER_MAPPED))
220 rq->cmd_flags |= REQ_COPY_USER;
222 blk_queue_bounce(q, &bio);
224 blk_rq_bio_prep(q, rq, bio);
225 rq->buffer = rq->data = NULL;
228 EXPORT_SYMBOL(blk_rq_map_user_iov);
231 * blk_rq_unmap_user - unmap a request with user data
232 * @bio: start of bio list
235 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
236 * supply the original rq->bio from the blk_rq_map_user() return, since
237 * the I/O completion may have changed rq->bio.
239 int blk_rq_unmap_user(struct bio *bio)
241 struct bio *mapped_bio;
246 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
247 mapped_bio = bio->bi_private;
249 ret2 = __blk_rq_unmap_user(mapped_bio);
260 EXPORT_SYMBOL(blk_rq_unmap_user);
263 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
264 * @q: request queue where request should be inserted
265 * @rq: request to fill
266 * @kbuf: the kernel buffer
267 * @len: length of user data
268 * @gfp_mask: memory allocation flags
271 * Data will be mapped directly if possible. Otherwise a bounce
274 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
275 unsigned int len, gfp_t gfp_mask)
278 unsigned int alignment;
279 int reading = rq_data_dir(rq) == READ;
283 if (len > (q->max_hw_sectors << 9))
288 kaddr = (unsigned long)kbuf;
289 alignment = queue_dma_alignment(q) | q->dma_pad_mask;
290 do_copy = ((kaddr & alignment) || (len & alignment) ||
291 object_is_on_stack(kbuf));
294 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
296 bio = bio_map_kern(q, kbuf, len, gfp_mask);
301 if (rq_data_dir(rq) == WRITE)
302 bio->bi_rw |= (1 << BIO_RW);
305 rq->cmd_flags |= REQ_COPY_USER;
307 blk_rq_bio_prep(q, rq, bio);
308 blk_queue_bounce(q, &rq->bio);
309 rq->buffer = rq->data = NULL;
312 EXPORT_SYMBOL(blk_rq_map_kern);