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, int null_mapped, gfp_t gfp_mask)
48 struct bio *bio, *orig_bio;
51 reading = rq_data_dir(rq) == READ;
54 * if alignment requirement is satisfied, map in user pages for
55 * direct dma. else, set up kernel bounce buffers
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);
61 bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);
67 bio->bi_flags |= (1 << BIO_NULL_MAPPED);
70 blk_queue_bounce(q, &bio);
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
78 ret = blk_rq_append_bio(q, rq, bio);
82 /* if it was boucned we must call the end io function */
84 __blk_rq_unmap_user(orig_bio);
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
99 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
100 * a kernel bounce buffer is used.
102 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
103 * still in process context.
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
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)
115 unsigned long bytes_read = 0;
116 struct bio *bio = NULL;
117 int ret, null_mapped = 0;
119 if (len > (q->max_hw_sectors << 9))
124 if (!map_data || rq_data_dir(rq) != READ)
129 while (bytes_read != len) {
130 unsigned long map_len, end, start;
132 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
133 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
135 start = (unsigned long)ubuf >> PAGE_SHIFT;
138 * A bad offset could cause us to require BIO_MAX_PAGES + 1
139 * pages. If this happens we just lower the requested
140 * mapping len by a page so that we can fit
142 if (end - start > BIO_MAX_PAGES)
143 map_len -= PAGE_SIZE;
145 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
146 null_mapped, gfp_mask);
155 map_data->offset += ret;
158 if (!bio_flagged(bio, BIO_USER_MAPPED))
159 rq->cmd_flags |= REQ_COPY_USER;
161 rq->buffer = rq->data = NULL;
164 blk_rq_unmap_user(bio);
168 EXPORT_SYMBOL(blk_rq_map_user);
171 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
172 * @q: request queue where request should be inserted
173 * @rq: request to map data to
174 * @map_data: pointer to the rq_map_data holding pages (if necessary)
175 * @iov: pointer to the iovec
176 * @iov_count: number of elements in the iovec
177 * @len: I/O byte count
178 * @gfp_mask: memory allocation flags
181 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
182 * a kernel bounce buffer is used.
184 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
185 * still in process context.
187 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
188 * before being submitted to the device, as pages mapped may be out of
189 * reach. It's the callers responsibility to make sure this happens. The
190 * original bio must be passed back in to blk_rq_unmap_user() for proper
193 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
194 struct rq_map_data *map_data, struct sg_iovec *iov,
195 int iov_count, unsigned int len, gfp_t gfp_mask)
198 int i, read = rq_data_dir(rq) == READ;
201 if (!iov || iov_count <= 0)
204 for (i = 0; i < iov_count; i++) {
205 unsigned long uaddr = (unsigned long)iov[i].iov_base;
207 if (uaddr & queue_dma_alignment(q)) {
213 if (unaligned || (q->dma_pad_mask & len) || map_data)
214 bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
217 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
222 if (bio->bi_size != len) {
224 * Grab an extra reference to this bio, as bio_unmap_user()
225 * expects to be able to drop it twice as it happens on the
226 * normal IO completion path
230 __blk_rq_unmap_user(bio);
234 if (!bio_flagged(bio, BIO_USER_MAPPED))
235 rq->cmd_flags |= REQ_COPY_USER;
237 blk_queue_bounce(q, &bio);
239 blk_rq_bio_prep(q, rq, bio);
240 rq->buffer = rq->data = NULL;
243 EXPORT_SYMBOL(blk_rq_map_user_iov);
246 * blk_rq_unmap_user - unmap a request with user data
247 * @bio: start of bio list
250 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
251 * supply the original rq->bio from the blk_rq_map_user() return, since
252 * the I/O completion may have changed rq->bio.
254 int blk_rq_unmap_user(struct bio *bio)
256 struct bio *mapped_bio;
261 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
262 mapped_bio = bio->bi_private;
264 ret2 = __blk_rq_unmap_user(mapped_bio);
275 EXPORT_SYMBOL(blk_rq_unmap_user);
278 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
279 * @q: request queue where request should be inserted
280 * @rq: request to fill
281 * @kbuf: the kernel buffer
282 * @len: length of user data
283 * @gfp_mask: memory allocation flags
286 * Data will be mapped directly if possible. Otherwise a bounce
289 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
290 unsigned int len, gfp_t gfp_mask)
292 int reading = rq_data_dir(rq) == READ;
296 if (len > (q->max_hw_sectors << 9))
301 do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf);
303 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
305 bio = bio_map_kern(q, kbuf, len, gfp_mask);
310 if (rq_data_dir(rq) == WRITE)
311 bio->bi_rw |= (1 << BIO_RW);
314 rq->cmd_flags |= REQ_COPY_USER;
316 blk_rq_bio_prep(q, rq, bio);
317 blk_queue_bounce(q, &rq->bio);
318 rq->buffer = rq->data = NULL;
321 EXPORT_SYMBOL(blk_rq_map_kern);