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 void __user *ubuf, unsigned int len,
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))
61 bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
63 bio = bio_copy_user(q, 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 * @ubuf: the user buffer
93 * @len: length of user data
94 * @gfp_mask: memory allocation flags
97 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
98 * a kernel bounce buffer is used.
100 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
101 * still in process context.
103 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
104 * before being submitted to the device, as pages mapped may be out of
105 * reach. It's the callers responsibility to make sure this happens. The
106 * original bio must be passed back in to blk_rq_unmap_user() for proper
109 int blk_rq_map_user(struct request_queue *q, struct request *rq,
110 void __user *ubuf, unsigned long len, gfp_t gfp_mask)
112 unsigned long bytes_read = 0;
113 struct bio *bio = NULL;
116 if (len > (q->max_hw_sectors << 9))
121 while (bytes_read != len) {
122 unsigned long map_len, end, start;
124 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
125 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
127 start = (unsigned long)ubuf >> PAGE_SHIFT;
130 * A bad offset could cause us to require BIO_MAX_PAGES + 1
131 * pages. If this happens we just lower the requested
132 * mapping len by a page so that we can fit
134 if (end - start > BIO_MAX_PAGES)
135 map_len -= PAGE_SIZE;
137 ret = __blk_rq_map_user(q, rq, ubuf, map_len, gfp_mask);
146 if (!bio_flagged(bio, BIO_USER_MAPPED))
147 rq->cmd_flags |= REQ_COPY_USER;
149 rq->buffer = rq->data = NULL;
152 blk_rq_unmap_user(bio);
156 EXPORT_SYMBOL(blk_rq_map_user);
159 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
160 * @q: request queue where request should be inserted
161 * @rq: request to map data to
162 * @iov: pointer to the iovec
163 * @iov_count: number of elements in the iovec
164 * @len: I/O byte count
165 * @gfp_mask: memory allocation flags
168 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
169 * a kernel bounce buffer is used.
171 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
172 * still in process context.
174 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
175 * before being submitted to the device, as pages mapped may be out of
176 * reach. It's the callers responsibility to make sure this happens. The
177 * original bio must be passed back in to blk_rq_unmap_user() for proper
180 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
181 struct sg_iovec *iov, int iov_count, unsigned int len,
185 int i, read = rq_data_dir(rq) == READ;
188 if (!iov || iov_count <= 0)
191 for (i = 0; i < iov_count; i++) {
192 unsigned long uaddr = (unsigned long)iov[i].iov_base;
194 if (uaddr & queue_dma_alignment(q)) {
200 if (unaligned || (q->dma_pad_mask & len))
201 bio = bio_copy_user_iov(q, iov, iov_count, read, gfp_mask);
203 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
208 if (bio->bi_size != len) {
214 if (!bio_flagged(bio, BIO_USER_MAPPED))
215 rq->cmd_flags |= REQ_COPY_USER;
217 blk_queue_bounce(q, &bio);
219 blk_rq_bio_prep(q, rq, bio);
220 rq->buffer = rq->data = NULL;
225 * blk_rq_unmap_user - unmap a request with user data
226 * @bio: start of bio list
229 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
230 * supply the original rq->bio from the blk_rq_map_user() return, since
231 * the I/O completion may have changed rq->bio.
233 int blk_rq_unmap_user(struct bio *bio)
235 struct bio *mapped_bio;
240 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
241 mapped_bio = bio->bi_private;
243 ret2 = __blk_rq_unmap_user(mapped_bio);
254 EXPORT_SYMBOL(blk_rq_unmap_user);
257 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
258 * @q: request queue where request should be inserted
259 * @rq: request to fill
260 * @kbuf: the kernel buffer
261 * @len: length of user data
262 * @gfp_mask: memory allocation flags
265 * Data will be mapped directly if possible. Otherwise a bounce
268 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
269 unsigned int len, gfp_t gfp_mask)
272 unsigned int alignment;
273 int reading = rq_data_dir(rq) == READ;
277 if (len > (q->max_hw_sectors << 9))
282 kaddr = (unsigned long)kbuf;
283 alignment = queue_dma_alignment(q) | q->dma_pad_mask;
284 do_copy = ((kaddr & alignment) || (len & alignment) ||
285 object_is_on_stack(kbuf));
288 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
290 bio = bio_map_kern(q, kbuf, len, gfp_mask);
295 if (rq_data_dir(rq) == WRITE)
296 bio->bi_rw |= (1 << BIO_RW);
299 rq->cmd_flags |= REQ_COPY_USER;
301 blk_rq_bio_prep(q, rq, bio);
302 blk_queue_bounce(q, &rq->bio);
303 rq->buffer = rq->data = NULL;
306 EXPORT_SYMBOL(blk_rq_map_kern);