Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame^] | 1 | /* |
| 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 | |
| 11 | int 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 | } |
| 26 | EXPORT_SYMBOL(blk_rq_append_bio); |
| 27 | |
| 28 | static 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 | |
| 42 | static 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; |
| 56 | if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) |
| 57 | bio = bio_map_user(q, NULL, uaddr, len, reading); |
| 58 | else |
| 59 | bio = bio_copy_user(q, uaddr, len, reading); |
| 60 | |
| 61 | if (IS_ERR(bio)) |
| 62 | return PTR_ERR(bio); |
| 63 | |
| 64 | orig_bio = bio; |
| 65 | blk_queue_bounce(q, &bio); |
| 66 | |
| 67 | /* |
| 68 | * We link the bounce buffer in and could have to traverse it |
| 69 | * later so we have to get a ref to prevent it from being freed |
| 70 | */ |
| 71 | bio_get(bio); |
| 72 | |
| 73 | ret = blk_rq_append_bio(q, rq, bio); |
| 74 | if (!ret) |
| 75 | return bio->bi_size; |
| 76 | |
| 77 | /* if it was boucned we must call the end io function */ |
| 78 | bio_endio(bio, 0); |
| 79 | __blk_rq_unmap_user(orig_bio); |
| 80 | bio_put(bio); |
| 81 | return ret; |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage |
| 86 | * @q: request queue where request should be inserted |
| 87 | * @rq: request structure to fill |
| 88 | * @ubuf: the user buffer |
| 89 | * @len: length of user data |
| 90 | * |
| 91 | * Description: |
| 92 | * Data will be mapped directly for zero copy io, if possible. Otherwise |
| 93 | * a kernel bounce buffer is used. |
| 94 | * |
| 95 | * A matching blk_rq_unmap_user() must be issued at the end of io, while |
| 96 | * still in process context. |
| 97 | * |
| 98 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() |
| 99 | * before being submitted to the device, as pages mapped may be out of |
| 100 | * reach. It's the callers responsibility to make sure this happens. The |
| 101 | * original bio must be passed back in to blk_rq_unmap_user() for proper |
| 102 | * unmapping. |
| 103 | */ |
| 104 | int blk_rq_map_user(struct request_queue *q, struct request *rq, |
| 105 | void __user *ubuf, unsigned long len) |
| 106 | { |
| 107 | unsigned long bytes_read = 0; |
| 108 | struct bio *bio = NULL; |
| 109 | int ret; |
| 110 | |
| 111 | if (len > (q->max_hw_sectors << 9)) |
| 112 | return -EINVAL; |
| 113 | if (!len || !ubuf) |
| 114 | return -EINVAL; |
| 115 | |
| 116 | while (bytes_read != len) { |
| 117 | unsigned long map_len, end, start; |
| 118 | |
| 119 | map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE); |
| 120 | end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1) |
| 121 | >> PAGE_SHIFT; |
| 122 | start = (unsigned long)ubuf >> PAGE_SHIFT; |
| 123 | |
| 124 | /* |
| 125 | * A bad offset could cause us to require BIO_MAX_PAGES + 1 |
| 126 | * pages. If this happens we just lower the requested |
| 127 | * mapping len by a page so that we can fit |
| 128 | */ |
| 129 | if (end - start > BIO_MAX_PAGES) |
| 130 | map_len -= PAGE_SIZE; |
| 131 | |
| 132 | ret = __blk_rq_map_user(q, rq, ubuf, map_len); |
| 133 | if (ret < 0) |
| 134 | goto unmap_rq; |
| 135 | if (!bio) |
| 136 | bio = rq->bio; |
| 137 | bytes_read += ret; |
| 138 | ubuf += ret; |
| 139 | } |
| 140 | |
| 141 | rq->buffer = rq->data = NULL; |
| 142 | return 0; |
| 143 | unmap_rq: |
| 144 | blk_rq_unmap_user(bio); |
| 145 | return ret; |
| 146 | } |
| 147 | |
| 148 | EXPORT_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 | */ |
| 171 | int 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 */ |
| 182 | bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ); |
| 183 | if (IS_ERR(bio)) |
| 184 | return PTR_ERR(bio); |
| 185 | |
| 186 | if (bio->bi_size != len) { |
| 187 | bio_endio(bio, 0); |
| 188 | bio_unmap_user(bio); |
| 189 | return -EINVAL; |
| 190 | } |
| 191 | |
| 192 | bio_get(bio); |
| 193 | blk_rq_bio_prep(q, rq, bio); |
| 194 | rq->buffer = rq->data = NULL; |
| 195 | return 0; |
| 196 | } |
| 197 | |
| 198 | EXPORT_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 | */ |
| 209 | int 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 | } |
| 230 | |
| 231 | EXPORT_SYMBOL(blk_rq_unmap_user); |
| 232 | |
| 233 | /** |
| 234 | * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage |
| 235 | * @q: request queue where request should be inserted |
| 236 | * @rq: request to fill |
| 237 | * @kbuf: the kernel buffer |
| 238 | * @len: length of user data |
| 239 | * @gfp_mask: memory allocation flags |
| 240 | */ |
| 241 | int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, |
| 242 | unsigned int len, gfp_t gfp_mask) |
| 243 | { |
| 244 | struct bio *bio; |
| 245 | |
| 246 | if (len > (q->max_hw_sectors << 9)) |
| 247 | return -EINVAL; |
| 248 | if (!len || !kbuf) |
| 249 | return -EINVAL; |
| 250 | |
| 251 | bio = bio_map_kern(q, kbuf, len, gfp_mask); |
| 252 | if (IS_ERR(bio)) |
| 253 | return PTR_ERR(bio); |
| 254 | |
| 255 | if (rq_data_dir(rq) == WRITE) |
| 256 | bio->bi_rw |= (1 << BIO_RW); |
| 257 | |
| 258 | blk_rq_bio_prep(q, rq, bio); |
| 259 | blk_queue_bounce(q, &rq->bio); |
| 260 | rq->buffer = rq->data = NULL; |
| 261 | return 0; |
| 262 | } |
| 263 | |
| 264 | EXPORT_SYMBOL(blk_rq_map_kern); |