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 #include <scsi/sg.h> /* for struct sg_iovec */ 9 10 #include "blk.h" 11 12 int 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 } 27 EXPORT_SYMBOL(blk_rq_append_bio); 28 29 static 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 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) 46 { 47 unsigned long uaddr; 48 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; 58 if (blk_rq_aligned(q, ubuf, len) && !map_data) 59 bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask); 60 else 61 bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask); 62 63 if (IS_ERR(bio)) 64 return PTR_ERR(bio); 65 66 if (map_data && map_data->null_mapped) 67 bio->bi_flags |= (1 << BIO_NULL_MAPPED); 68 69 orig_bio = bio; 70 blk_queue_bounce(q, &bio); 71 72 /* 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 75 */ 76 bio_get(bio); 77 78 ret = blk_rq_append_bio(q, rq, bio); 79 if (!ret) 80 return bio->bi_size; 81 82 /* if it was boucned we must call the end io function */ 83 bio_endio(bio, 0); 84 __blk_rq_unmap_user(orig_bio); 85 bio_put(bio); 86 return ret; 87 } 88 89 /** 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 97 * 98 * Description: 99 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 100 * a kernel bounce buffer is used. 101 * 102 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 103 * still in process context. 104 * 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 109 * unmapping. 110 */ 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) 114 { 115 unsigned long bytes_read = 0; 116 struct bio *bio = NULL; 117 int ret; 118 119 if (len > (q->max_hw_sectors << 9)) 120 return -EINVAL; 121 if (!len) 122 return -EINVAL; 123 124 if (!ubuf && (!map_data || !map_data->null_mapped)) 125 return -EINVAL; 126 127 while (bytes_read != len) { 128 unsigned long map_len, end, start; 129 130 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE); 131 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1) 132 >> PAGE_SHIFT; 133 start = (unsigned long)ubuf >> PAGE_SHIFT; 134 135 /* 136 * A bad offset could cause us to require BIO_MAX_PAGES + 1 137 * pages. If this happens we just lower the requested 138 * mapping len by a page so that we can fit 139 */ 140 if (end - start > BIO_MAX_PAGES) 141 map_len -= PAGE_SIZE; 142 143 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len, 144 gfp_mask); 145 if (ret < 0) 146 goto unmap_rq; 147 if (!bio) 148 bio = rq->bio; 149 bytes_read += ret; 150 ubuf += ret; 151 152 if (map_data) 153 map_data->offset += ret; 154 } 155 156 if (!bio_flagged(bio, BIO_USER_MAPPED)) 157 rq->cmd_flags |= REQ_COPY_USER; 158 159 rq->buffer = rq->data = NULL; 160 return 0; 161 unmap_rq: 162 blk_rq_unmap_user(bio); 163 rq->bio = NULL; 164 return ret; 165 } 166 EXPORT_SYMBOL(blk_rq_map_user); 167 168 /** 169 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 170 * @q: request queue where request should be inserted 171 * @rq: request to map data to 172 * @map_data: pointer to the rq_map_data holding pages (if necessary) 173 * @iov: pointer to the iovec 174 * @iov_count: number of elements in the iovec 175 * @len: I/O byte count 176 * @gfp_mask: memory allocation flags 177 * 178 * Description: 179 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 180 * a kernel bounce buffer is used. 181 * 182 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 183 * still in process context. 184 * 185 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 186 * before being submitted to the device, as pages mapped may be out of 187 * reach. It's the callers responsibility to make sure this happens. The 188 * original bio must be passed back in to blk_rq_unmap_user() for proper 189 * unmapping. 190 */ 191 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 192 struct rq_map_data *map_data, struct sg_iovec *iov, 193 int iov_count, unsigned int len, gfp_t gfp_mask) 194 { 195 struct bio *bio; 196 int i, read = rq_data_dir(rq) == READ; 197 int unaligned = 0; 198 199 if (!iov || iov_count <= 0) 200 return -EINVAL; 201 202 for (i = 0; i < iov_count; i++) { 203 unsigned long uaddr = (unsigned long)iov[i].iov_base; 204 205 if (uaddr & queue_dma_alignment(q)) { 206 unaligned = 1; 207 break; 208 } 209 } 210 211 if (unaligned || (q->dma_pad_mask & len) || map_data) 212 bio = bio_copy_user_iov(q, map_data, iov, iov_count, read, 213 gfp_mask); 214 else 215 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask); 216 217 if (IS_ERR(bio)) 218 return PTR_ERR(bio); 219 220 if (bio->bi_size != len) { 221 /* 222 * Grab an extra reference to this bio, as bio_unmap_user() 223 * expects to be able to drop it twice as it happens on the 224 * normal IO completion path 225 */ 226 bio_get(bio); 227 bio_endio(bio, 0); 228 __blk_rq_unmap_user(bio); 229 return -EINVAL; 230 } 231 232 if (!bio_flagged(bio, BIO_USER_MAPPED)) 233 rq->cmd_flags |= REQ_COPY_USER; 234 235 blk_queue_bounce(q, &bio); 236 bio_get(bio); 237 blk_rq_bio_prep(q, rq, bio); 238 rq->buffer = rq->data = NULL; 239 return 0; 240 } 241 EXPORT_SYMBOL(blk_rq_map_user_iov); 242 243 /** 244 * blk_rq_unmap_user - unmap a request with user data 245 * @bio: start of bio list 246 * 247 * Description: 248 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 249 * supply the original rq->bio from the blk_rq_map_user() return, since 250 * the I/O completion may have changed rq->bio. 251 */ 252 int blk_rq_unmap_user(struct bio *bio) 253 { 254 struct bio *mapped_bio; 255 int ret = 0, ret2; 256 257 while (bio) { 258 mapped_bio = bio; 259 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 260 mapped_bio = bio->bi_private; 261 262 ret2 = __blk_rq_unmap_user(mapped_bio); 263 if (ret2 && !ret) 264 ret = ret2; 265 266 mapped_bio = bio; 267 bio = bio->bi_next; 268 bio_put(mapped_bio); 269 } 270 271 return ret; 272 } 273 EXPORT_SYMBOL(blk_rq_unmap_user); 274 275 /** 276 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage 277 * @q: request queue where request should be inserted 278 * @rq: request to fill 279 * @kbuf: the kernel buffer 280 * @len: length of user data 281 * @gfp_mask: memory allocation flags 282 * 283 * Description: 284 * Data will be mapped directly if possible. Otherwise a bounce 285 * buffer is used. 286 */ 287 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 288 unsigned int len, gfp_t gfp_mask) 289 { 290 int reading = rq_data_dir(rq) == READ; 291 int do_copy = 0; 292 struct bio *bio; 293 294 if (len > (q->max_hw_sectors << 9)) 295 return -EINVAL; 296 if (!len || !kbuf) 297 return -EINVAL; 298 299 do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf); 300 if (do_copy) 301 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); 302 else 303 bio = bio_map_kern(q, kbuf, len, gfp_mask); 304 305 if (IS_ERR(bio)) 306 return PTR_ERR(bio); 307 308 if (rq_data_dir(rq) == WRITE) 309 bio->bi_rw |= (1 << BIO_RW); 310 311 if (do_copy) 312 rq->cmd_flags |= REQ_COPY_USER; 313 314 blk_rq_bio_prep(q, rq, bio); 315 blk_queue_bounce(q, &rq->bio); 316 rq->buffer = rq->data = NULL; 317 return 0; 318 } 319 EXPORT_SYMBOL(blk_rq_map_kern); 320