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 orig_bio = bio; 67 blk_queue_bounce(q, &bio); 68 69 /* 70 * We link the bounce buffer in and could have to traverse it 71 * later so we have to get a ref to prevent it from being freed 72 */ 73 bio_get(bio); 74 75 ret = blk_rq_append_bio(q, rq, bio); 76 if (!ret) 77 return bio->bi_size; 78 79 /* if it was boucned we must call the end io function */ 80 bio_endio(bio, 0); 81 __blk_rq_unmap_user(orig_bio); 82 bio_put(bio); 83 return ret; 84 } 85 86 /** 87 * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage 88 * @q: request queue where request should be inserted 89 * @rq: request structure to fill 90 * @map_data: pointer to the rq_map_data holding pages (if necessary) 91 * @ubuf: the user buffer 92 * @len: length of user data 93 * @gfp_mask: memory allocation flags 94 * 95 * Description: 96 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 97 * a kernel bounce buffer is used. 98 * 99 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 100 * still in process context. 101 * 102 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 103 * before being submitted to the device, as pages mapped may be out of 104 * reach. It's the callers responsibility to make sure this happens. The 105 * original bio must be passed back in to blk_rq_unmap_user() for proper 106 * unmapping. 107 */ 108 int blk_rq_map_user(struct request_queue *q, struct request *rq, 109 struct rq_map_data *map_data, void __user *ubuf, 110 unsigned long len, gfp_t gfp_mask) 111 { 112 unsigned long bytes_read = 0; 113 struct bio *bio = NULL; 114 int ret; 115 116 if (len > (q->max_hw_sectors << 9)) 117 return -EINVAL; 118 if (!len || !ubuf) 119 return -EINVAL; 120 121 while (bytes_read != len) { 122 unsigned long map_len, end, start; 123 124 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE); 125 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1) 126 >> PAGE_SHIFT; 127 start = (unsigned long)ubuf >> PAGE_SHIFT; 128 129 /* 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 133 */ 134 if (end - start > BIO_MAX_PAGES) 135 map_len -= PAGE_SIZE; 136 137 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len, 138 gfp_mask); 139 if (ret < 0) 140 goto unmap_rq; 141 if (!bio) 142 bio = rq->bio; 143 bytes_read += ret; 144 ubuf += ret; 145 } 146 147 if (!bio_flagged(bio, BIO_USER_MAPPED)) 148 rq->cmd_flags |= REQ_COPY_USER; 149 150 rq->buffer = rq->data = NULL; 151 return 0; 152 unmap_rq: 153 blk_rq_unmap_user(bio); 154 rq->bio = NULL; 155 return ret; 156 } 157 EXPORT_SYMBOL(blk_rq_map_user); 158 159 /** 160 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 161 * @q: request queue where request should be inserted 162 * @rq: request to map data to 163 * @map_data: pointer to the rq_map_data holding pages (if necessary) 164 * @iov: pointer to the iovec 165 * @iov_count: number of elements in the iovec 166 * @len: I/O byte count 167 * @gfp_mask: memory allocation flags 168 * 169 * Description: 170 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 171 * a kernel bounce buffer is used. 172 * 173 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 174 * still in process context. 175 * 176 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 177 * before being submitted to the device, as pages mapped may be out of 178 * reach. It's the callers responsibility to make sure this happens. The 179 * original bio must be passed back in to blk_rq_unmap_user() for proper 180 * unmapping. 181 */ 182 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 183 struct rq_map_data *map_data, struct sg_iovec *iov, 184 int iov_count, unsigned int len, gfp_t gfp_mask) 185 { 186 struct bio *bio; 187 int i, read = rq_data_dir(rq) == READ; 188 int unaligned = 0; 189 190 if (!iov || iov_count <= 0) 191 return -EINVAL; 192 193 for (i = 0; i < iov_count; i++) { 194 unsigned long uaddr = (unsigned long)iov[i].iov_base; 195 196 if (uaddr & queue_dma_alignment(q)) { 197 unaligned = 1; 198 break; 199 } 200 } 201 202 if (unaligned || (q->dma_pad_mask & len) || map_data) 203 bio = bio_copy_user_iov(q, map_data, iov, iov_count, read, 204 gfp_mask); 205 else 206 bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask); 207 208 if (IS_ERR(bio)) 209 return PTR_ERR(bio); 210 211 if (bio->bi_size != len) { 212 bio_endio(bio, 0); 213 bio_unmap_user(bio); 214 return -EINVAL; 215 } 216 217 if (!bio_flagged(bio, BIO_USER_MAPPED)) 218 rq->cmd_flags |= REQ_COPY_USER; 219 220 blk_queue_bounce(q, &bio); 221 bio_get(bio); 222 blk_rq_bio_prep(q, rq, bio); 223 rq->buffer = rq->data = NULL; 224 return 0; 225 } 226 EXPORT_SYMBOL(blk_rq_map_user_iov); 227 228 /** 229 * blk_rq_unmap_user - unmap a request with user data 230 * @bio: start of bio list 231 * 232 * Description: 233 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 234 * supply the original rq->bio from the blk_rq_map_user() return, since 235 * the I/O completion may have changed rq->bio. 236 */ 237 int blk_rq_unmap_user(struct bio *bio) 238 { 239 struct bio *mapped_bio; 240 int ret = 0, ret2; 241 242 while (bio) { 243 mapped_bio = bio; 244 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 245 mapped_bio = bio->bi_private; 246 247 ret2 = __blk_rq_unmap_user(mapped_bio); 248 if (ret2 && !ret) 249 ret = ret2; 250 251 mapped_bio = bio; 252 bio = bio->bi_next; 253 bio_put(mapped_bio); 254 } 255 256 return ret; 257 } 258 EXPORT_SYMBOL(blk_rq_unmap_user); 259 260 /** 261 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage 262 * @q: request queue where request should be inserted 263 * @rq: request to fill 264 * @kbuf: the kernel buffer 265 * @len: length of user data 266 * @gfp_mask: memory allocation flags 267 * 268 * Description: 269 * Data will be mapped directly if possible. Otherwise a bounce 270 * buffer is used. 271 */ 272 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 273 unsigned int len, gfp_t gfp_mask) 274 { 275 int reading = rq_data_dir(rq) == READ; 276 int do_copy = 0; 277 struct bio *bio; 278 279 if (len > (q->max_hw_sectors << 9)) 280 return -EINVAL; 281 if (!len || !kbuf) 282 return -EINVAL; 283 284 do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf); 285 if (do_copy) 286 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); 287 else 288 bio = bio_map_kern(q, kbuf, len, gfp_mask); 289 290 if (IS_ERR(bio)) 291 return PTR_ERR(bio); 292 293 if (rq_data_dir(rq) == WRITE) 294 bio->bi_rw |= (1 << BIO_RW); 295 296 if (do_copy) 297 rq->cmd_flags |= REQ_COPY_USER; 298 299 blk_rq_bio_prep(q, rq, bio); 300 blk_queue_bounce(q, &rq->bio); 301 rq->buffer = rq->data = NULL; 302 return 0; 303 } 304 EXPORT_SYMBOL(blk_rq_map_kern); 305