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 unsigned int alignment; 47 struct bio *bio, *orig_bio; 48 int reading, ret; 49 50 reading = rq_data_dir(rq) == READ; 51 52 /* 53 * if alignment requirement is satisfied, map in user pages for 54 * direct dma. else, set up kernel bounce buffers 55 */ 56 uaddr = (unsigned long) ubuf; 57 alignment = queue_dma_alignment(q) | q->dma_pad_mask; 58 if (!(uaddr & alignment) && !(len & alignment)) 59 bio = bio_map_user(q, NULL, uaddr, len, reading); 60 else 61 bio = bio_copy_user(q, uaddr, len, reading); 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_BLOCK_PC usage 88 * @q: request queue where request should be inserted 89 * @rq: request structure to fill 90 * @ubuf: the user buffer 91 * @len: length of user data 92 * 93 * Description: 94 * Data will be mapped directly for zero copy io, if possible. Otherwise 95 * a kernel bounce buffer is used. 96 * 97 * A matching blk_rq_unmap_user() must be issued at the end of io, while 98 * still in process context. 99 * 100 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 101 * before being submitted to the device, as pages mapped may be out of 102 * reach. It's the callers responsibility to make sure this happens. The 103 * original bio must be passed back in to blk_rq_unmap_user() for proper 104 * unmapping. 105 */ 106 int blk_rq_map_user(struct request_queue *q, struct request *rq, 107 void __user *ubuf, unsigned long len) 108 { 109 unsigned long bytes_read = 0; 110 struct bio *bio = NULL; 111 int ret; 112 113 if (len > (q->max_hw_sectors << 9)) 114 return -EINVAL; 115 if (!len || !ubuf) 116 return -EINVAL; 117 118 while (bytes_read != len) { 119 unsigned long map_len, end, start; 120 121 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE); 122 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1) 123 >> PAGE_SHIFT; 124 start = (unsigned long)ubuf >> PAGE_SHIFT; 125 126 /* 127 * A bad offset could cause us to require BIO_MAX_PAGES + 1 128 * pages. If this happens we just lower the requested 129 * mapping len by a page so that we can fit 130 */ 131 if (end - start > BIO_MAX_PAGES) 132 map_len -= PAGE_SIZE; 133 134 ret = __blk_rq_map_user(q, rq, ubuf, map_len); 135 if (ret < 0) 136 goto unmap_rq; 137 if (!bio) 138 bio = rq->bio; 139 bytes_read += ret; 140 ubuf += ret; 141 } 142 143 /* 144 * __blk_rq_map_user() copies the buffers if starting address 145 * or length isn't aligned to dma_pad_mask. As the copied 146 * buffer is always page aligned, we know that there's enough 147 * room for padding. Extend the last bio and update 148 * rq->data_len accordingly. 149 * 150 * On unmap, bio_uncopy_user() will use unmodified 151 * bio_map_data pointed to by bio->bi_private. 152 */ 153 if (len & q->dma_pad_mask) { 154 unsigned int pad_len = (q->dma_pad_mask & ~len) + 1; 155 struct bio *bio = rq->biotail; 156 157 bio->bi_io_vec[bio->bi_vcnt - 1].bv_len += pad_len; 158 bio->bi_size += pad_len; 159 160 rq->extra_len += pad_len; 161 } 162 163 rq->buffer = rq->data = NULL; 164 return 0; 165 unmap_rq: 166 blk_rq_unmap_user(bio); 167 rq->bio = NULL; 168 return ret; 169 } 170 EXPORT_SYMBOL(blk_rq_map_user); 171 172 /** 173 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage 174 * @q: request queue where request should be inserted 175 * @rq: request to map data to 176 * @iov: pointer to the iovec 177 * @iov_count: number of elements in the iovec 178 * @len: I/O byte count 179 * 180 * Description: 181 * Data will be mapped directly for zero copy io, if possible. Otherwise 182 * a kernel bounce buffer is used. 183 * 184 * A matching blk_rq_unmap_user() must be issued at the end of io, while 185 * still in process context. 186 * 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 191 * unmapping. 192 */ 193 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 194 struct sg_iovec *iov, int iov_count, unsigned int len) 195 { 196 struct bio *bio; 197 198 if (!iov || iov_count <= 0) 199 return -EINVAL; 200 201 /* we don't allow misaligned data like bio_map_user() does. If the 202 * user is using sg, they're expected to know the alignment constraints 203 * and respect them accordingly */ 204 bio = bio_map_user_iov(q, NULL, iov, iov_count, 205 rq_data_dir(rq) == READ); 206 if (IS_ERR(bio)) 207 return PTR_ERR(bio); 208 209 if (bio->bi_size != len) { 210 bio_endio(bio, 0); 211 bio_unmap_user(bio); 212 return -EINVAL; 213 } 214 215 bio_get(bio); 216 blk_rq_bio_prep(q, rq, bio); 217 rq->buffer = rq->data = NULL; 218 return 0; 219 } 220 221 /** 222 * blk_rq_unmap_user - unmap a request with user data 223 * @bio: start of bio list 224 * 225 * Description: 226 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 227 * supply the original rq->bio from the blk_rq_map_user() return, since 228 * the io completion may have changed rq->bio. 229 */ 230 int blk_rq_unmap_user(struct bio *bio) 231 { 232 struct bio *mapped_bio; 233 int ret = 0, ret2; 234 235 while (bio) { 236 mapped_bio = bio; 237 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 238 mapped_bio = bio->bi_private; 239 240 ret2 = __blk_rq_unmap_user(mapped_bio); 241 if (ret2 && !ret) 242 ret = ret2; 243 244 mapped_bio = bio; 245 bio = bio->bi_next; 246 bio_put(mapped_bio); 247 } 248 249 return ret; 250 } 251 EXPORT_SYMBOL(blk_rq_unmap_user); 252 253 /** 254 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage 255 * @q: request queue where request should be inserted 256 * @rq: request to fill 257 * @kbuf: the kernel buffer 258 * @len: length of user data 259 * @gfp_mask: memory allocation flags 260 */ 261 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 262 unsigned int len, gfp_t gfp_mask) 263 { 264 struct bio *bio; 265 266 if (len > (q->max_hw_sectors << 9)) 267 return -EINVAL; 268 if (!len || !kbuf) 269 return -EINVAL; 270 271 bio = bio_map_kern(q, kbuf, len, gfp_mask); 272 if (IS_ERR(bio)) 273 return PTR_ERR(bio); 274 275 if (rq_data_dir(rq) == WRITE) 276 bio->bi_rw |= (1 << BIO_RW); 277 278 blk_rq_bio_prep(q, rq, bio); 279 blk_queue_bounce(q, &rq->bio); 280 rq->buffer = rq->data = NULL; 281 return 0; 282 } 283 EXPORT_SYMBOL(blk_rq_map_kern); 284