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 <linux/uio.h> 9 10 #include "blk.h" 11 12 /* 13 * Append a bio to a passthrough request. Only works can be merged into 14 * the request based on the driver constraints. 15 */ 16 int blk_rq_append_bio(struct request *rq, struct bio *bio) 17 { 18 if (!rq->bio) { 19 rq->cmd_flags &= REQ_OP_MASK; 20 rq->cmd_flags |= (bio->bi_opf & REQ_OP_MASK); 21 blk_rq_bio_prep(rq->q, rq, bio); 22 } else { 23 if (!ll_back_merge_fn(rq->q, rq, bio)) 24 return -EINVAL; 25 26 rq->biotail->bi_next = bio; 27 rq->biotail = bio; 28 rq->__data_len += bio->bi_iter.bi_size; 29 } 30 31 return 0; 32 } 33 EXPORT_SYMBOL(blk_rq_append_bio); 34 35 static int __blk_rq_unmap_user(struct bio *bio) 36 { 37 int ret = 0; 38 39 if (bio) { 40 if (bio_flagged(bio, BIO_USER_MAPPED)) 41 bio_unmap_user(bio); 42 else 43 ret = bio_uncopy_user(bio); 44 } 45 46 return ret; 47 } 48 49 static int __blk_rq_map_user_iov(struct request *rq, 50 struct rq_map_data *map_data, struct iov_iter *iter, 51 gfp_t gfp_mask, bool copy) 52 { 53 struct request_queue *q = rq->q; 54 struct bio *bio, *orig_bio; 55 int ret; 56 57 if (copy) 58 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask); 59 else 60 bio = bio_map_user_iov(q, iter, gfp_mask); 61 62 if (IS_ERR(bio)) 63 return PTR_ERR(bio); 64 65 if (map_data && map_data->null_mapped) 66 bio_set_flag(bio, BIO_NULL_MAPPED); 67 68 iov_iter_advance(iter, bio->bi_iter.bi_size); 69 if (map_data) 70 map_data->offset += bio->bi_iter.bi_size; 71 72 orig_bio = bio; 73 blk_queue_bounce(q, &bio); 74 75 /* 76 * We link the bounce buffer in and could have to traverse it 77 * later so we have to get a ref to prevent it from being freed 78 */ 79 bio_get(bio); 80 81 ret = blk_rq_append_bio(rq, bio); 82 if (ret) { 83 bio_endio(bio); 84 __blk_rq_unmap_user(orig_bio); 85 bio_put(bio); 86 return ret; 87 } 88 89 return 0; 90 } 91 92 /** 93 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 94 * @q: request queue where request should be inserted 95 * @rq: request to map data to 96 * @map_data: pointer to the rq_map_data holding pages (if necessary) 97 * @iter: iovec iterator 98 * @gfp_mask: memory allocation flags 99 * 100 * Description: 101 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 102 * a kernel bounce buffer is used. 103 * 104 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 105 * still in process context. 106 * 107 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 108 * before being submitted to the device, as pages mapped may be out of 109 * reach. It's the callers responsibility to make sure this happens. The 110 * original bio must be passed back in to blk_rq_unmap_user() for proper 111 * unmapping. 112 */ 113 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 114 struct rq_map_data *map_data, 115 const struct iov_iter *iter, gfp_t gfp_mask) 116 { 117 bool copy = false; 118 unsigned long align = q->dma_pad_mask | queue_dma_alignment(q); 119 struct bio *bio = NULL; 120 struct iov_iter i; 121 int ret; 122 123 if (map_data) 124 copy = true; 125 else if (iov_iter_alignment(iter) & align) 126 copy = true; 127 else if (queue_virt_boundary(q)) 128 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter); 129 130 i = *iter; 131 do { 132 ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy); 133 if (ret) 134 goto unmap_rq; 135 if (!bio) 136 bio = rq->bio; 137 } while (iov_iter_count(&i)); 138 139 if (!bio_flagged(bio, BIO_USER_MAPPED)) 140 rq->rq_flags |= RQF_COPY_USER; 141 return 0; 142 143 unmap_rq: 144 __blk_rq_unmap_user(bio); 145 rq->bio = NULL; 146 return -EINVAL; 147 } 148 EXPORT_SYMBOL(blk_rq_map_user_iov); 149 150 int blk_rq_map_user(struct request_queue *q, struct request *rq, 151 struct rq_map_data *map_data, void __user *ubuf, 152 unsigned long len, gfp_t gfp_mask) 153 { 154 struct iovec iov; 155 struct iov_iter i; 156 int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i); 157 158 if (unlikely(ret < 0)) 159 return ret; 160 161 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask); 162 } 163 EXPORT_SYMBOL(blk_rq_map_user); 164 165 /** 166 * blk_rq_unmap_user - unmap a request with user data 167 * @bio: start of bio list 168 * 169 * Description: 170 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 171 * supply the original rq->bio from the blk_rq_map_user() return, since 172 * the I/O completion may have changed rq->bio. 173 */ 174 int blk_rq_unmap_user(struct bio *bio) 175 { 176 struct bio *mapped_bio; 177 int ret = 0, ret2; 178 179 while (bio) { 180 mapped_bio = bio; 181 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 182 mapped_bio = bio->bi_private; 183 184 ret2 = __blk_rq_unmap_user(mapped_bio); 185 if (ret2 && !ret) 186 ret = ret2; 187 188 mapped_bio = bio; 189 bio = bio->bi_next; 190 bio_put(mapped_bio); 191 } 192 193 return ret; 194 } 195 EXPORT_SYMBOL(blk_rq_unmap_user); 196 197 /** 198 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage 199 * @q: request queue where request should be inserted 200 * @rq: request to fill 201 * @kbuf: the kernel buffer 202 * @len: length of user data 203 * @gfp_mask: memory allocation flags 204 * 205 * Description: 206 * Data will be mapped directly if possible. Otherwise a bounce 207 * buffer is used. Can be called multiple times to append multiple 208 * buffers. 209 */ 210 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 211 unsigned int len, gfp_t gfp_mask) 212 { 213 int reading = rq_data_dir(rq) == READ; 214 unsigned long addr = (unsigned long) kbuf; 215 int do_copy = 0; 216 struct bio *bio; 217 int ret; 218 219 if (len > (queue_max_hw_sectors(q) << 9)) 220 return -EINVAL; 221 if (!len || !kbuf) 222 return -EINVAL; 223 224 do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf); 225 if (do_copy) 226 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); 227 else 228 bio = bio_map_kern(q, kbuf, len, gfp_mask); 229 230 if (IS_ERR(bio)) 231 return PTR_ERR(bio); 232 233 if (!reading) 234 bio_set_op_attrs(bio, REQ_OP_WRITE, 0); 235 236 if (do_copy) 237 rq->rq_flags |= RQF_COPY_USER; 238 239 ret = blk_rq_append_bio(rq, bio); 240 if (unlikely(ret)) { 241 /* request is too big */ 242 bio_put(bio); 243 return ret; 244 } 245 246 blk_queue_bounce(q, &rq->bio); 247 return 0; 248 } 249 EXPORT_SYMBOL(blk_rq_map_kern); 250