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 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_iter.bi_size; 24 } 25 return 0; 26 } 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_iov(struct request *rq, 43 struct rq_map_data *map_data, struct iov_iter *iter, 44 gfp_t gfp_mask, bool copy) 45 { 46 struct request_queue *q = rq->q; 47 struct bio *bio, *orig_bio; 48 int ret; 49 50 if (copy) 51 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask); 52 else 53 bio = bio_map_user_iov(q, iter, gfp_mask); 54 55 if (IS_ERR(bio)) 56 return PTR_ERR(bio); 57 58 if (map_data && map_data->null_mapped) 59 bio_set_flag(bio, BIO_NULL_MAPPED); 60 61 iov_iter_advance(iter, bio->bi_iter.bi_size); 62 if (map_data) 63 map_data->offset += bio->bi_iter.bi_size; 64 65 orig_bio = bio; 66 blk_queue_bounce(q, &bio); 67 68 /* 69 * We link the bounce buffer in and could have to traverse it 70 * later so we have to get a ref to prevent it from being freed 71 */ 72 bio_get(bio); 73 74 ret = blk_rq_append_bio(q, rq, bio); 75 if (ret) { 76 bio_endio(bio); 77 __blk_rq_unmap_user(orig_bio); 78 bio_put(bio); 79 return ret; 80 } 81 82 return 0; 83 } 84 85 /** 86 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 87 * @q: request queue where request should be inserted 88 * @rq: request to map data to 89 * @map_data: pointer to the rq_map_data holding pages (if necessary) 90 * @iter: iovec iterator 91 * @gfp_mask: memory allocation flags 92 * 93 * Description: 94 * Data will be mapped directly for zero copy I/O, 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 I/O, 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_iov(struct request_queue *q, struct request *rq, 107 struct rq_map_data *map_data, 108 const struct iov_iter *iter, gfp_t gfp_mask) 109 { 110 bool copy = false; 111 unsigned long align = q->dma_pad_mask | queue_dma_alignment(q); 112 struct bio *bio = NULL; 113 struct iov_iter i; 114 int ret; 115 116 if (map_data) 117 copy = true; 118 else if (iov_iter_alignment(iter) & align) 119 copy = true; 120 else if (queue_virt_boundary(q)) 121 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter); 122 123 i = *iter; 124 do { 125 ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy); 126 if (ret) 127 goto unmap_rq; 128 if (!bio) 129 bio = rq->bio; 130 } while (iov_iter_count(&i)); 131 132 if (!bio_flagged(bio, BIO_USER_MAPPED)) 133 rq->cmd_flags |= REQ_COPY_USER; 134 return 0; 135 136 unmap_rq: 137 __blk_rq_unmap_user(bio); 138 rq->bio = NULL; 139 return -EINVAL; 140 } 141 EXPORT_SYMBOL(blk_rq_map_user_iov); 142 143 int blk_rq_map_user(struct request_queue *q, struct request *rq, 144 struct rq_map_data *map_data, void __user *ubuf, 145 unsigned long len, gfp_t gfp_mask) 146 { 147 struct iovec iov; 148 struct iov_iter i; 149 int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i); 150 151 if (unlikely(ret < 0)) 152 return ret; 153 154 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask); 155 } 156 EXPORT_SYMBOL(blk_rq_map_user); 157 158 /** 159 * blk_rq_unmap_user - unmap a request with user data 160 * @bio: start of bio list 161 * 162 * Description: 163 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 164 * supply the original rq->bio from the blk_rq_map_user() return, since 165 * the I/O completion may have changed rq->bio. 166 */ 167 int blk_rq_unmap_user(struct bio *bio) 168 { 169 struct bio *mapped_bio; 170 int ret = 0, ret2; 171 172 while (bio) { 173 mapped_bio = bio; 174 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 175 mapped_bio = bio->bi_private; 176 177 ret2 = __blk_rq_unmap_user(mapped_bio); 178 if (ret2 && !ret) 179 ret = ret2; 180 181 mapped_bio = bio; 182 bio = bio->bi_next; 183 bio_put(mapped_bio); 184 } 185 186 return ret; 187 } 188 EXPORT_SYMBOL(blk_rq_unmap_user); 189 190 /** 191 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage 192 * @q: request queue where request should be inserted 193 * @rq: request to fill 194 * @kbuf: the kernel buffer 195 * @len: length of user data 196 * @gfp_mask: memory allocation flags 197 * 198 * Description: 199 * Data will be mapped directly if possible. Otherwise a bounce 200 * buffer is used. Can be called multiple times to append multiple 201 * buffers. 202 */ 203 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 204 unsigned int len, gfp_t gfp_mask) 205 { 206 int reading = rq_data_dir(rq) == READ; 207 unsigned long addr = (unsigned long) kbuf; 208 int do_copy = 0; 209 struct bio *bio; 210 int ret; 211 212 if (len > (queue_max_hw_sectors(q) << 9)) 213 return -EINVAL; 214 if (!len || !kbuf) 215 return -EINVAL; 216 217 do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf); 218 if (do_copy) 219 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); 220 else 221 bio = bio_map_kern(q, kbuf, len, gfp_mask); 222 223 if (IS_ERR(bio)) 224 return PTR_ERR(bio); 225 226 if (!reading) 227 bio->bi_rw |= REQ_WRITE; 228 229 if (do_copy) 230 rq->cmd_flags |= REQ_COPY_USER; 231 232 ret = blk_rq_append_bio(q, rq, bio); 233 if (unlikely(ret)) { 234 /* request is too big */ 235 bio_put(bio); 236 return ret; 237 } 238 239 blk_queue_bounce(q, &rq->bio); 240 return 0; 241 } 242 EXPORT_SYMBOL(blk_rq_map_kern); 243