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 static bool iovec_gap_to_prv(struct request_queue *q, 13 struct iovec *prv, struct iovec *cur) 14 { 15 unsigned long prev_end; 16 17 if (!queue_virt_boundary(q)) 18 return false; 19 20 if (prv->iov_base == NULL && prv->iov_len == 0) 21 /* prv is not set - don't check */ 22 return false; 23 24 prev_end = (unsigned long)(prv->iov_base + prv->iov_len); 25 26 return (((unsigned long)cur->iov_base & queue_virt_boundary(q)) || 27 prev_end & queue_virt_boundary(q)); 28 } 29 30 int blk_rq_append_bio(struct request_queue *q, struct request *rq, 31 struct bio *bio) 32 { 33 if (!rq->bio) 34 blk_rq_bio_prep(q, rq, bio); 35 else if (!ll_back_merge_fn(q, rq, bio)) 36 return -EINVAL; 37 else { 38 rq->biotail->bi_next = bio; 39 rq->biotail = bio; 40 41 rq->__data_len += bio->bi_iter.bi_size; 42 } 43 return 0; 44 } 45 46 static int __blk_rq_unmap_user(struct bio *bio) 47 { 48 int ret = 0; 49 50 if (bio) { 51 if (bio_flagged(bio, BIO_USER_MAPPED)) 52 bio_unmap_user(bio); 53 else 54 ret = bio_uncopy_user(bio); 55 } 56 57 return ret; 58 } 59 60 static int __blk_rq_map_user_iov(struct request *rq, 61 struct rq_map_data *map_data, struct iov_iter *iter, 62 gfp_t gfp_mask, bool copy) 63 { 64 struct request_queue *q = rq->q; 65 struct bio *bio, *orig_bio; 66 int ret; 67 68 if (copy) 69 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask); 70 else 71 bio = bio_map_user_iov(q, iter, gfp_mask); 72 73 if (IS_ERR(bio)) 74 return PTR_ERR(bio); 75 76 if (map_data && map_data->null_mapped) 77 bio_set_flag(bio, BIO_NULL_MAPPED); 78 79 iov_iter_advance(iter, bio->bi_iter.bi_size); 80 if (map_data) 81 map_data->offset += bio->bi_iter.bi_size; 82 83 orig_bio = bio; 84 blk_queue_bounce(q, &bio); 85 86 /* 87 * We link the bounce buffer in and could have to traverse it 88 * later so we have to get a ref to prevent it from being freed 89 */ 90 bio_get(bio); 91 92 ret = blk_rq_append_bio(q, rq, bio); 93 if (ret) { 94 bio_endio(bio); 95 __blk_rq_unmap_user(orig_bio); 96 bio_put(bio); 97 return ret; 98 } 99 100 return 0; 101 } 102 103 /** 104 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 105 * @q: request queue where request should be inserted 106 * @rq: request to map data to 107 * @map_data: pointer to the rq_map_data holding pages (if necessary) 108 * @iter: iovec iterator 109 * @gfp_mask: memory allocation flags 110 * 111 * Description: 112 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 113 * a kernel bounce buffer is used. 114 * 115 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 116 * still in process context. 117 * 118 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 119 * before being submitted to the device, as pages mapped may be out of 120 * reach. It's the callers responsibility to make sure this happens. The 121 * original bio must be passed back in to blk_rq_unmap_user() for proper 122 * unmapping. 123 */ 124 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 125 struct rq_map_data *map_data, 126 const struct iov_iter *iter, gfp_t gfp_mask) 127 { 128 struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0}; 129 bool copy = (q->dma_pad_mask & iter->count) || map_data; 130 struct bio *bio = NULL; 131 struct iov_iter i; 132 int ret; 133 134 if (!iter || !iter->count) 135 return -EINVAL; 136 137 iov_for_each(iov, i, *iter) { 138 unsigned long uaddr = (unsigned long) iov.iov_base; 139 140 if (!iov.iov_len) 141 return -EINVAL; 142 143 /* 144 * Keep going so we check length of all segments 145 */ 146 if ((uaddr & queue_dma_alignment(q)) || 147 iovec_gap_to_prv(q, &prv, &iov)) 148 copy = true; 149 150 prv.iov_base = iov.iov_base; 151 prv.iov_len = iov.iov_len; 152 } 153 154 i = *iter; 155 do { 156 ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy); 157 if (ret) 158 goto unmap_rq; 159 if (!bio) 160 bio = rq->bio; 161 } while (iov_iter_count(&i)); 162 163 if (!bio_flagged(bio, BIO_USER_MAPPED)) 164 rq->cmd_flags |= REQ_COPY_USER; 165 return 0; 166 167 unmap_rq: 168 __blk_rq_unmap_user(bio); 169 rq->bio = NULL; 170 return -EINVAL; 171 } 172 EXPORT_SYMBOL(blk_rq_map_user_iov); 173 174 int blk_rq_map_user(struct request_queue *q, struct request *rq, 175 struct rq_map_data *map_data, void __user *ubuf, 176 unsigned long len, gfp_t gfp_mask) 177 { 178 struct iovec iov; 179 struct iov_iter i; 180 int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i); 181 182 if (unlikely(ret < 0)) 183 return ret; 184 185 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask); 186 } 187 EXPORT_SYMBOL(blk_rq_map_user); 188 189 /** 190 * blk_rq_unmap_user - unmap a request with user data 191 * @bio: start of bio list 192 * 193 * Description: 194 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 195 * supply the original rq->bio from the blk_rq_map_user() return, since 196 * the I/O completion may have changed rq->bio. 197 */ 198 int blk_rq_unmap_user(struct bio *bio) 199 { 200 struct bio *mapped_bio; 201 int ret = 0, ret2; 202 203 while (bio) { 204 mapped_bio = bio; 205 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 206 mapped_bio = bio->bi_private; 207 208 ret2 = __blk_rq_unmap_user(mapped_bio); 209 if (ret2 && !ret) 210 ret = ret2; 211 212 mapped_bio = bio; 213 bio = bio->bi_next; 214 bio_put(mapped_bio); 215 } 216 217 return ret; 218 } 219 EXPORT_SYMBOL(blk_rq_unmap_user); 220 221 /** 222 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage 223 * @q: request queue where request should be inserted 224 * @rq: request to fill 225 * @kbuf: the kernel buffer 226 * @len: length of user data 227 * @gfp_mask: memory allocation flags 228 * 229 * Description: 230 * Data will be mapped directly if possible. Otherwise a bounce 231 * buffer is used. Can be called multiple times to append multiple 232 * buffers. 233 */ 234 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 235 unsigned int len, gfp_t gfp_mask) 236 { 237 int reading = rq_data_dir(rq) == READ; 238 unsigned long addr = (unsigned long) kbuf; 239 int do_copy = 0; 240 struct bio *bio; 241 int ret; 242 243 if (len > (queue_max_hw_sectors(q) << 9)) 244 return -EINVAL; 245 if (!len || !kbuf) 246 return -EINVAL; 247 248 do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf); 249 if (do_copy) 250 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); 251 else 252 bio = bio_map_kern(q, kbuf, len, gfp_mask); 253 254 if (IS_ERR(bio)) 255 return PTR_ERR(bio); 256 257 if (!reading) 258 bio->bi_rw |= REQ_WRITE; 259 260 if (do_copy) 261 rq->cmd_flags |= REQ_COPY_USER; 262 263 ret = blk_rq_append_bio(q, rq, bio); 264 if (unlikely(ret)) { 265 /* request is too big */ 266 bio_put(bio); 267 return ret; 268 } 269 270 blk_queue_bounce(q, &rq->bio); 271 return 0; 272 } 273 EXPORT_SYMBOL(blk_rq_map_kern); 274