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 /** 61 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 62 * @q: request queue where request should be inserted 63 * @rq: request to map data to 64 * @map_data: pointer to the rq_map_data holding pages (if necessary) 65 * @iter: iovec iterator 66 * @gfp_mask: memory allocation flags 67 * 68 * Description: 69 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 70 * a kernel bounce buffer is used. 71 * 72 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 73 * still in process context. 74 * 75 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 76 * before being submitted to the device, as pages mapped may be out of 77 * reach. It's the callers responsibility to make sure this happens. The 78 * original bio must be passed back in to blk_rq_unmap_user() for proper 79 * unmapping. 80 */ 81 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 82 struct rq_map_data *map_data, 83 const struct iov_iter *iter, gfp_t gfp_mask) 84 { 85 struct bio *bio; 86 int unaligned = 0; 87 struct iov_iter i; 88 struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0}; 89 90 if (!iter || !iter->count) 91 return -EINVAL; 92 93 iov_for_each(iov, i, *iter) { 94 unsigned long uaddr = (unsigned long) iov.iov_base; 95 96 if (!iov.iov_len) 97 return -EINVAL; 98 99 /* 100 * Keep going so we check length of all segments 101 */ 102 if ((uaddr & queue_dma_alignment(q)) || 103 iovec_gap_to_prv(q, &prv, &iov)) 104 unaligned = 1; 105 106 prv.iov_base = iov.iov_base; 107 prv.iov_len = iov.iov_len; 108 } 109 110 if (unaligned || (q->dma_pad_mask & iter->count) || map_data) 111 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask); 112 else 113 bio = bio_map_user_iov(q, iter, gfp_mask); 114 115 if (IS_ERR(bio)) 116 return PTR_ERR(bio); 117 118 if (map_data && map_data->null_mapped) 119 bio_set_flag(bio, BIO_NULL_MAPPED); 120 121 if (bio->bi_iter.bi_size != iter->count) { 122 /* 123 * Grab an extra reference to this bio, as bio_unmap_user() 124 * expects to be able to drop it twice as it happens on the 125 * normal IO completion path 126 */ 127 bio_get(bio); 128 bio_endio(bio); 129 __blk_rq_unmap_user(bio); 130 return -EINVAL; 131 } 132 133 if (!bio_flagged(bio, BIO_USER_MAPPED)) 134 rq->cmd_flags |= REQ_COPY_USER; 135 136 blk_queue_bounce(q, &bio); 137 bio_get(bio); 138 blk_rq_bio_prep(q, rq, bio); 139 return 0; 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