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 /** 43 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage 44 * @q: request queue where request should be inserted 45 * @rq: request to map data to 46 * @map_data: pointer to the rq_map_data holding pages (if necessary) 47 * @iter: iovec iterator 48 * @gfp_mask: memory allocation flags 49 * 50 * Description: 51 * Data will be mapped directly for zero copy I/O, if possible. Otherwise 52 * a kernel bounce buffer is used. 53 * 54 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while 55 * still in process context. 56 * 57 * Note: The mapped bio may need to be bounced through blk_queue_bounce() 58 * before being submitted to the device, as pages mapped may be out of 59 * reach. It's the callers responsibility to make sure this happens. The 60 * original bio must be passed back in to blk_rq_unmap_user() for proper 61 * unmapping. 62 */ 63 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 64 struct rq_map_data *map_data, 65 const struct iov_iter *iter, gfp_t gfp_mask) 66 { 67 struct bio *bio; 68 int unaligned = 0; 69 struct iov_iter i; 70 struct iovec iov; 71 72 if (!iter || !iter->count) 73 return -EINVAL; 74 75 iov_for_each(iov, i, *iter) { 76 unsigned long uaddr = (unsigned long) iov.iov_base; 77 78 if (!iov.iov_len) 79 return -EINVAL; 80 81 /* 82 * Keep going so we check length of all segments 83 */ 84 if (uaddr & queue_dma_alignment(q)) 85 unaligned = 1; 86 } 87 88 if (unaligned || (q->dma_pad_mask & iter->count) || map_data) 89 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask); 90 else 91 bio = bio_map_user_iov(q, iter, gfp_mask); 92 93 if (IS_ERR(bio)) 94 return PTR_ERR(bio); 95 96 if (map_data && map_data->null_mapped) 97 bio->bi_flags |= (1 << BIO_NULL_MAPPED); 98 99 if (bio->bi_iter.bi_size != iter->count) { 100 /* 101 * Grab an extra reference to this bio, as bio_unmap_user() 102 * expects to be able to drop it twice as it happens on the 103 * normal IO completion path 104 */ 105 bio_get(bio); 106 bio_endio(bio); 107 __blk_rq_unmap_user(bio); 108 return -EINVAL; 109 } 110 111 if (!bio_flagged(bio, BIO_USER_MAPPED)) 112 rq->cmd_flags |= REQ_COPY_USER; 113 114 blk_queue_bounce(q, &bio); 115 bio_get(bio); 116 blk_rq_bio_prep(q, rq, bio); 117 return 0; 118 } 119 EXPORT_SYMBOL(blk_rq_map_user_iov); 120 121 int blk_rq_map_user(struct request_queue *q, struct request *rq, 122 struct rq_map_data *map_data, void __user *ubuf, 123 unsigned long len, gfp_t gfp_mask) 124 { 125 struct iovec iov; 126 struct iov_iter i; 127 int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i); 128 129 if (unlikely(ret < 0)) 130 return ret; 131 132 return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask); 133 } 134 EXPORT_SYMBOL(blk_rq_map_user); 135 136 /** 137 * blk_rq_unmap_user - unmap a request with user data 138 * @bio: start of bio list 139 * 140 * Description: 141 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must 142 * supply the original rq->bio from the blk_rq_map_user() return, since 143 * the I/O completion may have changed rq->bio. 144 */ 145 int blk_rq_unmap_user(struct bio *bio) 146 { 147 struct bio *mapped_bio; 148 int ret = 0, ret2; 149 150 while (bio) { 151 mapped_bio = bio; 152 if (unlikely(bio_flagged(bio, BIO_BOUNCED))) 153 mapped_bio = bio->bi_private; 154 155 ret2 = __blk_rq_unmap_user(mapped_bio); 156 if (ret2 && !ret) 157 ret = ret2; 158 159 mapped_bio = bio; 160 bio = bio->bi_next; 161 bio_put(mapped_bio); 162 } 163 164 return ret; 165 } 166 EXPORT_SYMBOL(blk_rq_unmap_user); 167 168 /** 169 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage 170 * @q: request queue where request should be inserted 171 * @rq: request to fill 172 * @kbuf: the kernel buffer 173 * @len: length of user data 174 * @gfp_mask: memory allocation flags 175 * 176 * Description: 177 * Data will be mapped directly if possible. Otherwise a bounce 178 * buffer is used. Can be called multiple times to append multiple 179 * buffers. 180 */ 181 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, 182 unsigned int len, gfp_t gfp_mask) 183 { 184 int reading = rq_data_dir(rq) == READ; 185 unsigned long addr = (unsigned long) kbuf; 186 int do_copy = 0; 187 struct bio *bio; 188 int ret; 189 190 if (len > (queue_max_hw_sectors(q) << 9)) 191 return -EINVAL; 192 if (!len || !kbuf) 193 return -EINVAL; 194 195 do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf); 196 if (do_copy) 197 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); 198 else 199 bio = bio_map_kern(q, kbuf, len, gfp_mask); 200 201 if (IS_ERR(bio)) 202 return PTR_ERR(bio); 203 204 if (!reading) 205 bio->bi_rw |= REQ_WRITE; 206 207 if (do_copy) 208 rq->cmd_flags |= REQ_COPY_USER; 209 210 ret = blk_rq_append_bio(q, rq, bio); 211 if (unlikely(ret)) { 212 /* request is too big */ 213 bio_put(bio); 214 return ret; 215 } 216 217 blk_queue_bounce(q, &rq->bio); 218 return 0; 219 } 220 EXPORT_SYMBOL(blk_rq_map_kern); 221