block/blk-map.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Functions related to mapping data to requests
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/sched/task_stack.h>
   7 #include <linux/module.h>
   8 #include <linux/bio.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/uio.h>
  11
  12 #include "blk.h"
  13
  14 /*
  15  * Append a bio to a passthrough request.  Only works can be merged into
  16  * the request based on the driver constraints.
  17  */
  18 int blk_rq_append_bio(struct request *rq, struct bio *bio)
  19 {
  20         blk_queue_bounce(rq->q, &bio);
  21
  22         if (!rq->bio) {
  23                 blk_rq_bio_prep(rq->q, rq, bio);
  24         } else {
  25                 if (!ll_back_merge_fn(rq->q, rq, bio))
  26                         return -EINVAL;
  27
  28                 rq->biotail->bi_next = bio;
  29                 rq->biotail = bio;
  30                 rq->__data_len += bio->bi_iter.bi_size;
  31         }
  32
  33         return 0;
  34 }
  35 EXPORT_SYMBOL(blk_rq_append_bio);
  36
  37 static int __blk_rq_unmap_user(struct bio *bio)
  38 {
  39         int ret = 0;
  40
  41         if (bio) {
  42                 if (bio_flagged(bio, BIO_USER_MAPPED))
  43                         bio_unmap_user(bio);
  44                 else
  45                         ret = bio_uncopy_user(bio);
  46         }
  47
  48         return ret;
  49 }
  50
  51 static int __blk_rq_map_user_iov(struct request *rq,
  52                 struct rq_map_data *map_data, struct iov_iter *iter,
  53                 gfp_t gfp_mask, bool copy)
  54 {
  55         struct request_queue *q = rq->q;
  56         struct bio *bio, *orig_bio;
  57         int ret;
  58
  59         if (copy)
  60                 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
  61         else
  62                 bio = bio_map_user_iov(q, iter, gfp_mask);
  63
  64         if (IS_ERR(bio))
  65                 return PTR_ERR(bio);
  66
  67         bio->bi_opf &= ~REQ_OP_MASK;
  68         bio->bi_opf |= req_op(rq);
  69
  70         orig_bio = bio;
  71
  72         /*
  73          * We link the bounce buffer in and could have to traverse it
  74          * later so we have to get a ref to prevent it from being freed
  75          */
  76         ret = blk_rq_append_bio(rq, bio);
  77         bio_get(bio);
  78         if (ret) {
  79                 bio_endio(bio);
  80                 __blk_rq_unmap_user(orig_bio);
  81                 bio_put(bio);
  82                 return ret;
  83         }
  84
  85         return 0;
  86 }
  87
  88 /**
  89  * blk_rq_map_user_iov - map user data to a request, for passthrough requests
  90  * @q:          request queue where request should be inserted
  91  * @rq:         request to map data to
  92  * @map_data:   pointer to the rq_map_data holding pages (if necessary)
  93  * @iter:       iovec iterator
  94  * @gfp_mask:   memory allocation flags
  95  *
  96  * Description:
  97  *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
  98  *    a kernel bounce buffer is used.
  99  *
 100  *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
 101  *    still in process context.
 102  *
 103  *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
 104  *    before being submitted to the device, as pages mapped may be out of
 105  *    reach. It's the callers responsibility to make sure this happens. The
 106  *    original bio must be passed back in to blk_rq_unmap_user() for proper
 107  *    unmapping.
 108  */
 109 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 110                         struct rq_map_data *map_data,
 111                         const struct iov_iter *iter, gfp_t gfp_mask)
 112 {
 113         bool copy = false;
 114         unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
 115         struct bio *bio = NULL;
 116         struct iov_iter i;
 117         int ret;
 118
 119         if (!iter_is_iovec(iter))
 120                 goto fail;
 121
 122         if (map_data)
 123                 copy = true;
 124         else if (iov_iter_alignment(iter) & align)
 125                 copy = true;
 126         else if (queue_virt_boundary(q))
 127                 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
 128
 129         i = *iter;
 130         do {
 131                 ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
 132                 if (ret)
 133                         goto unmap_rq;
 134                 if (!bio)
 135                         bio = rq->bio;
 136         } while (iov_iter_count(&i));
 137
 138         if (!bio_flagged(bio, BIO_USER_MAPPED))
 139                 rq->rq_flags |= RQF_COPY_USER;
 140         return 0;
 141
 142 unmap_rq:
 143         __blk_rq_unmap_user(bio);
 144 fail:
 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 passthrough requests
 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         bio->bi_opf &= ~REQ_OP_MASK;
 234         bio->bi_opf |= req_op(rq);
 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         return 0;
 247 }
 248 EXPORT_SYMBOL(blk_rq_map_kern);