block/blk-map.c

   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 /*
  13  * Append a bio to a passthrough request.  Only works can be merged into
  14  * the request based on the driver constraints.
  15  */
  16 int blk_rq_append_bio(struct request *rq, struct bio *bio)
  17 {
  18         if (!rq->bio) {
  19                 rq->cmd_flags &= REQ_OP_MASK;
  20                 rq->cmd_flags |= (bio->bi_opf & REQ_OP_MASK);
  21                 blk_rq_bio_prep(rq->q, rq, bio);
  22         } else {
  23                 if (!ll_back_merge_fn(rq->q, rq, bio))
  24                         return -EINVAL;
  25
  26                 rq->biotail->bi_next = bio;
  27                 rq->biotail = bio;
  28                 rq->__data_len += bio->bi_iter.bi_size;
  29         }
  30
  31         return 0;
  32 }
  33 EXPORT_SYMBOL(blk_rq_append_bio);
  34
  35 static int __blk_rq_unmap_user(struct bio *bio)
  36 {
  37         int ret = 0;
  38
  39         if (bio) {
  40                 if (bio_flagged(bio, BIO_USER_MAPPED))
  41                         bio_unmap_user(bio);
  42                 else
  43                         ret = bio_uncopy_user(bio);
  44         }
  45
  46         return ret;
  47 }
  48
  49 static int __blk_rq_map_user_iov(struct request *rq,
  50                 struct rq_map_data *map_data, struct iov_iter *iter,
  51                 gfp_t gfp_mask, bool copy)
  52 {
  53         struct request_queue *q = rq->q;
  54         struct bio *bio, *orig_bio;
  55         int ret;
  56
  57         if (copy)
  58                 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
  59         else
  60                 bio = bio_map_user_iov(q, iter, gfp_mask);
  61
  62         if (IS_ERR(bio))
  63                 return PTR_ERR(bio);
  64
  65         if (map_data && map_data->null_mapped)
  66                 bio_set_flag(bio, BIO_NULL_MAPPED);
  67
  68         iov_iter_advance(iter, bio->bi_iter.bi_size);
  69         if (map_data)
  70                 map_data->offset += bio->bi_iter.bi_size;
  71
  72         orig_bio = bio;
  73         blk_queue_bounce(q, &bio);
  74
  75         /*
  76          * We link the bounce buffer in and could have to traverse it
  77          * later so we have to get a ref to prevent it from being freed
  78          */
  79         bio_get(bio);
  80
  81         ret = blk_rq_append_bio(rq, bio);
  82         if (ret) {
  83                 bio_endio(bio);
  84                 __blk_rq_unmap_user(orig_bio);
  85                 bio_put(bio);
  86                 return ret;
  87         }
  88
  89         return 0;
  90 }
  91
  92 /**
  93  * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
  94  * @q:          request queue where request should be inserted
  95  * @rq:         request to map data to
  96  * @map_data:   pointer to the rq_map_data holding pages (if necessary)
  97  * @iter:       iovec iterator
  98  * @gfp_mask:   memory allocation flags
  99  *
 100  * Description:
 101  *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
 102  *    a kernel bounce buffer is used.
 103  *
 104  *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
 105  *    still in process context.
 106  *
 107  *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
 108  *    before being submitted to the device, as pages mapped may be out of
 109  *    reach. It's the callers responsibility to make sure this happens. The
 110  *    original bio must be passed back in to blk_rq_unmap_user() for proper
 111  *    unmapping.
 112  */
 113 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 114                         struct rq_map_data *map_data,
 115                         const struct iov_iter *iter, gfp_t gfp_mask)
 116 {
 117         bool copy = false;
 118         unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
 119         struct bio *bio = NULL;
 120         struct iov_iter i;
 121         int ret;
 122
 123         if (!iter_is_iovec(iter))
 124                 goto fail;
 125
 126         if (map_data)
 127                 copy = true;
 128         else if (iov_iter_alignment(iter) & align)
 129                 copy = true;
 130         else if (queue_virt_boundary(q))
 131                 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
 132
 133         i = *iter;
 134         do {
 135                 ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
 136                 if (ret)
 137                         goto unmap_rq;
 138                 if (!bio)
 139                         bio = rq->bio;
 140         } while (iov_iter_count(&i));
 141
 142         if (!bio_flagged(bio, BIO_USER_MAPPED))
 143                 rq->rq_flags |= RQF_COPY_USER;
 144         return 0;
 145
 146 unmap_rq:
 147         __blk_rq_unmap_user(bio);
 148 fail:
 149         rq->bio = NULL;
 150         return -EINVAL;
 151 }
 152 EXPORT_SYMBOL(blk_rq_map_user_iov);
 153
 154 int blk_rq_map_user(struct request_queue *q, struct request *rq,
 155                     struct rq_map_data *map_data, void __user *ubuf,
 156                     unsigned long len, gfp_t gfp_mask)
 157 {
 158         struct iovec iov;
 159         struct iov_iter i;
 160         int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i);
 161
 162         if (unlikely(ret < 0))
 163                 return ret;
 164
 165         return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
 166 }
 167 EXPORT_SYMBOL(blk_rq_map_user);
 168
 169 /**
 170  * blk_rq_unmap_user - unmap a request with user data
 171  * @bio:               start of bio list
 172  *
 173  * Description:
 174  *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must
 175  *    supply the original rq->bio from the blk_rq_map_user() return, since
 176  *    the I/O completion may have changed rq->bio.
 177  */
 178 int blk_rq_unmap_user(struct bio *bio)
 179 {
 180         struct bio *mapped_bio;
 181         int ret = 0, ret2;
 182
 183         while (bio) {
 184                 mapped_bio = bio;
 185                 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
 186                         mapped_bio = bio->bi_private;
 187
 188                 ret2 = __blk_rq_unmap_user(mapped_bio);
 189                 if (ret2 && !ret)
 190                         ret = ret2;
 191
 192                 mapped_bio = bio;
 193                 bio = bio->bi_next;
 194                 bio_put(mapped_bio);
 195         }
 196
 197         return ret;
 198 }
 199 EXPORT_SYMBOL(blk_rq_unmap_user);
 200
 201 /**
 202  * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
 203  * @q:          request queue where request should be inserted
 204  * @rq:         request to fill
 205  * @kbuf:       the kernel buffer
 206  * @len:        length of user data
 207  * @gfp_mask:   memory allocation flags
 208  *
 209  * Description:
 210  *    Data will be mapped directly if possible. Otherwise a bounce
 211  *    buffer is used. Can be called multiple times to append multiple
 212  *    buffers.
 213  */
 214 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 215                     unsigned int len, gfp_t gfp_mask)
 216 {
 217         int reading = rq_data_dir(rq) == READ;
 218         unsigned long addr = (unsigned long) kbuf;
 219         int do_copy = 0;
 220         struct bio *bio;
 221         int ret;
 222
 223         if (len > (queue_max_hw_sectors(q) << 9))
 224                 return -EINVAL;
 225         if (!len || !kbuf)
 226                 return -EINVAL;
 227
 228         do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
 229         if (do_copy)
 230                 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
 231         else
 232                 bio = bio_map_kern(q, kbuf, len, gfp_mask);
 233
 234         if (IS_ERR(bio))
 235                 return PTR_ERR(bio);
 236
 237         if (!reading)
 238                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 239
 240         if (do_copy)
 241                 rq->rq_flags |= RQF_COPY_USER;
 242
 243         ret = blk_rq_append_bio(rq, bio);
 244         if (unlikely(ret)) {
 245                 /* request is too big */
 246                 bio_put(bio);
 247                 return ret;
 248         }
 249
 250         blk_queue_bounce(q, &rq->bio);
 251         return 0;
 252 }
 253 EXPORT_SYMBOL(blk_rq_map_kern);