block/blk-map.c

   1 /*
   2  * Functions related to mapping data to requests
   3  */
   4 #include <linux/kernel.h>
   5 #include <linux/sched/task_stack.h>
   6 #include <linux/module.h>
   7 #include <linux/bio.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/uio.h>
  10
  11 #include "blk.h"
  12
  13 /*
  14  * Append a bio to a passthrough request.  Only works can be merged into
  15  * the request based on the driver constraints.
  16  */
  17 int blk_rq_append_bio(struct request *rq, struct bio *bio)
  18 {
  19         blk_queue_bounce(rq->q, &bio);
  20
  21         if (!rq->bio) {
  22                 blk_rq_bio_prep(rq->q, rq, bio);
  23         } else {
  24                 if (!ll_back_merge_fn(rq->q, rq, bio))
  25                         return -EINVAL;
  26
  27                 rq->biotail->bi_next = bio;
  28                 rq->biotail = bio;
  29                 rq->__data_len += bio->bi_iter.bi_size;
  30         }
  31
  32         return 0;
  33 }
  34 EXPORT_SYMBOL(blk_rq_append_bio);
  35
  36 static int __blk_rq_unmap_user(struct bio *bio)
  37 {
  38         int ret = 0;
  39
  40         if (bio) {
  41                 if (bio_flagged(bio, BIO_USER_MAPPED))
  42                         bio_unmap_user(bio);
  43                 else
  44                         ret = bio_uncopy_user(bio);
  45         }
  46
  47         return ret;
  48 }
  49
  50 static int __blk_rq_map_user_iov(struct request *rq,
  51                 struct rq_map_data *map_data, struct iov_iter *iter,
  52                 gfp_t gfp_mask, bool copy)
  53 {
  54         struct request_queue *q = rq->q;
  55         struct bio *bio, *orig_bio;
  56         int ret;
  57
  58         if (copy)
  59                 bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
  60         else
  61                 bio = bio_map_user_iov(q, iter, gfp_mask);
  62
  63         if (IS_ERR(bio))
  64                 return PTR_ERR(bio);
  65
  66         bio->bi_opf &= ~REQ_OP_MASK;
  67         bio->bi_opf |= req_op(rq);
  68
  69         if (map_data && map_data->null_mapped)
  70                 bio_set_flag(bio, BIO_NULL_MAPPED);
  71
  72         iov_iter_advance(iter, bio->bi_iter.bi_size);
  73         if (map_data)
  74                 map_data->offset += bio->bi_iter.bi_size;
  75
  76         orig_bio = bio;
  77
  78         /*
  79          * We link the bounce buffer in and could have to traverse it
  80          * later so we have to get a ref to prevent it from being freed
  81          */
  82         ret = blk_rq_append_bio(rq, bio);
  83         bio_get(bio);
  84         if (ret) {
  85                 bio_endio(bio);
  86                 __blk_rq_unmap_user(orig_bio);
  87                 bio_put(bio);
  88                 return ret;
  89         }
  90
  91         return 0;
  92 }
  93
  94 /**
  95  * blk_rq_map_user_iov - map user data to a request, for passthrough requests
  96  * @q:          request queue where request should be inserted
  97  * @rq:         request to map data to
  98  * @map_data:   pointer to the rq_map_data holding pages (if necessary)
  99  * @iter:       iovec iterator
 100  * @gfp_mask:   memory allocation flags
 101  *
 102  * Description:
 103  *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
 104  *    a kernel bounce buffer is used.
 105  *
 106  *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
 107  *    still in process context.
 108  *
 109  *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
 110  *    before being submitted to the device, as pages mapped may be out of
 111  *    reach. It's the callers responsibility to make sure this happens. The
 112  *    original bio must be passed back in to blk_rq_unmap_user() for proper
 113  *    unmapping.
 114  */
 115 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 116                         struct rq_map_data *map_data,
 117                         const struct iov_iter *iter, gfp_t gfp_mask)
 118 {
 119         bool copy = false;
 120         unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
 121         struct bio *bio = NULL;
 122         struct iov_iter i;
 123         int ret;
 124
 125         if (!iter_is_iovec(iter))
 126                 goto fail;
 127
 128         if (map_data)
 129                 copy = true;
 130         else if (iov_iter_alignment(iter) & align)
 131                 copy = true;
 132         else if (queue_virt_boundary(q))
 133                 copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
 134
 135         i = *iter;
 136         do {
 137                 ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
 138                 if (ret)
 139                         goto unmap_rq;
 140                 if (!bio)
 141                         bio = rq->bio;
 142         } while (iov_iter_count(&i));
 143
 144         if (!bio_flagged(bio, BIO_USER_MAPPED))
 145                 rq->rq_flags |= RQF_COPY_USER;
 146         return 0;
 147
 148 unmap_rq:
 149         __blk_rq_unmap_user(bio);
 150 fail:
 151         rq->bio = NULL;
 152         return -EINVAL;
 153 }
 154 EXPORT_SYMBOL(blk_rq_map_user_iov);
 155
 156 int blk_rq_map_user(struct request_queue *q, struct request *rq,
 157                     struct rq_map_data *map_data, void __user *ubuf,
 158                     unsigned long len, gfp_t gfp_mask)
 159 {
 160         struct iovec iov;
 161         struct iov_iter i;
 162         int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i);
 163
 164         if (unlikely(ret < 0))
 165                 return ret;
 166
 167         return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
 168 }
 169 EXPORT_SYMBOL(blk_rq_map_user);
 170
 171 /**
 172  * blk_rq_unmap_user - unmap a request with user data
 173  * @bio:               start of bio list
 174  *
 175  * Description:
 176  *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must
 177  *    supply the original rq->bio from the blk_rq_map_user() return, since
 178  *    the I/O completion may have changed rq->bio.
 179  */
 180 int blk_rq_unmap_user(struct bio *bio)
 181 {
 182         struct bio *mapped_bio;
 183         int ret = 0, ret2;
 184
 185         while (bio) {
 186                 mapped_bio = bio;
 187                 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
 188                         mapped_bio = bio->bi_private;
 189
 190                 ret2 = __blk_rq_unmap_user(mapped_bio);
 191                 if (ret2 && !ret)
 192                         ret = ret2;
 193
 194                 mapped_bio = bio;
 195                 bio = bio->bi_next;
 196                 bio_put(mapped_bio);
 197         }
 198
 199         return ret;
 200 }
 201 EXPORT_SYMBOL(blk_rq_unmap_user);
 202
 203 /**
 204  * blk_rq_map_kern - map kernel data to a request, for passthrough requests
 205  * @q:          request queue where request should be inserted
 206  * @rq:         request to fill
 207  * @kbuf:       the kernel buffer
 208  * @len:        length of user data
 209  * @gfp_mask:   memory allocation flags
 210  *
 211  * Description:
 212  *    Data will be mapped directly if possible. Otherwise a bounce
 213  *    buffer is used. Can be called multiple times to append multiple
 214  *    buffers.
 215  */
 216 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 217                     unsigned int len, gfp_t gfp_mask)
 218 {
 219         int reading = rq_data_dir(rq) == READ;
 220         unsigned long addr = (unsigned long) kbuf;
 221         int do_copy = 0;
 222         struct bio *bio;
 223         int ret;
 224
 225         if (len > (queue_max_hw_sectors(q) << 9))
 226                 return -EINVAL;
 227         if (!len || !kbuf)
 228                 return -EINVAL;
 229
 230         do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
 231         if (do_copy)
 232                 bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
 233         else
 234                 bio = bio_map_kern(q, kbuf, len, gfp_mask);
 235
 236         if (IS_ERR(bio))
 237                 return PTR_ERR(bio);
 238
 239         bio->bi_opf &= ~REQ_OP_MASK;
 240         bio->bi_opf |= req_op(rq);
 241
 242         if (do_copy)
 243                 rq->rq_flags |= RQF_COPY_USER;
 244
 245         ret = blk_rq_append_bio(rq, bio);
 246         if (unlikely(ret)) {
 247                 /* request is too big */
 248                 bio_put(bio);
 249                 return ret;
 250         }
 251
 252         return 0;
 253 }
 254 EXPORT_SYMBOL(blk_rq_map_kern);