Eric Lee / linux-smarc-t335x-v3.2

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Commit 68154e90c9d1492d570671ae181d9a8f8530da55

Authored by FUJITA Tomonori
Committed by Jens Axboe
1 parent 657e93be35
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

block: add dma alignment and padding support to blk_rq_map_kern 

This patch adds bio_copy_kern similar to
bio_copy_user. blk_rq_map_kern uses bio_copy_kern instead of
bio_map_kern if necessary.

bio_copy_kern uses temporary pages and the bi_end_io callback frees
these pages. bio_copy_kern saves the original kernel buffer at
bio->bi_private it doesn't use something like struct bio_map_data to
store the information about the caller.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Showing 3 changed files with 112 additions and 1 deletions Side-by-side Diff

... ... @@ -255,10 +255,18 @@
255 255 * @kbuf: the kernel buffer
256 256 * @len: length of user data
257 257 * @gfp_mask: memory allocation flags
  258 + *
  259 + * Description:
  260 + * Data will be mapped directly if possible. Otherwise a bounce
  261 + * buffer is used.
258 262 */
259 263 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
260 264 unsigned int len, gfp_t gfp_mask)
261 265 {
  266 + unsigned long kaddr;
  267 + unsigned int alignment;
  268 + int reading = rq_data_dir(rq) == READ;
  269 + int do_copy = 0;
262 270 struct bio *bio;
263 271  
264 272 if (len > (q->max_hw_sectors << 9))
265 273  
... ... @@ -266,12 +274,23 @@
266 274 if (!len || !kbuf)
267 275 return -EINVAL;
268 276  
269   - bio = bio_map_kern(q, kbuf, len, gfp_mask);
  277 + kaddr = (unsigned long)kbuf;
  278 + alignment = queue_dma_alignment(q) | q->dma_pad_mask;
  279 + do_copy = ((kaddr & alignment) || (len & alignment));
  280 +
  281 + if (do_copy)
  282 + bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
  283 + else
  284 + bio = bio_map_kern(q, kbuf, len, gfp_mask);
  285 +
270 286 if (IS_ERR(bio))
271 287 return PTR_ERR(bio);
272 288  
273 289 if (rq_data_dir(rq) == WRITE)
274 290 bio->bi_rw |= (1 << BIO_RW);
  291 +
  292 + if (do_copy)
  293 + rq->cmd_flags |= REQ_COPY_USER;
275 294  
276 295 blk_rq_bio_prep(q, rq, bio);
277 296 blk_queue_bounce(q, &rq->bio);
... ... @@ -937,6 +937,95 @@
937 937 return ERR_PTR(-EINVAL);
938 938 }
939 939  
  940 +static void bio_copy_kern_endio(struct bio *bio, int err)
  941 +{
  942 + struct bio_vec *bvec;
  943 + const int read = bio_data_dir(bio) == READ;
  944 + char *p = bio->bi_private;
  945 + int i;
  946 +
  947 + __bio_for_each_segment(bvec, bio, i, 0) {
  948 + char *addr = page_address(bvec->bv_page);
  949 +
  950 + if (read && !err)
  951 + memcpy(p, addr, bvec->bv_len);
  952 +
  953 + __free_page(bvec->bv_page);
  954 + p += bvec->bv_len;
  955 + }
  956 +
  957 + bio_put(bio);
  958 +}
  959 +
  960 +/**
  961 + * bio_copy_kern - copy kernel address into bio
  962 + * @q: the struct request_queue for the bio
  963 + * @data: pointer to buffer to copy
  964 + * @len: length in bytes
  965 + * @gfp_mask: allocation flags for bio and page allocation
  966 + *
  967 + * copy the kernel address into a bio suitable for io to a block
  968 + * device. Returns an error pointer in case of error.
  969 + */
  970 +struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
  971 + gfp_t gfp_mask, int reading)
  972 +{
  973 + unsigned long kaddr = (unsigned long)data;
  974 + unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  975 + unsigned long start = kaddr >> PAGE_SHIFT;
  976 + const int nr_pages = end - start;
  977 + struct bio *bio;
  978 + struct bio_vec *bvec;
  979 + int i, ret;
  980 +
  981 + bio = bio_alloc(gfp_mask, nr_pages);
  982 + if (!bio)
  983 + return ERR_PTR(-ENOMEM);
  984 +
  985 + while (len) {
  986 + struct page *page;
  987 + unsigned int bytes = PAGE_SIZE;
  988 +
  989 + if (bytes > len)
  990 + bytes = len;
  991 +
  992 + page = alloc_page(q->bounce_gfp | gfp_mask);
  993 + if (!page) {
  994 + ret = -ENOMEM;
  995 + goto cleanup;
  996 + }
  997 +
  998 + if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) {
  999 + ret = -EINVAL;
  1000 + goto cleanup;
  1001 + }
  1002 +
  1003 + len -= bytes;
  1004 + }
  1005 +
  1006 + if (!reading) {
  1007 + void *p = data;
  1008 +
  1009 + bio_for_each_segment(bvec, bio, i) {
  1010 + char *addr = page_address(bvec->bv_page);
  1011 +
  1012 + memcpy(addr, p, bvec->bv_len);
  1013 + p += bvec->bv_len;
  1014 + }
  1015 + }
  1016 +
  1017 + bio->bi_private = data;
  1018 + bio->bi_end_io = bio_copy_kern_endio;
  1019 + return bio;
  1020 +cleanup:
  1021 + bio_for_each_segment(bvec, bio, i)
  1022 + __free_page(bvec->bv_page);
  1023 +
  1024 + bio_put(bio);
  1025 +
  1026 + return ERR_PTR(ret);
  1027 +}
  1028 +
940 1029 /*
941 1030 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
942 1031 * for performing direct-IO in BIOs.
... ... @@ -1273,6 +1362,7 @@
1273 1362 EXPORT_SYMBOL(bio_map_user);
1274 1363 EXPORT_SYMBOL(bio_unmap_user);
1275 1364 EXPORT_SYMBOL(bio_map_kern);
  1365 +EXPORT_SYMBOL(bio_copy_kern);
1276 1366 EXPORT_SYMBOL(bio_pair_release);
1277 1367 EXPORT_SYMBOL(bio_split);
1278 1368 EXPORT_SYMBOL(bio_split_pool);
... ... @@ -324,6 +324,8 @@
324 324 extern void bio_unmap_user(struct bio *);
325 325 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
326 326 gfp_t);
  327 +extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
  328 + gfp_t, int);
327 329 extern void bio_set_pages_dirty(struct bio *bio);
328 330 extern void bio_check_pages_dirty(struct bio *bio);
329 331 extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);