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block: bounce: don't access bio->bi_io_vec in copy_to_high_bio_irq 

Firstly this patch introduces BVEC_ITER_ALL_INIT for iterating one bio
from start to end.

As we need to support multipage bvecs, don't access bio->bi_io_vec
in copy_to_high_bio_irq(), and just use the standard iterator for that.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2017-12-18 20:22:07 +08:00 committed by Jens Axboe
parent 7891f05cbf
commit 3c892a098b
2 changed files with 20 additions and 5 deletions
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16
block/bounce.c
View File

@ -113,24 +113,30 @@ int init_emergency_isa_pool(void)
static void copy_to_high_bio_irq(struct bio *to, struct bio *from) static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
{ {
unsigned char *vfrom; unsigned char *vfrom;
struct bio_vec tovec, *fromvec = from->bi_io_vec; struct bio_vec tovec, fromvec;
struct bvec_iter iter; struct bvec_iter iter;
/*
* The bio of @from is created by bounce, so we can iterate
* its bvec from start to end, but the @from->bi_iter can't be
* trusted because it might be changed by splitting.
*/
struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;
bio_for_each_segment(tovec, to, iter) { bio_for_each_segment(tovec, to, iter) {
if (tovec.bv_page != fromvec->bv_page) { fromvec = bio_iter_iovec(from, from_iter);
if (tovec.bv_page != fromvec.bv_page) {
/* /*
* fromvec->bv_offset and fromvec->bv_len might have * fromvec->bv_offset and fromvec->bv_len might have
* been modified by the block layer, so use the original * been modified by the block layer, so use the original
* copy, bounce_copy_vec already uses tovec->bv_len * copy, bounce_copy_vec already uses tovec->bv_len
*/ */
vfrom = page_address(fromvec->bv_page) + vfrom = page_address(fromvec.bv_page) +
tovec.bv_offset; tovec.bv_offset;
bounce_copy_vec(&tovec, vfrom); bounce_copy_vec(&tovec, vfrom);
flush_dcache_page(tovec.bv_page); flush_dcache_page(tovec.bv_page);
} }
bio_advance_iter(from, &from_iter, tovec.bv_len);
fromvec++;
} }
} }

9
include/linux/bvec.h
View File

@ -125,4 +125,13 @@ static inline bool bvec_iter_rewind(const struct bio_vec *bv,
((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len)) bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
/* for iterating one bio from start to end */
#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
{ \
.bi_sector = 0, \
.bi_size = UINT_MAX, \
.bi_idx = 0, \
.bi_bvec_done = 0, \
}
#endif /* __LINUX_BVEC_ITER_H */ #endif /* __LINUX_BVEC_ITER_H */