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Commit 3c892a09 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

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: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7891f05c

block/bounce.c

+11 −5
Original line number Original line Diff line number Diff line
@@ -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++;

	}

	}

}

}

include/linux/bvec.h

+9 −0
Original line number Original line Diff line number Diff line
@@ -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 */