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Commit cacc7b05 authored by Ming Lei's avatar Ming Lei Committed by Mike Snitzer
Browse files

dm io: use bvec iterator helpers to implement .get_page and .next_page 



Firstly we have mature bvec/bio iterator helper for iterate each
page in one bio, not necessary to reinvent a wheel to do that.

Secondly the coming multipage bvecs requires this patch.

Also add comments about the direct access to bvec table.

Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 4f9c74c6

drivers/md/dm-io.c

+24 −10
Original line number Diff line number Diff line
@@ -162,7 +162,10 @@ struct dpages { 
			 struct page **p, unsigned long *len, unsigned *offset);

	void (*next_page)(struct dpages *dp);



	union {

		unsigned context_u;

		struct bvec_iter context_bi;

	};

	void *context_ptr;



	void *vma_invalidate_address;
@@ -204,25 +207,36 @@ static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offse 
static void bio_get_page(struct dpages *dp, struct page **p,

			 unsigned long *len, unsigned *offset)

{

	struct bio_vec *bvec = dp->context_ptr;

	*p = bvec->bv_page;

	*len = bvec->bv_len - dp->context_u;

	*offset = bvec->bv_offset + dp->context_u;

	struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr,

					     dp->context_bi);



	*p = bvec.bv_page;

	*len = bvec.bv_len;

	*offset = bvec.bv_offset;



	/* avoid figuring it out again in bio_next_page() */

	dp->context_bi.bi_sector = (sector_t)bvec.bv_len;

}



static void bio_next_page(struct dpages *dp)

{

	struct bio_vec *bvec = dp->context_ptr;

	dp->context_ptr = bvec + 1;

	dp->context_u = 0;

	unsigned int len = (unsigned int)dp->context_bi.bi_sector;



	bvec_iter_advance((struct bio_vec *)dp->context_ptr,

			  &dp->context_bi, len);

}



static void bio_dp_init(struct dpages *dp, struct bio *bio)

{

	dp->get_page = bio_get_page;

	dp->next_page = bio_next_page;

	dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);

	dp->context_u = bio->bi_iter.bi_bvec_done;



	/*

	 * We just use bvec iterator to retrieve pages, so it is ok to

	 * access the bvec table directly here

	 */

	dp->context_ptr = bio->bi_io_vec;

	dp->context_bi = bio->bi_iter;

}



/*