block: bounce: make sure that bvec table is updated (8f4e80da) · Commits · 戴 / test

Block bounce needs to allocate new page for doing IO, and the new page has to be updated to bvec table. Commit switches __blk_queue_bounce() to use the new bio_for_each_segment_all() interface. Unfortunately the new bio_for_each_segment_all() can't be used to update bvec table. This patch fixes this issue by retrieving bvec from the table directly, then the new allocated page can be updated to the bio. This way is safe because the cloned bio is single page bvec. Fixes: ("block: allow bio_for_each_segment_all() to iterate over multi-page bvec") Cc: Christoph Hellwig <hch@lst.de> Cc: Omar Sandoval <osandov@fb.com> Signed-off-by:

Ming Lei <ming.lei@redhat.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/bounce.c

+6 −2

Original line number	Original line	Diff line number	Diff line
	@@ -295,7 +295,6 @@ static void __blk_queue_bounce(struct request_queue q, struct bio *bio_orig,
	bool bounce = false;		bool bounce = false;
	int sectors = 0;		int sectors = 0;
	bool passthrough = bio_is_passthrough(*bio_orig);		bool passthrough = bio_is_passthrough(*bio_orig);
	struct bvec_iter_all iter_all;

	bio_for_each_segment(from, *bio_orig, iter) {		bio_for_each_segment(from, *bio_orig, iter) {
	if (i++ < BIO_MAX_PAGES)		if (i++ < BIO_MAX_PAGES)
	@@ -315,7 +314,12 @@ static void __blk_queue_bounce(struct request_queue q, struct bio *bio_orig,
	bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :		bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :
	&bounce_bio_set);		&bounce_bio_set);

	bio_for_each_segment_all(to, bio, i, iter_all) {		/*
			* Bvec table can't be updated by bio_for_each_segment_all(),
			* so retrieve bvec from the table directly. This way is safe
			* because the 'bio' is single-page bvec.
			*/
			for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) {
	struct page *page = to->bv_page;		struct page *page = to->bv_page;

	if (page_to_pfn(page) <= q->limits.bounce_pfn)		if (page_to_pfn(page) <= q->limits.bounce_pfn)

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