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Commit 6bc454d1 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bounce: Refactor __blk_queue_bounce to not use bi_io_vec 



A bunch of what __blk_queue_bounce() was doing was problematic for the
immutable bvec work; this cleans that up and the code is quite a bit
smaller, too.

The __bio_for_each_segment() in copy_to_high_bio_irq() was changed
because that one's looping over the original bio, not the bounce bio -
a later patch renames __bio_for_each_segment() ->
bio_for_each_segment_all(), and documents that
bio_for_each_segment_all() is only for code that owns the bio.

Signed-off-by: default avatarKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
parent d3b45c2a

mm/bounce.c

+19 −54
Original line number Diff line number Diff line
@@ -101,7 +101,7 @@ static void copy_to_high_bio_irq(struct bio *to, struct bio *from) 
	struct bio_vec *tovec, *fromvec;

	int i;



	__bio_for_each_segment(tovec, to, i, 0) {

	bio_for_each_segment(tovec, to, i) {

		fromvec = from->bi_io_vec + i;



		/*
@@ -218,78 +218,43 @@ static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio) 
static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,

			       mempool_t *pool, int force)

{

	struct page *page;

	struct bio *bio = NULL;

	int i, rw = bio_data_dir(*bio_orig);

	struct bio *bio;

	int rw = bio_data_dir(*bio_orig);

	struct bio_vec *to, *from;

	unsigned i;



	bio_for_each_segment(from, *bio_orig, i) {

		page = from->bv_page;



		/*

		 * is destination page below bounce pfn?

		 */

		if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)

			continue;



		/*

		 * irk, bounce it

		 */

		if (!bio) {

			unsigned int cnt = (*bio_orig)->bi_vcnt;

	bio_for_each_segment(from, *bio_orig, i)

		if (page_to_pfn(from->bv_page) > queue_bounce_pfn(q))

			goto bounce;



			bio = bio_alloc(GFP_NOIO, cnt);

			memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));

		}

	return;

bounce:

	bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);



	bio_for_each_segment(to, bio, i) {

		struct page *page = to->bv_page;



		to = bio->bi_io_vec + i;

		if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)

			continue;



		to->bv_page = mempool_alloc(pool, q->bounce_gfp);

		to->bv_len = from->bv_len;

		to->bv_offset = from->bv_offset;

		inc_zone_page_state(to->bv_page, NR_BOUNCE);

		to->bv_page = mempool_alloc(pool, q->bounce_gfp);



		if (rw == WRITE) {

			char *vto, *vfrom;



			flush_dcache_page(from->bv_page);

			flush_dcache_page(page);



			vto = page_address(to->bv_page) + to->bv_offset;

			vfrom = kmap(from->bv_page) + from->bv_offset;

			vfrom = kmap_atomic(page) + to->bv_offset;

			memcpy(vto, vfrom, to->bv_len);

			kunmap(from->bv_page);

			kunmap_atomic(vfrom);

		}

	}



	/*

	 * no pages bounced

	 */

	if (!bio)

		return;



	trace_block_bio_bounce(q, *bio_orig);



	/*

	 * at least one page was bounced, fill in possible non-highmem

	 * pages

	 */

	__bio_for_each_segment(from, *bio_orig, i, 0) {

		to = bio_iovec_idx(bio, i);

		if (!to->bv_page) {

			to->bv_page = from->bv_page;

			to->bv_len = from->bv_len;

			to->bv_offset = from->bv_offset;

		}

	}



	bio->bi_bdev = (*bio_orig)->bi_bdev;

	bio->bi_flags |= (1 << BIO_BOUNCED);

	bio->bi_sector = (*bio_orig)->bi_sector;

	bio->bi_rw = (*bio_orig)->bi_rw;



	bio->bi_vcnt = (*bio_orig)->bi_vcnt;

	bio->bi_idx = (*bio_orig)->bi_idx;

	bio->bi_size = (*bio_orig)->bi_size;



	if (pool == page_pool) {

		bio->bi_end_io = bounce_end_io_write;