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Commit a09ded8e authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Fix merge_bvec_fn usage for when it modifies the bvm 



Stacked md devices reuse the bvm for the subordinate device, causing
problems...

Reported-by: default avatarMichael Balser <michael.balser@profitbricks.com>
Signed-off-by: default avatarKent Overstreet <koverstreet@google.com>
parent 1545f137

drivers/md/bcache/io.c

+8 −9
Original line number Diff line number Diff line
@@ -163,13 +163,6 @@ static unsigned bch_bio_max_sectors(struct bio *bio) 
	struct bio_vec *bv, *end = bio_iovec(bio) +

		min_t(int, bio_segments(bio), max_segments);



	struct bvec_merge_data bvm = {

		.bi_bdev	= bio->bi_bdev,

		.bi_sector	= bio->bi_sector,

		.bi_size	= 0,

		.bi_rw		= bio->bi_rw,

	};



	if (bio->bi_rw & REQ_DISCARD)

		return min(ret, q->limits.max_discard_sectors);
@@ -178,12 +171,18 @@ static unsigned bch_bio_max_sectors(struct bio *bio) 
		ret = 0;



		for (bv = bio_iovec(bio); bv < end; bv++) {

			struct bvec_merge_data bvm = {

				.bi_bdev	= bio->bi_bdev,

				.bi_sector	= bio->bi_sector,

				.bi_size	= ret << 9,

				.bi_rw		= bio->bi_rw,

			};



			if (q->merge_bvec_fn &&

			    q->merge_bvec_fn(q, &bvm, bv) < (int) bv->bv_len)

				break;



			ret += bv->bv_len >> 9;

			bvm.bi_size	+= bv->bv_len;

		}

	}