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Commit d2044a94 authored by Alasdair G Kergon's avatar Alasdair G Kergon Committed by Linus Torvalds
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[PATCH] dm: bio split bvec fix 



The code that handles bios that span table target boundaries by breaking
them up into smaller bios will not split an individual struct bio_vec into
more than two pieces.  Sometimes more than that are required.

This patch adds a loop to break the second piece up into as many pieces as
are necessary.

Cc: "Abhishek Gupta" <abhishekgupt@gmail.com>
Cc: Dan Smith <danms@us.ibm.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 06f9d4f9

drivers/md/dm.c

+24 −19
Original line number Diff line number Diff line
@@ -533,30 +533,35 @@ static void __clone_and_map(struct clone_info *ci) 


	} else {

		/*

		 * Create two copy bios to deal with io that has

		 * been split across a target.

		 * Handle a bvec that must be split between two or more targets.

		 */

		struct bio_vec *bv = bio->bi_io_vec + ci->idx;

		sector_t remaining = to_sector(bv->bv_len);

		unsigned int offset = 0;



		clone = split_bvec(bio, ci->sector, ci->idx,

				   bv->bv_offset, max);

		__map_bio(ti, clone, tio);



		ci->sector += max;

		ci->sector_count -= max;

		do {

			if (offset) {

				ti = dm_table_find_target(ci->map, ci->sector);

				max = max_io_len(ci->md, ci->sector, ti);



		len = to_sector(bv->bv_len) - max;

		clone = split_bvec(bio, ci->sector, ci->idx,

				   bv->bv_offset + to_bytes(max), len);

				tio = alloc_tio(ci->md);

				tio->io = ci->io;

				tio->ti = ti;

				memset(&tio->info, 0, sizeof(tio->info));

			}



			len = min(remaining, max);



			clone = split_bvec(bio, ci->sector, ci->idx,

					   bv->bv_offset + offset, len);



			__map_bio(ti, clone, tio);



			ci->sector += len;

			ci->sector_count -= len;

			offset += to_bytes(len);

		} while (remaining -= len);



		ci->idx++;

	}

}