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Commit 596f138e authored by Jun'ichi Nomura's avatar Jun'ichi Nomura Committed by Linus Torvalds
Browse files

dm io: fix panic on large request 



bio_alloc_bioset() will return NULL if 'num_vecs' is too large.
Use bio_get_nr_vecs() to get estimation of maximum number.

Cc: stable@kernel.org
Signed-off-by: default avatar"Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c95bc206

drivers/md/dm-io.c

+4 −1
Original line number Diff line number Diff line
@@ -293,7 +293,10 @@ static void do_region(int rw, unsigned int region, struct io_region *where, 
		 * bvec for bio_get/set_region() and decrement bi_max_vecs

		 * to hide it from bio_add_page().

		 */

		num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;

		num_bvecs = dm_sector_div_up(remaining,

					     (PAGE_SIZE >> SECTOR_SHIFT));

		num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev),

				      num_bvecs);

		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);

		bio->bi_sector = where->sector + (where->count - remaining);

		bio->bi_bdev = where->bdev;