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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: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jun'ichi Nomura 2007-07-12 17:27:45 +01:00 committed by Linus Torvalds
parent c95bc206da
commit 596f138eed
1 changed files with 4 additions and 1 deletions
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5
drivers/md/dm-io.c
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@ -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;