From: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Date: Thu, 12 Jul 2007 16:27:45 +0000 (+0100)
Subject: dm io: fix another panic on large request
X-Git-Tag: v2.6.22.2~14
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3bca2f557175e72b20f76d7489695f4c76ca0bf4;p=thirdparty%2Fkernel%2Fstable.git

dm io: fix another 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.

Signed-off-by: Junichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 352c6fbeac53a..f3a772486437e 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -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;