commit 1e0f7a21b2fffc70f27cc4a454c60321501045b1
author Roger Pau Monne <roger.pau@citrix.com> Sat Jun 22 09:59:17 2013 +0200
committer Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Tue Jun 25 10:00:58 2013 -0400
tree 0a6eb8b048e694cc4ffb69af6f94f2bd5e8105cd
parent 294caaf29c26cfed3b446fb46393b8b39ea1c0d3

xen-blkback: check the number of iovecs before allocating a bios

With the introduction of indirect segments we can receive requests
with a number of segments bigger than the maximum number of allowed
iovecs in a bios, so make sure that blkback doesn't try to allocate a
bios with more iovecs than BIO_MAX_PAGES

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkback/blkback.c

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 4662217..bf4b9d2 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -1247,7 +1247,8 @@
 				     seg[i].nsec << 9,
 				     seg[i].offset) == 0)) {
 
-			bio = bio_alloc(GFP_KERNEL, nseg-i);
+			int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES);
+			bio = bio_alloc(GFP_KERNEL, nr_iovecs);
 			if (unlikely(bio == NULL))
 				goto fail_put_bio;