[PATCH v2 3/4] xen-blkback: check the number of iovecs before allocating a bios

From: Roger Pau Monne
Date: Sat Jun 22 2013 - 04:03:21 EST

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 Monnà <roger.pau@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
drivers/block/xen-blkback/blkback.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index d622d86..b3897f5d 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -1236,7 +1236,8 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
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;

-- (Apple Git-26)

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