2013-04-19 16:42:18

by Namjae Jeon

[permalink] [raw]
Subject: [PATCH v2 7/9] brd: use generic helper to set max_discard_sectors

From: Namjae Jeon <[email protected]>

It is better to use blk_queue_max_discard_sectors helper
function to set max_discard_sectors as it checks
max_discard_sectors upper limit UINT_MAX >> 9

similar issue was reported for mmc in below link

If multiple discard requests get merged, merged discard request's
size exceeds 4GB, there is possibility that merged discard request's
__data_len field may overflow.

This patch fixes this issue.

Signed-off-by: Namjae Jeon <[email protected]>
Signed-off-by: Vivek Trivedi <[email protected]>
drivers/block/brd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index f1a29f8..108646d 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -479,7 +479,7 @@ static struct brd_device *brd_alloc(int i)
blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);

brd->brd_queue->limits.discard_granularity = PAGE_SIZE;
- brd->brd_queue->limits.max_discard_sectors = UINT_MAX;
+ blk_queue_max_discard_sectors(brd->brd_queue, UINT_MAX >> 9);
brd->brd_queue->limits.discard_zeroes_data = 1;
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);