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
https://lkml.org/lkml/2013/4/1/292

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/md/bcache/super.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index f3bf310..d87ab31 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -746,7 +746,7 @@ static int bcache_device_init(struct bcache_device *d, 
unsigned block_size)
        q->limits.max_sectors           = UINT_MAX;
        q->limits.max_segment_size      = UINT_MAX;
        q->limits.max_segments          = BIO_MAX_PAGES;
-       q->limits.max_discard_sectors   = UINT_MAX;
+       blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
        q->limits.io_min                = block_size;
        q->limits.logical_block_size    = block_size;
        q->limits.physical_block_size   = block_size;
-- 
1.7.9.5


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