[PATCH v2 3/9] sd: use generic helper to set max_discard_sectors

From: Namjae Jeon
Date: Fri Apr 19 2013 - 12:41:16 EST


From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>

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 <namjae.jeon@xxxxxxxxxxx>
Signed-off-by: Vivek Trivedi <t.vivek@xxxxxxxxxxx>
---
drivers/scsi/sd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 7992635..93c26b3 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -632,7 +632,8 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
break;
}

- q->limits.max_discard_sectors = max_blocks * (logical_block_size >> 9);
+ blk_queue_max_discard_sectors(q,
+ max_blocks * (logical_block_size >> 9));
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
}

--
1.7.9.5

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