[PATCH 2/4] Limit max_discard_sectors to UINT_MAX>>9

From: Gwendal Grignou
Date: Tue Mar 25 2014 - 19:49:54 EST


max_discard_sectors can not be larger than UINT_MAX>>9,
otherwise, there is a risk that discard requests would be merged
into a request larger than 4GB.

Signed-off-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
---
block/blk-lib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 9b5b561..67bb0e7 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -64,7 +64,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
* Ensure that max_discard_sectors is of the proper
* granularity, so that requests stay aligned after a split.
*/
- max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+ max_discard_sectors = q->limits.max_discard_sectors;
max_discard_sectors -= max_discard_sectors % granularity;
if (unlikely(!max_discard_sectors)) {
/* Avoid infinite loop below. Being cautious never hurts. */
--
1.9.1.423.g4596e3a

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