linux-kernel - [PATCH] null_blk: fix wrong capacity when bs is not 512 bytes

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Message-Id: <1438084824-29730-1-git-send-email-mb@lightnvm.io>
Date:	Tue, 28 Jul 2015 14:00:24 +0200
From:	Matias Bjørling <mb@...htnvm.io>
To:	axboe@...com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	Matias Bjørling <m@...rling.me>
Subject: [PATCH] null_blk: fix wrong capacity when bs is not 512 bytes

From: Matias Bjørling <m@...rling.me>

set_capacity() sets device's capacity using 512 bytes sectors.
null_blk calculates the number of sectors by size / bs, which
set_capacity is called with. This led to null_blk exposing the
wrong number of sectors when bs is not 512 bytes.

Signed-off-by: Matias Bjørling <m@...rling.me>
---
 drivers/block/null_blk.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 6f9b753..bf8f764 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -588,8 +588,7 @@ static int null_add_dev(void)
 	blk_queue_physical_block_size(nullb->q, bs);
 
 	size = gb * 1024 * 1024 * 1024ULL;
-	sector_div(size, bs);
-	set_capacity(disk, size);
+	set_capacity(disk, size >> 9);
 
 	disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
 	disk->major		= null_major;
-- 
2.1.4

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