linux-kernel - [PATCH 4/4] brd: Request from fdisk 4k alignment

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53E21317.7080403@plexistor.com>
Date:	Wed, 06 Aug 2014 14:35:51 +0300
From:	Boaz Harrosh <boaz@...xistor.com>
To:	Jens Axboe <axboe@...nel.dk>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
CC:	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: [PATCH 4/4] brd: Request from fdisk 4k alignment


Because of the direct_access() API which returns a PFN. partitions
better start on 4K boundary, else offset ZERO of a partition will
not be aligned and blk_direct_access() will fail the call.

By setting blk_queue_physical_block_size(PAGE_SIZE) we can communicate
this to fdisk and friends.
Note that blk_queue_physical_block_size() also trashes io_min, but
we can leave this one to be 512.

Signed-off-by: Boaz Harrosh <boaz@...xistor.com>
---
 drivers/block/brd.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 9673704..514cfe1 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -495,10 +495,17 @@ static struct brd_device *brd_alloc(int i)
 	brd->brd_queue = blk_alloc_queue(GFP_KERNEL);
 	if (!brd->brd_queue)
 		goto out_free_dev;
+
 	blk_queue_make_request(brd->brd_queue, brd_make_request);
 	blk_queue_max_hw_sectors(brd->brd_queue, 1024);
 	blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);
 
+	/* This is so fdisk will align partitions on 4k, because of
+	 * direct_access API needing 4k alignment, returning a PFN
+	 */
+	blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);
+	brd->brd_queue->limits.io_min = 512; /* Don't use the accessor */
+
 	brd->brd_queue->limits.discard_granularity = PAGE_SIZE;
 	brd->brd_queue->limits.max_discard_sectors = UINT_MAX;
 	brd->brd_queue->limits.discard_zeroes_data = 1;
-- 
1.9.3


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/