From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.de>
Subject: [PATCH] dm raid: ensure metadata IO matches device block
	size.
Date: Wed, 15 Oct 2014 12:19:07 +1100
Message-ID: <20141015121907.265b3aed@notabene.brown>
Reply-To: device-mapper development <dm-devel@redhat.com>
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To: Mike Snitzer <snitzer@redhat.com>
Cc: Liuhua Wang <lwang@suse.com>, Heinz Mauelshagen <heinzm@redhat.com>, device-mapper development <dm-devel@redhat.com>, Alasdair G Kergon <agk@redhat.com>
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dm_raid_superblock is 512.
Reading or writing this on a 512-byte sector works fine.
On a 4096-byte sector device, this fails.

If we round up rdev->sb_size to match the block size of
the device, all IO will work correctly.

Reported-by: "Liuhua Wang" <lwang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

---
this issue has been discussed already a bit. See email thread
 Subject: Re: [dm-devel] [PATCH] fix mirror device creation with lvcreate f=
ailed
I think this is the best fix.  It handles boths read and writes, and (I thi=
nk)
at the best level.

Thanks,
NeilBrown


diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 4880b69e2e9e..31bdd73bc368 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -858,7 +858,8 @@ static int super_load(struct md_rdev *rdev, struct md_r=
dev *refdev)
 	uint64_t events_sb, events_refsb;
=20
 	rdev->sb_start =3D 0;
-	rdev->sb_size =3D sizeof(*sb);
+	rdev->sb_size =3D roundup(sizeof(*sb),
+				bdev_logical_block_size(rdev->meta_bdev));
=20
 	ret =3D read_disk_sb(rdev, rdev->sb_size);
 	if (ret)

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