[PATCH] dm raid: ensure metadata IO matches device block size.

[NeilBrown <neilb@suse.de>]

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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 failed
I think this is the best fix.  It handles boths read and writes, and (I think)
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_rdev *refdev)
 	uint64_t events_sb, events_refsb;
 
 	rdev->sb_start = 0;
-	rdev->sb_size = sizeof(*sb);
+	rdev->sb_size = roundup(sizeof(*sb),
+				bdev_logical_block_size(rdev->meta_bdev));
 
 	ret = read_disk_sb(rdev, rdev->sb_size);
 	if (ret)

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