[3.11.y.z extended stable] Patch "dm cache metadata: do not allow the data block size to change" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dm cache metadata: do not allow the data block size to change

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 49f4201c0b3e498ea5da8c25d09a2ed8a9d87c76 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer at redhat.com>
Date: Mon, 14 Jul 2014 16:59:39 -0400
Subject: dm cache metadata: do not allow the data block size to change

commit 048e5a07f282c57815b3901d4a68a77fa131ce0a upstream.

The block size for the dm-cache's data device must remained fixed for
the life of the cache.  Disallow any attempt to change the cache's data
block size.

Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Acked-by: Joe Thornber <ejt at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/dm-cache-metadata.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 1c53495960f2..24d96fa91a26 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -407,6 +407,15 @@ static int __open_metadata(struct dm_cache_metadata *cmd)

 	disk_super = dm_block_data(sblock);

+	/* Verify the data block size hasn't changed */
+	if (le32_to_cpu(disk_super->data_block_size) != cmd->data_block_size) {
+		DMERR("changing the data block size (from %u to %llu) is not supported",
+		      le32_to_cpu(disk_super->data_block_size),
+		      (unsigned long long)cmd->data_block_size);
+		r = -EINVAL;
+		goto bad;
+	}
+
 	r = __check_incompat_features(disk_super, cmd);
 	if (r < 0)
 		goto bad;
--
1.9.1