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

[Kamal Mostafa]

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-3.13.y-queue branch of the 3.13.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-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.6.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f77b8efdb230da8cc14cf8781086070e1af0a028 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: Kamal Mostafa <kamal 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 5320332..a87d3fa 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -425,6 +425,15 @@ 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