From: Mike Snitzer <snitzer@redhat.com>
Date: Mon, 14 Jul 2014 20:59:39 +0000 (-0400)
Subject: dm cache metadata: do not allow the data block size to change
X-Git-Tag: firefly_0821_release~3679^2~1757
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=8a09a31a13d9efce4e253e4facd63d631809b89e;p=firefly-linux-kernel-4.4.55.git

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@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index a33e07f4222e..de737ba1d351 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -384,6 +384,15 @@ 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;