linux-kernel - [PATCH 3.10 52/56] dm cache metadata: do not allow the data block size to change

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Message-Id: <20140726190201.779867481@linuxfoundation.org>
Date:	Sat, 26 Jul 2014 12:02:45 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Mike Snitzer <snitzer@...hat.com>,
	Joe Thornber <ejt@...hat.com>
Subject: [PATCH 3.10 52/56] dm cache metadata: do not allow the data block size to change

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <snitzer@...hat.com>

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

---
 drivers/md/dm-cache-metadata.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -384,6 +384,15 @@ static int __open_metadata(struct dm_cac
 
 	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;


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