[PATCH 3.14 79/87] dm cache metadata: do not allow the data block size to change

From: Greg Kroah-Hartman
Date: Sat Jul 26 2014 - 15:39:20 EST

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


From: Mike Snitzer <snitzer@xxxxxxxxxx>

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@xxxxxxxxxx>
Acked-by: Joe Thornber <ejt@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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
@@ -425,6 +425,15 @@ 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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