[PATCH 4.14 165/176] dm era: Verify the data block size hasnt changed

[Greg Kroah-Hartman]

From: Nikos Tsironis <ntsiro...@arrikto.com>

commit c8e846ff93d5eaa5384f6f325a1687ac5921aade upstream.

dm-era doesn't support changing the data block size of existing devices,
so check explicitly that the requested block size for a new target
matches the one stored in the metadata.

Fixes: eec40579d84873 ("dm: add era target")
Cc: sta...@vger.kernel.org # v3.15+
Signed-off-by: Nikos Tsironis <ntsiro...@arrikto.com>
Reviewed-by: Ming-Hung Tsai <mt...@redhat.com>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/md/dm-era-target.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/md/dm-era-target.c
+++ b/drivers/md/dm-era-target.c
@@ -563,6 +563,15 @@ static int open_metadata(struct era_meta
        }
 
        disk = dm_block_data(sblock);
+
+       /* Verify the data block size hasn't changed */
+       if (le32_to_cpu(disk->data_block_size) != md->block_size) {
+               DMERR("changing the data block size (from %u to %llu) is not 
supported",
+                     le32_to_cpu(disk->data_block_size), md->block_size);
+               r = -EINVAL;
+               goto bad;
+       }
+
        r = dm_tm_open_with_sm(md->bm, SUPERBLOCK_LOCATION,
                               disk->metadata_space_map_root,
                               sizeof(disk->metadata_space_map_root),
@@ -574,7 +583,6 @@ static int open_metadata(struct era_meta
 
        setup_infos(md);
 
-       md->block_size = le32_to_cpu(disk->data_block_size);
        md->nr_blocks = le32_to_cpu(disk->nr_blocks);
        md->current_era = le32_to_cpu(disk->current_era);