Commit 9aec8629 authored Jul 14, 2014 by Mike Snitzer

dm thin metadata: do not allow the data block size to change



The block size for the thin-pool's data device must remained fixed for
the life of the thin-pool.  Disallow any attempt to change the
thin-pool's data block size.

It should be noted that attempting to change the data block size via
thin-pool table reload will be ignored as a side-effect of the thin-pool
handover that the thin-pool target does during thin-pool table reload.

Here is an example outcome of attempting to load a thin-pool table that
reduced the thin-pool's data block size from 1024K to 512K.

Before:
kernel: device-mapper: thin: 253:4: growing the data device from 204800 to 409600 blocks

After:
kernel: device-mapper: thin metadata: changing the data block size (from 2048 to 1024) is not supported
kernel: device-mapper: table: 253:4: thin-pool: Error creating metadata object
kernel: device-mapper: ioctl: error adding target to table

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Cc: stable@vger.kernel.org

parent 7a7a3b45

drivers/md/dm-thin-metadata.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -613,6 +613,15 @@ static int __open_metadata(struct dm_pool_metadata *pmd)

		disk_super = dm_block_data(sblock);

		/* Verify the data block size hasn't changed */
		if (le32_to_cpu(disk_super->data_block_size) != pmd->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)pmd->data_block_size);
		r = -EINVAL;
		goto bad_unlock_sblock;
		}

		r = __check_incompat_features(disk_super, pmd);
		if (r < 0)
		goto bad_unlock_sblock;