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

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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
This commit is contained in:
Mike Snitzer 2014-07-14 16:35:54 -04:00
parent 7a7a3b45fe
commit 9aec8629ec
1 changed files with 9 additions and 0 deletions
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9
drivers/md/dm-thin-metadata.c
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@ -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;