On Mon, Apr 15 2019 at 5:17pm -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > Otherwise, just loading a thin-pool and then removing it will cause its > metadata to be changed (e.g. superblock written) -- even without any > thin devices being made active or metadata snapshot being manipulated. > > Add 'changed' flag to struct dm_pool_metadata. Set both td->changed and > pmd->changed using __set_thin_changed() -- this assures pmd->changed is > always set when td->changed is. For methods that don't involve changing > a td, set pmd->changed directly. > > Rename __delete_device() to __delete_thin() -- improves symmetry with > __create_thin(). > > Update dm_pool_changed_this_transaction() to simply return pmd->changed. > > Fix dm_pool_commit_metadata() to open the next transaction if the return > from __commit_transaction() is 0. Not seeing why the early return ever > made since for a return of 0 given that dm-io's async_io(), as used by > bufio, always returns 0. This v1 patch was incomplete. However this approach's need to establish pmd->changed everywhere that alters metadata, without doing so in terms of a thin device, is like whack-a-mole. But I think this could be simplified to only set a 'pmd->accessed' (never clear it) and only__commit_transaction() if pmd->accessed -- so only pool messages that change metadata would need to set pmd->accessed. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
