On Wed, Mar 11, 2020 at 01:40:12AM +0100, David Sterba wrote: > On Wed, Mar 04, 2020 at 04:57:35PM -0800, Roman Gushchin wrote: > > Currently btrfs doesn't provide a migratepage callback. It means that > > fallback_migrate_page() is used to migrate btrfs pages. > > The callback exists for the metadata pages (btree_migratepage), so I've > added 'for data pages' where appropriate. Agree. > > > fallback_migrate_page() cannot move dirty pages, instead it tries to > > flush them (in sync mode) or just fails (in async mode). > > > > In the sync mode pages which are scheduled to be processed by > > btrfs_writepage_fixup_worker() can't be effectively flushed by the > > migration code, because there is no established way to wait for the > > completion of the delayed work. > > > > It all leads to page migration failures. > > > > To fix it the patch implements a btrs-specific migratepage callback, > > which is similar to iomap_migrate_page() used by some other fs, except > > it does take care of the PagePrivate2 flag which is used for data > > ordering purposes. > > > > v3: fixed the build issue once again > > v2: fixed the build issue found by the kbuild test robot <lkp@xxxxxxxxx> > > > > Signed-off-by: Roman Gushchin <guro@xxxxxx> > > Reviewed-by: Chris Mason <clm@xxxxxx> > > Added to devel queue, thanks. Thank you! Roman
