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. > 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.
