Messages in this thread | | | From | "Chris Mason" <> | Subject | Re: [PATCH] btrfs: implement migratepage callback | Date | Wed, 04 Mar 2020 14:53:21 -0500 |
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On 4 Mar 2020, at 14:50, Roman Gushchin wrote:
> Currently btrfs doesn't provide a migratepage callback. It means that > fallback_migrate_page() is used to migrate btrfs pages. > > 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.
Since the default migratepage didn’t copy PagePrivate2, didn’t you find it was also causing pages to get funneled into the fixup worker flow?
-chris
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