| Message ID | 20200305005735.583008-1-guro@fb.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] btrfs: implement migratepage callback | expand |
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@intel.com> > > Signed-off-by: Roman Gushchin <guro@fb.com> > Reviewed-by: Chris Mason <clm@fb.com> Added to devel queue, thanks.
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@intel.com> > > > > Signed-off-by: Roman Gushchin <guro@fb.com> > > Reviewed-by: Chris Mason <clm@fb.com> > > Added to devel queue, thanks. Thank you! Roman
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 7735ce6127c3..6ed6df4afe5a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -28,6 +28,7 @@ #include <linux/magic.h> #include <linux/iversion.h> #include <linux/swap.h> +#include <linux/migrate.h> #include <linux/sched/mm.h> #include <asm/unaligned.h> #include "misc.h" @@ -8323,6 +8324,39 @@ static int btrfs_releasepage(struct page *page, gfp_t gfp_flags) return __btrfs_releasepage(page, gfp_flags); } +#ifdef CONFIG_MIGRATION +static int btrfs_migratepage(struct address_space *mapping, + struct page *newpage, struct page *page, + enum migrate_mode mode) +{ + int ret; + + ret = migrate_page_move_mapping(mapping, newpage, page, 0); + if (ret != MIGRATEPAGE_SUCCESS) + return ret; + + if (page_has_private(page)) { + ClearPagePrivate(page); + get_page(newpage); + set_page_private(newpage, page_private(page)); + set_page_private(page, 0); + put_page(page); + SetPagePrivate(newpage); + } + + if (PagePrivate2(page)) { + ClearPagePrivate2(page); + SetPagePrivate2(newpage); + } + + if (mode != MIGRATE_SYNC_NO_COPY) + migrate_page_copy(newpage, page); + else + migrate_page_states(newpage, page); + return MIGRATEPAGE_SUCCESS; +} +#endif + static void btrfs_invalidatepage(struct page *page, unsigned int offset, unsigned int length) { @@ -10525,6 +10559,9 @@ static const struct address_space_operations btrfs_aops = { .direct_IO = btrfs_direct_IO, .invalidatepage = btrfs_invalidatepage, .releasepage = btrfs_releasepage, +#ifdef CONFIG_MIGRATION + .migratepage = btrfs_migratepage, +#endif .set_page_dirty = btrfs_set_page_dirty, .error_remove_page = generic_error_remove_page, .swap_activate = btrfs_swap_activate,