From: David Hildenbrand <david@redhat.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
linux-aio@kvack.org, linux-btrfs@vger.kernel.org,
linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com,
linux-mm@kvack.org, linux-xfs@vger.kernel.org,
linux-nfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net,
ocfs2-devel@oss.oracle.com, linux-mtd@lists.infradead.org,
virtualization@lists.linux-foundation.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2 03/19] fs: Add aops->migrate_folio
Date: Thu, 9 Jun 2022 14:50:20 +0200 [thread overview]
Message-ID: <b2a81248-03fc-afb3-1041-d8206e95e08a@redhat.com> (raw)
In-Reply-To: <20220608150249.3033815-4-willy@infradead.org>
On 08.06.22 17:02, Matthew Wilcox (Oracle) wrote:
> Provide a folio-based replacement for aops->migratepage. Update the
> documentation to document migrate_folio instead of migratepage.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
> Documentation/filesystems/locking.rst | 5 ++--
> Documentation/filesystems/vfs.rst | 13 ++++++-----
> Documentation/vm/page_migration.rst | 33 ++++++++++++++-------------
> include/linux/fs.h | 4 +++-
> mm/compaction.c | 4 +++-
> mm/migrate.c | 11 +++++----
> 6 files changed, 40 insertions(+), 30 deletions(-)
>
> diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
> index c0fe711f14d3..3d28b23676bd 100644
> --- a/Documentation/filesystems/locking.rst
> +++ b/Documentation/filesystems/locking.rst
> @@ -253,7 +253,8 @@ prototypes::
> void (*free_folio)(struct folio *);
> int (*direct_IO)(struct kiocb *, struct iov_iter *iter);
> bool (*isolate_page) (struct page *, isolate_mode_t);
> - int (*migratepage)(struct address_space *, struct page *, struct page *);
> + int (*migrate_folio)(struct address_space *, struct folio *dst,
> + struct folio *src, enum migrate_mode);
> void (*putback_page) (struct page *);
isolate_page/putback_page are leftovers from the previous patch, no?
> int (*launder_folio)(struct folio *);
> bool (*is_partially_uptodate)(struct folio *, size_t from, size_t count);
> @@ -281,7 +282,7 @@ release_folio: yes
> free_folio: yes
> direct_IO:
> isolate_page: yes
> -migratepage: yes (both)
> +migrate_folio: yes (both)
> putback_page: yes
Dito.
> launder_folio: yes
> is_partially_uptodate: yes
> diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
> index a08c652467d7..3ae1b039b03f 100644
> --- a/Documentation/filesystems/vfs.rst
> +++ b/Documentation/filesystems/vfs.rst
> @@ -740,7 +740,8 @@ cache in your filesystem. The following members are defined:
> /* isolate a page for migration */
> bool (*isolate_page) (struct page *, isolate_mode_t);
> /* migrate the contents of a page to the specified target */
> - int (*migratepage) (struct page *, struct page *);
> + int (*migrate_folio)(struct mapping *, struct folio *dst,
> + struct folio *src, enum migrate_mode);
> /* put migration-failed page back to right list */
> void (*putback_page) (struct page *);
Dito.
> int (*launder_folio) (struct folio *);
> @@ -935,12 +936,12 @@ cache in your filesystem. The following members are defined:
> is successfully isolated, VM marks the page as PG_isolated via
> __SetPageIsolated.
>
> -``migrate_page``
> +``migrate_folio``
> This is used to compact the physical memory usage. If the VM
> - wants to relocate a page (maybe off a memory card that is
> - signalling imminent failure) it will pass a new page and an old
> - page to this function. migrate_page should transfer any private
> - data across and update any references that it has to the page.
> + wants to relocate a folio (maybe from a memory device that is
> + signalling imminent failure) it will pass a new folio and an old
> + folio to this function. migrate_folio should transfer any private
> + data across and update any references that it has to the folio.
>
> ``putback_page``
> Called by the VM when isolated page's migration fails.
Dito.
> diff --git a/Documentation/vm/page_migration.rst b/Documentation/vm/page_migration.rst
> index 8c5cb8147e55..e0f73ddfabb1 100644
> --- a/Documentation/vm/page_migration.rst
> +++ b/Documentation/vm/page_migration.rst
> @@ -181,22 +181,23 @@ which are function pointers of struct address_space_operations.
> Once page is successfully isolated, VM uses page.lru fields so driver
> shouldn't expect to preserve values in those fields.
>
> -2. ``int (*migratepage) (struct address_space *mapping,``
> -| ``struct page *newpage, struct page *oldpage, enum migrate_mode);``
> -
> - After isolation, VM calls migratepage() of driver with the isolated page.
> - The function of migratepage() is to move the contents of the old page to the
> - new page
> - and set up fields of struct page newpage. Keep in mind that you should
> - indicate to the VM the oldpage is no longer movable via __ClearPageMovable()
> - under page_lock if you migrated the oldpage successfully and returned
> - MIGRATEPAGE_SUCCESS. If driver cannot migrate the page at the moment, driver
> - can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time
> - because VM interprets -EAGAIN as "temporary migration failure". On returning
> - any error except -EAGAIN, VM will give up the page migration without
> - retrying.
> -
> - Driver shouldn't touch the page.lru field while in the migratepage() function.
> +2. ``int (*migrate_folio) (struct address_space *mapping,``
> +| ``struct folio *dst, struct folio *src, enum migrate_mode);``
> +
> + After isolation, VM calls the driver's migrate_folio() with the
> + isolated folio. The purpose of migrate_folio() is to move the contents
> + of the source folio to the destination folio and set up the fields
> + of destination folio. Keep in mind that you should indicate to the
> + VM the source folio is no longer movable via __ClearPageMovable()
> + under folio if you migrated the source successfully and returned
> + MIGRATEPAGE_SUCCESS. If driver cannot migrate the folio at the
> + moment, driver can return -EAGAIN. On -EAGAIN, VM will retry folio
> + migration in a short time because VM interprets -EAGAIN as "temporary
> + migration failure". On returning any error except -EAGAIN, VM will
> + give up the folio migration without retrying.
> +
> + Driver shouldn't touch the folio.lru field while in the migrate_folio()
> + function.
>
> 3. ``void (*putback_page)(struct page *);``
Hmm, here it's a bit more complicated now, because we essentially have
two paths: LRU+migrate_folio or !LRU+movable_ops
(isolate/migrate/putback page)
--
Thanks,
David / dhildenb
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http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2022-06-09 12:51 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-08 15:02 [PATCH v2 00/19] Convert aops->migratepage to aops->migrate_folio Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 01/19] secretmem: Remove isolate_page Matthew Wilcox (Oracle)
2022-06-09 12:46 ` David Hildenbrand
2022-06-08 15:02 ` [PATCH v2 02/19] mm: Convert all PageMovable users to movable_operations Matthew Wilcox (Oracle)
2022-06-09 10:23 ` David Hildenbrand
2022-06-08 15:02 ` [PATCH v2 03/19] fs: Add aops->migrate_folio Matthew Wilcox (Oracle)
2022-06-09 12:50 ` David Hildenbrand [this message]
2022-06-09 14:35 ` Matthew Wilcox
2022-06-10 10:17 ` David Hildenbrand
2022-06-08 15:02 ` [PATCH v2 04/19] mm/migrate: Convert fallback_migrate_page() to fallback_migrate_folio() Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 05/19] mm/migrate: Convert writeout() to take a folio Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 06/19] mm/migrate: Convert buffer_migrate_page() to buffer_migrate_folio() Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 07/19] mm/migrate: Convert expected_page_refs() to folio_expected_refs() Matthew Wilcox (Oracle)
2022-07-08 2:50 ` Hugh Dickins
2022-07-08 3:29 ` Matthew Wilcox
2022-06-08 15:02 ` [PATCH v2 08/19] btrfs: Convert btree_migratepage to migrate_folio Matthew Wilcox (Oracle)
2022-06-09 16:25 ` David Sterba
2022-06-08 15:02 ` [PATCH v2 09/19] nfs: Convert " Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 10/19] mm/migrate: Convert migrate_page() to migrate_folio() Matthew Wilcox (Oracle)
2022-06-09 16:26 ` David Sterba
2022-06-08 15:02 ` [PATCH v2 11/19] mm/migrate: Add filemap_migrate_folio() Matthew Wilcox (Oracle)
2022-06-08 15:22 ` Darrick J. Wong
2022-06-08 15:02 ` [PATCH v2 12/19] btrfs: Convert btrfs_migratepage to migrate_folio Matthew Wilcox (Oracle)
2022-06-09 16:33 ` David Sterba
2022-06-09 17:40 ` Matthew Wilcox
2022-06-09 23:05 ` David Sterba
2022-06-08 15:02 ` [PATCH v2 13/19] ubifs: Convert to filemap_migrate_folio() Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 14/19] f2fs: " Matthew Wilcox (Oracle)
2022-06-15 8:11 ` [f2fs-dev] " Chao Yu
2022-06-08 15:02 ` [PATCH v2 15/19] aio: Convert to migrate_folio Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 16/19] hugetlb: " Matthew Wilcox (Oracle)
2022-06-09 3:53 ` Muchun Song
2022-06-09 20:51 ` Mike Kravetz
2022-06-08 15:02 ` [PATCH v2 17/19] secretmem: " Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 18/19] fs: Remove aops->migratepage() Matthew Wilcox (Oracle)
2022-06-08 15:02 ` [PATCH v2 19/19] mm/folio-compat: Remove migration compatibility functions Matthew Wilcox (Oracle)
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