Re: [PATCH v2 11/19] mm/migrate: Add filemap_migrate_folio()

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jun 08, 2022 at 04:02:41PM +0100, Matthew Wilcox (Oracle) wrote:
> There is nothing iomap-specific about iomap_migratepage(), and it fits
> a pattern used by several other filesystems, so move it to mm/migrate.c,
> convert it to be filemap_migrate_folio() and convert the iomap filesystems
> to use it.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

LGTM
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/gfs2/aops.c          |  2 +-
>  fs/iomap/buffered-io.c  | 25 -------------------------
>  fs/xfs/xfs_aops.c       |  2 +-
>  fs/zonefs/super.c       |  2 +-
>  include/linux/iomap.h   |  6 ------
>  include/linux/pagemap.h |  6 ++++++
>  mm/migrate.c            | 20 ++++++++++++++++++++
>  7 files changed, 29 insertions(+), 34 deletions(-)
> 
> diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
> index 106e90a36583..57ff883d432c 100644
> --- a/fs/gfs2/aops.c
> +++ b/fs/gfs2/aops.c
> @@ -774,7 +774,7 @@ static const struct address_space_operations gfs2_aops = {
>  	.invalidate_folio = iomap_invalidate_folio,
>  	.bmap = gfs2_bmap,
>  	.direct_IO = noop_direct_IO,
> -	.migratepage = iomap_migrate_page,
> +	.migrate_folio = filemap_migrate_folio,
>  	.is_partially_uptodate = iomap_is_partially_uptodate,
>  	.error_remove_page = generic_error_remove_page,
>  };
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 66278a14bfa7..5a91aa1db945 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -489,31 +489,6 @@ void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len)
>  }
>  EXPORT_SYMBOL_GPL(iomap_invalidate_folio);
>  
> -#ifdef CONFIG_MIGRATION
> -int
> -iomap_migrate_page(struct address_space *mapping, struct page *newpage,
> -		struct page *page, enum migrate_mode mode)
> -{
> -	struct folio *folio = page_folio(page);
> -	struct folio *newfolio = page_folio(newpage);
> -	int ret;
> -
> -	ret = folio_migrate_mapping(mapping, newfolio, folio, 0);
> -	if (ret != MIGRATEPAGE_SUCCESS)
> -		return ret;
> -
> -	if (folio_test_private(folio))
> -		folio_attach_private(newfolio, folio_detach_private(folio));
> -
> -	if (mode != MIGRATE_SYNC_NO_COPY)
> -		folio_migrate_copy(newfolio, folio);
> -	else
> -		folio_migrate_flags(newfolio, folio);
> -	return MIGRATEPAGE_SUCCESS;
> -}
> -EXPORT_SYMBOL_GPL(iomap_migrate_page);
> -#endif /* CONFIG_MIGRATION */
> -
>  static void
>  iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
>  {
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 8ec38b25187b..5d1a995b15f8 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -570,7 +570,7 @@ const struct address_space_operations xfs_address_space_operations = {
>  	.invalidate_folio	= iomap_invalidate_folio,
>  	.bmap			= xfs_vm_bmap,
>  	.direct_IO		= noop_direct_IO,
> -	.migratepage		= iomap_migrate_page,
> +	.migrate_folio		= filemap_migrate_folio,
>  	.is_partially_uptodate  = iomap_is_partially_uptodate,
>  	.error_remove_page	= generic_error_remove_page,
>  	.swap_activate		= xfs_iomap_swapfile_activate,
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index bcb21aea990a..d4c3f28f34ee 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -237,7 +237,7 @@ static const struct address_space_operations zonefs_file_aops = {
>  	.dirty_folio		= filemap_dirty_folio,
>  	.release_folio		= iomap_release_folio,
>  	.invalidate_folio	= iomap_invalidate_folio,
> -	.migratepage		= iomap_migrate_page,
> +	.migrate_folio		= filemap_migrate_folio,
>  	.is_partially_uptodate	= iomap_is_partially_uptodate,
>  	.error_remove_page	= generic_error_remove_page,
>  	.direct_IO		= noop_direct_IO,
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index e552097c67e0..758a1125e72f 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -231,12 +231,6 @@ void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
>  bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);
>  bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
>  void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
> -#ifdef CONFIG_MIGRATION
> -int iomap_migrate_page(struct address_space *mapping, struct page *newpage,
> -		struct page *page, enum migrate_mode mode);
> -#else
> -#define iomap_migrate_page NULL
> -#endif
>  int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
>  		const struct iomap_ops *ops);
>  int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 1caccb9f99aa..2a67c0ad7348 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -1078,6 +1078,12 @@ static inline int __must_check write_one_page(struct page *page)
>  int __set_page_dirty_nobuffers(struct page *page);
>  bool noop_dirty_folio(struct address_space *mapping, struct folio *folio);
>  
> +#ifdef CONFIG_MIGRATION
> +int filemap_migrate_folio(struct address_space *mapping, struct folio *dst,
> +		struct folio *src, enum migrate_mode mode);
> +#else
> +#define filemap_migrate_folio NULL
> +#endif
>  void page_endio(struct page *page, bool is_write, int err);
>  
>  void folio_end_private_2(struct folio *folio);
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 785e32d0cf1b..4d8115ca93bb 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -784,6 +784,26 @@ int buffer_migrate_folio_norefs(struct address_space *mapping,
>  }
>  #endif
>  
> +int filemap_migrate_folio(struct address_space *mapping,
> +		struct folio *dst, struct folio *src, enum migrate_mode mode)
> +{
> +	int ret;
> +
> +	ret = folio_migrate_mapping(mapping, dst, src, 0);
> +	if (ret != MIGRATEPAGE_SUCCESS)
> +		return ret;
> +
> +	if (folio_get_private(src))
> +		folio_attach_private(dst, folio_detach_private(src));
> +
> +	if (mode != MIGRATE_SYNC_NO_COPY)
> +		folio_migrate_copy(dst, src);
> +	else
> +		folio_migrate_flags(dst, src);
> +	return MIGRATEPAGE_SUCCESS;
> +}
> +EXPORT_SYMBOL_GPL(filemap_migrate_folio);
> +
>  /*
>   * Writeback a folio to clean the dirty state
>   */
> -- 
> 2.35.1
> 

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