[PATCH 1/4] ubifs: Convert from writepage to writepages

[Zhihao Cheng]

在 2023/6/6 0:50, Matthew Wilcox (Oracle) 写道:
Hi,
> This is a simplistic conversion to separate out any effects of
> no longer having a writepage method.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy at infradead.org>
> ---
>   fs/ubifs/file.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index 979ab1d9d0c3..8bb4cb9d528f 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -1003,8 +1003,10 @@ static int do_writepage(struct page *page, int len)
>    * on the page lock and it would not write the truncated inode node to the
>    * journal before we have finished.
>    */
> -static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
> +static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc,
> +		void *data)
>   {
> +	struct page *page = &folio->page;
>   	struct inode *inode = page->mapping->host;
>   	struct ubifs_info *c = inode->i_sb->s_fs_info;
>   	struct ubifs_inode *ui = ubifs_inode(inode);
> @@ -1076,6 +1078,12 @@ static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
>   	return err;
>   }
>   
> +static int ubifs_writepages(struct address_space *mapping,
> +		struct writeback_control *wbc)
> +{
> +	return write_cache_pages(mapping, wbc, ubifs_writepage, NULL);
> +}
> +

There is a small difference.
before patch applied:
do_writepages -> write_cache_pages -> writepage_cb:
  ubifs_writepage
  mapping_set_error(mapping, ret)

So, we can get error returned from errseq_check_and_advance in syncfs 
syscall if ubifs_writepage occurs EIO.

after patch applied:

do_writepages -> ubifs_writepages -> write_cache_pages -> 
ubifs_writepage, mapping won't be set error if ubifs_writepage failed. 
Unfortunately, ubifs is not a block filesystem, so 
sync_filesystem->sync_blockdev_nowait will return 0. Finally, syncfs 
syscall will return 0.


>   /**
>    * do_attr_changes - change inode attributes.
>    * @inode: inode to change attributes for
> @@ -1636,7 +1644,7 @@ static int ubifs_symlink_getattr(struct mnt_idmap *idmap,
>   
>   const struct address_space_operations ubifs_file_address_operations = {
>   	.read_folio     = ubifs_read_folio,
> -	.writepage      = ubifs_writepage,
> +	.writepages     = ubifs_writepages,
>   	.write_begin    = ubifs_write_begin,
>   	.write_end      = ubifs_write_end,
>   	.invalidate_folio = ubifs_invalidate_folio,
>