Re: [PATCH v2 3/7] filemap: introduce filemap_invalidate_pages

[Christoph Hellwig <hch@infradead.org>]

On Thu, Aug 22, 2024 at 04:35:53AM +0100, Pavel Begunkov wrote:
> kiocb_invalidate_pages() is useful for the write path, however not
> everything is backed by kiocb and we want to reuse the function for bio
> based discard implementation. Extract and and reuse a new helper called
> filemap_invalidate_pages(), which takes a argument indicating whether it
> should be non-blocking and might return -EAGAIN.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>  include/linux/pagemap.h |  2 ++
>  mm/filemap.c            | 18 +++++++++++++-----
>  2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index d9c7edb6422b..e39c3a7ce33c 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -32,6 +32,8 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
>  		pgoff_t start, pgoff_t end);
>  int kiocb_invalidate_pages(struct kiocb *iocb, size_t count);
>  void kiocb_invalidate_post_direct_write(struct kiocb *iocb, size_t count);
> +int filemap_invalidate_pages(struct address_space *mapping,
> +			     loff_t pos, loff_t end, bool nowait);
>  
>  int write_inode_now(struct inode *, int sync);
>  int filemap_fdatawrite(struct address_space *);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index d62150418b91..74baec119239 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2712,14 +2712,12 @@ int kiocb_write_and_wait(struct kiocb *iocb, size_t count)
>  }
>  EXPORT_SYMBOL_GPL(kiocb_write_and_wait);
>  
> -int kiocb_invalidate_pages(struct kiocb *iocb, size_t count)
> +int filemap_invalidate_pages(struct address_space *mapping,
> +			     loff_t pos, loff_t end, bool nowait)
>  {
> -	struct address_space *mapping = iocb->ki_filp->f_mapping;
> -	loff_t pos = iocb->ki_pos;
> -	loff_t end = pos + count - 1;
>  	int ret;
>  
> -	if (iocb->ki_flags & IOCB_NOWAIT) {
> +	if (nowait) {
>  		/* we could block if there are any pages in the range */
>  		if (filemap_range_has_page(mapping, pos, end))
>  			return -EAGAIN;
> @@ -2738,6 +2736,16 @@ int kiocb_invalidate_pages(struct kiocb *iocb, size_t count)
>  	return invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT,
>  					     end >> PAGE_SHIFT);
>  }
> +
> +int kiocb_invalidate_pages(struct kiocb *iocb, size_t count)
> +{
> +	struct address_space *mapping = iocb->ki_filp->f_mapping;
> +	loff_t pos = iocb->ki_pos;
> +	loff_t end = pos + count - 1;
> +
> +	return filemap_invalidate_pages(mapping, pos, end,

No real need for the end variable here.  And maybe not for pos either.