Re: [PATCH 2/3] mm: use filemap_range_needs_writeback() for O_DIRECT reads

[Jan Kara <jack@suse.cz>]

On Wed 24-02-21 09:44:54, Jens Axboe wrote:
> For the generic page cache read helper, use the better variant of checking
> for the need to call filemap_write_and_wait_range() when doing O_DIRECT
> reads. This avoids falling back to the slow path for IOCB_NOWAIT, if there
> are no pages to wait for (or write out).
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  mm/filemap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Looks good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 13338f877677..77f1b527541e 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2645,8 +2645,8 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
>  
>  		size = i_size_read(inode);
>  		if (iocb->ki_flags & IOCB_NOWAIT) {
> -			if (filemap_range_has_page(mapping, iocb->ki_pos,
> -						   iocb->ki_pos + count - 1))
> +			if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
> +						iocb->ki_pos + count - 1))
>  				return -EAGAIN;
>  		} else {
>  			retval = filemap_write_and_wait_range(mapping,
> -- 
> 2.30.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR