linux-kernel - Re: [PATCH v2 1/3] fs: remove redundant cache invalidation after async direct-io write

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Message-ID: <20191121162153.GA18158@quack2.suse.cz>
Date:   Thu, 21 Nov 2019 17:21:53 +0100
From:   Jan Kara <jack@...e.cz>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>, Jan Kara <jack@...e.cz>,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 1/3] fs: remove redundant cache invalidation after
 async direct-io write

On Sat 02-11-19 16:12:58, Konstantin Khlebnikov wrote:
> Function generic_file_direct_write() invalidates cache at entry. Second
> time this should be done when request completes. But this function calls
> second invalidation at exit unconditionally even for async requests.
> 
> This patch skips second invalidation for async requests (-EIOCBQUEUED).
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>

Looks good to me. You can add:

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

								Honza

> ---
>  mm/filemap.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 85b7d087eb45..288e38199068 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3218,9 +3218,11 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
>  	 * Most of the time we do not need this since dio_complete() will do
>  	 * the invalidation for us. However there are some file systems that
>  	 * do not end up with dio_complete() being called, so let's not break
> -	 * them by removing it completely
> +	 * them by removing it completely.
> +	 *
> +	 * Skip invalidation for async writes or if mapping has no pages.
>  	 */
> -	if (mapping->nrpages)
> +	if (written > 0 && mapping->nrpages)
>  		invalidate_inode_pages2_range(mapping,
>  					pos >> PAGE_SHIFT, end);
>  
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR