linux-kernel - Re: [PATCH v2 1/4] mm: consolidate dax / non-dax checks for writeback

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Date:   Thu, 27 Jul 2017 10:43:41 +0200
From:   Jan Kara <jack@...e.cz>
To:     Jeff Layton <jlayton@...nel.org>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
        "J . Bruce Fields" <bfields@...ldses.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Matthew Wilcox <willy@...radead.org>,
        Bob Peterson <rpeterso@...hat.com>,
        Steven Whitehouse <swhiteho@...hat.com>,
        cluster-devel@...hat.com
Subject: Re: [PATCH v2 1/4] mm: consolidate dax / non-dax checks for writeback

On Wed 26-07-17 13:55:35, Jeff Layton wrote:
> From: Jeff Layton <jlayton@...hat.com>
> 
> We have this complex conditional copied to several places. Turn it into
> a helper function.
> 
> Signed-off-by: Jeff Layton <jlayton@...hat.com>

Looks good. You can add:

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

								Honza

> ---
>  mm/filemap.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index e1cca770688f..72e46e6f0d9a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -522,12 +522,17 @@ int filemap_fdatawait(struct address_space *mapping)
>  }
>  EXPORT_SYMBOL(filemap_fdatawait);
>  
> +static bool mapping_needs_writeback(struct address_space *mapping)
> +{
> +	return (!dax_mapping(mapping) && mapping->nrpages) ||
> +	    (dax_mapping(mapping) && mapping->nrexceptional);
> +}
> +
>  int filemap_write_and_wait(struct address_space *mapping)
>  {
>  	int err = 0;
>  
> -	if ((!dax_mapping(mapping) && mapping->nrpages) ||
> -	    (dax_mapping(mapping) && mapping->nrexceptional)) {
> +	if (mapping_needs_writeback(mapping)) {
>  		err = filemap_fdatawrite(mapping);
>  		/*
>  		 * Even if the above returned error, the pages may be
> @@ -566,8 +571,7 @@ int filemap_write_and_wait_range(struct address_space *mapping,
>  {
>  	int err = 0;
>  
> -	if ((!dax_mapping(mapping) && mapping->nrpages) ||
> -	    (dax_mapping(mapping) && mapping->nrexceptional)) {
> +	if (mapping_needs_writeback(mapping)) {
>  		err = __filemap_fdatawrite_range(mapping, lstart, lend,
>  						 WB_SYNC_ALL);
>  		/* See comment of filemap_write_and_wait() */
> @@ -656,8 +660,7 @@ int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
>  	int err = 0, err2;
>  	struct address_space *mapping = file->f_mapping;
>  
> -	if ((!dax_mapping(mapping) && mapping->nrpages) ||
> -	    (dax_mapping(mapping) && mapping->nrexceptional)) {
> +	if (mapping_needs_writeback(mapping)) {
>  		err = __filemap_fdatawrite_range(mapping, lstart, lend,
>  						 WB_SYNC_ALL);
>  		/* See comment of filemap_write_and_wait() */
> -- 
> 2.13.3
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR