Re: [PATCH] ceph: don't implement writepage

["Luís Henriques" <lhenriques@suse.de>]

Jeff Layton <jlayton@kernel.org> writes:

> Remove ceph_writepage as it's not strictly required these days.
>
> To quote from commit 21b4ee7029c9 (xfs: drop ->writepage completely):
>
>     ->writepage is only used in one place - single page writeback from
>     memory reclaim. We only allow such writeback from kswapd, not from
>     direct memory reclaim, and so it is rarely used. When it comes from
>     kswapd, it is effectively random dirty page shoot-down, which is
>     horrible for IO patterns. We will already have background writeback
>     trying to clean all the dirty pages in memory as efficiently as
>     possible, so having kswapd interrupt our well formed IO stream only
>     slows things down. So get rid of xfs_vm_writepage() completely.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/ceph/addr.c | 25 -------------------------
>  1 file changed, 25 deletions(-)

The diffstat in particular looks great ;-)

Reviewed-by: Luís Henriques <lhenriques@suse.de>

Cheers
-- 
Luís


>
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index 40830cb9b599..3489444c55b9 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -680,30 +680,6 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
>  	return err;
>  }
>  
> -static int ceph_writepage(struct page *page, struct writeback_control *wbc)
> -{
> -	int err;
> -	struct inode *inode = page->mapping->host;
> -	BUG_ON(!inode);
> -	ihold(inode);
> -
> -	if (wbc->sync_mode == WB_SYNC_NONE &&
> -	    ceph_inode_to_client(inode)->write_congested)
> -		return AOP_WRITEPAGE_ACTIVATE;
> -
> -	wait_on_page_fscache(page);
> -
> -	err = writepage_nounlock(page, wbc);
> -	if (err == -ERESTARTSYS) {
> -		/* direct memory reclaimer was killed by SIGKILL. return 0
> -		 * to prevent caller from setting mapping/page error */
> -		err = 0;
> -	}
> -	unlock_page(page);
> -	iput(inode);
> -	return err;
> -}
> -
>  /*
>   * async writeback completion handler.
>   *
> @@ -1394,7 +1370,6 @@ static int ceph_write_end(struct file *file, struct address_space *mapping,
>  const struct address_space_operations ceph_aops = {
>  	.readpage = netfs_readpage,
>  	.readahead = netfs_readahead,
> -	.writepage = ceph_writepage,
>  	.writepages = ceph_writepages_start,
>  	.write_begin = ceph_write_begin,
>  	.write_end = ceph_write_end,
> -- 
>
> 2.36.1
>