linux-kernel - Re: [PATCH] fs/ceph: use release

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Date:   Fri, 09 Aug 2019 07:24:59 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     john.hubbard@...il.com
Cc:     LKML <linux-kernel@...r.kernel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Sage Weil <sage@...hat.com>, Ilya Dryomov <idryomov@...il.com>,
        ceph-devel@...r.kernel.org
Subject: Re: [PATCH] fs/ceph: use release_pages() directly

On Thu, 2019-08-08 at 20:56 -0700, john.hubbard@...il.com wrote:
> From: John Hubbard <jhubbard@...dia.com>
> 
> release_pages() has been available to modules since Oct, 2010,
> when commit 0be8557bcd34 ("fuse: use release_pages()") added
> EXPORT_SYMBOL(release_pages). However, this ceph code was still
> using a workaround.
> 
> Remove the workaround, and call release_pages() directly.
> 
> Cc: Jeff Layton <jlayton@...nel.org>
> Cc: Sage Weil <sage@...hat.com>
> Cc: Ilya Dryomov <idryomov@...il.com>
> Cc: ceph-devel@...r.kernel.org
> Signed-off-by: John Hubbard <jhubbard@...dia.com>
> ---
> 
> Hi,
> 
> I noticed this while I trying to understand mlock.c's use of
> pagevec_release(). So I was looking around for examples, and stumbled
> across this, which seems worth cleaning up.
> 
> thanks,
> John Hubbard
> NVIDIA
> 
>  fs/ceph/addr.c | 19 +------------------
>  1 file changed, 1 insertion(+), 18 deletions(-)
> 
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index e078cc55b989..22ed45d143be 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -679,23 +679,6 @@ static int ceph_writepage(struct page *page, struct writeback_control *wbc)
>  	return err;
>  }
>  
> -/*
> - * lame release_pages helper.  release_pages() isn't exported to
> - * modules.
> - */
> -static void ceph_release_pages(struct page **pages, int num)
> -{
> -	struct pagevec pvec;
> -	int i;
> -
> -	pagevec_init(&pvec);
> -	for (i = 0; i < num; i++) {
> -		if (pagevec_add(&pvec, pages[i]) == 0)
> -			pagevec_release(&pvec);
> -	}
> -	pagevec_release(&pvec);
> -}
> -
>  /*
>   * async writeback completion handler.
>   *
> @@ -769,7 +752,7 @@ static void writepages_finish(struct ceph_osd_request *req)
>  		dout("writepages_finish %p wrote %llu bytes cleaned %d pages\n",
>  		     inode, osd_data->length, rc >= 0 ? num_pages : 0);
>  
> -		ceph_release_pages(osd_data->pages, num_pages);
> +		release_pages(osd_data->pages, num_pages);
>  	}
>  
>  	ceph_put_wrbuffer_cap_refs(ci, total_pages, snapc);

Thanks John. Running tests on it now, and will probably push to our
testing branch later today. It should make v5.4.

-- 
Jeff Layton <jlayton@...nel.org>