linux-kernel - Re: [PATCH 4/7] Use vfs __set_page_dirty interface instead of doing it inside filesystem

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Date:	Wed, 4 Jul 2012 16:27:24 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Sha Zhengju <handai.szj@...il.com>
Cc:	linux-mm@...ck.org, cgroups@...r.kernel.org,
	kamezawa.hiroyu@...fujitsu.com, gthelen@...gle.com,
	yinghan@...gle.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
	sage@...dream.net, ceph-devel@...r.kernel.org,
	Sha Zhengju <handai.szj@...bao.com>
Subject: Re: [PATCH 4/7] Use vfs __set_page_dirty interface instead of doing
 it inside filesystem

On Thu 28-06-12 19:03:43, Sha Zhengju wrote:
> From: Sha Zhengju <handai.szj@...bao.com>
> 
> Following we will treat SetPageDirty and dirty page accounting as an integrated
> operation. Filesystems had better use vfs interface directly to avoid those details.
> 
> Signed-off-by: Sha Zhengju <handai.szj@...bao.com>
> ---
>  fs/buffer.c                 |    2 +-
>  fs/ceph/addr.c              |   20 ++------------------
>  include/linux/buffer_head.h |    2 ++
>  3 files changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index e8d96b8..55522dd 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -610,7 +610,7 @@ EXPORT_SYMBOL(mark_buffer_dirty_inode);
>   * If warn is true, then emit a warning if the page is not uptodate and has
>   * not been truncated.
>   */
> -static int __set_page_dirty(struct page *page,
> +int __set_page_dirty(struct page *page,
>  		struct address_space *mapping, int warn)
>  {
>  	if (unlikely(!mapping))
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index 8b67304..d028fbe 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -5,6 +5,7 @@
>  #include <linux/mm.h>
>  #include <linux/pagemap.h>
>  #include <linux/writeback.h>	/* generic_writepages */
> +#include <linux/buffer_head.h>
>  #include <linux/slab.h>
>  #include <linux/pagevec.h>
>  #include <linux/task_io_accounting_ops.h>
> @@ -73,14 +74,8 @@ static int ceph_set_page_dirty(struct page *page)
>  	int undo = 0;
>  	struct ceph_snap_context *snapc;
>  
> -	if (unlikely(!mapping))
> -		return !TestSetPageDirty(page);
> -
> -	if (TestSetPageDirty(page)) {
> -		dout("%p set_page_dirty %p idx %lu -- already dirty\n",
> -		     mapping->host, page, page->index);

I am not familiar with the code but this looks we loose an information
about something bad(?) is going on?

> +	if (!__set_page_dirty(page, mapping, 1))
>  		return 0;
> -	}
>  
>  	inode = mapping->host;
>  	ci = ceph_inode(inode);
-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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