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Subject: Re: [PATCH UPDATED] fs/buffer.c: call __block_write_begin() if we
 have page
From: Namhyung Kim <namhyung@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
In-Reply-To: <20101025161137.5f0b642d.akpm@linux-foundation.org>
References: <1287848786-13347-1-git-send-email-namhyung@gmail.com>
	 <1287850314-13663-1-git-send-email-namhyung@gmail.com>
	 <20101025161137.5f0b642d.akpm@linux-foundation.org>
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Date: Tue, 26 Oct 2010 17:06:34 +0900
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2010-10-25 (월), 16:11 -0700, Andrew Morton:
> On Sun, 24 Oct 2010 01:11:54 +0900
> Namhyung Kim <namhyung@gmail.com> wrote:
> 
> > If we have the appropriate page already, call __block_write_begin()
> > directly instead of releasing and regrabbing it inside of
> > block_write_begin().
> > 
> > Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> > ---
> > Fix error path.
> > 
> >  fs/buffer.c |   12 +++++++-----
> >  1 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/fs/buffer.c b/fs/buffer.c
> > index 7f0b9b0..f5755f7 100644
> > --- a/fs/buffer.c
> > +++ b/fs/buffer.c
> > @@ -2466,11 +2466,13 @@ int nobh_write_begin(struct address_space *mapping,
> >  	*fsdata = NULL;
> >  
> >  	if (page_has_buffers(page)) {
> > -		unlock_page(page);
> > -		page_cache_release(page);
> > -		*pagep = NULL;
> > -		return block_write_begin(mapping, pos, len, flags, pagep,
> > -					 get_block);
> > +		ret = __block_write_begin(page, pos, len, get_block);
> > +		if (unlikely(ret)) {
> > +			unlock_page(page);
> > +			page_cache_release(page);
> > +			*pagep = NULL;
> > +		}
> > +		return ret;
> >  	}
> >  
> >  	if (PageMappedToDisk(page))
> 
> It looks OK.  Was it tested?  (ext2 mounted with -o nobh)

I just did tar && untar with current kernel source several times on UML.
It worked find for me. Thanks.


-- 
Regards,
Namhyung Kim