linux-ext4 - Re: [PATCH 0/3] Make block_page_mkwrite() handle frozen fs (V2)

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Date:	Thu, 19 May 2011 09:34:52 -0700
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
	Al Viro <viro@...IV.linux.org.uk>, tytso@....edu,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 0/3] Make block_page_mkwrite() handle frozen fs (V2)

On Thu, May 19, 2011 at 02:30:29PM +0200, Jan Kara wrote:
> On Wed 18-05-11 11:00:22, Darrick J. Wong wrote:
> > On Wed, May 18, 2011 at 05:17:59PM +0200, Jan Kara wrote:
> > > 
> > >   Hi,
> > > 
> > >   this is a second version of my patches which rewrite ext4_page_mkwrite() to
> > > use generic helper. When we are already changing this code, I also added proper
> > > handling of frozen filesystem there in patch 2/3. I've incorporated suggestions
> > > from Christoph in the patches which resulted in some patch reorg. I'd like to
> > > get these patches reviewed and then get them merged possibly via ext4-tree
> > > (although the first two patches might go via Al but that would complicate
> > > merging of ext4 part where I expect more conflicts with ongoing work).
> > 
> > Do you want me to generate a patch to add wait_on_page_writeback to the
> > appropriate place(s) in your new *_page_mkwrite functions, or do you plan to
> > add them yourself?
> > 
> > (iow: is there an order for pushing these ext4_page_mkwrite changes?)
>   Attached is a rebase of your block_page_mkwrite change on top of my
> patches. I'm not sure what is the actual status your series - have you
> pushed VFS changes to Al?

Yes, the previous set of patches was sent to Al.  I guess I should resend
without the parts that have gone upstream or aren't really needed.

--D
> 
> 									Honza

> From 408d0a667ebdc7edd24d05c8de4b42cc1629e84f Mon Sep 17 00:00:00 2001
> From: Darrick J. Wong <djwong@...ibm.com>
> Date: Thu, 19 May 2011 14:14:11 +0200
> Subject: [PATCH] vfs: Wait in __block_page_mkwrite for IO to finish
> 
> For filesystems such as nilfs2 and xfs that use block_page_mkwrite, modify that
> function to wait for pending writeback before allowing the page to become
> writable. This is needed to stabilize pages during writeback for those two
> filesystems.
> 
> Signed-off-by: Darrick J. Wong <djwong@...ibm.com>
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
>  fs/buffer.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index b0675bf..161685d 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2365,6 +2365,8 @@ int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
> 
>  	if (unlikely(ret < 0))
>  		goto out_unlock;
> +	/* Wait so that we don't change page under IO */
> +	wait_on_page_writeback(page);
>  	/*
>  	 * Freezing in progress? We check after the page is marked dirty and
>  	 * with page lock held so if the test here fails, we are sure freezing
> -- 
> 1.7.1
> 

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