[PATCH 4/5] xfs: use GFP_NOFS for page cache allocation

[Christoph Hellwig]

On Thu, Jul 15, 2010 at 10:38:19AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> Avoid a lockdep warning by preventing page cache allocation from
> recursing back into the filesystem during memory reclaim.

Yeah, I already have this in my queue too.  Noticed that we don't
need it because of i_mutex as suggested in the stack overflow thread,
but for the XFS ilock.

> @@ -1501,8 +1501,9 @@ xfs_vm_write_begin(
>  	void			**fsdata)
>  {
>  	*pagep = NULL;
> -	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
> -								xfs_get_blocks);
> +	return block_write_begin(file, mapping, pos, len,
> +				 (flags | AOP_FLAG_NOFS),
> +				 pagep, fsdata, xfs_get_blocks);


No need for the bracing:

	return block_write_begin(file, mapping, pos, len, flags | AOP_FLAG_NOFS,
				 pagep, fsdata, xfs_get_blocks);


And with my truncate rework in the vfs tree we'll get rejection galore in
linux-next, but Stephen has been pretty good at handling these..

Reviewed-by: Christoph Hellwig <hch at lst.de>