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Subject: Re: [PATCH] VM: Fix the gfp_mask in invalidate_complete_page2
From: Trond Myklebust <Trond.Myklebust@netapp.com>
To: David Howells <dhowells@redhat.com>
Cc: Andrew Morton <akpm@osdl.org>, Steve Dickson <SteveD@redhat.com>,
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Date: Tue, 10 Oct 2006 09:15:19 -0400
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On Tue, 2006-10-10 at 13:49 +0100, David Howells wrote:
> Trond Myklebust <Trond.Myklebust@netapp.com> wrote:
> 
> > No. Invalidatepage does precisely the wrong thing: it invalidates dirty
> > data instead of committing it to disk. If you need to have the data
> > invalidated, then you should call truncate_inode_pages().
> 
> Hmmm... Good point, but you still need to handle try_to_release_page() failing,
> but that only means checking the return value of invalidate_inode_pages2_range
> (which you don't do, I notice).  Or is it defined that if must succeed if
> __GFP_WAIT is set?

The only way for it to fail if __GFP_IO is set, is if someone kills the
process.
Note that since the NFS client itself will flush out all dirty data to
disk prior to calling invalidate_inode_pages2, the only thing we're
trying to do here is to avoid races while invalidating those pages.

> With the two-phase thing, I think I'm thinking of the wrong portion of that
> file (I'm thinking of truncate_inode_pages_range()).
> 
> Should invalidate_inode_pages2_range() take a gfp_t argument to pass on down?

Maybe. Do any of the current callers care? NFS should be quite happy
with the patch that is currently in Andrew's tree.

  Trond