From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     "Trond Myklebust" <trondmy@hammerspace.com>
Cc:     anna.schumaker@netapp.com, linux-nfs@vger.kernel.org
Subject: Re: [PATCH] NFS: Don't use page_file_mapping after removing the page
Date:   Mon, 04 Feb 2019 14:20:31 -0500
Message-ID: <9857F7D4-FA2E-43D0-8D4B-4C753A81687C@redhat.com>
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On 4 Feb 2019, at 14:07, Benjamin Coddington wrote:

> On 4 Feb 2019, at 14:03, Benjamin Coddington wrote:
>
>> On 4 Feb 2019, at 13:32, Trond Myklebust wrote:
>>
>>> On Mon, 2019-02-04 at 13:13 -0500, Benjamin Coddington wrote:
>>>> If nfs_page_async_flush() removes the page from the mapping, then 
>>>> we
>>>> can't
>>>> use page_file_mapping() on it as nfs_updatepate() is wont to do 
>>>> when
>>>> receiving an error.  Instead, simplify nfs_zap_mapping() to take 
>>>> the
>>>> inode.
>>>>
>>>
>>> Won't this break NFS swap?
>>
>> I guess it may, but then I wonder: is that a thing that anyone does?  
>> It
>> sounds like a terrible idea..
>>
>> I'm curious enough though, and doing some research on it.
>
> There's enough to commits in the tree fixing problem or supporting 
> swap on
> NFS, so I suppose I've just missed all that.

So for diskless systems, ah.  It makes sense.

But does it make any sense to set NFS_INO_INVALID_DATA on a swap file?  
Does anyone share them?

Dazed and confused, but trying to continue..

Ben