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Date:   Fri, 17 Dec 2021 16:20:00 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     David Howells <dhowells@redhat.com>
Cc:     jlayton@kernel.org, ceph-devel@vger.kernel.org, idryomov@gmail.com,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] ceph: Uninline the data on a file opened for
 writing
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On Fri, Dec 17, 2021 at 03:29:45PM +0000, David Howells wrote:
> If a ceph file is made up of inline data, uninline that in the ceph_open()
> rather than in ceph_page_mkwrite(), ceph_write_iter(), ceph_fallocate() or
> ceph_write_begin().

I don't think this is the right approach.  Just opening a file with
O_RDWR shouldn't take it out of inline mode; an actual write (or fault)
should be required to uninline it.

> This makes it easier to convert to using the netfs library for VM write
> hooks.

I don't understand.  You're talking about the fault path?  Surely
the filesystem gets called with the vm_fault parameter only, then
calls into the netfs code, passing vmf and the operations struct?
And ceph could uninline there.