Re: [PATCH 2/3] ceph: Uninline the data on a file opened for writing

From: Matthew Wilcox <willy@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: ceph-devel@vger.kernel.org, jlayton@kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/3] ceph: Uninline the data on a file opened for writing
Date: Mon, 17 Jan 2022 17:50:28 +0000	[thread overview]
Message-ID: <YeWsZDO8U3PU4sdx@casper.infradead.org> (raw)
In-Reply-To: <2883819.1642438775@warthog.procyon.org.uk>

On Mon, Jan 17, 2022 at 04:59:35PM +0000, David Howells wrote:
> Matthew Wilcox <willy@infradead.org> wrote:
> 
> > > +	if (folio_test_uptodate(folio))
> > > +		goto out_put_folio;
> > 
> > Er ... if (!folio_test_uptodate(folio)), perhaps?  And is it even
> > worth testing if read_mapping_folio() returned success?  I feel like
> > we should take ->readpage()'s word for it that success means the
> > folio is now uptodate.
> 
> Actually, no, I shouldn't need to do this since it comes out with the page
> lock still held.

No.  The page is unlocked upon IO completion.  After calling ->readpage,
                folio_wait_locked(folio);