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From:   David Howells <dhowells@redhat.com>
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To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     dhowells@redhat.com, Steve French <stfrench@microsoft.com>,
        Vishal Moola <vishal.moola@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jan Kara <jack@suse.cz>, Paulo Alcantara <pc@cjr.nz>,
        Matthew Wilcox <willy@infradead.org>,
        Huang Ying <ying.huang@intel.com>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        Xin Hao <xhao@linux.alibaba.com>, linux-mm@kvack.org,
        mm-commits@vger.kernel.org, linux-cifs@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] cifs: Improve use of filemap_get_folios_tag()
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Date:   Fri, 24 Feb 2023 17:22:57 +0000
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Linus Torvalds <torvalds@linux-foundation.org> wrote:

> Of course, I'd be even happier if Willy is right and the code could
> use the generic write_cache_pages() and avoid all of these things
> entirely. I'm not clear on why cifs and afs are being so different in
> the first place, and some of the differences are just odd (like that
> skip count).

The main reason is that write_cache_pages() doesn't (and can't) check
PG_fscache (btrfs uses PG_private_2 for other purposes).  NFS, 9p and ceph,
for the moment, don't cache files that are open for writing, but I'm intending
to change that at some point.  The intention is to unify the writepages code
for at least 9p, afs, ceph and cifs in netfslib in the future.

David