linux-kernel - Re: [PATCH 1/2] netfs: release the folio lock and put the folio before retrying

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Message-ID: <2187946.1657027284@warthog.procyon.org.uk>
Date:   Tue, 05 Jul 2022 14:21:24 +0100
From:   David Howells <dhowells@...hat.com>
To:     Jeff Layton <jlayton@...nel.org>
Cc:     dhowells@...hat.com, xiubli@...hat.com, idryomov@...il.com,
        vshankar@...hat.com, linux-kernel@...r.kernel.org,
        ceph-devel@...r.kernel.org, willy@...radead.org,
        keescook@...omium.org, linux-fsdevel@...r.kernel.org,
        linux-cachefs@...hat.com
Subject: Re: [PATCH 1/2] netfs: release the folio lock and put the folio before retrying

Jeff Layton <jlayton@...nel.org> wrote:

> I don't know here... I think it might be better to just expect that when
> this function returns an error that the folio has already been unlocked.
> Doing it this way will mean that you will lock and unlock the folio a
> second time for no reason.

I seem to remember there was some reason you wanted the folio unlocking and
putting.  I guess you need to drop the ref to flush it.

Would it make sense for ->check_write_begin() to be passed a "struct folio
**folio" rather than "struct folio *folio" and then the filesystem can clear
*folio if it disposes of the page?

David