From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Weinberger Subject: Re: [PATCH] hostfs: Use noop_fsync for directories Date: Wed, 14 Jan 2015 09:43:53 +0100 Message-ID: <54B62C49.7030309@nod.at> References: <1421187358-32600-1-git-send-email-richard@nod.at> <20150113221958.GA27739@infradead.org> <54B59B9E.4000806@nod.at> <20150114083951.GA29714@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: user-mode-linux-devel@lists.sourceforge.net, dxld@darkboxed.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org To: Christoph Hellwig Return-path: In-Reply-To: <20150114083951.GA29714@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Am 14.01.2015 um 09:39 schrieb Christoph Hellwig: > On Tue, Jan 13, 2015 at 11:26:38PM +0100, Richard Weinberger wrote: >> hostfs tries do reduce the amount of syscall between guest and host as much >> as possible. For file operations it passes everything down to the host but >> for directory operations only ->iterate() does. >> >> It is already horrible slow, if we add an ->open() for directory too it would >> get even more slower. :-( > > This sounds fairlt dangerous. At least add some good documentation > explaining these semantics. Understood. Maybe it is time to rebenchmark hostfs with full directory pass-through support. Daniel, are you interested in a small kernel project? As explained on IRC adding real support for directory fsync() should be an easy task. The only interesting point is how much overhead it will add. Thanks, //richard