From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp02-ext3.udag.de (smtp02-ext3.udag.de [62.146.106.33]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5177437A490; Fri, 27 Feb 2026 11:37:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.146.106.33 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772192277; cv=none; b=tWve86MUOrkb8zlC/We3eihFzkW+AVMb2yrIujRmkcPhUaOPKSR7tFC5FDhdmEbNkcvQk8Ea6km2r8tHIHxT0M/uO9v0tQfk8HONm3EPJkAkQsOD2zwHSZ/zzg38YELi8DHCkRZif5MVJajl/UbL6+f7O4WLQ1qG9tmE/pX0TvY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772192277; c=relaxed/simple; bh=4dQLacNTmqo95rbQ0DgIh1Ww0hVfKTNLacN4JHuSpmA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uqqfDpWeOnB+pAwvrZNFbLuK4U+pwqwYtz2qCMts04bXfZCSHHpjlX3Nj0pDRiuyVhtsgwfljAoT5z6LdZVSwYjYSA99yN9hmLC9rdiwM7DqvytPBN6IfqtozBfAKP/zqsjwHRPxdAfavUdaMQAvIi4/BuQCOKwXM3ZvZUr4tJI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=birthelmer.de; spf=pass smtp.mailfrom=birthelmer.de; arc=none smtp.client-ip=62.146.106.33 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=birthelmer.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=birthelmer.de Received: from localhost (200-143-067-156.ip-addr.inexio.net [156.67.143.200]) by smtp02-ext3.udag.de (Postfix) with ESMTPA id 08BBFE02E5; Fri, 27 Feb 2026 12:37:52 +0100 (CET) Authentication-Results: smtp02-ext3.udag.de; auth=pass smtp.auth=birthelmercom-0001 smtp.mailfrom=horst@birthelmer.de Date: Fri, 27 Feb 2026 12:37:52 +0100 From: Horst Birthelmer To: Miklos Szeredi Cc: Horst Birthelmer , Bernd Schubert , Joanne Koong , Luis Henriques , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Horst Birthelmer Subject: Re: Re: Re: [PATCH v6 1/3] fuse: add compound command to combine multiple requests Message-ID: References: <20260226-fuse-compounds-upstream-v6-0-8585c5fcd2fc@ddn.com> <20260226-fuse-compounds-upstream-v6-1-8585c5fcd2fc@ddn.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Feb 27, 2026 at 12:29:00PM +0100, Miklos Szeredi wrote: > On Fri, 27 Feb 2026 at 11:48, Horst Birthelmer wrote: > > > > FUSE_SUB_IS_ENTRY - this sub request will return a new entry on > > > success (nodeid, filehandle) > > > FUSE_SUB_DEP_ENTRY - this sub request depends on the result of a previous lookup > > > > > > > we don't need this if we use my converters from above. > > Dependencies need to be handled by the kernel and libfuse as well. > Makes no sense to have two separate mechanisms for handling > dependencies, so the kernel should use the same flags. > OK, got it. > > Could you maybe provide some examples of usecases, that I should try to drill the > > new logic? > > - LOOKUP + GETATTR[L] > - MKOBJ + (SETXATTR[L] (only for posix_acl inheritance)) + GETATTR[L] > + (OPEN[L] (optional) > - SETATTR + SETXATTR (setting posix_acl that modifies mode or setting > mode on file with posix_acl) > - INIT + LOOKUP_ROOT + GETATTR[L] > - OPEN + IOCTL[O] + RELEASE[O] (fileattr_get/set) > > Only two dependencies here: lookup or open. Both are simple in terms > of just needing to copy a field from a previous request to the current > one with fixed positions in all of the above cases. > > The LOOKUP + MKNOD one *is* more complicated, because it makes > execution of the MKNOD dependent on the result of the LOOKUP, so the > dependency handler needs to look inside the result and decide how to > proceed based on that. Some pros and cons of both approaches, so I'm > curious to see how yours looks like. > I really am greateful for this list. Helps me a lot, since I was looking at this from the perspective of the fuse server, which truns out to be different. > > I have used compounds to send groups of semantically linked requests to the fuse server > > signalling to it if the kernel expects it to be one atomic operation or a preferred > > 'group' of requests (like open+getattr, nothing happens if those are not processed atomic > > in a distributed file system) > > Which is the case where the kernel expects them to be atomic? > I naively thought that fuse_atomic_open() was actually there to do an atomic open ... ;-) > Thanks, > Miklos > Thanks, Horst