From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id AC4D47F3F for ; Tue, 10 Nov 2015 13:17:52 -0600 (CST) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 9D8F0304032 for ; Tue, 10 Nov 2015 11:17:49 -0800 (PST) Received: from fieldses.org (fieldses.org [173.255.197.46]) by cuda.sgi.com with ESMTP id SlYCD3la5JJL1XH6 for ; Tue, 10 Nov 2015 11:17:46 -0800 (PST) Date: Tue, 10 Nov 2015 14:17:45 -0500 From: "J. Bruce Fields" Subject: Re: [PATCH v15 00/22] Richacls (Core and Ext4) Message-ID: <20151110191745.GA19379@fieldses.org> References: <1447067343-31479-1-git-send-email-agruenba@redhat.com> <20151110112943.GA17038@infradead.org> <20151110170703.GB17530@fieldses.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Andreas Gruenbacher Cc: "linux-cifs@vger.kernel.org" , Linux NFS Mailing List , Theodore Ts'o , Linux API , Trond Myklebust , LKML , XFS Developers , Christoph Hellwig , Steve French , Andreas Dilger , Alexander Viro , linux-fsdevel , Jeff Layton , linux-ext4 , Anna Schumaker On Tue, Nov 10, 2015 at 06:58:19PM +0100, Andreas Gruenbacher wrote: > On Tue, Nov 10, 2015 at 6:07 PM, J. Bruce Fields wrote: > > On Tue, Nov 10, 2015 at 10:43:46AM -0600, Steve French wrote: > >> I don't have strong disagreement with using pseudo-xattrs to > >> store/retrieve ACLs (we already do this) but retrieving/setting an ACL > >> all at once can be awkward when ACLs are quite large e.g. when it > >> encodes to over 1MB > > > > At least in the NFS case, that's also a limitation of the protocol. > > I couldn't find a limit in the NFSv4 specification, but the client and > server implementations both define arbitrary ACL size limits. In > addition, the xattr syscalls allow attributes to be up to 64k long. I don't recall 4.0 specifying any limit, 4.1 does include negotiation of maximum rpc calls and replies, and that effectively limits ACL sizes since they have to fit in a single rpc. > The bigger problem would be incrementally setting ACLs. To prevent > processes from racing with each other, we would need a locking > mechanism. In addition, the memory overhead would be prohibitive and > access decisions would become extremely slow; we would have to come up > with mechanisms to avoid those problems. Right. Anyway, not worth the trouble, I think. (Though what might be worth thinking about at some point is just making sure we fail in helpful ways.) --b. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs