Date: Mon, 08 Sep 2014 11:55:13 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Richard Yao <ryao@gentoo.org>, Rick Macklem <rmacklem@uoguelph.ca>, Lionel Cons <lionelcons1972@gmail.com>, Jan Bramkamp <crest@rlwinm.de> Subject: Re: Tool to access ZFS/NFSv4 alternate data streams on FreeBSD? Message-ID: <2154953.PmiECqQQIi@ralph.baldwin.cx> In-Reply-To: <1538621043.33014113.1409955190712.JavaMail.root@uoguelph.ca> References: <1538621043.33014113.1409955190712.JavaMail.root@uoguelph.ca>
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On Friday, September 05, 2014 06:13:10 PM Rick Macklem wrote: > Lionel Cons wrote: > > On 5 September 2014 19:26, Richard Yao <ryao@gentoo.org> wrote: > > > On 09/05/2014 11:35 AM, Jan Bramkamp wrote: > > >> On 05.09.2014 16:25, Lionel Cons wrote:> Is there any tool which > > >> can be > > >> used to access ZFS and NFSv4 alternate > > >> > > >>> data streams on FreeBSD? > > >> > > >> Are you looking for lsextattr(8) and getextattr(8)? > > >> _______________________________________________ > > >> freebsd-hackers@freebsd.org mailing list > > >> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > >> To unsubscribe, send any mail to > > >> "freebsd-hackers-unsubscribe@freebsd.org" > > > > > > Do you mean Solaris extended attributes? Those tend to be called > > > resource forks on other platforms. Unifying extended attributes and > > > resource forks was clever. > > > > Yes, they are also called resource forks, or alternate data streams. > > The attribute files which can be accessed via O_XATTR or cd -@ > > file/dir on newer ksh/ksh93/bash revisions. > > For FreeBSD's NFSv4 the answer is definitely no. Because the Linux/FreeBSD > style setextattr() assumes an atomic replacement of the extended attribute, > it is not semantically compatible (ie. cannot be accurately emulated) by > resource forks. > > I do not know of any work for ZFS on FreeBSD w.r.t. this, but I'm not a > ZFS guy. Does the NFSv4 protocol support resource forks as a separate entity from EAs though? Presumably O_XATTR would turn into a new VOP (VOP_OPENFORK() or some such), it wouldn't be shoehorned into the EA APIs. -- John Baldwin
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