From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="URJSr+uj" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 816B01BC for ; Mon, 11 Dec 2023 16:25:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702340721; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dE/L1p12DsePAH1U47j78HD42kv4ryjF7faWGJKyav8=; b=URJSr+ujGLBsiZYpb5/pXuzjz4KXCKQ43ROgTf1bcTS3jzMTuG5M21B/5cygS1i156oNjP o/2Katik25O0GzPt054CzzqbGAO0oyXLkR78NsrTKEmbdfxUtKh8J15ZBdmpzg+vuGFNHe PIqqlrFYC/5yvP+szsuATBNnPEnwTzg= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-653-IyPzwy6NPZCIMC-8vAs2WQ-1; Mon, 11 Dec 2023 19:25:18 -0500 X-MC-Unique: IyPzwy6NPZCIMC-8vAs2WQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CCCCA83BA86; Tue, 12 Dec 2023 00:25:17 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id ABE2C3C25; Tue, 12 Dec 2023 00:25:16 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <170233878712.12910.112528191448334241@noble.neil.brown.name> References: <170233878712.12910.112528191448334241@noble.neil.brown.name> <12f711f9-70a2-408e-8588-2839e599b668@molgen.mpg.de>, <170181366042.7109.5045075782421670339@noble.neil.brown.name>, <97375d00-4bf7-4c4f-96ec-47f4078abb3d@molgen.mpg.de>, <170199821328.12910.289120389882559143@noble.neil.brown.name>, <20231208013739.frhvlisxut6hexnd@moria.home.lan>, <170200162890.12910.9667703050904306180@noble.neil.brown.name>, <20231208024919.yjmyasgc76gxjnda@moria.home.lan>, <630fcb48-1e1e-43df-8b27-a396a06c9f37@molgen.mpg.de>, <20231208200247.we3zrwmnkwy5ibbz@moria.home.lan>, <170233460764.12910.276163802059260666@noble.neil.brown.name>, <20231211233231.oiazgkqs7yahruuw@moria.home.lan> To: "NeilBrown" Cc: dhowells@redhat.com, "Kent Overstreet" , "Donald Buczek" , linux-bcachefs@vger.kernel.org, "Stefan Krueger" , linux-fsdevel@vger.kernel.org, jaltman@auristor.com Subject: Re: file handle in statx (was: Re: How to cope with subvolumes and snapshots on muti-user systems?) Precedence: bulk X-Mailing-List: linux-bcachefs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2801136.1702340715.1@warthog.procyon.org.uk> Date: Tue, 12 Dec 2023 00:25:15 +0000 Message-ID: <2801137.1702340715@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 NeilBrown wrote: > I'm not in favour of any filesystem depending on this for correct > functionality today. As long as the filesystem isn't so large that > inum+volnum simply cannot fit in 64 bits, we should make a reasonable > effort to present them both in 64 bits. The Auristor version of AFS (which is supported by the in-kernel afs filesystem) has a file handle (FID) that consists of a 64-bit volume ID (which is arguably a superblock-level thing), a 96-bit vnode ID (equivalent to the inode number) and a 32-bit uniquifier. I don't think the capacity of these values is fully utilised by the server... yet, but I can't support them correctly with the UAPI that we have. Allowing some expansion of stx_ino and/or replacing that with an stx_fid would be helpful in that regard. That said, getting userspace to be able to handle this is I think going to be a large undertaking with lots of auditing required. David