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AJvYcCUC3uq0e1H1w6r7RiXXimaBlZboAttv/sQzmOLAJM7ZfLNy0SlNvW3N/nIT6/xhbnhGw/JwX0Ns4w==@kvack.org X-Gm-Message-State: AOJu0Ywa+isVIhbPdH7mf0vuMNk4GfTgjgLYDc8cDpdQip+ZRbUNt1cC IyKd5sXRsZfMLLev0Oh+oGkRqcdT6PCDuK0yJo3Nd6azV0PYt4S2NGTwKlDtm46tQ6g01thJMjl 8hktVj692w4vhau9dRFyQ62q/J9/xc2Q= X-Gm-Gg: AY/fxX6nnJYfOC0xO7kaTLkDkpUGtcThNrQA+nX5awltlhZPnt3shgD3K+noog9fC7E Q7M56M3BN/3VqLk3hnZTW5IvxQn3EWeiBxWqU/NmJzd6WqIsH2JHOOID9jpW/z+xW6uvoYK/X1l CAvsQUbEVV4lQYKwCczyk130Jh+j4JcF4LF21d/5pdQImsEQZOq5IVPl4X6b1VEMdKVuljzmDC7 yDN+gcOoUCXDkaLOFyu/+eRQ2snXysa04yB7Chf7L+cP4G6ReSfviT13wDuUaVaSg80kY31ZL+L P33fDv3N/Y2QX5WAwQ8Poejg76VMdg== X-Received: by 2002:a05:6402:268e:b0:64b:7231:da3d with SMTP id 4fb4d7f45d1cf-654b955cf01mr167575a12.9.1768506459177; Thu, 15 Jan 2026 11:47:39 -0800 (PST) MIME-Version: 1.0 References: <20260115-exportfs-nfsd-v1-0-8e80160e3c0c@kernel.org> <4d9967cc-a454-46cf-909b-b8ab2d18358d@kernel.org> In-Reply-To: <4d9967cc-a454-46cf-909b-b8ab2d18358d@kernel.org> From: Amir Goldstein Date: Thu, 15 Jan 2026 20:47:27 +0100 X-Gm-Features: AZwV_QhMfL4hQaeUnA-dk4TL1Qjc8lTmxpbV_QcnWyLhkyyZFquuhwL6kPGc4Cw Message-ID: Subject: Re: [PATCH 00/29] fs: require filesystems to explicitly opt-in to nfsd export support To: Chuck Lever Cc: Jeff Layton , Christian Brauner , Alexander Viro , Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Hugh Dickins , Baolin Wang , Andrew Morton , Theodore Tso , Andreas Dilger , Jan Kara , Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Sandeep Dhavale , Hongbo Li , Chunhai Guo , Carlos Maiolino , Ilya Dryomov , Alex Markuze , Viacheslav Dubeyko , Chris Mason , David Sterba , Luis de Bethencourt , Salah Triki , Phillip Lougher , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Bharath SM , Miklos Szeredi , Mike Marshall , Martin Brandenburg , Mark Fasheh , Joel Becker , Joseph Qi , Konstantin Komarov , Ryusuke Konishi , Trond Myklebust , Anna Schumaker , Dave Kleikamp , David Woodhouse , Richard Weinberger , Jan Kara , Andreas Gruenbacher , OGAWA Hirofumi , Jaegeuk Kim , Christoph Hellwig , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-xfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-unionfs@vger.kernel.org, devel@lists.orangefs.org, ocfs2-devel@lists.linux.dev, ntfs3@lists.linux.dev, linux-nilfs@vger.kernel.org, jfs-discussion@lists.sourceforge.net, linux-mtd@lists.infradead.org, gfs2@lists.linux.dev, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: ED1A1180003 X-Stat-Signature: 9dqrg1kkwjze74ka69fqdy7huu84ccq6 X-Rspam-User: X-HE-Tag: 1768506460-990855 X-HE-Meta: U2FsdGVkX19yN01yZuiR3YUiVNlA74Cb4gIbQiP8ZvStAYWQGhlXfSC5ptmRyttiMZrJrPlbuzIoBhj2+HMool5Dbx/dSp8wTcOCrII1b/rYMJU1bCqb1IwkeukAi+du3Kf493YPf3WlcefjyqjCsM1WCkiDhGEpGwkK/E/7a45skst5NKi1oRLg3fGdpZ8GtZy4+34vc2hET5ZzJ+6c29ptyiu09I5T9K5wGHMSIJTGtAOfVuOH4q+zh1EcjmuQW3zAA0MRuj0FXAeMnfhDecuMzBBn6YPFWJKYcMKHLXhIZR/RZrB0BUpuBlOFk6W6M3sD1Qjzrdtb45LrnXg/F+9wi0bL2nGeB2hGSWXzlMtehDQTsAlhSTX1PJyIF3oJNGs1ZGb8AMl1W+xnV5h4j7J1RjV2tFybchIiUlTgMU5Dnv2BuAA4agSHJizMzuWH26kvqfJ+0IZJPNo4naHC/P9SuKmA3rze3V0eafwjj6Sj2W8/L5N4lZ5tUolQCvoZTKMl9UTeAXEiLI5RyJrcic+IlOYDyElb6LEDzk14oVQzUoV0enaLhwOgtZyHZJNLk/2RPSAwfvj9DYXKVH3SpTsJUBJJApbdQmvEh7390+ektJF8/pNB+O3UsLHNTRvBSDB9SgLCOM0xy3B20U/BzE+GzrTuE9ZeHNHUCTpbX4vT2lQt1S3eNKXA6J/8H23KMVqRg6LKb8FMJcKRIgreT1rlZscFvZuHpPGqHnHISrd+PziCd9FM0pvPZPxBIZkVYFKu7V3NrB8Nd1fMd5gpiLd0Y//dHd51orWlbEjgF61LHHexRInJxfJuuv3pLgh+raNyPiEvV8LSz8stl4AoheEucJ0tprt7Yuvsi6eihFIz1wqMYeW/HmBhD52vVXikEjfiUnJIPOBsjKJWmQAfyeuWZappQRrxXdEj65Z1rM7GLru9JahL5bkjAiv6bCIguFai8TiVGa+6n5vzla9 DCA+LLtO 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jan 15, 2026 at 8:37=E2=80=AFPM Chuck Lever wrote: > > On 1/15/26 2:14 PM, Amir Goldstein wrote: > > On Thu, Jan 15, 2026 at 7:32=E2=80=AFPM Chuck Lever wr= ote: > >> > >> > >> > >> On Thu, Jan 15, 2026, at 1:17 PM, Amir Goldstein wrote: > >>> On Thu, Jan 15, 2026 at 6:48=E2=80=AFPM Jeff Layton wrote: > >>>> > >>>> In recent years, a number of filesystems that can't present stable > >>>> filehandles have grown struct export_operations. They've mostly done > >>>> this for local use-cases (enabling open_by_handle_at() and the like)= . > >>>> Unfortunately, having export_operations is generally sufficient to m= ake > >>>> a filesystem be considered exportable via nfsd, but that requires th= at > >>>> the server present stable filehandles. > >>> > >>> Where does the term "stable file handles" come from? and what does it= mean? > >>> Why not "persistent handles", which is described in NFS and SMB specs= ? > >>> > >>> Not to mention that EXPORT_OP_PERSISTENT_HANDLES was Acked > >>> by both Christoph and Christian: > >>> > >>> https://lore.kernel.org/linux-fsdevel/20260115-rundgang-leihgabe-1201= 8e93c00c@brauner/ > >>> > >>> Am I missing anything? > >> > >> PERSISTENT generally implies that the file handle is saved on > >> persistent storage. This is not true of tmpfs. > > > > That's one way of interpreting "persistent". > > Another way is "continuing to exist or occur over a prolonged period." > > which works well for tmpfs that is mounted for a long time. > > I think we can be a lot more precise about the guarantee: The file > handle does not change for the life of the inode it represents. It > has nothing to do with whether the file system is mounted. > > > > But I am confused, because I went looking for where Jeff said that > > you suggested stable file handles and this is what I found that you wro= te: > > > > "tmpfs filehandles align quite well with the traditional definition > > of persistent filehandles. tmpfs filehandles live as long as tmpfs fil= es do, > > and that is all that is required to be considered "persistent". > > I changed my mind about the name, and I let Jeff know that privately > when he asked me to look at these patches this morning. > > > >> The use of "stable" means that the file handle is stable for > >> the life of the file. This /is/ true of tmpfs. > > > > I can live with STABLE_HANDLES I don't mind as much, > > I understand what it means, but the definition above is invented, > > whereas the term persistent handles is well known and well defined. > > Another reason not to adopt the same terminology as NFS is that > someone might come along and implement NFSv4's VOLATILE file > handles in Linux, and then say "OK, /now/ can we export cgroupfs?" > And then Linux will be stuck with overloaded terminology and we'll > still want to say "NO, NFS doesn't support cgroupfs". > > Just a random thought. Good argument. I'm fine with stable as well :) Thanks, Amir.