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[49.181.47.239]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-70ead8af074sm7303132b3a.218.2024.07.29.16.08.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jul 2024 16:08:07 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1sYZTJ-00G40t-0V; Tue, 30 Jul 2024 09:08:05 +1000 Date: Tue, 30 Jul 2024 09:08:05 +1000 From: Dave Chinner To: Florian Weimer Cc: Mateusz Guzik , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Dave Chinner Subject: Re: Testing if two open descriptors refer to the same inode Message-ID: References: <874j88sn4d.fsf@oldenburg.str.redhat.com> <875xsoqy58.fsf@oldenburg.str.redhat.com> <87sevspit1.fsf@oldenburg.str.redhat.com> Precedence: bulk X-Mailing-List: linux-api@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: <87sevspit1.fsf@oldenburg.str.redhat.com> On Mon, Jul 29, 2024 at 12:57:14PM +0200, Florian Weimer wrote: > * Mateusz Guzik: > > > On Mon, Jul 29, 2024 at 12:40:35PM +0200, Florian Weimer wrote: > >> * Mateusz Guzik: > >> > >> > On Mon, Jul 29, 2024 at 08:55:46AM +0200, Florian Weimer wrote: > >> >> It was pointed out to me that inode numbers on Linux are no longer > >> >> expected to be unique per file system, even for local file systems. > >> > > >> > I don't know if I'm parsing this correctly. > >> > > >> > Are you claiming on-disk inode numbers are not guaranteed unique per > >> > filesystem? It sounds like utter breakage, with capital 'f'. > >> > >> Yes, POSIX semantics and traditional Linux semantics for POSIX-like > >> local file systems are different. > > > > Can you link me some threads about this? > > Sorry, it was an internal thread. It's supposed to be common knowledge > among Linux file system developers. btrfs has been dealing with this issue since snapshots/subvols were first introduced some 15-odd years ago. This isn't a new problem... https://lore.kernel.org/linux-fsdevel/20231025210654.GA2892534@perftesting/ > Aleksa referenced LSF/MM > discussions. I also referenced those discussions and the -fsdevel discussions that have been happening for quite some time. I'll reference some of them here again, because they are all out in the open.... https://lwn.net/Articles/975444/ https://lore.kernel.org/linux-fsdevel/?q=st_vol https://lore.kernel.org/linux-fsdevel/20231211233231.oiazgkqs7yahruuw@moria.home.lan/ -Dave. -- Dave Chinner david@fromorbit.com