From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [PATCH 0/8] FUSE improvements + VFS changes Date: Tue, 25 Oct 2005 21:02:47 +0100 Message-ID: <20051025200247.GA32540@mail.shareable.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Miklos Szeredi , akpm@osdl.org, linux-fsdevel@vger.kernel.org, viro@ftp.linux.org.uk Return-path: Received: from mail.shareable.org ([81.29.64.88]:22938 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S932315AbVJYUDE (ORCPT ); Tue, 25 Oct 2005 16:03:04 -0400 To: Bryan Henderson Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Bryan Henderson wrote: > Besides the scope of statfs, I know another thing that defines the > separation between two filesystems: you can't link or relink across > filesystems. In sshfs, you probably get a failure if you try to move a > file from a directory in one remote filesystem to one in another remote > filesystem, even though according to the Linux view, they're both in the > same filesystem. (And even if it doesn't fail, it certainly doesn't do > what you expect from rename()). Other things that various software depends on: st_dev changes across a mount point (inode number space), so that (st_dev, st_ino) uniquely identifies each file (as long as they are open, on some filesystems that don't have real inode numbers). In particular, identical (st_dev, st_ino) for two paths imply the paths are hard links. After finding st_nlink different paths referring to the same (st_dev, st_ino) pair, one may assume that's all the links to a file. (That's broken by bind mounts, unfortunately). -- Jamie