Date: Fri, 14 Jul 95 19:44:56 MDT From: terry@cs.weber.edu (Terry Lambert) To: gurney_j@efn.org (John-Mark Gurney) Cc: hackers@freebsd.org Subject: Re: problems with mount/umount Message-ID: <9507150144.AA01450@cs.weber.edu> In-Reply-To: <Pine.NEB.3.91.950714183700.3540C-100000@unix.nike.efn.org> from "John-Mark Gurney" at Jul 14, 95 06:41:17 pm
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> once I was mounting a cdrom on /usr/anon/pub/cdrom... and I run the shell > tcsh... so I wass using name completion... so I ran the command > "mount_cd9660 /dev/cd0c /usr/anon/pub/cdrom/" the problem is that it > mounts fine... but when you try to umount it it with "umount > /usr/anon/pub/cdrom/" or "umount /usr/anon/pub/cdrom" it doesn't work... > if you take a look at the file systems with df... you will see that it has > the trailing slash... but I guess umount just drops it... the only what I > was able to umount was to reboot... is this a bug? or just a typing problem? This is a bug in the mount code, actually. It should cannonize the name before allowing the mount. You need to eliminate the '/' on the end of the mountpoint as a workaround. There are actually several problems in the kernel and user space code for mount and umount that should be resolved. There's at least one problem in the path length (there's a limit of 50 characters -- it's an explicit value instead of a manifest constant -- for CDROM mount point paths if you want umount to work, and a limit of 90 characters for a UFS/MFS/etc. mount path). There's also at least one problem in the mfs code that could result in a panic when using the MFS as a root and it failing to fall back to the normal mount point. This would show when booting a fixit floppy and mounting the hard disk as root instead of the MFS. I've actually been waiting for some response on my earlier mail to this list; I have a number of patches that end up changing ffs and mfs; I haven't bothered with pushing them into LFS, though I should probably do that too (now that I'm thinking about it, I'll do it tonight). I have a number of changes to the mount code and specifically the root mount code that I want to put in before I start beating on the unmount code as well. Probably they will require a rebuild of the C library (it has functions that deal with mount lists) and the consumers of the C library code (no changes to the C library itself -- changes to the size of two fields in the statfs structure). Until all this happens, just avoid using the trailing slash and you should be fine. Terry Lambert terry@cs.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.
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