Bug 31432
| Summary: | umount(8) and unmount(2) don't corespond by semantic | ||
|---|---|---|---|
| Product: | Base System | Reporter: | vova <vova> |
| Component: | bin | Assignee: | freebsd-bugs (Nobody) <bugs> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | ||
| Priority: | Normal | ||
| Version: | 5.0-CURRENT | ||
| Hardware: | Any | ||
| OS: | Any | ||
This is not a bug. You can unmount a mounted filesytem by: 1. the mounted directory 2. the mounted name. It is clear that if you rename a mountpoint, that you can't unmount it by the name itself. The checks umount(8) does, are rather complex. umount(8) does a check, if the mounted name matches the original mountpoint. We need this to handle overlay mounts properly. Your suggestion does break overlay mounts unmounting order ! If it is not possible to unmount like in your example, you have to unmount the mounted name: umount linprocfs That's it. Martin -- Martin Blapp, mb@imp.ch ------------------------------------------------------------------ Improware AG, UNIX solution and service provider Zurlindenstrasse 29, 4133 Pratteln, Switzerland Phone: +41 061 826 93 00: +41 61 826 93 01 PGP Fingerprint: 57E 7CCD 2769 E7AC C5FA DF2C 19C6 DCD1 1B3A EC9C ------------------------------------------------------------------ State Changed From-To: open->closed Not a bug, as described by Martin Blapp. |
umount(8) first tries to lookup a mountpoint in result list returned by getfsstat() then, if found, calls unmount(2). If any directory component above mountpoint was renamed, it is not possible to unmount this mountpoint because lookup fails. So unmount(2) needs real directory corresponding to the mountpoint to be unmounted, but umount(8) tries to compare it with list of paths saved by mount(2) and fails in case of rename. Fix: Remove getfsstat() lookup in umount(8). How-To-Repeat: # mount -t linprocfs none /tmp/x/y # mv /tmp/x /tmp/z # umount /tmp/z/y umount: /tmp/z/y not found in mount table, unmounted it anyway # umount /tmp/x/y umount: unmount of /usr/tmp/x/y failed: No such file or directory # cat > um.c main(int ac, char **av) { unmount(av[1], 0); } ^D # gcc um.c # ./a.out /tmp/z/y # mount | grep linproc #