remounting a samba share as read-only mounts it twice

[Sebastian Stickel]

When I remount a mounted samba share as read-only, it gets mounted a second time, according to /etc/mtab
Thought the mount point is only read-only accessible from now on, it is still listed as rw AND ro.

- Problem exists on two different machines running an upgraded 12.04
- Tested with two different smb shares coming from two different machines (WinServer and Debian)
- This doesn't affect loop mounts. (Tested with a mkfs.ext4 formatted and mounted file)

Ubuntu Version:
root / # lsb_release -rd
Description: Ubuntu 12.04.1 LTS
Release: 12.04
root / # uname -a
Linux MACHINE 3.2.0-30-generic #48-Ubuntu SMP Fri Aug 24 16:52:48 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

What I expected to happen:
The mount point should be listed only once in /etc/mtab
When umounting it, it should completely disappear from /etc/mtab on the first try.

What happened instead:
The mount point appears a second time in /etc/mtab
When I umount it still appears in mtab as mounted rw but is no longer accessible
When I then try to umount again I get an error that it is not mounted any longer, which also makes the entry in mtab disappear.

Steps to reproduce
1.) Get 12.04 and update it.
2.) mount any samba share via "mount -t cifs..." or smbmount or "mount -t smbfs..."
3.) remount it with "mount -o remount -r /path/to/mountpoint"
4.) cat "/etc/mtab"
5.) try to write to "/path/to/mountpoint" (which should not be possible)
6.) umount "/path/to/mountpoint"
7.) "cat /etc/mtab"
8.) try to access /path/to/mountpoint again (which was not possible to me)
9.) umount again (which should threw an error at me)
10.) "cat /etc/mtab" a last time

If any more information is needed just tell me.

/Edit: Typo

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.