symbolic links on shared folder: Ubuntu Host and Guest

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symbolic links on shared folder: Ubuntu Host and Guest

Postby lucky13bbq » 30. Dec 2011, 05:32

Hi all, happy holidays,

I've searched on these forums and haven't seen anyone with the same error so here goes:

The Problem: On the guest OS and within a shared folder with full access, creating a symbolic link gives me the following error: ln: creating symbolic link `asdf': Read-only file system

The details:
The exact command: ln -s /mnt/SharedFolder/blah/folder /mnt/SharedFolder/blah/link
Yes, I have full access to /mnt/SharedFolder/blah as I am able to create, edit, remove files and subdirectories and yes, mnt/SharedFolder/blah/folder is a real folder not a sym link. No problems on NON-shared folders i.e. sudo ln -s /usr /link or sudo ln -s /mnt/SharedFolder/blah /link (both are ok).

The workaround: I must ssh into the Host OS in order to create the desired symbolic link.

My setup:
Host OS: Ubuntu 9.10 32-bit
Guest OS: Ubuntu 10.04 64-bit
Virtualbox 4.1.8 r75467 with the appropriate extension pack (on host) and appropriate guest additions installed (on guest)
host file system of shared folder: ext4
shared folder mounted via fstab and vboxsf

I suspect it is a vboxsf limitation but I hope I am proven wrong.

Thanks,
Andrew
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby Sasquatch » 30. Dec 2011, 13:57

How have you mounted the SF? What permissions does the normal user have, and are you executing the ln command with a user that has modify/create privileges? It's also best to use relative paths instead of absolute, because the symlink will then work on the Host too (unless you have the same file/folder structure there). And you can't create a link that has the same name as the source if the link goes into the same location, but I guess you already knew that.
Read the Forum Posting Guide before opening a topic.
VirtualBox FAQ: Check this before asking questions.
Online User Manual: A must read if you want to know what we're talking about.
Howto: Install Linux Guest Additions
Howto: Use Shared Folders on Linux Guest
See the Tutorials and FAQ section at the top of the Forum for more guides.
Try searching the forums first with Google and add the site filter for this forum.
E.g. install guest additions site:forums.virtualbox.org

Retired from this Forum since OSSO introduction.
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby lucky13bbq » 30. Dec 2011, 15:03

Yes the shared folder is mounted via fstab and vboxsf on the guest.

On the guest OS, the user has full 777 permissions and is able to do it all except create sym links.

Yes I have same file/folder structure but cd'ing to the desired folder and using relative paths results in the same error.

Yes I know about sym links requiring different names in same path.

Do I assume then that you are unable to reproduce the problem?
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby Sasquatch » 30. Dec 2011, 16:09

Well, you haven't given the command how the SF is mounted. Since I use the command noted in my guide, I can pretty much do what I want. But you're right, I can't create symlinks either. I think they made it as a limitation. Can you see anything about it in the documentation? Else create a bug report in the Bugtracker (separate account needed).
Read the Forum Posting Guide before opening a topic.
VirtualBox FAQ: Check this before asking questions.
Online User Manual: A must read if you want to know what we're talking about.
Howto: Install Linux Guest Additions
Howto: Use Shared Folders on Linux Guest
See the Tutorials and FAQ section at the top of the Forum for more guides.
Try searching the forums first with Google and add the site filter for this forum.
E.g. install guest additions site:forums.virtualbox.org

Retired from this Forum since OSSO introduction.
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby lucky13bbq » 30. Dec 2011, 16:23

Oops, here's the fstab line:

SharedFolder /mnt/SharedFolder vboxsf rw,uid=1000,auto,exec 0 0

Will wait a few days to see if there's any other suggestions then I guess I'll go the suggested route and submit a bug report. Thanks.
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby robguttman » 30. Dec 2011, 18:31

We may be having the same problem once we upgraded from 4.1.6 to 4.1.8.

Host: Mac OS X 10.7.2 (Lion)
Guest: Ubuntu 10.04 LTS Server

Symlinks can no longer be created within ubuntu from a shared folder location. All permissions meticulously checked both on the host (mac) side and within the VM (ubuntu). This used to work with exact same configuration when running 4.1.6.

Our workaround has been to downgrade to 4.1.6 - and now everything works again. So something seems to have "broken" this capability in 4.1.8.
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby lucky13bbq » 30. Dec 2011, 19:23

Ah, thanks for the tip and for joining the forum to share. Will try downgrading as suggested to confirm if I can reproduce your observation when I have more time after jan 9.
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby matteiuspi » 12. Jan 2012, 05:40

Thanks for the info, I also just now have noticed this problem, I must have upgraded Virtual Box over the holidays. I develop our linux systems platform from within Windows so the ability to create functional symlinks is a "must-have" for me. :-/
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby matteiuspi » 12. Jan 2012, 05:48

I just uninstalled VirtualBox-4.1.8-75467-Win and installed my old VirtualBox-4.1.6-74713-Win except now my super import VM is not booting:

Failed to open a session for the Virtual Machine
CSDemo

The device helper structure has changed.

Result Code:
E_FAIL (0x80004005)
Component:
Console
Interface:
IConsole {1968b7d3-e3bf-4ceb-99e0-cb7c913317bb}
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby matteiuspi » 12. Jan 2012, 05:55

How frustrating, there are no comments or documentation out there as to how the file format has changed for one to even know how to change it back. I would like to know, but instead I am forced to reinstall 4.1.8 and hope that my machines boot. How lame!
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby lucky13bbq » 12. Jan 2012, 06:13

Hi,

While I regret being unable to help you with your problem, I might be able to help others like me running an Ubuntu Host and Guest:

After a week of frustration with VB's shared folders (first the symbolic links issue and, more recently, performance issues during moments of medium to high I/O where the VM will suddenly slowdown almost to a standstill), I have given up on VB's SF and will wait until the next major release to try again. The alternative, as suggested in one of the links below, is to mount the host's folders from within the guest using either samba or nfs. Essentially, it would be like sharing folders over the network (even though the virtual machine is located on the host machine) as if both machines were two physical machines. This is a workaround that solves both my symbolic links and performance issues.

Some additional links for those that are interested:

https://www.virtualbox.org/ticket/8388
http://blog.clock.co.uk/2011/01/07/virt ... till-slow/
http://blog.clock.co.uk/2011/02/20/virt ... er-update/
http://www.dark.ca/2010/01/29/workaroun ... albox-3-x/
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby Victor Li » 8. Mar 2012, 03:29

Yes, I ran into the same problem yesterday with 4.1.8 :cry:
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby PenelopeFudd » 17. Apr 2012, 22:49

I'm experiencing this too, with VirtualBox 4.1.12 r77245 with MacOSX Host and Fedora14 Guest.
Symlinks give a read-only filesystem error,
Hardlinks give an Operation not permitted error.
Existing symlinks work fine.
I can create and delete ordinary files and directories.

The share was set up with the gui, giving full access, permanently, with automount.

I hope this gets fixed soon, it's an in-your-face regression!
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby segimon » 23. Apr 2012, 16:52

I experience the same problem with 4.1.12. My host is Ubuntu 10.04. I observe the problem with different guests (Fedora 13 and 16, Ubuntu 10.04 and 11.10, Debian 6.0.4).
It looks like this regression was introduced with the 4.1.8 release and still exists in 4.1.12. Is there any bug created in the bug tracker?
Kind regards
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Re: symbolic links on shared folder: Ubuntu Host and Guest

Postby vestigal » 1. May 2012, 01:28

I am also seeing this issue. I'm not really comfortable with my setup to be sure that it's not an issue on my side, though.

Has anyone else had a chance to file a bug report for this?
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