WSL Ext4 (mount --bare) problem when shared on network

[marcal]

Windows Version

Microsoft Windows [version 10.0.22631.3296]

WSL Version

2.0.14.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

5.15.133.1-1

Distro Version

Ubuntu 22.04.4 LTS

Other Software

No response

Repro Steps

1. wsl --mount \.\PHYSICALDRIVE2 --bare
2. Create a Ext4 partition on a hard drive (or one that already exist ext4 but I would like zfs or btrfs).
   lsblk says the drive is in sdc1
3. mkdir /mnt/d/Test
4. mount /dev/sdc1 /mnt/d/Test
5. Copy files from wsl to /mnt/d/Test and they are not in windows
6. Copy files from windows to d:\Test and they are not in wsl

Expected Behavior

A file copied from one OS to the other shoult be there (I took ext4 as it is supplied but it would be for btrfs or ZFS).

Actual Behavior

dir from windows shows nothinf while ls in linux works
(and reverse when a copy is made in Windows)

Diagnostic Logs

No response
EDIT : I know I can use
\wsl.localhost\Ubuntu\mnt\ext4\ (with subst too)
if I mount in the /mnt/ext4 folder
but in that case I can't share the drive on the network for other computers so I would like so put it in a specific map
Can you please help me?

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[OneBlue]

@marcal: This is most likely a mount namespace issue. WSL uses two different mount namespaces depending on whether you're running elevated or not.

/mnt/wsl is shared between both namespaces though, so can you try mounting the disk there and see if that solves the issue ?

[marcal]

Hello,
I have made the mount again (/mnt/wsl/ext4)
then the mklink to mount the wsl in a share on the host. (d:\Share\ext4)
I can access the ext4 like before from the link but only locally. (so I can go to d:\Share\ext4 and copy files)
From another computer, accessing the share works , but not the link to the wsl (so the ext4). Here is the error I have
(\marc-PC\Share), I see ext4 but I have an error accessing it. The other parts of the share (not wsl) work perfectly.

Thanks again for the help

[OneBlue]

@marcal: This is unfortunately by design. \wsl.localhost is per-user, so if you create a link with let's say mklink, that will lose user information depending on which actual user account the filesystem access is made from.

If you want to share the content of a WSL distro of the networking, running a samba server would be your best best.

[marcal]

Hello,
Bit if I do that, I won't be able so use SMB3 to put virtual machines on the linux partition? Is it correct? Or is there an other type of symbolic link?
Thank you for the help

[oldshensheep]

SMB3 operates at the file level, for virtual machines, you require block-level access, which can be achieved using the iSCSI protocol. Currently, I'm utilizing ZFS on WSL2 and tgt iSCSI. I'm waiting for ZFS on Windows to become more mature before switching to it.

[marcal]

Hello,
Thank you for the information. What I don't like with ISCSI is that I lose the possibility to use the iscsi zvol in the WSL.
And IScsi can be done in a true virtual machine (not wsl) but I will give it a try (only for testing of course)

[oldshensheep]

You can use iSCSI zvol in the WSL and you can use iSCSI in WSL, just need something like targetcli-fb, for zvol you can compile kernel with ZFS and change the configuration to replace the original kernel.

[marcal]

Hello,
Thanks for the information.
For my tests with ZFS I used
https://github.com/alexhaydock/zfs-on-wsl?tab=readme-ov-file
but I think the standard kernel doesn't have Microsoft changes so I don't know what I lose with ZFS.
There is no problem with the same zvol with ISCSI used in 2 different OS at the same time (last time I tried 8 years ago with vsphere and truenas and Windows there were conflicts when writing datas)?

[oldshensheep]

I was aware that, so I change the kernel source to https://github.com/microsoft/WSL2-Linux-Kernel .
https://github.com/oldshensheep/zfs-on-wsl .

ISCSI used in 2 different OS at the same time

Years ago, I tested it to run games, and it worked fine. But for writing the same data, data corruption may occur. Read only is safer, if you want to write, mount iSCSI as read only and using something like overlayfs for writing. Reads go to Server, writes go to client(I think you can add another iSCSI block device… so all go to server).