Why can I not mount my storage device inside WSL?

[Mr Beedell, Roke Julian Lockhart (beedell-roke)]

I'm trying to mount one of my two BTRFS-formatted NVMe SSDs:

PS C:\Users\rokej> GET-CimInstance -query "SELECT * from Win32_DiskDrive"

DeviceID           Caption                           Partitions Size          Model
--------           -------                           ---------- ----          -----
\\.\PHYSICALDRIVE1 addlink M.2 PCIE G4x4 NVMe        4          2000396321280 addlink M.2 PCIE G4x4 NVMe
\\.\PHYSICALDRIVE4 Generic STORAGE DEVICE USB Device 1          24675840      Generic STORAGE DEVICE USB Device
\\.\PHYSICALDRIVE5 Generic Flash Disk USB Device     2          15512878080   Generic Flash Disk USB Device
\\.\PHYSICALDRIVE3 Samsung SSD 980 PRO 250GB         2          250056737280  Samsung SSD 980 PRO 250GB
\\.\PHYSICALDRIVE2 addlink M.2 PCIE G4x4 NVMe        1          2000396321280 addlink M.2 PCIE G4x4 NVMe
\\.\PHYSICALDRIVE0 SK hynix PC401 HFS256GD9TNG-62A0A 1          256052966400  SK hynix PC401 HFS256GD9TNG-62A0A

I've elevated to Administrator:

PS C:\Users\rokej> wsl --mount \\.\PHYSICALDRIVE1
Failed to attach disk '\\.\PHYSICALDRIVE1' to WSL2: Error: 0x80040315
Error code: Wsl/Service/AttachDisk/MountDisk/WSL_E_ELEVATION_NEEDED_TO_MOUNT_DISK

However, it fails:

PS C:\Users\rokej> sudo wsl --mount \\.\PHYSICALDRIVE1
The disk was attached but failed to mount: No such device.
For more details, run 'dmesg' inside WSL2.
To detach the disk, run 'wsl.exe --unmount \\.\PHYSICALDRIVE1'.

Get-Error is useless here, but dmesg returns:

[  714.267351] scsi 0:0:0:4: Direct-Access     NVMe     addlink M.2 PCIE 31.6 PQ: 0 ANSI: 6
[  714.271266] sd 0:0:0:4: Attached scsi generic sg4 type 0
[  714.271469] sd 0:0:0:4: [sde] 3907029168 512-byte logical blocks: (2.00 TB/1.82 TiB)
[  714.272089] sd 0:0:0:4: [sde] 4096-byte physical blocks
[  714.273149] sd 0:0:0:4: [sde] Write Protect is off
[  714.273404] sd 0:0:0:4: [sde] Mode Sense: 0f 00 10 00
[  714.276367] sd 0:0:0:4: [sde] Write cache: enabled, read cache: enabled, supports DPO and FUA
[  714.282104]  sde: sde1 sde2 sde3 sde4
[  714.282815] sd 0:0:0:4: [sde] Attached SCSI disk
[  714.294191] WSL (549 - DiskMount): Detected  filesystem for device: /dev/sde
[  714.299142] WSL (549 - DiskMount) ERROR: UtilMount:1704: mount(/dev/sde, /mnt/wsl/PHYSICALDRIVE1, , 0x0x, ) failed 19

I'd have used journalctl, but it's somehow empty.

[Mr Beedell, Roke Julian Lockhart (beedell-roke)]

I needed to mount it as a --bare FS, ascertain what its ID was with lsblk, then create a directory to mount in (sudo mkdir /mnt/test), then mount it there with sudo mount -t btrfs /dev/sde4 /mnt/test.