[virtiofs] Case-insensitive CreateDirectory creates duplicate directory even if directory already exists in a different case

[meltah]

With case-insensitive mode on, creating a directory with two different casings creates two directories which overlap.

To Reproduce
In a directory with a subdirectory foo, create another subdirectory FOO (e.g. via mkdir or CreateDirectory). The directory will now contain two subdirectories, foo and FOO.

Expected behavior
The second creation should fail saying that the directory already exists.

Host:

• Distro: NixOS
• Kernel version: 6.18.39
• QEMU version: 11.0.2
• libvirt version: 12.4.0
• libvirt XML file:

<filesystem type='mount' accessmode='passthrough'>
 <driver type='virtiofs' queue='1024'/>
 <binary path='/nix/store/38plps11zfac2zgw4j29km85s30r2cf5-virtiofsd-1.14.0/bin/virtiofsd'/>
 <source dir='/run/winshare'/>
 <target dir='winshare'/>
 <alias name='fs0'/>
 <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
</filesystem>

VM:

• Windows version/commit hash: (don't currently have this information)
• Which driver has a problem: virtiofs