Mounting ntfs-3g file systems at Guix System boot time

[Tobias Geerinckx-Rice]

Théo,

Théo Tyburn 写道：
> Hi :)

Welcome!

> From what I found here
> https://wiki.archlinux.org/title/Udisks#NTFS_mount_failing
> the problem might come from the fact that the ntfs used is that 
> from the kernel
> and not the version from ntfs-3g.

They are correct.

Guix System doesn't currently support auto-mounting anything with 
ntfs-3g from the initrd (and maybe at all?  I didn't check).

> This might also be linked to another problem : notice I add the 
> field
> (check? #f).
> Without it I got the error :
> "ntfsfix : no such file or directory"

Oops, that's a bug.  I have a static ntfsfix in my local tree but 
it needs to be cleaned up before I can push it.  I'll try to do so 
this weekend but it's a busy one.  Until then, (check? #f) for 
NTFS is perfectly fine.  Maybe it should even become the default.

> I guess ntfsfix also comes bundled with ntfs-3g
> so it would make sense that these two bugs have the same origin.

Kind of, in the abstract, but also not really.  For ntfsfix we can 
simply add it to the existing per-file-system logic in (gnu system 
initrd).

For actually mounting ntfs-3g file systems, things aren't so 
simple, because we call the mount syscall directly.  This works 
fine for ‘real’ file systems supported by the kernel, but it cuts 
out the ‘mount helper’ workflow that things like ntfs-3g and FUSE 
in general like to use.

We'd have to add a quick hack for ntfs-3g or a general interface 
for calling mount helper binaries, which will take a bit more 
thought and time…

> So the question is : how do I make make guix use the ntfs-3g 
> package
> in my operating system definition ?

So for ‘use == mounting at boot time’, I don't think this is 
currently possible.

> I looked a bit at the source but couldn't figure out how the 
> command
> (mount.ntfs or mount.ntfs-3g)
> is selected depending on the fs type.

So, nowhere.  We never call the mount binary and it's not 
available in the initrd.

> The decisive steps seem to happen in the "mount-file-system" 
> define*
> at the end of gnu/build/file-system.scm.
> What I don't understand there is what "(mount source target type 
> flags
> options)" does,
> because I don't find where (mount) is defined.

Check out (guix build syscalls) :-)

Aside: the coming ntfs3 (no relation despite the similar name) 
driver promises to replace the old & slow ntfs-3g entirely, and 
wouldn't suffer from this trouble.  Of course a general plan to 
mount other FUSE file systems at Guix boot would still be nice.

Kind regards,

T G-R

[0]: http://lkml.iu.edu/hypermail/linux/kernel/2109.0/03094.html

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