Description Enji Cooper 2013-01-03 01:00:00 UTC

Error messages printed out by mount(2) are unfortunately not helpful when
trying to determine whether or not an unsupported (or non-existent)
filesystem is invoked. Example:

$ sudo mount -t foobarfs foo $PWD
mount: foo: Operation not supported by device

The issue is with the following call in vfs_mount.c:

1079                 if (vfsp == NULL)
1080                         return (ENODEV);
1081                 if (jailed(td->td_ucred) && !(vfsp->vfc_flags & VFCF_JAIL))
1082                         return (EPERM);

and this call in vfs_init.c:

131         /* Try to load the respective module. */
132         *error = kern_kldload(td, fstype, &fileid);
133         if (*error)
134                 return (NULL);

It seems like the error should be either EINVAL or ENOENT, but doing the latter
in mount(2) would be bad form.

How-To-Repeat: mount -t foobarfs foo /