Re: Problem installing Guix on OpenVZ host that uses zfs

[ludo@gnu.org (Ludovic Courtès)]

Hello!

Stefan Reichör <stefan@xsteve.at> skribis:

> Here is the part that triggers the problem as I assume (I can send the
> full log as well when it is needed):
>
> [pid 31032] open("/proc/self/mountinfo", O_RDONLY) = 17
> [pid 31032] read(17, "2860 2854 0:102 / / rw,noatime m"..., 4096) = 4076
> [pid 31032] read(17, "", 4096)          = 0
> [pid 31032] close(17)                   = 0
> [pid 31032] mount(NULL, "/", NULL, MS_PRIVATE, NULL) = -1 EACCES (Permission denied)
> [pid 31032] futex(0x7f827449c190, FUTEX_WAKE_PRIVATE, 2147483647) = 0
> [pid 31032] write(2, "while setting up the build envir"..., 97) = 97
> [pid 31032] exit_group(1)               = ?
> [pid 31028] close(16)                   = 0
>
> The entry for "/" in /proc/self/mountinfo is:
> 3966 3548 0:102 / / rw,noatime master:129 - zfs satazpool/data/subvol-618-disk-1 rw,xattr,posixacl

The corresponding code in nix/libstore/build.cc is this:

--8<---------------cut here---------------start------------->8---
            /* Make all filesystems private.  This is necessary
               because subtrees may have been mounted as "shared"
               (MS_SHARED).  (Systemd does this, for instance.)  Even
               though we have a private mount namespace, mounting
               filesystems on top of a shared subtree still propagates
               outside of the namespace.  Making a subtree private is
               local to the namespace, though, so setting MS_PRIVATE
               does not affect the outside world. */
            Strings mounts = tokenizeString<Strings>(readFile("/proc/self/mountinfo", true), "\n");
            foreach (Strings::iterator, i, mounts) {
                vector<string> fields = tokenizeString<vector<string> >(*i, " ");
                string fs = decodeOctalEscaped(fields.at(4));
                if (mount(0, fs.c_str(), 0, MS_PRIVATE, 0) == -1)
                    throw SysError(format("unable to make filesystem `%1%' private") % fs);
            }
--8<---------------cut here---------------end--------------->8---

So “fs.c_str()” evaluates to “/”, as expected.

Now maybe zfs-on-linux doesn’t implement MS_PRIVATE or has specific
constraints (is it on FUSE?).  Perhaps you should check with the
zfs-on-linux people what they think of it.

Thanks,
Ludo’.