Re: RFC: use of mdmfs "new" options in fstab

This email is a bit old, but nobody else has commented,
so ...

Matteo Riondato wrote:
During the years, mdmfs(8) has got many options which are not
available in the "mount_mfs" compatibility mode (activated by
specifing -C on the command line or by calling mount_mfs).

This means that it's impossible to use mdmfs "new" option in fstab,
which is quite limiting.

Yes, it's a real PITA. For example, I would like to mount
several memory file systems from within fstab, but I don't
need nor want soft-updates. Howver, the -S option is not
available for mount_mfs.

(On a related note, I also don't want the .snap directory
to appear on those memory file systems. newfs(8) has the
-n option to suppress it, but mdmfs doesn't.)

I think there are two possibilities to solve this:

1) install mdmfs as mount_md (or mount_$something) and teach mount to
recognize it. See attached mdmfsmakefile_mount.c.diff . This will
allow to specify the following line in fstab (the -P option is not
available in compatability mode):

md /usr/jail/jail1 md ro,-P,-F/usr/jailmd/jail1.md 0 0

2)disable bug-for-bug compatibility with mount_mfs when the
program name is "mount_mfs" or "mfs". The "-C" otion will still be
available for those who want compatibility. See attached
mdmfs.c.diff .

I would prefer option #2, but any comment is really appreciated.

Personally, I would love to see #2 committed (and MFCed).

There's only one thing which could cause breakage: When
mdmfs is called as mount_mfs (hence -C is implied), the
option -p 1777 is the default, which is appropriate for
/tmp. People who have mount_mfs in their fstab and
expect that default behaviour will be surprised to see
that their /tmp suddenly isn't mode 1777 anymore.

Therefore I propose that your patch #2 be slightly
modified: When mdmfs is called as mount_mfs, don't
imply -C (hence all options are available), but do
imply -p 1777. Then it shouldn't break any existing
usages, as far as I can imagine.

Best regards
Oliver

--
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.

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main(){for(;b=c,c-=14;i=printf("%04d",e+d/a),e=d%a)
while(g=--b*2)d=h*b+a*(i?f[b]:a/5),h=d/--g,f[b]=d%g;}
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