[systemd-devel] RequiresMountsFor and the noauto option.
NeilBrown
neilb at suse.com
Mon Jan 23 00:13:52 UTC 2017
hi,
according to "man systemd.unit" :
RequiresMountsFor=
Takes a space-separated list of absolute paths.
Automatically adds dependencies of type Requires= and
After= for all mount units required to access the
specified path.
Mount points marked with noauto are not mounted
automatically and will be ignored for the purposes of
this option. If such a mount should be a requirement for
this unit, direct dependencies on the mount units may be
added (Requires= and After= or some other combination).
I understand this to mean that if a mount point has the "noauto" option in
/etc/fstab, and if a systemd service has RequiresMountsFor the path to
that mount point, then the service will *not* require the mount point,
and it will start even if that mountpoint cannot be mounted.
I recently made a change to nfs-utils to make use of this
functionality. A generator creates RequiresMountsFor dependences for
nfs-server so that it won't start until all exported filesystems
(listed in /etc/exports) are mounted. I assumed this would not trigger
the mounting of filesystems marked as "noauto". I really want After
functionality, but not Requires.
However, this is not how it works.
The "noauto" option stops a "Requires" dependency being created for
local-fs.target, but does not stop a "Requires" dependency being
created for a service which "RequiresMountsFor". There is no checking
for "noauto" in unit_add_mount_dependencies().
If this a bug in the documentation, or a bug in the code? I'm hoping
the later, otherwise I'll need to find a different solution for
nfs-utils, and that will probably require having my generator read
/etc/fstab and duplicate the work of fstab-generator.c
If the documentation is wrong, and the code is correct, would it be
possible to get "AfterMountsFor=" as that is the functionality that I
really want.
Thanks,
NeilBrown
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