Currently we have no way how to specify dependencies between fstab
entries (or another units) in the /etc/fstab. It means that users are
forced to bypass fstab and write .mount units manually.
The patch introduces new systemd fstab options:
x-systemd.requires=<PATH>
- to specify dependence an another mount (PATH is translated to unit name)
x-systemd.requires=<UNIT>
- to specify dependence on arbitrary UNIT
x-systemd.requires-mounts-for=<PATH ...>
- to specify dependence on another paths, implemented by
RequiresMountsFor=. The option may be specified more than once.
For example two bind mounts where B depends on A:
/mnt/test/A /mnt/test/A none bind,defaults
/mnt/test/A /mnt/test/B none bind,x-systemd.requires=/mnt/test/A
More complex example with overlay FS where one mount point depends on
"low" and "upper" directories:
/dev/sdc1 /mnt/low ext4 defaults
/dev/sdc2 /mnt/high ext4 defaults
overlay /mnt/merged overlay lowerdir=/mnt/low,upperdir=/mnt/high/data,workdir=/mnt/high/work,x-systemd.requires-mounts-for=/mnt/low,x-systemd.requires-mounts-for=mnt/high
https://bugzilla.redhat.com/show_bug.cgi?id=812826https://bugzilla.redhat.com/show_bug.cgi?id=1164334
This fixes parsing of options in shared/generator.c. Existing code
had some issues:
- it would treate whitespace and semicolons as seperators. fstab(5)
is pretty clear that only commas matter. And the syntax does
not allow for spaces to be inserted in the field in fstab.
Whitespace might be escaped, but then it should not seperate
options. Treat whitespace and semicolons as any other character.
- it assumed that x-systemd.device-timeout would always be followed
by "=". But this is not guaranteed, hasmntopt will return this
option even if there's no value. Uninitialized memory could be read.
- some error paths would log, and inconsistently, some would just
return an error code.
Filtering is split out to a separate function and tests are added.
Similar code paths in other places are adjusted to use the new function.
Kay Sievers
Karel Zak
Zbigniew Jędrzejewski-Szmek