On Wed, Aug 21, 2019, 01:15 Tony Rodriguez <unixpro1970@xxxxxxxxx> wrote:
I modified systemd-219 functionality to meet a custom requirement for
detecting filesystems/devices that use iscsi without using the _netdev
keyword in /etc/fstab. It is a strict requirement regarding not using
_netdev that I have no control over. However, I am stuck.
From my understanding, src/fstab-generator.c is used to determine
LOCAL-FS and REMOTE-FS. I have modified fstab-generator.c to search for
iscsi udev devices which works, provided the system is already fully
booted (typical multi-user state type of thing). I can also find
/dev/disk/ block devices including iscsi devices using my logic within
fstab-generator.c. The problem is when the system reboots, it appears
systemd using the same fstab-generator logic that I implemented is
unable to detect any iscsi devices. After doing some research, it
appears normal systemd behavior is to mount / and /usr then invoke
fstab-generator.c to determine if a given filesystem in /etc/fstab
should be a local or remote target.
/ and /usr are mounted by initramfs before systemd starts.
(If your initramfs itself uses systemd, that's mostly independent from the main-root systemd – they're two separate worlds.)
The problem is I have no way to tell if a given iscsi filesystem/device
specified in /etc/fstab (without the _netdev keyord ) is local/remote
during the booting state. Mainly because devices are not yet populated
in /dev/disk or udev. Is there a way I can determine if a
filesystem/mount point/device specified in /etc/fstab is local or remote
without the _netdev or fstype (which handles nfs, etc) keywords within
fstab-generator.c?
By design, generators run before any services have started, so no udev yet.
(But if you had udev in the initramfs, it could store data in /run that you could then read from a generator.)
If checking udev and /dev/disk are not possible
within fstab-generator.c, because such devices are not yet populated,
then what should I modify within the systemd source so I can determine
such local/remote targets myself and pass it to fstab-generator.c
(especially when the system is in that / and /usr mounting state and
udev devices are not yet populated?
If you can't use _netdev, then use custom options. Fstab now supports arbitrary "x-" prefixed options, and systemd fstab generator already recognizes several such as "x-systemd.requires=iscsid-is-ready.target". (I think they're listed in the systemd.mount manpage?)
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