[systemd-devel] systemd-growfs blocks boot until completed

[Mirza Krak]

Hi,

I have been using the systemd-growfs feature for a while, and been
happy with it so far.

But recently I upgraded my distribution (custom based on Yocto) which
also upgraded systemd from 239 to 241, and I can see that there has
been a change in behavior of the "systemd-growfs" feature.

In systemd 241, it blocks the boot process while it is growing the
filesystem, here is an example log:

         Mounting /data...
[   10.693190] EXT4-fs (mmcblk0p4): mounted filesystem with ordered
data mode. Opts: (null)
[  OK  ] Mounted /data.
         Starting Grow File System on /data...
[   10.780109] EXT4-fs (mmcblk0p4): resizing filesystem from 131072 to
30773248 blocks
[    **] A start job is running for Grow File System on /data (11s /
no limit)
[  *** ] A start job is running for Grow File System on /data (21s /
no limit)
[***   ] A start job is running for Grow File System on /data (30s / no limit)
[***   ] A start job is running for Grow File System on /data (42s / no limit)
[    **] A start job is running for Grow File System on /data (52s / no limit)
[**    ] A start job is running for Grow Filâ…stem on /data (1min 2s / no limit)
[ ***  ] A start job is running for Grow Filâ…tem on /data (1min 15s / no limit)
[  *** ] A start job is running for Grow Filâ…tem on /data (1min 26s / no limit)
[  *** ] A start job is running for Grow Filâ…tem on /data (1min 36s / no limit)
[ ***  ] A start job is running for Grow Filâ…tem on /data (1min 46s / no limit)
[   ***] A start job is running for Grow Filâ…tem on /data (1min 56s / no limit)
[**    ] A start job is running for Grow Filâ…stem on /data (2min 6s / no limit)
[    **] A start job is running for Grow Filâ…tem on /data (2min 17s / no limit)
[*     ] A start job is running for Grow Filâ…tem on /data (2min 27s / no limit)
[ ***  ] A start job is running for Grow Filâ…tem on /data (2min 35s / no limit)

In the previous version (239), this occurred in the background and did
not obstruct the boot process in any noticeable way. Which matched my
expectations on how this feature would work.

So my question is, was the change intentional and if so, what was the reasoning?

Thank you

/ Mirza