Hello, I recently tried to send a very long email to this list that seems to have never arrived. Rather than repeat the contents of that email, I'll ask a simple question regarding how locking is used by udevd and by util-linux's fsck.
You have the following article on how such locking is intended to work: https://systemd.io/BLOCK_DEVICE_LOCKING/ However, with the introduction of the following commit, util-linux's fsck no longer takes its lock on the same device file that udevd's workers do. It takes a lock on /run/fsck/<drive>.lock instead of /dev/<drive>. https://github.com/util-linux/util-linux/commit/3bbdae633f4a1dda5f95ee6c61f18a1c8ef12250 That as the culmination of this discussion: https://bugs.freedesktop.org/show_bug.cgi?__goaway_challenge=resource-load&__goaway_id=899961c5b88f8a3e09b3bafce7c5b56e&id=79576 That being the case, the locking is not effective, correct? Ubuntu is carrying a patch to verify a udevd/libblkid superblock read's checksum and retry. They got a report showing evidence of contention between udevd and fsck: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/2090972 https://marc.info/?l=util-linux-ng&m=173196251132352&w=2 Unfortunately, at work I am running with that patch, and it does not prevent a very similar failure to mount ext4 filesystems, about once every 1000 boots with a certain test configuration. (I intend to contact them but am having launchpad issues.) Except in my case it comes from the fs UUID not being read in response to a rule in 60-persistant-storage.rules and the lack of UUID causing the by-uuid symlink to be removed, which triggers the corresponding [email protected] instance to be stopped and prevents the mount happening on boot. This is in the post root pivot phase. I believe the symlink and udev db entry was created during the initramfs script phase and then removed in a second udev run processing the add uevent for the filesystem's partition device node. I can share more details of my mount failure if you like. Or if there's a way for you to look at submitted emails that did not reach the list, this past Monday I wrote you a very long email with every detail I thought might be of value (and then some?). Regards, Mike Small
