[systemd-devel] udev and dm inotify problems

[Oleksii Shevchuk]

Hi list.

I ran into the strange problem.
After creating encrypted swap (with crypttab) boot hangs. That happens
because systemd waits for dev-mapper-swap.device.

Udev doesn't report that this device active, because SYSTEMD_READY
environment set to "0".

That happens because "change" event was not generated.

"Change" event was not generated, because udev doesn't receive inotify
event after mkswap closes device.

I come to this after verifying manually these steps:
1. Set udev log_level to debug
2. Attach device with systemd-cryptsetup
3. Verify that inotify for device was added (no errors in debug log,
   device in /run/udev/watch). Also I attach strace to systemd-udev.
4. Run mkswap /dev/mapper/swap
5. Check, that there was no any activity by systemd-udev (according to
   strace - no event, according to the logs - no processing)

After figuring out this, I double check systemd requirements with
/README.txt

I'm running linux-4.1.3, systemd (c11ae0bacee4ab835526a7408f619a754b3b848e)
Also I have this in config

CONFIG_FHANDLE=y
CONFIG_CGROUPS=y
CONFIG_CGROUP_SCHED=y
CONFIG_FAIR_GROUP_SCHED=y
CONFIG_CHECKPOINT_RESTORE=y
CONFIG_NET_NS=y
CONFIG_EPOLL=y
CONFIG_SIGNALFD=y
CONFIG_TIMERFD=y
CONFIG_SECCOMP_FILTER=y
CONFIG_BLK_DEV_BSG=y
CONFIG_EFI_PARTITION=y
CONFIG_SECCOMP=y
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_DEVPTS_MULTIPLE_INSTANCES=y
CONFIG_DMIID=y
CONFIG_EXT3_FS_POSIX_ACL=y
CONFIG_EXT4_FS_POSIX_ACL=y
CONFIG_REISERFS_FS_POSIX_ACL=y
CONFIG_XFS_POSIX_ACL=y
CONFIG_BTRFS_FS_POSIX_ACL=y
CONFIG_F2FS_FS_POSIX_ACL=y
CONFIG_FS_POSIX_ACL=y
CONFIG_INOTIFY_USER=y
CONFIG_AUTOFS4_FS=m
CONFIG_PROC_FS=y
CONFIG_SYSFS=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_TMPFS_XATTR=y
CONFIG_EFIVAR_FS=m
CONFIG_SCHED_DEBUG=y
CONFIG_SCHEDSTATS=y

I use next workaround:

cat /etc/systemd/system/systemd-cryptsetup at swap.service.d/override.conf 
[Service]
ExecStartPost=/usr/bin/udevadm trigger -t devices -p SYSTEMD_READY=0

So.. What I should check to make all that run properly?

// wbr
// Oleksii Shevchuk