Richard Yao 803884217f Implement ZPOOL_IMPORT_UDEV_TIMEOUT_MS ... Since 0.7.0, zpool import would unconditionally block on udev for 30 seconds. This introduced a regression in initramfs environments that lack udev (particularly mdev based environments), yet use a zfs userland tools intended for the system that had been built against udev. Gentoo's genkernel is the main example, although custom user initramfs environments would be similarly impacted unless special builds of the ZFS userland utilities were done for them. Such environments already have their own mechanisms for blocking until device nodes are ready (such as genkernel's scandelay parameter), so it is unnecessary for zpool import to block on a non-existent udev until a timeout is reached inside of them. Rather than trying to intelligently determine whether udev is available on the system to avoid unnecessarily blocking in such environments, it seems best to just allow the environment to override the timeout. I propose that we add an environment variable called ZPOOL_IMPORT_UDEV_TIMEOUT_MS. Setting it to 0 would restore the 0.6.x behavior that was more desirable in mdev based initramfs environments. This allows the system user land utilities to be reused when building mdev-based initramfs archives. Reviewed-by: Igor Kozhukhov <igor@dilos.org> Reviewed-by: Jorgen Lundman <lundman@lundman.net> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Georgy Yakovlev <gyakovlev@gentoo.org> Signed-off-by: Richard Yao <ryao@gentoo.org> Closes #9436		2019-10-11 09:52:48 -07:00
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linux	Implement ZPOOL_IMPORT_UDEV_TIMEOUT_MS	2019-10-11 09:52:48 -07:00