zfs/contrib/dracut/90zfs/zfs-nonroot-necessities.ser...

[Unit]
Before=initrd-root-fs.target
After=sysroot.mount
DefaultDependencies=no
ConditionEnvironment=BOOTFS

[Service]
Type=oneshot
PassEnvironment=BOOTFS
ExecStart=/bin/sh -c '                                                \
    . /lib/dracut-zfs-lib.sh;                                         \
    _zfs_nonroot_necessities_cb() {                                   \
        @sbindir@/zfs mount | grep -m1 -q "^$1 " && return 0;         \
        echo "Mounting $1 on /sysroot$2";                             \
        mount -o zfsutil -t zfs "$1" "/sysroot$2";                    \
    };                                                                \
    for_relevant_root_children "${BOOTFS}" _zfs_nonroot_necessities_cb'

[Install]
RequiredBy=initrd-root-fs.target
contrib: dracut: fix race with root=zfs:dset when necessities required This had always worked in my testing, but a user on hardware reported this to happen 100%, and I reproduced it once with cold VM host caches. dracut-zfs-generator runs as a systemd generator, i.e. at Some Relatively Early Time; if root= is a fixed dataset, it tries to "solve [necessities] statically at generation time". If by that point zfs-import.target hasn't popped (because the import is taking a non-negligible amount of time for whatever reason), it'll see no children for the root datase, and as such generate no mounts. This has never had any right to work. No-one caught this earlier because it's just that much more convenient to have root=zfs:AUTO, which orders itself properly. To fix this, always run zfs-nonroot-necessities.service; this additionally simplifies the implementation by: * making BOOTFS from zfs-env-bootfs.service be the real, canonical, root dataset name, not just "whatever the first bootfs is", and only set it if we're ZFS-booting * zfs-{rollback,snapshot}-bootfs.service can use this instead of re-implementing it * having zfs-env-bootfs.service also set BOOTFSFLAGS * this means the sysroot.mount drop-in can be fixed text * zfs-nonroot-necessities.service can also be constant and always enabled, because it's conditioned on BOOTFS being set There is no longer any code generated at run-time (the sysroot.mount drop-in is an unavoidable gratuitous cp). The flow of BOOTFS{,FLAGS} from zfs-env-bootfs.service to sysroot.mount is not noted explicitly in dracut.zfs(7), because (a) at some point it's just visual noise and (b) it's already ordered via d-p-m.s from z-i.t. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Closes #14690 2023-03-31 16:47:48 +00:00			`[Unit]`
			`Before=initrd-root-fs.target`
			`After=sysroot.mount`
			`DefaultDependencies=no`
			`ConditionEnvironment=BOOTFS`

			`[Service]`
			`Type=oneshot`
			`PassEnvironment=BOOTFS`
			`ExecStart=/bin/sh -c ' \`
			`. /lib/dracut-zfs-lib.sh; \`
			`_zfs_nonroot_necessities_cb() { \`
			`@sbindir@/zfs mount \| grep -m1 -q "^$1 " && return 0; \`
			`echo "Mounting $1 on /sysroot$2"; \`
			`mount -o zfsutil -t zfs "$1" "/sysroot$2"; \`
			`}; \`
			`for_relevant_root_children "${BOOTFS}" _zfs_nonroot_necessities_cb'`

			`[Install]`
			`RequiredBy=initrd-root-fs.target`