zfs: fix LINUX_ROOT_DEVICE when grub-probe fails

When grub-probe fails, the current code is to just stuff an empty result
in which causes the user to not knowingly have a system that no longer
boots. grub-probe can fail because the ZFS pool that contains the root
filesystem might have features that grub does not yet support which is a
common configuration for people with a rpool and a bpool. This behavior
uses the zdb utility to dump the same value as the filesystem label
would print.

Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
Gbp-Pq: Topic upstream
Gbp-Pq: Name zfs-fix-LINUX_ROOT_DEVICE-when-grub-probe-fails.patch

diff --git a/util/grub.d/10_linux.in b/util/grub.d/10_linux.in
index 041521c12df54a348e3719503c217b090db87f46..611cc3eadf349029e9ee7f14b0069148ad66dff4 100644 (file)
--- a/util/grub.d/10_linux.in
+++ b/util/grub.d/10_linux.in
@@ -94,7 +94,7 @@ case x"$GRUB_FS" in
            GRUB_CMDLINE_LINUX="rootflags=subvol=${rootsubvol} ${GRUB_CMDLINE_LINUX}"
        fi;;
     xzfs)
-       rpool=`${grub_probe} --device ${GRUB_DEVICE} --target=fs_label 2>/dev/null || true`
+       rpool=`${grub_probe} --device ${GRUB_DEVICE} --target=fs_label 2>/dev/null || zdb -l ${GRUB_DEVICE} | awk -F \' '/ name/ { print $2 }'`
        bootfs="`make_system_path_relative_to_its_root / | sed -e "s,@$,,"`"
        LINUX_ROOT_DEVICE="ZFS=${rpool}${bootfs%/}"
        ;;

diff --git a/util/grub.d/20_linux_xen.in b/util/grub.d/20_linux_xen.in
index a0c2d71f044255ff7af150a5e104ae124db75cca..7d67587bf76a3b9e44657452974e9bb084261a23 100644 (file)
--- a/util/grub.d/20_linux_xen.in
+++ b/util/grub.d/20_linux_xen.in
@@ -86,7 +86,7 @@ case x"$GRUB_FS" in
            GRUB_CMDLINE_LINUX="rootflags=subvol=${rootsubvol} ${GRUB_CMDLINE_LINUX}"
        fi;;
     xzfs)
-       rpool=`${grub_probe} --device ${GRUB_DEVICE} --target=fs_label 2>/dev/null || true`
+       rpool=`${grub_probe} --device ${GRUB_DEVICE} --target=fs_label 2>/dev/null || zdb -l ${GRUB_DEVICE} | awk -F \' '/ name/ { print $2 }'`
        bootfs="`make_system_path_relative_to_its_root / | sed -e "s,@$,,"`"
        LINUX_ROOT_DEVICE="ZFS=${rpool}${bootfs%/}"
        ;;