mirror_zfs/cmd/zvol_wait/zvol_wait
Pavel Zakharov 26b6047469 New service that waits on zvol links to be created
The zfs-volume-wait.service scans existing zvols and waits for their
links under /dev to be created. Any service that depends on zvol
links to be there should add a dependency on zfs-volumes.target.
By default, this target is not enabled.

Reviewed-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
Reviewed-by: Antonio Russo <antonio.e.russo@gmail.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: John Gallagher <john.gallagher@delphix.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Pavel Zakharov <pzakharov@delphix.com>
Closes #8975
2019-07-17 15:33:05 -07:00

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#!/bin/sh
count_zvols() {
if [ -z "$zvols" ]; then
echo 0
else
echo "$zvols" | wc -l
fi
}
filter_out_zvols_with_links() {
while read -r zvol; do
if [ ! -L "/dev/zvol/$zvol" ]; then
echo "$zvol"
fi
done
}
filter_out_deleted_zvols() {
while read -r zvol; do
if zfs list "$zvol" >/dev/null 2>&1; then
echo "$zvol"
fi
done
}
list_zvols() {
zfs list -t volume -H -o name,volmode | while read -r zvol_line; do
name=$(echo "$zvol_line" | awk '{print $1}')
volmode=$(echo "$zvol_line" | awk '{print $2}')
# /dev links are not created for zvols with volmode = "none".
[ "$volmode" = "none" ] || echo "$name"
done
}
zvols=$(list_zvols)
zvols_count=$(count_zvols)
if [ "$zvols_count" -eq 0 ]; then
echo "No zvols found, nothing to do."
exit 0
fi
echo "Testing $zvols_count zvol links"
outer_loop=0
while [ "$outer_loop" -lt 20 ]; do
outer_loop=$((outer_loop + 1))
old_zvols_count=$(count_zvols)
inner_loop=0
while [ "$inner_loop" -lt 30 ]; do
inner_loop=$((inner_loop + 1))
zvols="$(echo "$zvols" | filter_out_zvols_with_links)"
zvols_count=$(count_zvols)
if [ "$zvols_count" -eq 0 ]; then
echo "All zvol links are now present."
exit 0
fi
sleep 1
done
echo "Still waiting on $zvols_count zvol links ..."
#
# Although zvols should normally not be deleted at boot time,
# if that is the case then their links will be missing and
# we would stall.
#
if [ "$old_zvols_count" -eq "$zvols_count" ]; then
echo "No progress since last loop."
echo "Checking if any zvols were deleted."
zvols=$(echo "$zvols" | filter_out_deleted_zvols)
zvols_count=$(count_zvols)
if [ "$old_zvols_count" -ne "$zvols_count" ]; then
echo "$((old_zvols_count - zvols_count)) zvol(s) deleted."
fi
if [ "$zvols_count" -ne 0 ]; then
echo "Remaining zvols:"
echo "$zvols"
else
echo "All zvol links are now present."
exit 0
fi
fi
done
echo "Timed out waiting on zvol links"
exit 1