275 lines
7.4 KiB
Bash
Executable File
275 lines
7.4 KiB
Bash
Executable File
#!/bin/bash
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# Usage: block-snapshot add|remove img-file cow-file
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#
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# This creates dm-snapshot device on given arguments
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dir=$(dirname "$0")
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if [ "$1" = "prepare" ] || [ "$1" = "cleanup" ]; then
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. "$dir/xen-hotplug-common.sh"
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command=$1
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else
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. "$dir/block-common.sh"
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fi
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shopt -s nullglob
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if [ -n "$XENBUS_PATH" ]; then
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HOTPLUG_STORE="/var/run/xen-hotplug/${XENBUS_PATH//\//-}"
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fi
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get_dev() {
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dev=$1
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if [ -L "$dev" ]; then
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dev=$(readlink -f "$dev") || fatal "$dev link does not exist."
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fi
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if [ -f "$dev" ]; then
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file=$dev
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loopdev=$(losetup -j $file | head -1 | cut -d : -f 1)
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if [ -n "$loopdev" ]; then
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# found existing loop to this file
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echo $loopdev
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return
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fi
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# assign new loop device
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loopdev=$(losetup -f 2>/dev/null || find_free_loopback_dev)
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if [ "$loopdev" = '' ]
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then
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release_lock "block"
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fatal 'Failed to find an unused loop device'
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fi
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do_or_die losetup "$loopdev" "$file"
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echo $loopdev
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else
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test -e "$dev" || fatal "$dev does not exist."
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test -b "$dev" || fatal "$dev is not a block device nor file."
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fi
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}
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get_dm_snapshot_name() {
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base=$1
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cow=$2
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echo snapshot-$(stat -c '%D:%i' "$base")-$(stat -c '%D:%i' "$cow")
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}
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create_dm_snapshot() {
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local base_dev cow_dev base_sz
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dm_devname=$1
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base=$2
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cow=$3
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if [ ! -e /dev/mapper/$dm_devname ]; then
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# prepare new snapshot device
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base_dev=$(get_dev $base)
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cow_dev=$(get_dev $cow)
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base_sz=$(blockdev --getsz $base_dev)
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do_or_die dmsetup create $dm_devname --table "0 $base_sz snapshot $base_dev $cow_dev P 256"
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fi
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}
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create_dm_snapshot_origin() {
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local base_dev base_sz
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dm_devname=$1
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base=$2
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if [ ! -e /dev/mapper/$dm_devname ]; then
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# prepare new snapshot-origin device
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base_dev=$(get_dev $base)
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base_sz=$(blockdev --getsz $base_dev)
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do_or_die dmsetup create $dm_devname --table "0 $base_sz snapshot-origin $base_dev"
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fi
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}
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t=$(xenstore_read_default "$XENBUS_PATH/type" 'MISSING')
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case "$command" in
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add)
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case $t in
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snapshot|origin)
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p=$(xenstore_read_default "$XENBUS_PATH/params" 'MISSING')
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if [ "$p" == "MISSING" ]; then
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fatal "Missing device parameters ($t $XENBUS_PATH/params)"
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fi
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base=${p/:*/}
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cow=${p/*:/}
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if [ -L "$base" ]; then
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base=$(readlink -f "$base") || fatal "$base link does not exist."
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fi
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if [ -L "$cow" ]; then
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cow=$(readlink -f "$cow") || fatal "$cow link does not exist."
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fi
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# first ensure that snapshot device exists (to write somewhere changes from snapshot-origin)
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dm_devname=$(get_dm_snapshot_name "$base" "$cow")
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claim_lock "block"
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# prepare snapshot device
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create_dm_snapshot $dm_devname "$base" "$cow"
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if [ "$t" == "snapshot" ]; then
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#that's all for snapshot, store name of prepared device
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xenstore_write "$XENBUS_PATH/node" "/dev/mapper/$dm_devname"
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echo "/dev/mapper/$dm_devname" > "$HOTPLUG_STORE-node"
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write_dev /dev/mapper/$dm_devname
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elif [ "$t" == "origin" ]; then
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# for origin - prepare snapshot-origin device and store its name
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dm_devname=origin-$(stat -c '%D:%i' "$base")
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create_dm_snapshot_origin $dm_devname "$base"
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xenstore_write "$XENBUS_PATH/node" "/dev/mapper/$dm_devname"
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echo "/dev/mapper/$dm_devname" > "$HOTPLUG_STORE-node"
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write_dev /dev/mapper/$dm_devname
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fi
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# Save domain name for template commit on device remove
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domain=$(xenstore_read_default "$XENBUS_PATH/domain" '')
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if [ -z "$domain" ]; then
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domid=$(xenstore_read "$XENBUS_PATH/frontend-id")
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domain=$(xl domname $domid)
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fi
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echo $domain > "$HOTPLUG_STORE-domain"
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release_lock "block"
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exit 0
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;;
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esac
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;;
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prepare)
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t=$2
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case $t in
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snapshot|origin)
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p=$3
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base=${p/:*/}
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cow=${p/*:/}
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if [ -L "$base" ]; then
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base=$(readlink -f "$base") || fatal "$base link does not exist."
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fi
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if [ -L "$cow" ]; then
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cow=$(readlink -f "$cow") || fatal "$cow link does not exist."
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fi
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# first ensure that snapshot device exists (to write somewhere changes from snapshot-origin)
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dm_devname=$(get_dm_snapshot_name "$base" "$cow")
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claim_lock "block"
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# prepare snapshot device
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create_dm_snapshot $dm_devname "$base" "$cow"
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if [ "$t" == "snapshot" ]; then
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#that's all for snapshot, store name of prepared device
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echo "/dev/mapper/$dm_devname"
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elif [ "$t" == "origin" ]; then
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# for origin - prepare snapshot-origin device and store its name
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dm_devname=origin-$(stat -c '%D:%i' "$base")
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create_dm_snapshot_origin $dm_devname "$base"
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echo "/dev/mapper/$dm_devname"
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fi
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release_lock "block"
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exit 0
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;;
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esac
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;;
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remove|cleanup)
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if [ "$command" = "cleanup" ]; then
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t=$2
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else
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t=$(cat $HOTPLUG_STORE-type 2>/dev/null || echo 'MISSING')
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fi
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case "$t" in
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snapshot|origin)
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if [ "$command" = "cleanup" ]; then
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node=$3
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else
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node=$(cat "$HOTPLUG_STORE-node" 2> /dev/null)
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fi
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if [ -z "$node" ]; then
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#fatal "No device node to remove"
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#Most likely already removed
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exit 0
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fi
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if [ ! -e "$node" ]; then
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fatal "Device $node does not exists"
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fi
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claim_lock "block"
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use_count=$(dmsetup info $node|grep Open|awk '{print $3}')
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# do not remove snapshot if snapshot origin is still present
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if [ "${node/snapshot/}" != "$node" -a -e "/dev/mapper/origin-$(echo $node|cut -d- -f2)" ]; then
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use_count=1
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fi
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if [ "$use_count" -gt 0 ]; then
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log info "Device $node still in use - not removing"
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release_lock "block"
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exit 0
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fi
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# get list of used (loop) devices
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deps="$(dmsetup deps $node | cut -d: -f2 | sed -e 's#(7, \([0-9]\+\))#/dev/loop\1#g')"
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# if this is origin
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if [ "${node/origin/}" != "$node" ]; then
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# remove unused snapshots
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for snap in /dev/mapper/snapshot-$(echo $node|cut -d- -f2)-*; do
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use_count=$(dmsetup info $snap|grep Open|awk '{print $3}')
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if [ "$use_count" -eq 0 ]; then
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# unused snapshot - remove it
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deps="$deps $(dmsetup deps $snap | cut -d: -f2 | sed -e 's#(7, \([0-9]\+\))#/dev/loop\1#g')"
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log debug "Removing $snap"
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dmsetup remove $snap
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fi
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done
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if [ "$command" = "remove" ]; then
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# Commit template changes
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domain=$(cat "$HOTPLUG_STORE-domain")
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if [ "$domain" ]; then
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# Dont stop on errors
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/usr/bin/qvm-template-commit "$domain" || true
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fi
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fi
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fi
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if [ -e $node ]; then
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log debug "Removing $node"
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dmsetup remove $node
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fi
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# try to free loop devices
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for dev in $deps; do
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if [ -b "$dev" ]; then
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log debug "Removing $dev"
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losetup -d $dev 2> /dev/null || true
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fi
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done
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if [ -n "$HOTPLUG_STORE" ]; then
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rm $HOTPLUG_STORE-*
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fi
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release_lock "block"
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exit 0
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;;
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esac
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;;
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esac
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# vim:sw=2:et:
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