dom0+vm/qvm-block: automatically detach device when physical dev removed (#226)

This will work when device is unmounted. On mounted device backend will be
removed (after 3s timeout), but frontend will left in "closing" state - manual
'xl block-detach' will be needed.

common/block_cleanup

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+DEVID=$[ $MAJOR * 256 + $MINOR ]
+
+XS_PATH="device/vbd/$DEVID"
+
+# Double check that DEVID is not empty
+[ -n "$DEVID" ] && xenstore-rm $XS_PATH

common/block_remove

@@ -3,3 +3,30 @@
 NAME=${DEVNAME#/dev/}
 XS_KEY="qubes-block-devices/$NAME"
 xenstore-rm "$XS_KEY"
+
+# If device was connected to some VM - detach it
+# Notice: this can be run also in VM, so we cannot use xl...
+
+device_detach() {
+    xs_path=$1
+
+    xenstore-write $xs_path/online 0 $xs_path/state 5
+
+    # Wait for backend to finish dev shutdown
+    try=30
+    # -lt will break loop also when 'state' will be empty
+    while [ "`xenstore-read $xs_path/state 2> /dev/null`" -lt 6 ]; do
+        try=$[ $try - 1 ]
+        [ "$try" -le 0 ] && break
+        sleep 0.1
+    done
+    xenstore-rm $xs_path
+}
+
+for XS_DEV_PATH in `xenstore-ls -f backend/vbd | grep 'backend/vbd/[0-9]*/[0-9]* ' | cut -f 1 -d ' '`; do
+    CUR_DEVICE=`xenstore-read "$XS_DEV_PATH/params"`
+    if [ "$CUR_DEVICE" == "$DEVNAME" ]; then
+        device_detach "$XS_DEV_PATH"
+        exit 0
+    fi
+done

common/qubes_block.rules

@@ -17,3 +17,6 @@ ACTION=="change", RUN+="/usr/lib/qubes/block_add_change"
 ACTION=="remove", RUN+="/usr/lib/qubes/block_remove"
 
 LABEL="qubes_block_end"
+
+# Cleanup disconnected frontend from xenstore
+ACTION=="remove", SUBSYSTEM=="block", ENV{MAJOR}=="202", RUN+="/usr/lib/qubes/block_cleanup"

rpm_spec/core-commonvm.spec

@@ -84,6 +84,7 @@ cp setup_ip $RPM_BUILD_ROOT/usr/lib/qubes/
 cp qubes_download_dom0_updates.sh $RPM_BUILD_ROOT/usr/lib/qubes/
 cp block_add_change $RPM_BUILD_ROOT/usr/lib/qubes/
 cp block_remove $RPM_BUILD_ROOT/usr/lib/qubes/
+cp block_cleanup $RPM_BUILD_ROOT/usr/lib/qubes/
 mkdir -p $RPM_BUILD_ROOT/etc/yum/post-actions
 cp qubes_trigger_sync_appmenus.action $RPM_BUILD_ROOT/etc/yum/post-actions/
 mkdir -p $RPM_BUILD_ROOT/usr/lib/qubes
@@ -254,4 +255,5 @@ rm -rf $RPM_BUILD_ROOT
 /usr/lib/qubes/qubes_download_dom0_updates.sh
 /usr/lib/qubes/block_add_change
 /usr/lib/qubes/block_remove
+/usr/lib/qubes/block_cleanup
 /lib/firmware/updates