Ensure that data block device is ready before formatting

deploy/iso/minikube-iso/package/automount/minikube-automount

@@ -6,10 +6,111 @@ echo "automount ...";
 LABEL=boot2docker-data
 MAGIC="boot2docker, please format-me"
 
-# If there is a partition with `boot2docker-data` as its label, use it and be
-# very happy. Thus, you can come along if you feel like a room without a roof.
-BOOT2DOCKER_DATA=`blkid -o device -l -t LABEL=$LABEL`
-UNPARTITIONED_HD="/dev/$(lsblk | grep disk | cut -f1 -d' ')"
+# This function will unbind and rebind the driver for the block device
+# in question. This has the same effect of rebooting (in terms of forcing
+# the kernel to re-read the partition table synchronously), but without
+# the cost of actually rebooting.
+#
+# Rather than arbitrarily sleep, this function blocks on the readiness of the block device,
+# specifically, that all partitions are present and acknowledged by the kernel.
+#
+# Note: that this is not safe to do if a disk is mounted or in use,
+# but should be safe otherwise
+rebind_block_device()
+{
+  device=$(basename $1)
+
+  # Try and force partition sync's before doing anything
+  sync
+  partprobe
+  blockdev_path="/sys/class/block/${device}/device/"
+  driver_dir=$(cd ${blockdev_path} && cd $(readlink "driver") && pwd)
+  device_path=$(find ${blockdev_path}/driver/* -type l)
+  device_id=$(basename ${device_path})
+  pci_device_relative_id=$(readlink ${device_path})
+  pci_device_id="/sys/${pci_device_relative_id#"../../../../"}"
+
+  echo ${device_id} > "${driver_dir}/unbind"
+  wait_for 5 block_dev_not_exists ${pci_device_id}
+  echo ${device_id} > "${driver_dir}/bind"
+  wait_for 5 block_dev_exists ${pci_device_id}
+  wait_for 5 block_dev_partitions_exist ${pci_device_id}
+  wait_for 5 device_partitions_exist ${device}
+
+  # Forcefully partprobe again but these are likely not necessary, and are just for good meassure.
+  wait_for 5 sync
+  wait_for 5 partprobe
+}
+
+# Check if any block device exists for this PCI device
+# First arg: path to PCI device.
+# Return: true if PCI device exists
+block_dev_exists()
+{
+  block_dev="${1}/block"
+  [ -d "${block_dev}" ] && [ -n $( ls "${block_dev}" ) ]
+}
+
+# Check if any block device, at a particular PCI path, exists.
+# First arg: path to PCI device.
+# Return: true if there are no block devices for this PCI device
+block_dev_not_exists()
+{
+  block_dev="${1}/block"
+  [ ! -d "${block_dev}" ]
+}
+
+# Further examines a block device, to determine if it has exactly 2 partitions
+# First arg: path to PCI device.
+# Return: true if both partitions present
+block_dev_partitions_exist()
+{
+  block_dev="${1}/block"
+  block_dev_id=$(ls "${1}/block" | head -n 1) # there should only ever be able to be one block device per PCI id
+  [ -d "${block_dev}/${block_dev_id}/${block_dev_id}1" ] && # first partition
+  [ -d "${block_dev}/${block_dev_id}/${block_dev_id}2" ] # second partition
+}
+
+# It is possible for the block device to be initialized in /sys but not /dev, check there
+# and ensure that poth partitions are present
+# First arg: the block device root name (eg, sda / vda)
+# Return: true if both partitions present in /dev
+device_partitions_exist()
+{
+  device="${1}"
+  [ -b "/dev/${device}1" ] && # first partition
+  [ -b "/dev/${device}2" ] # second partition
+}
+
+# DRY up polling
+# First arg: Max seconds to wait for a condition to be true
+# Remaining arg: A condition (preferably a function handle that evaluates a contition) with
+# any further args passed to the function being called, if any.
+# Return: none
+wait_for()
+{
+  max_wait="${1}"
+  shift
+
+  echo "Waiting for '$@' to be true"
+  local timer=0
+  until $@ || [ "$timer" -gt "$(( $max_wait * 2 ))" ]; do
+      timer=$((timer + 1))
+      sleep 0.5
+  done
+}
+
+# Helper to ensure that this global variable is current / correct
+find_b2d_device()
+{
+  # If there is a partition with `boot2docker-data` as its label, use it and be
+  # very happy. Thus, you can come along if you feel like a room without a roof.
+  BOOT2DOCKER_DATA=`blkid -o device -l -t LABEL=$LABEL`
+  UNPARTITIONED_HD="/dev/$(lsblk | grep disk | cut -f1 -d' ')"
+}
+
+find_b2d_device
+
 echo $BOOT2DOCKER_DATA
 if [ ! -n "$BOOT2DOCKER_DATA" ]; then
     echo "Is the disk unpartitioned?, test for the 'boot2docker format-me' string"
@@ -26,33 +127,24 @@ if [ ! -n "$BOOT2DOCKER_DATA" ]; then
             dd if=$UNPARTITIONED_HD of=/userdata.tar bs=1 count=4096 2>/dev/null
             # Create the partition, format it and then mount it
             echo "NEW boot2docker managed disk image ($UNPARTITIONED_HD): formatting it for use"
-
             # Add a swap partition (so Docker doesn't complain about it missing)
             (echo n; echo p; echo 2; echo ; echo +1000M ; echo w) | fdisk $UNPARTITIONED_HD
-            # Let kernel re-read partition table
-            partprobe
+            # Set the type of the disk
             (echo t; echo 82; echo w) | fdisk $UNPARTITIONED_HD
-            # Let kernel re-read partition table
-            partprobe
-            # wait for the partition to actually exist, timeout after about 5 seconds
-            local timer=0
-            while [ "$timer" -lt 10 -a ! -b "${UNPARTITIONED_HD}2" ]; do
-                timer=$((timer + 1))
-                sleep 0.5
-            done
-            mkswap "${UNPARTITIONED_HD}2"
             # Add the data partition
             (echo n; echo p; echo 1; echo ; echo ; echo w) | fdisk $UNPARTITIONED_HD
-            # Let kernel re-read partition table
-            partprobe
-            # wait for the partition to actually exist, timeout after about 5 seconds
-            timer=0
-            while [ "$timer" -lt 10 -a ! -b "${UNPARTITIONED_HD}1" ]; do
-                timer=$((timer + 1))
-                sleep 0.5
-            done
-            BOOT2DOCKER_DATA=`echo "${UNPARTITIONED_HD}1"`
-            mkfs.ext4 -i 2048 -L $LABEL $BOOT2DOCKER_DATA
+
+            # Force the device state to be in sync by rebinding the driver for it
+            rebind_block_device "${UNPARTITIONED_HD}"
+
+            BOOT2DOCKER_DATA="${UNPARTITIONED_HD}1"
+            BOOT2DOCKER_SWAP="${UNPARTITIONED_HD}2"
+
+            # Format the swap partition
+            wait_for 5 mkswap "${BOOT2DOCKER_SWAP}"
+
+            # Format the ext4 partition
+            wait_for 5 mkfs.ext4 -i 2048 -L $LABEL $BOOT2DOCKER_DATA
         fi
 
         DISK_VENDOR=$(cat /sys/class/block/$(basename $UNPARTITIONED_HD /dev/)/device/vendor /sys/class/block/$(basename $UNPARTITIONED_HD /dev/)/device/model | tr -d "\n")
@@ -64,7 +156,7 @@ if [ ! -n "$BOOT2DOCKER_DATA" ]; then
                 # As there are no partitions, let's make sure the disk is empty for real
                 dd if=$UNPARTITIONED_HD of=device_test_file bs=1k count=256 > /dev/null 2>&1
                 NON_NUL=$(<device_test_file tr -d '\0\n' | wc -c)
-                if [ $NON_NUL == 0 ]; then                    
+                if [ $NON_NUL == 0 ]; then
                     # Create the partition, format it and then mount it
                     echo "NEW VMware boot2docker managed disk image ($UNPARTITIONED_HD): formatting it for use"