[arch-releng] [RFC] [PATCH] [archiso] Make a list of used block devices

[Gerardo Exequiel Pozzi]

NOTE: Not tested yet, but should work(tm).

This list includes block devices of ( /run/archiso/used_block_devices ):
* Boot medium [archisodevice] (only if no copytoram= is used)
* Loop medium [img_dev] (only if no copytoram= is used)
* COW space [cowdevice] (only if cowdevice= is used (no tmpfs is used))
* Loop devices used for SquashFS images.
* Loop devices used for device-mapper devices (two per each dm-device, one RO{*.fs} and one RW{*.cow})

Aditionally all loop devices except for backing COW files, all are setup as read-only.

In configs/releng profile, a symlink is made at boot-time for AIF:
/run/aif/ignore_devs -> /run/archiso/used_block_devices
---
 archiso/hooks/archiso                              |   20 ++++++++++++++++----
 archiso/hooks/archiso_loop_mnt                     |    3 ++-
 .../rc.d/functions.d/symlink_used_block_devices    |    7 +++++++
 3 files changed, 25 insertions(+), 5 deletions(-)
 create mode 100644 configs/releng/root-image/etc/rc.d/functions.d/symlink_used_block_devices

diff --git a/archiso/hooks/archiso b/archiso/hooks/archiso
index 3518d16..22b67e9 100644
--- a/archiso/hooks/archiso
+++ b/archiso/hooks/archiso
@@ -10,7 +10,8 @@ _mnt_fs() {
 
     mkdir -p "${newroot}${mnt}"
 
-    ro_dev=$(losetup --find --show "${img}")
+    ro_dev=$(losetup --find --show --read-only "${img}")
+    echo ${ro_dev} >> /run/archiso/used_block_devices
     ro_dev_size=$(blockdev --getsz ${ro_dev})
 
     if [[ "${cow_persistent}" == "P" ]]; then
@@ -30,6 +31,7 @@ _mnt_fs() {
     fi
 
     rw_dev=$(losetup --find --show "/run/archiso/cowspace/${cow_directory}/${img_name}.cow")
+    echo ${rw_dev} >> /run/archiso/used_block_devices
 
     echo "0 ${ro_dev_size} snapshot ${ro_dev} ${rw_dev} ${cow_persistent} 8" | dmsetup create ${dm_snap_name}
 
@@ -39,6 +41,7 @@ _mnt_fs() {
         launch_interactive_shell
     else
         echo "/dev/mapper/${dm_snap_name} ${mnt} auto defaults 0 0" >> ${newroot}/etc/fstab
+        echo /dev/mapper/${dm_snap_name} >> /run/archiso/used_block_devices
     fi
 }
 
@@ -46,7 +49,8 @@ _mnt_fs() {
 _mnt_sfs() {
     local img="${1}"
     local mnt="${2}"
-    local img_fullname="${img##*/}";
+    local img_fullname="${img##*/}"
+    local sfs_dev
 
     mkdir -p "${mnt}"
 
@@ -60,7 +64,9 @@ _mnt_sfs() {
         msg "done."
     fi
     msg ":: Mounting '${img}' (SquashFS) to '${mnt}'"
-    if ! mount -r "${img}" "${mnt}" &> /dev/null ; then
+    sfs_dev=$(losetup --find --show --read-only "${img}")
+    echo ${sfs_dev} >> /run/archiso/used_block_devices
+    if ! mount -r "${sfs_dev}" "${mnt}" &> /dev/null ; then
         echo "ERROR: while mounting '${img}' to '${mnt}'"
         launch_interactive_shell
     fi
@@ -137,7 +143,12 @@ run_hook() {
 archiso_mount_handler() {
     local newroot="${1}"
 
-    mountpoint -q "/run/archiso/bootmnt" || _mnt_dev "${archisodevice}" "/run/archiso/bootmnt" "-r"
+    if ! mountpoint -q "/run/archiso/bootmnt"; then
+        _mnt_dev "${archisodevice}" "/run/archiso/bootmnt" "-r"
+        if [[ "${copytoram}" != "y" ]]; then
+            echo $(readlink -f ${archisodevice}) >> /run/archiso/used_block_devices
+        fi
+    fi
 
     if [[ ! -f "${aitab}" ]]; then
         echo "ERROR: '${aitab}' file does not exist."
@@ -170,6 +181,7 @@ archiso_mount_handler() {
 
     if [[ -n "${cow_device}" ]]; then
         _mnt_dev "${cow_device}" "/run/archiso/cowspace" "-r"
+        echo $(readlink -f ${cow_device}) >> /run/archiso/used_block_devices
         mount -o remount,rw "/run/archiso/cowspace"
     else
         msg ":: Mounting /run/archiso/cowspace (tmpfs) filesystem, size=${cowspace_size}..."
diff --git a/archiso/hooks/archiso_loop_mnt b/archiso/hooks/archiso_loop_mnt
index 664f3a5..808100d 100644
--- a/archiso/hooks/archiso_loop_mnt
+++ b/archiso/hooks/archiso_loop_mnt
@@ -15,7 +15,7 @@ archiso_loop_mount_handler () {
     msg ":: Setup a loop device from ${img_loop} located at device ${img_dev}"
     _mnt_dev "${img_dev}" "/run/archiso/img_dev" "-r"
 
-    if ! _dev_loop=$(losetup --find --show "/run/archiso/img_dev/${img_loop}"); then
+    if ! _dev_loop=$(losetup --find --show --read-only "/run/archiso/img_dev/${img_loop}"); then
         echo "ERROR: Setting loopback device for file '/run/archiso/img_dev/${img_loop}'"
         launch_interactive_shell
     fi
@@ -27,5 +27,6 @@ archiso_loop_mount_handler () {
         umount /run/archiso/img_dev
     else
         echo ${_dev_loop} > /run/archiso/img_dev_loop
+        echo $(readlink -f ${img_dev}) >> /run/archiso/used_block_devices
     fi
 }
diff --git a/configs/releng/root-image/etc/rc.d/functions.d/symlink_used_block_devices b/configs/releng/root-image/etc/rc.d/functions.d/symlink_used_block_devices
new file mode 100644
index 0000000..e2b9fc1
--- /dev/null
+++ b/configs/releng/root-image/etc/rc.d/functions.d/symlink_used_block_devices
@@ -0,0 +1,7 @@
+symlink_used_block_devices()
+{
+    mkdir /run/aif
+    ln -s /run/archiso/used_block_devices /run/aif/ignore_devs
+}
+
+add_hook multi_end symlink_used_block_devices
-- 
1.7.9.1