From 565857e91b7e8c671ec3f4314cb21b0a85c01d0f Mon Sep 17 00:00:00 2001
From: Ian Kelling <iank@fsf.org>
Date: Tue, 2 Apr 2019 21:05:34 -0400
Subject: [PATCH] btrfs mount fix for new and recovery systems

---
 check-subvol-stale  | 26 ++++++++++++++++----------
 mount-latest-subvol | 31 ++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/check-subvol-stale b/check-subvol-stale
index c585cea..9959421 100644
--- a/check-subvol-stale
+++ b/check-subvol-stale
@@ -28,11 +28,12 @@ usage: $0 SUBVOL_MOUNTPOINT...
 In git, this is not not executable because it's meant to be installed
 using ./install-my-scripts
 
-If latest subvols \$@ are not mounted, exit 1, print message, and touch
-/nocow/btrfs-stale/\$subvol
+If latest subvols \$@ are not mounted, exit 1, print message, and print
+the unstale subvol name into /nocow/btrfs-stale/\$subvol
 
-Either SUBVOL_MOUNTPOINT is a snapshot of the latest, or
-the latest snapshot is snapshot of SUBVOL_MOUNTPOINT.
+Fresh is opposite of stale. To be fresh, either SUBVOL_MOUNTPOINT is a
+snapshot of the latest, or the latest snapshot is snapshot of
+SUBVOL_MOUNTPOINT.
 
 -d         Enable debug output
 -h|--help  Print help and exit.
@@ -81,23 +82,28 @@ d() {
 ret=0
 for d; do
     vol=${d##*/}
-    dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab|head -n1)
+    # second field, non-comment line == $d
+    dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab /etc/mtab|head -n1)
     d dev=$dev
-    subvol_dir=$(sed -rn "s,^\s*[^#]\S*\s+$d\s.*\bsubvol=([a-zA-A/]+).*,\1,p" /etc/fstab|head -n1)
+    subvol_dir=$(sed -rn "s,^\s*[^#]\S*\s+$d\s.*\bsubvol=([a-zA-A/]+).*,\1,p" /etc/fstab /etc/mtab|head -n1)
     d subvol_dir=$subvol_dir
     # note, we need $dev because $d might not be mounted, and we do this loop
     # because the device in fstab for the rootfs can be different.
     for devx in $(btrfs fi show $dev| sed -rn 's#.*path (/\S+)$#\1#p'); do
-        root_dir=$(sed -rn "s,^\s*$devx\s+(\S+).*\bsubvolid=0\b.*,\1,p" /etc/fstab|head -n1)
+        root_dir=$(sed -rn "s,^\s*$devx\s+(\S+).*\bsubvolid=[05]\b.*,\1,p" /etc/mtab|head -n1)
         if [[ $root_dir ]]; then break; fi
     done
-    svp=$root_dir/$subvol_dir # subvolume path
-    d svp=$svp
+    if [[ ! $root_dir ]]; then
+      echo "$0: error could not find root subvol mount for $dev" >&2
+      exit 1
+    fi
+    svp=$root_dir/$subvol_dir
+    d "svp=$svp # subvolume path"
 
     snaps=($root_dir/btrbk/$subvol_dir.20*) # Assumes we are in the 21st century.
     if [[ ! $snaps ]]; then
         # no snapshots yet
-        echo "$0: warning. no snapshots found. this is expected for a brand new volume"
+      echo "$0: warning: no snapshots found at $root_dir/btrbk/$subvol_dir.20*. this is expected for a brand new volume"
         continue
     fi
 
diff --git a/mount-latest-subvol b/mount-latest-subvol
index 2ebcca0..d36685f 100644
--- a/mount-latest-subvol
+++ b/mount-latest-subvol
@@ -126,9 +126,25 @@ fi
 ret=0
 
 ##### begin setup fstab for subvols we care about ######
-first_root_crypt=$(awk '$2 == "/" {print $1}' /etc/mtab)
+root_dev=$(awk '$2 == "/" {print $1}' /etc/mtab)
+
+
+if cryptsetup status $root_dev &>/dev/null; then
+  crypt_dev=$root_dev
+else # if we are in a recovery boot, find the next best crypt device
+  noauto=,noauto
+  for dev in $(dmsetup ls --target crypt | awk '{print $1}'); do
+    dev=/dev/mapper/$dev
+    if awk '{print $1}' /etc/mtab | grep -Fx $dev &>/dev/null; then
+      crypt_dev=$dev
+      break
+    fi
+  done
+fi
+
+
 fstab <<EOF
-$first_root_crypt  /a  btrfs  noatime,subvol=a  0 0
+$crypt_dev  /a  btrfs  noatime,subvol=a$noauto  0 0
 EOF
 
 shopt -s nullglob
@@ -140,22 +156,22 @@ shopt -s nullglob
 f=(/mnt/root/btrbk/q.*)
 if [[ -e $f ]]; then
   fstab <<EOF
-$first_root_crypt  /q  btrfs  noatime,subvol=q,gid=1000  0 0
-/q/p  /p  none  bind  0 0
+$crypt_dev  /q  btrfs  noatime,subvol=q,gid=1000$noauto  0 0
+/q/p  /p  none  bind$noauto  0 0
 EOF
 fi
 
 f=(/mnt/root/btrbk/o.*)
 if [[ -e $f ]]; then
   fstab <<EOF
-$first_root_crypt  /o  btrfs  noatime,subvol=o  0 0
-/o/m  /m  none  bind  0 0
+$crypt_dev  /o  btrfs  noatime,subvol=o$noauto  0 0
+/o/m  /m  none  bind$noauto  0 0
 EOF
 fi
 
 if [[ $HOSTNAME == frodo ]]; then
   fstab <<EOF
-$first_root_crypt  /i  btrfs  noatime,subvol=i  0 0
+$crypt_dev  /i  btrfs  noatime,subvol=i$noauto  0 0
 EOF
 fi
 ##### end setup fstab for subvols we care about ######
@@ -208,6 +224,7 @@ for vol in q a o i; do
     continue
   fi
 
+  # populated by check-subvol-stale
   fresh_snap=$(</nocow/btrfs-stale/$vol)
   if [[ ! $fresh_snap ]]; then
     echo "$0: error. empty fresh_snap var"
-- 
2.30.2