From 6ca23a68da3b26ee590cbdd70739f965d85a926f Mon Sep 17 00:00:00 2001
From: Ian Kelling <ian@iankelling.org>
Date: Mon, 30 Sep 2024 19:24:01 -0400
Subject: [PATCH] refactor to run single lsof that is slower but more robust

---
 filesystem/usr/local/bin/mount-latest-subvol | 274 ++++++++++---------
 filesystem/usr/local/bin/umount-funcs        |  88 +++---
 2 files changed, 192 insertions(+), 170 deletions(-)

diff --git a/filesystem/usr/local/bin/mount-latest-subvol b/filesystem/usr/local/bin/mount-latest-subvol
index c7f2971..fd2aaf4 100755
--- a/filesystem/usr/local/bin/mount-latest-subvol
+++ b/filesystem/usr/local/bin/mount-latest-subvol
@@ -242,12 +242,8 @@ fi
 ##### end setup fstab for subvols we care about ######
 
 
-for vol in ${all_vols[@]}; do
+vol-setup() {
   d=/$vol
-  if ! awk '$3 == "btrfs" {print $2}' /etc/fstab | grep -xF $d &>/dev/null; then
-    continue
-  fi
-
 
   ##### begin building up list of bind mounts  ######
   binds=() # list of bind mounts
@@ -266,29 +262,16 @@ for vol in ${all_vols[@]}; do
     roots=( ${new_roots[@]} )
   done
   ##### end building up list of bind mounts  ######
+}
 
 
-
-  # if latest is already mounted, make sure binds are mounted and move on
-  m check-subvol-stale $d
-  # populated by check-subvol-stale if stale
-  if ! fresh_snap=$(cat /nocow/btrfs-stale/$vol 2>/dev/null); then
-    mnt $d
-    did=$(stat -c%d $d)
-    for b in ${binds[@]}; do
-      if mountpoint -q $b; then
-        bid=$(stat -c%d $b)
-        if [[ $did != "$bid" ]]; then
-          umount-kill $b
-        fi
-      fi
-      mnt $b
-    done
+### begin pruning volumes ###
+pruned_vols=()
+for vol in ${all_vols[@]}; do
+  if ! awk '$3 == "btrfs" {print $2}' /etc/fstab | grep -xF /$vol &>/dev/null; then
     continue
   fi
-
-
-  ##### begin checking for loopback mounts ####
+  ##### begin checking for loopback mounts #####
   found_loop=false
   for l in $(losetup -ln|awk '{print $6}'); do
     for dir in $d ${binds[@]}; do
@@ -306,126 +289,155 @@ for vol in ${all_vols[@]}; do
   if $found_loop; then
     continue
   fi
-  ##### end end checking loopback mounts ####
+  ##### end end checking loopback mounts #####
 
+  pruned_vols+=("$vol")
+done
+### end pruning volumes ###
 
-  ## not using arbtt at the moment
-  # if [[ $vol == q ]]; then
-  #   ## allow to fail, user might not be logged in
-  #   x sudo -u $(id -nu 1000) XDG_RUNTIME_DIR=/run/user/1000 systemctl --user stop arbtt ||:
-  # fi
-  umount_ret=true
-  unmounted=()
-  for dir in $(echo $d ${binds[*]}\ |tac -s\ ); do
-    umount-kill $dir
-  done
+umount_dirs=()
+declare -A umount_vols
 
-  # if we unmounted some but not all, restore them and move on
-  if ! $umount_ret; then
-    for dir in ${unmounted[@]}; do
-      mnt $dir
-    done
-    continue
-  fi
 
-  #### begin dealing with leaf vols ####
+for vol in ${pruned_vols[@]}; do
+  vol-setup
 
-  ### begin getting root_dir
-  ### this is duplicated in check-subvol-stale
-
-  dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab /etc/mtab|head -n1)
-  d dev=$dev
-  # 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 fil show $dev| sed -rn 's#.*path (\S+)$#\1#p'); do
-    if [[ $devx == dm-* ]]; then
-      devx=/dev/$devx
-      mapper-dev devx
-    fi
-    d devx=$devx
-    root_dir=$(sed -rn "s,^\s*$devx\s+(\S+).*\bsubvolid=[05]\b.*,\1,p" /etc/mtab /etc/fstab|head -n1)
-    if [[ $root_dir ]]; then
-      d root_dir=$root_dir
-      break
-    fi
-  done
-  if [[ ! $root_dir ]]; then
-    echo "$0: error could not find root subvol mount for $dev" >&2
-    exit 1
+  # if latest is already mounted, make sure binds are mounted and move on
+  m check-subvol-stale $d
+  # populated by check-subvol-stale if stale
+  if [[ -s /nocow/btrfs-stale/$vol ]]; then
+    for b in ${binds[@]}; do
+      # note: if we ever did binds of binds, the ordering of umount_dirs
+      # would need to be reversed here.
+      if mountpoint -q $b; then
+        umount_dirs+=($b)
+      fi
+    done
+    umount_dirs+=($d)
+    umount_vols[$vol]=t
+  else
+    mnt $d
+    did=$(stat -c%d $d)
+    for b in ${binds[@]}; do
+      if mountpoint -q $b; then
+        bid=$(stat -c%d $b)
+        if [[ $did != "$bid" ]]; then
+          umount_dirs+=($b)
+          umount_vols[$vol]=t
+        fi
+      else
+        mnt $b
+      fi
+    done
   fi
-  ### end getting root_dir
-
-  cd $root_dir
-  if [[ -e $vol  ]]; then
-    if [[ $vol == qd ]]; then
-      b btrfs sub del qd
-    else
-      leaf=$vol.leaf.$(date +%Y-%m-%dT%H:%M:%S%z)
-      b mv $vol $leaf
-      b btrfs property set -ts $leaf ro true
-
-      ### begin check if leaf is different, delete it if not ###
-      parentid=$(btrfs sub show $leaf | awk '$1 == "Parent" && $2 == "UUID:" {print $3}')
-      bsubs=(btrbk/$vol.*)
-      bsub= # base subvolume
-      # go in reverse order as its more likely to be at the end
-      for ((i=${#bsubs[@]}-1; i>=0; i--)); do
-        if [[ $parentid == $(btrfs sub show ${bsubs[i]} | awk '$1 == "UUID:" {print $2}') ]]; then
-          bsub=${bsubs[i]}
+done
+
+if (( ${#umount_dirs[@]} >= 1 )); then
+  umount_ret=true
+  unmounted=()
+  umount-kill ${umount_dirs[@]}
+
+  if $umount_ret; then
+    for vol in ${!umount_vols[@]}; do
+      vol-setup
+      fresh_snap=$(cat /nocow/btrfs-stale/$vol 2>/dev/null)
+
+      #### begin dealing with leaf vols ####
+
+      ### begin getting root_dir
+      ### this is duplicated in check-subvol-stale
+
+      dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab /etc/mtab|head -n1)
+      d dev=$dev
+      # 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 fil show $dev| sed -rn 's#.*path (\S+)$#\1#p'); do
+        if [[ $devx == dm-* ]]; then
+          devx=/dev/$devx
+          mapper-dev devx
+        fi
+        d devx=$devx
+        root_dir=$(sed -rn "s,^\s*$devx\s+(\S+).*\bsubvolid=[05]\b.*,\1,p" /etc/mtab /etc/fstab|head -n1)
+        if [[ $root_dir ]]; then
+          d root_dir=$root_dir
           break
         fi
       done
-      if [[ $bsub ]]; then
-        # in testing, same subvol is 136 bytes. allow some overhead. 32 happens sometimes under systemd.
-        # $ errno 32
-        # EPIPE 32 Broken pipe
-        lines=$(btrfs send --no-data -p $bsub $leaf | btrfs receive --dump | head -n 100 | wc -l || [[ $? == 141 || ${PIPESTATUS[0]} == 32 ]])
-        if [[ $lines == 0 ]]; then
-          # example output of no differences:
-          # snapshot        ./qrtest                        uuid=c41ff6b7-0527-f34d-95ac-190eecf54ff5 transid=2239 parent_uuid=64949e1b-4a3e-3945-9a8e-cd7b7c15d7d6 parent_transid=2239
-          echo suspected identical: $bsub $leaf
-          b btrfs sub del $leaf
-        fi
+      if [[ ! $root_dir ]]; then
+        echo "$0: error could not find root subvol mount for $dev" >&2
+        exit 1
       fi
-      ### end check if leaf is different, delete it if not ###
-
-      ## begin expire leaf vols ##
-      leaf_vols=($vol.leaf.*)
-      count=${#leaf_vols[@]}
-      leaf_limit_time=$(( EPOCHSECONDS - 60*60*24*60 )) # 60 days
-      leaf_new_limit_time=$(( EPOCHSECONDS - 60*60*24 * 5 )) # 5 days this
-      # goes backwards from oldest. leaf_new_limit_time is a safety
-      # measure to ensure we don't delete very recent leafs.
-      for leaf in ${leaf_vols[@]}; do
-        leaf_time=$(date -d ${leaf#"$vol".leaf.} +%s)
-        if (( leaf_limit_time > leaf_time || ( leaf_new_limit_time > leaf_time && count > 30 ) )); then
-          b btrfs sub del $leaf
+      ### end getting root_dir
+
+      cd $root_dir
+      if [[ -e $vol  ]]; then
+        if [[ $vol == qd ]]; then
+          b btrfs sub del qd
+        else
+          leaf=$vol.leaf.$(date +%Y-%m-%dT%H:%M:%S%z)
+          b mv $vol $leaf
+          b btrfs property set -ts $leaf ro true
+
+          ### begin check if leaf is different, delete it if not ###
+          parentid=$(btrfs sub show $leaf | awk '$1 == "Parent" && $2 == "UUID:" {print $3}')
+          bsubs=(btrbk/$vol.*)
+          bsub= # base subvolume
+          # go in reverse order as its more likely to be at the end
+          for ((i=${#bsubs[@]}-1; i>=0; i--)); do
+            if [[ $parentid == $(btrfs sub show ${bsubs[i]} | awk '$1 == "UUID:" {print $2}') ]]; then
+              bsub=${bsubs[i]}
+              break
+            fi
+          done
+          if [[ $bsub ]]; then
+            # in testing, same subvol is 136 bytes. allow some overhead. 32 happens sometimes under systemd.
+            # $ errno 32
+            # EPIPE 32 Broken pipe
+            lines=$(btrfs send --no-data -p $bsub $leaf | btrfs receive --dump | head -n 100 | wc -l || [[ $? == 141 || ${PIPESTATUS[0]} == 32 ]])
+            if [[ $lines == 0 ]]; then
+              # example output of no differences:
+              # snapshot        ./qrtest                        uuid=c41ff6b7-0527-f34d-95ac-190eecf54ff5 transid=2239 parent_uuid=64949e1b-4a3e-3945-9a8e-cd7b7c15d7d6 parent_transid=2239
+              echo suspected identical: $bsub $leaf
+              b btrfs sub del $leaf
+            fi
+          fi
+          ### end check if leaf is different, delete it if not ###
+
+          ## begin expire leaf vols ##
+          leaf_vols=($vol.leaf.*)
+          count=${#leaf_vols[@]}
+          leaf_limit_time=$(( EPOCHSECONDS - 60*60*24*60 )) # 60 days
+          leaf_new_limit_time=$(( EPOCHSECONDS - 60*60*24 * 5 )) # 5 days this
+          # goes backwards from oldest. leaf_new_limit_time is a safety
+          # measure to ensure we don't delete very recent leafs.
+          for leaf in ${leaf_vols[@]}; do
+            leaf_time=$(date -d ${leaf#"$vol".leaf.} +%s)
+            if (( leaf_limit_time > leaf_time || ( leaf_new_limit_time > leaf_time && count > 30 ) )); then
+              b btrfs sub del $leaf
+            fi
+            count=$((count-1))
+          done
         fi
-        count=$((count-1))
+        ## end expire leaf vols ##
+      fi
+      #### end dealing with leaf vols ####
+
+      # Note, we make a few assumptions in this script, like
+      # $d was not a different subvol id than $vol, and
+      # things otherwise didn't get mounted very strangely.
+      b btrfs sub snapshot $fresh_snap $vol
+      for dir in $d ${binds[@]}; do
+        m mnt $dir
       done
-    fi
-    ## end expire leaf vols ##
+      rm -f /nocow/btrfs-stale/$vol
+    done
+  else
+    # If we unmounted some but not all, restore them.
+    for dir in ${unmounted[@]}; do
+      mnt $dir
+    done
   fi
-  #### end dealing with leaf vols ####
-
-  # Note, we make a few assumptions in this script, like
-  # $d was not a different subvol id than $vol, and
-  # things otherwise didn't get mounted very strangely.
-  b btrfs sub snapshot $fresh_snap $vol
-  for dir in $d ${binds[@]}; do
-    m mnt $dir
-  done
-
-  ## arbtt disabled for now
-  # if [[ $vol == q ]]; then
-  #   # maybe this will fail if X is not running
-  #   x sudo -u $(id -nu 1000) XDG_RUNTIME_DIR=/run/user/1000 systemctl --user start arbtt ||:
-  # fi
-
-  stale_dir=/nocow/btrfs-stale
-  rm -f $stale_dir/$d
-done
-
+fi
 
 
 for dir in /mnt/r7/amy/{root/root,boot/boot}_ubuntubionic /mnt/{root2/root,boot2/boot}_ubuntubionic; do
diff --git a/filesystem/usr/local/bin/umount-funcs b/filesystem/usr/local/bin/umount-funcs
index f45c6f3..29f0ddf 100644
--- a/filesystem/usr/local/bin/umount-funcs
+++ b/filesystem/usr/local/bin/umount-funcs
@@ -36,29 +36,36 @@ pid-check() {
     done
   done
 }
-kill-dir() {
-  for sig; do
-    echo kill-dir $sig
-    found_pids=false
-    if pids=$(timeout 4 lsof -t $dir); then
-      found_pids=true
-      timeout 4 lsof -w $dir
-      pid-check
-      kill -$sig $pids
-    fi
-    # fuser will find open sockets that lsof won't, for example from gpg-agent.
-    # note: -v shows kernel processes, which then doesn't return true when we want
-    if pids=$(timeout 4 fuser -m $dir 2>/dev/null); then
-      pid-check
-      found_pids=true
-      fuser -$sig -mvk $dir
+get-pids() {
+  local i dir_regex
+  for (( i=0; i < ${#kill_dirs[@]}; i++ )); do
+    if (( i == 0 )); then
+      dir_regex="${kill_dirs[$i]}"
+    else
+      dir_regex="$dir_regex|${kill_dirs[$i]}"
     fi
-    sleep .8
-    if ! $found_pids; then
+  done
+  pids=$(timeout 30 lsof -XF n | awk 'BEGIN { RS = "\np" }; {if($1 in printed_pids) next; for(i=2;i<=NF;i++){ if($i ~ "^n('$dir_regex')(/|$)")  { printed_pids[$1]=1; printf("%s ", $1); break} } }')
+}
+
+kill-dir() {
+  local pids i
+
+  sigs=("$@")
+  for (( i=0; i<= $#; i++ )); do
+    get-pids
+    if [[ ! $pids ]]; then
       return 0
     fi
+    # ran out of signals to try:
+    if (( i == $# )); then
+      return 1
+    fi
+    sig=${sigs[$i]}
+    pid-check
+    echo kill-dir $sig
+    kill -$sig $pids
   done
-  return 1
 }
 
 umount-try() {
@@ -74,27 +81,30 @@ umount-try() {
 
 # leaf function. others are just used by this one.
 umount-kill() {
-  dir=$1
-  if mountpoint -q $dir; then
-    if ! umount-try $dir; then
-      if ! kill-dir TERM TERM TERM INT INT HUP HUP TERM TERM TERM INT INT HUP HUP; then
-        if [[ $force ]] && $force; then  kill-dir KILL; fi
-      fi
+  local -a kill_dirs
+  for dir; do
+    if ! mountpoint -q $dir; then
+      echo "expected mountpoint args, got $dir"
+      return 1
+    fi
+  done
 
-      if ! umount-try $dir; then
-        # 2024-08, i've been noticing emacs randomly holding open /a
-        # without its pid being found by fuser or lsof.
-        # i'm on commit b9da5ee06f2e4ae807336dd6a641ae797831d097
-        if m pkill -xf 'emacs --daemon'; then
-          sleep 2
-          umount-try $dir ||:
-        fi
-      fi
-      if ! $umounted; then
-        echo "$0: failed to umount $dir"
-        umount_ret=false
-        ret=1
-      fi
+  for dir; do
+    if ! umount-try $dir; then
+      kill_dirs+=($dir)
     fi
+  done
+
+  if ! kill-dir TERM TERM TERM INT INT HUP HUP TERM TERM TERM INT INT HUP HUP; then
+    if [[ $force ]] && $force; then  kill-dir KILL; fi
+  fi
+
+  # If we fail, consider trying this to see if it catches more processes:
+  # fuser -m $dir
+  umount-try $dir ||:
+  if ! $umounted; then
+    echo "$0: failed to umount $dir"
+    umount_ret=false
+    ret=1
   fi
 }
-- 
2.30.2