btrfs-mksnapshot[-rootfs]: Clean up, use findmnt(8)

[ax-linux.git] / btrfs / mksnapshot / btrfs-mksnapshot

diff --git a/btrfs/mksnapshot/btrfs-mksnapshot b/btrfs/mksnapshot/btrfs-mksnapshot
index 59b8c5644efe07da0100114a1a99d56f3680f45a..3d2fde80af191ba0a97d734d59679eb95c31aa82 100755 (executable)
--- a/btrfs/mksnapshot/btrfs-mksnapshot
+++ b/btrfs/mksnapshot/btrfs-mksnapshot
@@ -1,7 +1,7 @@
-#!/bin/bash -e
+#!/bin/bash
 #
 # btrfs-mksnapshot -- Make snapshots of btrfs filesystems
-# Copyright (c)2013 Alexander Barton (alex@barton.de)
+# Copyright (c)2013-2020 Alexander Barton (alex@barton.de)
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -9,9 +9,9 @@
 # (at your option) any later version.
 #
 
-NAME=`basename "$0"`
+NAME=$(basename "$0")
 
-function Usage()
+Usage()
 {
        echo "Usage: $NAME [-1] [<path>]"; echo
        echo " -1      Create only one shapshot per day."
@@ -25,7 +25,7 @@ DRY_RUN=
 
 while [ $# -ge 1 ]; do
        case "$1" in
-         [^\-]*)
+         [^-]*)
                break
                ;;
          -1)
@@ -49,12 +49,7 @@ done
 [ -z "$DRY_RUN" ] || echo "VOLUME_PATH=$VOLUME_PATH"
 
 # Detect btrfs filesystem
-FS_NAME=`grep " btrfs " /etc/fstab \
-       | grep "^LABEL=" \
-       | grep " $VOLUME_PATH " \
-       | cut -d'"' -f2 \
-       | cut -d'=' -f2- \
-       | cut -d' ' -f1`
+FS_NAME=$(btrfs filesystem show -m "$VOLUME_PATH" 2>/dev/null | head -1 | cut -d"'" -f2)
 if [ -z "$FS_NAME" ]; then
        echo "$NAME: Failed to detect btrfs filesystem label for \"$VOLUME_PATH\"!"
        exit 1
@@ -63,16 +58,20 @@ fi
 [ -z "$DRY_RUN" ] || echo "FS_NAME=$FS_NAME"
 
 # Detect btrfs subvolume name
-VOLUME_NAME=`grep " btrfs " /etc/fstab \
-       | grep "subvol=" \
-       | grep " $VOLUME_PATH " \
-       | sed -r 's|.*subvol=([[:alnum:]]*).*|\1|'`
+VOLUME_NAME=$(findmnt -nf -o source "$VOLUME_PATH" | grep -F '[' | sed -r 's|^.*\[/(.*)\]|\1|')
+if [ -z "$VOLUME_NAME" ] && [ "$VOLUME_PATH" = "/" ]; then
+       VOLUME_NAME=$(btrfs subvolume get-default / | cut -d' ' -f9)
+fi
 if [ -z "$VOLUME_NAME" ]; then
        echo "$NAME: Failed to detect btrfs subvolume name for \"$VOLUME_PATH\"!"
        exit 1
 fi
+BASE_VOLUME_NAME=$(echo "$VOLUME_NAME" | cut -d'@' -f1)
 
-[ -z "$DRY_RUN" ] || echo "VOLUME_NAME=$VOLUME_NAME"
+if [ -n "$DRY_RUN" ]; then
+       echo "VOLUME_NAME=$VOLUME_NAME"
+       echo "BASE_VOLUME_NAME=$BASE_VOLUME_NAME"
+fi
 
 # Detect mount point of the whole btrfs filesystem
 FS_MOUNT_PATH="/media/$FS_NAME"
@@ -80,32 +79,35 @@ if [ ! -d "$FS_MOUNT_PATH" ]; then
        echo "$NAME: Directory \"$FS_MOUNT_PATH\" does not exist!"
        exit 1
 fi
-grep " btrfs " /proc/mounts | grep " $FS_MOUNT_PATH " >/dev/null 2>&1
-if [ $? -ne 0 ]; then
+if ! grep -q " $FS_MOUNT_PATH btrfs " /proc/mounts; then
        echo "$NAME: btrfs \"$FS_NAME\" seems not to be mounted on \"$FS_MOUNT_PATH\"!"
        exit 1
 fi
 
 [ -z "$DRY_RUN" ] || echo "FS_MOUNT_PATH=$FS_MOUNT_PATH"
 
-[ -z "$DRY_RUN" ] || exit 0
-
 # Generate snapshot name
 i=1
-date=`date +%Y%m%d`
+date=$(date +%Y%m%d)
 while true; do
        id="$date-$i"
-       [ -e "$FS_MOUNT_PATH/$VOLUME_NAME-$id" ] || break
+       [ -e "$FS_MOUNT_PATH/$BASE_VOLUME_NAME@$id" ] || break
        if [ -n "$ONLY_ONE_PER_DAY" ]; then
-               echo "Daily snapshot of \"$VOLUME_PATH\" (\"$VOLUME_NAME\") in btrfs \"$FS_NAME\" already exists."
+               echo "Snapshot \"$BASE_VOLUME_NAME@$id\" of \"$VOLUME_PATH\" (\"$VOLUME_NAME\") in btrfs \"$FS_NAME\" already exists."
                exit 0
        fi
-       i=`expr $i + 1`
+       i=$((i + 1))
 done
+NEW_VOLUME_NAME="$BASE_VOLUME_NAME@$id"
+
+[ -z "$DRY_RUN" ] || echo "NEW_VOLUME_NAME=$NEW_VOLUME_NAME"
+
+[ -z "$DRY_RUN" ] || exit 0
 
 echo "Creating snapshot of \"$VOLUME_PATH\" (\"$VOLUME_NAME\") in btrfs \"$FS_NAME\" ..."
 set -x
 
-cd "$FS_MOUNT_PATH"
-btrfs subvolume snapshot "$VOLUME_NAME" "$VOLUME_NAME-$id"
-find . -maxdepth 1 -name "$VOLUME_NAME"'*' -exec ls -1d {} \; | column
+cd "$FS_MOUNT_PATH" || exit 1
+btrfs subvolume snapshot -r "$VOLUME_NAME" "$NEW_VOLUME_NAME"
+find . -maxdepth 1 \( -name "$BASE_VOLUME_NAME" -o \
+ -name "$BASE_VOLUME_NAME"@'*' \) -exec ls -1d {} \; | sort | column