btrfs-snapshots.sh 1.1

#!/bin/sh

# btrfs-snapshots.sh 1.1
# Create hourly, daily, weekly, and monthly snapshots of btrfs filesystems

# See https://copy.com/WI9AXqTH2nD4 or as a "subversion" of http://pastebin.com/YfZUnytT

# Based somewhat on http://article.gmane.org/gmane.comp.file-systems.btrfs/12609
# Here's my crontab:
# 00,15,30,45  * * * *  /usr/local/bin/btrfs-snapshots.sh frequently  4
# 38           * * * *  /usr/local/bin/btrfs-snapshots.sh hourly     24
# 08          00 * * *  /usr/local/bin/btrfs-snapshots.sh daily       7
# 08          12 * * 0  /usr/local/bin/btrfs-snapshots.sh weekly      4

if [ "$#" -ne 2 ]; then
    echo "Usage: $0 SNAPSHOT_TAG NUM_SNAPSHOTS
Create hourly, daily, weekly, and monthly snapshots of btrfs filesystems.

Based somewhat on http://article.gmane.org/gmane.comp.file-systems.btrfs/12609
Here's my crontab:
00,15,30,45  * * * *  $0 frequently  4
38           * * * *  $0 hourly     24
08          00 * * *  $0 daily       7
08          12 * * 0  $0 weekly      4"
    exit 1
fi

# "Tag" to use for snapshots
SNAPSHOT_TAG="$1"
# How many of those snapshots to keep
NUM_SNAPSHOTS="$2"

# Helper veriables
# A "prefix" for all the snapshots
snap_prefix="snapshot:$SNAPSHOT_TAG:"
# "Now"
snap_date="`date +%Y-%m-%d--%H.%M.%S.%N`"
# Name of the script
script_name=`basename "$0"`

# Messages are logged to syslog
# facility: auth, authpriv (for security information of a sensitive nature), cron, daemon, ftp, kern (can't be generated from user process), lpr, mail, news, security (deprecated synonym for auth), syslog, user, uucp, and local0 to local7
log_fac="local5"
# tag
log_tag="$script_name"

# Add path to btrfs-progs dev version to beginning of $PATH
# Needs a post 2013-02-01 15:55:06 (commit 64edc851da59c47b92ee6830101be0854add7f09)
# version of btrfs-progs from http://git.kernel.org/cgit/linux/kernel/git/mason/btrfs-progs.git/commit/
# because of issues with "btrfs subv list"
btrfs_progs_dev_path="/home/a/Copy/Computerkram/Programme/btrfs-progs.dev/bin"
PATH="$btrfs_progs_dev_path:$PATH"

# Find all btrfs filesystems
btrfs fi show 2>/dev/null | awk '/ path / {print $NF}' | while read dev; do
    # Find uuid and label
    set -- `btrfs fi show 2>/dev/null | grep -B2 " path $dev" | grep "Label:" | sed  's,.*: \(.*\)  uuid: \(.*\),\1 \2,'`
    label="$1"
    uuid="$2"
    logger -t "$log_tag" -p "$log_fac.info" -- "Processing filesystem with label $label and uuid $uuid on $dev"
    # Change the "dev" name ("path") so, that it is usable; ie. / -> .
    safe_dev=`echo "$dev" | tr / .`
    # Create a directory for the temporary mountpoint
    tmp_mount_dir=`mktemp -d "/tmp/.btrfs.mount.$uuid.$safe_dev.XXXXXX"`
    # Mount the current btrfs there
    if ! mount -t btrfs "$dev" "$tmp_mount_dir"; then
        logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: mount -t btrfs $dev $tmp_mount_dir"
        exit 1
    fi

    # Create snapshots for the "root" volume
    if ! btrfs subv snaps -r "$tmp_mount_dir" "$tmp_mount_dir/,$snap_prefix$snap_date" > /dev/null; then
        logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: btrfs subv snaps -r $tmp_mount_dir $tmp_mount_dir/,$snap_prefix$snap_date"
        exit 1
    else
        logger -t "$log_tag" -p "$log_fac.info" -- "Created snapshot $Path,$snap_prefix$snap_date for root volume of fs with uuid $uuid"
    fi
    # Find old, no longer wanted snapshots with the "tag" of this subvolume
    # - list all (read only + writable) snapshots of this filesystem
    # - list only those for current "path" (-> subvolume) and prefix
    # - list only the last $NUM_SNAPSHOTS snapshots -> those are to "survive"
    # - again list all snapshots of current path
    # - sort and list only only those, which are shown just once
    # - -> a list of those snapshots, which are to go
    (btrfs subv list -r "$tmp_mount_dir" | grep " path ,$snap_prefix" | tail -"$NUM_SNAPSHOTS"; btrfs subv list -r "$tmp_mount_dir" | grep " path ,$snap_prefix") | sort | uniq -u | while read __id IdDel __gen GenDel __top __level ToplevelDel __path PathDel; do
        # Delete the snapshot
        if ! btrfs subv del "$tmp_mount_dir/$PathDel" > /dev/null; then
            logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: btrfs subv del $tmp_mount_dir/$PathDel"
            exit 1
        else
            logger -t "$log_tag" -p "$log_fac.info" -- "Removed snapshot $PathDel"
        fi
    done

    # List all non read-only (ie. writable) subvolumes
    # - create a list of ALL subvolumes (read only + writable)
    # - create a list of writable subvolumes
    # - sort those two lists
    # - list only those, which are show just once; ie. the read only subvolumes
    (btrfs subv list -ar $tmp_mount_dir; btrfs subv list -a $tmp_mount_dir) | sort | uniq -u | while read _id Id _gen Gen _top _level Toplevel _path Path; do
        # Create the snapshot
        if ! btrfs subv snaps -r "$tmp_mount_dir/$Path" "$tmp_mount_dir/$Path,$snap_prefix$snap_date" > /dev/null; then
            logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: btrfs subv snaps -r $tmp_mount_dir/$Path $tmp_mount_dir/$Path,$snap_prefix$snap_date"
            exit 1
        else
            logger -t "$log_tag" -p "$log_fac.info" -- "Created snapshot $Path,$snap_prefix$snap_date for subvolume $Path"
        fi
        # Find old, no longer wanted snapshots with the "tag" of this subvolume
        # - list all (read only + writable) snapshots of this filesystem
        # - list only those for current "path" (-> subvolume) and prefix
        # - list only the last $NUM_SNAPSHOTS snapshots -> those are to "survive"
        # - again list all snapshots of current path
        # - sort and list only only those, which are shown just once
        # - -> a list of those snapshots, which are to go
        (btrfs subv list -r "$tmp_mount_dir" | grep " path $Path,$snap_prefix" | tail -"$NUM_SNAPSHOTS"; btrfs subv list -r "$tmp_mount_dir" | grep " path $Path,$snap_prefix") | sort | uniq -u | while read __id IdDel __gen GenDel __top __level ToplevelDel __path PathDel; do
            # Delete the snapshot
            if ! btrfs subv del "$tmp_mount_dir/$PathDel" > /dev/null; then
                logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: btrfs subv del $tmp_mount_dir/$PathDel"
                exit 1
            else
                logger -t "$log_tag" -p "$log_fac.info" -- "Removed snapshot $PathDel"
            fi
        done
    done
    # Unmount the filesystem
    if ! umount "$tmp_mount_dir"; then
        logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: umount$tmp_mount_dir"
        # Not fatal
        # exit 1
    fi
    # Remove the directory where the filesystem was mounted
    if ! rmdir "$tmp_mount_dir"; then
        logger -t "$log_tag" -p "$log_fac.err" -- "Error! Could not do: rmdir $tmp_mount_dir"
        # Not fatal
        # exit 1
    fi
done

# Done ☺
exit 0
# EOF