71 lines
1.6 KiB
Bash
Executable File
71 lines
1.6 KiB
Bash
Executable File
#!/bin/sh
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#
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# BTRFS delta snapshots with incomplete send handling
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# CC0 ~caskd
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: ${SRC:?'Source not defined'}
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: ${SNAPDIR:?'Snapdir not defined'}
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: ${DEST:?'Destination not defined'}
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CDATE="$(date '+%s')"
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SNAPSRC="$SRC"
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SNAPPATH="$SNAPSRC/$SNAPDIR"
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PREV="$SNAPPATH/prev"
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CUR="$SNAPPATH/cur"
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TMP="$SNAPPATH/tmp"
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SNAPDEST="$SNAPPATH/$CDATE"
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PARENTNAME="parent"
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DESTNAME="data"
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msg() {
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echo "$1" >&2
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}
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compress() {
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zstd -T0 -z -9
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}
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delta() {
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local TS_PARENT="$(basename "$(realpath "$CUR")")"
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local TS_CURRENT="$(basename "$(realpath "$TMP")")"
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[ -d "$(realpath "$CUR")" ] || return 1
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[ -e "$DEST/$TS_PARENT/$DATA" ] || return
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msg "Attempting to send delta"
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mkdir -vp "$DEST/$TS_CURRENT"
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ln -sv "../$TS_PARENT" "$DEST/$TS_CURRENT/$PARENTNAME"
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btrfs -v send --compressed-data -p "$CUR" "$TMP" | compress > "$DEST/$TS_CURRENT/$DESTNAME.tmp"
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mv -v "$DEST/$TS_CURRENT/$DESTNAME.tmp" "$DEST/$TS_CURRENT/$DESTNAME"
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}
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full() {
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local TS_CURRENT="$(basename "$(realpath "$TMP")")"
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msg "Attempting to send full"
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mkdir -vp "$DEST/$TS_CURRENT"
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btrfs -v send --compressed-data "$TMP" | compress > "$DEST/$TS_CURRENT/$DESTNAME.tmp"
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mv -v "$DEST/$TS_CURRENT/$DESTNAME.tmp" "$DEST/$TS_CURRENT/$DESTNAME"
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}
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symdel() {
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if [ -L "$1" ]; then
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btrfs subvolume delete "$1" >&2 || true
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rm -v "$1" >&2
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fi
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}
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mkdir -vp "$SNAPPATH" >&2
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symdel "$TMP"
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symdel "$PREV"
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ln -sv "$CDATE" "$TMP" >&2
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btrfs subvolume snapshot -r "$SNAPSRC" "$SNAPDEST" >&2
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delta || full || return 1
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# Mark snapshot transmission as complete
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[ -L "$CUR" ] && \
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mv -v "$CUR" "$PREV" >&2
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mv -v "$TMP" "$CUR" >&2
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