X-Git-Url: https://iankelling.org/git/?p=distro-setup;a=blobdiff_plain;f=check-subvol-stale;h=bdb47492ef07b132914b21ec6773014675dca38f;hp=c6497b5c3f1c0b030c3032ffe5502deab01497d0;hb=65351382939fa95fb1e05d7d83eb58d27c3c6133;hpb=e7708e1261357b00d17f4baffb7051e97f7e8623

diff --git a/check-subvol-stale b/check-subvol-stale
index c6497b5..bdb4749 100644
--- a/check-subvol-stale
+++ b/check-subvol-stale
@@ -35,78 +35,110 @@ if [[ ! $@ ]]; then
     echo "$0: error: expected mountpoint argument"
 fi
 
+stale-file() {
+    stale_dir=/nocow/btrfs-stale
+    stale_file=$stale_dir/$vol
+    if $stale; then
+        mkdir -p $stale_dir
+        printf "%s\n" $freshest_snap > $stale_file
+        ret=1
+    else
+        rm -f $stale_file
+    fi
+
+}
+
 ret=0
 for d; do
     vol=${d##*/}
-    cd /mnt/root/btrbk
-    snaps=($vol.20*) # Assumes we are in the 21st century.
+    dev=$(sed -rn "s,^\s*([^#]\S*)\s+$d\s.*,\1,p" /etc/fstab|head -n1)
+    subvol_dir=$(sed -rn "s,^\s*[^#]\S*\s+$d\s.*\bsubvol=([a-zA-A/]+).*,\1,p" /etc/fstab|head -n1)
+    # 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)
+        if [[ $root_dir ]]; then break; fi
+    done
+    svp=$root_dir/$subvol_dir # subvolume path
+
+    snaps=($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"
         continue
     fi
+
+    # get info on last received sub
+    last_received_gen=0
+    for f in ${snaps[@]}; do
+        show="$(btrfs sub show $f)"
+        if echo "$show" | grep -E "Received UUID:\s+[[:alnum:]]" &>/dev/null; then
+            cgen=$(echo "$show" | sed -rn 's,^\s*Gen at creation:\s+([0-9]+).*,\1,p')
+            if [[ $cgen -gt $last_received_gen ]]; then
+                last_received_cgen=$cgen
+                last_received=$f
+            fi
+        fi
+    done
+
+    # Get last_snap by date.
     # when a btrbk bugfix makes it into the distro,
     # we might replace this with btrbk list latest /mnt/root/$vol | ...
-    # note: this is duplicated in mount-latest-subvol
     last_snap=$(
-        for f in ${snaps[@]}; do
-            printf "%s %s\n" $(date -d $(sed -r  's/(.{4})(..)(.{5})(..)(.*)/\1-\2-\3:\4:\5/' <<<${f#$vol.}) +%s) $f
+        for s in ${snaps[@]}; do
+            f=${s##*/}
+            unix_time=$(date -d $(sed -r  's/(.{4})(..)(.{5})(..)(.*)/\1-\2-\3:\4:\5/' <<<${f#$vol.}) +%s)
+            printf "%s %s\n" $unix_time $s
         done | sort -r | head -n 1 | awk '{print $2}'
              )
     if [[ ! $last_snap ]]; then
         # should not happen.
-        echo "$0: error: could not find latest snapshot for $d among ${snaps[@]}"
+        echo "$0: error: could not find latest snapshot for $svp among ${snaps[*]}"
         ret=1
         continue
     fi
 
-    # check that $d has $last_snap as a snapshot,
-    # or else $d is a snapshot of $last_snap. In the second
-    # case, we use a uuid comparison, which if I remember from the
-    # docs, is a bit more robust, perhaps to renames.
-    if btrfs sub show $d 2>/dev/null | sed '0,/^\s*Snapshot(s):/d;s/^\s*//' | \
-            grep -xF btrbk/$last_snap &>/dev/null; then
-        stale=false
-    else
-        last_snap_uuid=$(btrfs sub show $last_snap| awk '$1 == "UUID:" {print $2}')
-        if btrfs sub show $d| grep "^\s*Parent UUID:\s*$last_snap_uuid$" &>/dev/null; then
-            stale=false
-        fi
+    if [[ ! -e $svp ]]; then
+        echo "$0: warning: subvol does not exist: $svp"
+        echo "$0 assuming this host was just for receiving and latest snap is freshest"
+        freshest_snap=$last_snap
+        stale=true
+        stale-file
+        continue
     fi
 
-    # check if $d is a snapshot of any of the btrbk backups other than the latest
-    if [[ ! $stale ]]; then
-        for f in ${snaps[@]}; do
-            if [[ $f == $last_snap ]]; then continue; fi
-            uuid=$(btrfs sub show $f| awk '$1 == "UUID:" {print $2}')
-            if btrfs sub show $d| grep "^\s*Parent UUID:\s*$uuid$" &>/dev/null; then
-                stale=true
-                echo "$d stale: it's a snapshot of $f"
-                break
-            fi
-        done
-    fi
-    # check if $d generation is later than last_snap
-    if [[ ! $stale ]]; then
-        last_snap_gen=$(btrfs sub show $last_snap| awk '$1 == "Generation:" {print $2}')
-        d_gen=$(btrfs sub show $d| awk '$1 == "Generation:" {print $2}')
-        if (( d_gen < last_snap_gen  )); then
+
+    # if there is a last_received, we can assume stale or fresh if we are newer/older
+    if [[ $last_received ]]; then
+        svp_cgen=$(btrfs sub show $svp | sed -rn 's,^\s*Gen at creation:\s+([0-9]+).*,\1,p')
+        if [[ $svp_cgen -ge $last_received_cgen ]]; then
             stale=false
         else
-            echo "$d stale: it's generation, $d_gen, is earlier than the last snapshot's, $last_snap_gen"
+            echo "$svp stale: it's gen at creation, $svp_cgen, is earlier than the last received snapshot, $last_received's gen at creation: $last_received_cgen"
+            freshest_snap=$last_received
             stale=true
         fi
+        stale-file
+        continue
     fi
 
-
-    stale_dir=/nocow/btrfs-stale
-    stale_file=$stale_dir/$vol
-    if $stale; then
-        mkdir -p $stale_dir
-        printf "%s\n" $last_snap > $stale_file
-        ret=1
-        continue
-    else
-        rm -f $stale_file
+    # fallback to using last_snap as the freshest
+    freshest_snap=$last_snap
+    stale=true
+    # fresh if $svp has $last_snap as a snapshot,
+    if btrfs sub show $svp 2>/dev/null | sed '0,/^\s*Snapshot(s):/d;s/^\s*//' | \
+            grep -xF btrbk/$last_snap &>/dev/null; then
+        stale=false
+    else # or else $svp is a snapshot of $last_snap. we use a uuid
+        # comparison, which if I remember from the docs, is a bit more
+        # robust, perhaps to renames.
+        last_snap_uuid=$(btrfs sub show $last_snap| awk '$1 == "UUID:" {print $2}')
+        if btrfs sub show $svp| grep "^\s*Parent UUID:\s*$last_snap_uuid$" &>/dev/null; then
+            stale=false
+        fi
     fi
+
+    stale-file
+
 done
 exit $ret