MDEV-29893: SST fails when having datadir set to a symlink

SST for mariabackup may not destroy old files if datadir or
other working directory is declared as a symlink due to the lack
of the "-L" option among the find utility options, similarly SST
for rsync in some cases may not transfer data directories if they
are created as symlinks. This fix adds the missing option and
generally unifies the work with find utility options to avoid
failures in the interpretation of directories and regular
expressions.

scripts/wsrep_sst_mariabackup.sh

@@ -439,7 +439,7 @@ get_transfer()
 get_footprint()
 {
     cd "$DATA_DIR"
-    local payload_data=$(find . \
+    local payload_data=$(find $findopt . \
         -regex '.*undo[0-9]+$\|.*\.ibd$\|.*\.MYI$\|.*\.MYD$\|.*ibdata1$' \
         -type f -print0 | du --files0-from=- --block-size=1 -c -s | \
         awk 'END { print $1 }')
@@ -1035,6 +1035,9 @@ setup_commands()
 get_stream
 get_transfer
 
+findopt='-L'
+[ "$OS" = 'FreeBSD' ] && findopt="$findopt -E"
+
 if [ "$WSREP_SST_OPT_ROLE" = 'donor' ]; then
 
     trap cleanup_at_exit EXIT
@@ -1428,21 +1431,13 @@ else # joiner
 
         wsrep_log_info \
             "Cleaning the existing datadir and innodb-data/log directories"
-        if [ "$OS" = 'FreeBSD' ]; then
-            find -E ${ib_home_dir:+"$ib_home_dir"} \
-                    ${ib_undo_dir:+"$ib_undo_dir"} \
-                    ${ib_log_dir:+"$ib_log_dir"} \
-                    ${ar_log_dir:+"$ar_log_dir"} \
-                    "$DATA" -mindepth 1 -prune -regex "$cpat" \
-                    -o -exec rm -rf {} >&2 \+
-        else
-            find ${ib_home_dir:+"$ib_home_dir"} \
-                 ${ib_undo_dir:+"$ib_undo_dir"} \
-                 ${ib_log_dir:+"$ib_log_dir"} \
-                 ${ar_log_dir:+"$ar_log_dir"} \
-                 "$DATA" -mindepth 1 -prune -regex "$cpat" \
-                 -o -exec rm -rf {} >&2 \+
-        fi
+
+        find $findopt ${ib_home_dir:+"$ib_home_dir"} \
+                ${ib_undo_dir:+"$ib_undo_dir"} \
+                ${ib_log_dir:+"$ib_log_dir"} \
+                ${ar_log_dir:+"$ar_log_dir"} \
+                "$DATA" -mindepth 1 -prune -regex "$cpat" \
+                -o -exec rm -rf {} >&2 \+
 
         TDATA="$DATA"
         DATA="$DATA/.sst"
@@ -1464,7 +1459,7 @@ else # joiner
             exit 2
         fi
 
-        qpfiles=$(find "$DATA" -maxdepth 1 -type f -name '*.qp' -print -quit)
+        qpfiles=$(find $findopt "$DATA" -maxdepth 1 -type f -name '*.qp' -print -quit)
         if [ -n "$qpfiles" ]; then
             wsrep_log_info "Compressed qpress files found"
 
@@ -1480,7 +1475,7 @@ else # joiner
             if [ -n "$progress" -a "$progress" != 'none' ] && \
                pv --help | grep -qw -F -- '--line-mode'
             then
-                count=$(find "$DATA" -maxdepth 1 -type f -name '*.qp' | wc -l)
+                count=$(find $findopt "$DATA" -maxdepth 1 -type f -name '*.qp' | wc -l)
                 count=$(( count*2 ))
                 pvopts='-f -l -N Decompression'
                 pvformat="-F '%N => Rate:%r Elapsed:%t %e Progress: [%b/$count]'"
@@ -1492,13 +1487,13 @@ else # joiner
             # Decompress the qpress files
             wsrep_log_info "Decompression with $nproc threads"
             timeit 'Joiner-Decompression' \
-                   "find '$DATA' -type f -name '*.qp' -printf '%p\n%h\n' | \
+                   "find $findopt '$DATA' -type f -name '*.qp' -printf '%p\n%h\n' | \
                    $dcmd"
             extcode=$?
 
             if [ $extcode -eq 0 ]; then
                 wsrep_log_info "Removing qpress files after decompression"
-                find "$DATA" -type f -name '*.qp' -delete
+                find $findopt "$DATA" -type f -name '*.qp' -delete
                 if [ $? -ne 0 ]; then
                     wsrep_log_error \
                         "Something went wrong with deletion of qpress files." \

scripts/wsrep_sst_rsync.sh

@@ -673,9 +673,12 @@ FILTER="-f '- /lost+found'
 
         cd "$DATA"
 
-        find . -maxdepth 1 -mindepth 1 -type d -not -name 'lost+found' \
+        findopt='-L'
+        [ "$OS" = 'FreeBSD' ] && findopt="$findopt -E"
+
+        find $findopt . -maxdepth 1 -mindepth 1 -type d -not -name 'lost+found' \
              -not -name '.zfs' -not -name .snapshot -print0 \
-	     | xargs -I{} -0 -P $backup_threads \
+             | xargs -I{} -0 -P $backup_threads \
              rsync ${STUNNEL:+--rsh="$STUNNEL"} \
              --owner --group --perms --links --specials --ignore-times \
              --inplace --recursive --delete --quiet $WHOLE_FILE_OPT \