zvol_wait: fix for zvols with spaces in name, optimise

list_zvols() would happily, for zvols with spaces in their names,
assign the second half to volmode, &c., so use a normal read
and set IFS to a tab instead of using 4 separate AWK processes(?)

Similarly, in filter_out_deleted_zvols(), run zfs(8) once and use the
output directly instead of spawning a zfs(8) process per zvol

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Pavel Zakharov <[email protected]>
Reviewed-by: Ryan Moeller <[email protected]>
Signed-off-by: Ahelenia Ziemiańska <[email protected]>
Closes #11859

1 files changed, 12 insertions, 16 deletions

diff --git a/cmd/zvol_wait/zvol_wait b/cmd/zvol_wait/zvol_wait
index eb1b3e81f..90a4bf8dd 100755
--- a/cmd/zvol_wait/zvol_wait
+++ b/cmd/zvol_wait/zvol_wait
@@ -9,29 +9,25 @@ count_zvols() {
 }
 
 filter_out_zvols_with_links() {
-	while read -r zvol; do
-		if [ ! -L "/dev/zvol/$zvol" ]; then
+	echo "$zvols" | tr ' ' '+' | while read -r zvol; do
+		if ! [ -L "/dev/zvol/$zvol" ]; then
 			echo "$zvol"
 		fi
-	done
+	done | tr '+' ' '
 }
 
 filter_out_deleted_zvols() {
-	while read -r zvol; do
-		if zfs list "$zvol" >/dev/null 2>&1; then
-			echo "$zvol"
-		fi
-	done
+	OIFS="$IFS"
+	IFS="
+"
+	zfs list -H -o name $zvols 2>/dev/null
+	IFS="$OIFS"
 }
 
 list_zvols() {
 	zfs list -t volume -H -o \
-		name,volmode,receive_resume_token,redact_snaps |
-		while read -r zvol_line; do
-		name=$(echo "$zvol_line" | awk '{print $1}')
-		volmode=$(echo "$zvol_line" | awk '{print $2}')
-		token=$(echo "$zvol_line" | awk '{print $3}')
-		redacted=$(echo "$zvol_line" | awk '{print $4}')
+	    name,volmode,receive_resume_token,redact_snaps |
+	    while IFS="	" read -r name volmode token redacted; do # IFS=\t here!
 		#
 		# /dev links are not created for zvols with volmode = "none"
 		# or for redacted zvols.
@@ -75,7 +71,7 @@ while [ "$outer_loop" -lt 20 ]; do
 	while [ "$inner_loop" -lt 30 ]; do
 		inner_loop=$((inner_loop + 1))
 
-		zvols="$(echo "$zvols" | filter_out_zvols_with_links)"
+		zvols="$(filter_out_zvols_with_links)"
 
 		zvols_count=$(count_zvols)
 		if [ "$zvols_count" -eq 0 ]; then
@@ -95,7 +91,7 @@ while [ "$outer_loop" -lt 20 ]; do
 		echo "No progress since last loop."
 		echo "Checking if any zvols were deleted."
 
-		zvols=$(echo "$zvols" | filter_out_deleted_zvols)
+		zvols=$(filter_out_deleted_zvols)
 		zvols_count=$(count_zvols)
 
 		if [ "$old_zvols_count" -ne "$zvols_count" ]; then