Skip snapshot in zfs_iter_mounted()

The intention of the zfs_iter_mounted() is to traverse the dataset
and its descendants, not the snapshots. The current code can cause
a mounted snapshot to be included and thus zfs_open() on the snapshot
with ZFS_TYPE_FILESYSTEM would print confusing message such as "cannot
open 'rpool/fs@snap': snapshot delimiter '@' is not expected here".

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Youzhong Yang <yyang@mathworks.com>
Closes #12447
Closes #12448

lib/libzfs/libzfs_iter.c

@@ -575,8 +575,11 @@ zfs_iter_mounted(zfs_handle_t *zhp, zfs_iter_f func, void *data)
 
 		/* Ignore datasets not within the provided dataset */
 		if (strncmp(entry.mnt_special, zhp->zfs_name, namelen) != 0 ||
-		    (entry.mnt_special[namelen] != '/' &&
-		    entry.mnt_special[namelen] != '@'))
+		    entry.mnt_special[namelen] != '/')
+			continue;
+
+		/* Skip snapshot of any child dataset */
+		if (strchr(entry.mnt_special, '@') != NULL)
 			continue;
 
 		if ((mtab_zhp = zfs_open(zhp->zfs_hdl, entry.mnt_special,

tests/test-runner/include/logapi.shlib

@@ -68,6 +68,16 @@ function log_must
 	(( $? != 0 )) && log_fail
 }
 
+# Execute a positive test (expecting no stderr) and exit $STF_FAIL
+# if test fails
+# $@ - command to execute
+
+function log_must_nostderr
+{
+	log_pos_nostderr "$@"
+	(( $? != 0 )) && log_fail
+}
+
 # Execute a positive test but retry the command on failure if the output
 # matches an expected pattern.  Otherwise behave like log_must and exit
 # $STF_FAIL is test fails.
@@ -292,6 +302,46 @@ function log_pos
 	return $status
 }
 
+# Execute and print command with status where success equals zero result
+# and no stderr output
+#
+# $@ command to execute
+#
+# return 0 if command succeeds and no stderr output
+# return 1 othersie
+
+function log_pos_nostderr
+{
+	typeset out=""
+	typeset logfile="/tmp/log.$$"
+
+	while [[ -e $logfile ]]; do
+		logfile="$logfile.$$"
+	done
+
+	"$@" 2>$logfile
+	typeset status=$?
+	out="cat $logfile"
+	typeset out_msg=$($out)
+
+	if (( $status != 0 )) ; then
+		print -u2 $out_msg
+		_printerror "$@" "exited $status"
+	else
+		if [[ ! -z "$out_msg" ]]; then
+			print -u2 $out_msg
+			_printerror "$@" "message in stderr" \
+				" exited $status"
+			status=1
+		else
+			[[ -n $LOGAPI_DEBUG ]] && cat $logfile
+			_printsuccess "$@"
+		fi
+	fi
+	_recursive_output $logfile "false"
+	return $status
+}
+
 # Set an exit handler
 #
 # $@ - function(s) to perform on exit

tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_nested.ksh

@@ -83,7 +83,7 @@ for d in ${test_depths[@]}; do
 	log_must zfs snapshot $TESTPOOL/$ds@snap
 	# force snapshot mount in .zfs
 	log_must ls /$TESTPOOL/$ds/.zfs/snapshot/snap
-	log_must zfs unmount $TESTPOOL/$ds
+	log_must_nostderr zfs unmount $TESTPOOL/$ds
 
 	if ! ismounted $TESTPOOL/$ds_pre; then
 		log_fail "$ds_pre is not mounted"
@@ -113,7 +113,7 @@ for d in ${test_depths[@]}; do
 	log_must zfs snapshot $TESTPOOL/$ds@snap
 	# force snapshot mount in .zfs
 	log_must ls /$TESTPOOL/$ds/.zfs/snapshot/snap
-	log_must zfs unmount $TESTPOOL/$ds
+	log_must_nostderr zfs unmount $TESTPOOL/$ds
 
 	if ! ismounted $TESTPOOL/$ds_pre; then
 		log_fail "$TESTPOOL/$ds_pre (pre) not mounted"
@@ -143,7 +143,7 @@ for d in ${test_depths[@]}; do
 	log_must zfs snapshot $TESTPOOL/$ds@snap
 	# force snapshot mount in .zfs
 	log_must ls /$TESTPOOL/$ds/.zfs/snapshot/snap
-	log_must zfs unmount $TESTPOOL/$ds
+	log_must_nostderr zfs unmount $TESTPOOL/$ds
 
 	if ! ismounted $TESTPOOL/$ds_pre; then
 		log_fail "$TESTPOOL/$ds_pre (pre) not mounted"
@@ -173,7 +173,7 @@ for d in ${test_depths[@]}; do
 	log_must zfs snapshot $TESTPOOL/$ds@snap
 	# force snapshot mount in .zfs
 	log_must ls /$TESTPOOL/$ds/.zfs/snapshot/snap
-	log_must zfs unmount $TESTPOOL/$ds
+	log_must_nostderr zfs unmount $TESTPOOL/$ds
 
 	if ! ismounted $TESTPOOL/$ds_pre; then
 		log_fail "$ds_pre is not mounted"