ZTS: zfs_list_004_neg should not check paths that belong to ZFS

When ZFS is on root, /tmp is a ZFS. This causes zfs_list_004_neg to
fail since `zfs list` on /tmp passes when the test expects it not to.
The fix is to exclude paths that belong to ZFS.

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Palash Gandhi <pbg4930@rit.edu>
Closes #12744

tests/zfs-tests/tests/functional/cli_user/zfs_list/zfs_list.kshlib

@@ -116,3 +116,22 @@ function verify_reverse_sort { # command list name
 			"unexpected number of filesystems found in list output!"
 	fi
 }
+
+function is_fs_type_zfs {
+
+    typeset dirname=$1
+    typeset fs="$(df $dirname | tail -1 | awk '{print $NF}')"
+
+    if is_freebsd; then
+        fs_type=$(mount | awk -v fs=$fs '{if ($3 == fs) print $4}' \
+            | sed -n 's/(\(.*\),/\1/p')
+    elif is_linux; then
+        fs_type=$(mount | awk -v fs=$fs '{if ($3 == fs) print $5}')
+    fi
+
+    if [[ $fs_type == "zfs" ]]; then
+        true
+    else
+        false
+    fi
+}

tests/zfs-tests/tests/functional/cli_user/zfs_list/zfs_list_004_neg.ksh

@@ -29,7 +29,7 @@
 # Copyright (c) 2013, 2016 by Delphix. All rights reserved.
 #
 
-. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/cli_user/zfs_list/zfs_list.kshlib
 
 #
 # DESCRIPTION:
@@ -55,8 +55,12 @@ paths="$TESTPOOL/NONEXISTFS $TESTPOOL/$TESTFS/NONEXISTFS \
 cd /tmp
 
 for fs in $paths ; do
-	log_mustnot zfs list $fs
-	log_mustnot zfs list -r $fs
+    # In cases when ZFS is on root, /tmp will belong to ZFS and hence must be
+    # skipped
+    if ! is_fs_type_zfs $fs; then
+        log_mustnot zfs list $fs
+        log_mustnot zfs list -r $fs
+    fi
 done
 
 log_pass "'zfs list [-r]' fails while the given dataset/path does not exist " \