Log ZTS test name to dmesg

Log each test name to dmesg to help post-mortem test failures.
Specifically, to help debug #10940.

Signed-off-by: Tony Hutter <hutter2@llnl.gov>

TEST

@@ -5,21 +5,21 @@
 #TEST_PREPARE_SHARES="yes"
 
 ### ztest
-#TEST_ZTEST_SKIP="yes"
+TEST_ZTEST_SKIP="yes"
 #TEST_ZTEST_TIMEOUT=1800
 #TEST_ZTEST_DIR="/var/tmp/"
 #TEST_ZTEST_OPTIONS="-V"
 #TEST_ZTEST_CORE_DIR="/mnt/zloop"
 
 ### zimport
-#TEST_ZIMPORT_SKIP="yes"
+TEST_ZIMPORT_SKIP="yes"
 #TEST_ZIMPORT_DIR="/var/tmp/zimport"
 #TEST_ZIMPORT_VERSIONS="master installed"
 #TEST_ZIMPORT_POOLS="zol-0.6.1 zol-0.6.2 master installed"
 #TEST_ZIMPORT_OPTIONS="-c"
 
 ### xfstests
-#TEST_XFSTESTS_SKIP="yes"
+TEST_XFSTESTS_SKIP="yes"
 #TEST_XFSTESTS_URL="https://github.com/behlendorf/xfstests/archive/"
 #TEST_XFSTESTS_VER="zfs.tar.gz"
 #TEST_XFSTESTS_POOL="tank"
@@ -38,7 +38,7 @@
 #TEST_ZFSTESTS_TAGS="functional"
 
 ### zfsstress
-#TEST_ZFSSTRESS_SKIP="yes"
+TEST_ZFSSTRESS_SKIP="yes"
 #TEST_ZFSSTRESS_URL="https://github.com/nedbass/zfsstress/archive/"
 #TEST_ZFSSTRESS_VER="master.tar.gz"
 #TEST_ZFSSTRESS_RUNTIME=300

tests/zfs-tests/include/libtest.shlib

@@ -268,6 +268,30 @@ function default_setup_no_mountpoint
 	log_pass
 }
 
+
+function backtrace {
+        typeset -a stack 
+        # Use "set -u" and an undefined variable access in a subshell
+        # to figure out how we got here.  Each token of the result is
+        # stored as an element in an indexed array named "stack".
+        set -A stack $(exec 2>&1; set -u; unset __unset__; echo $__unset__)
+
+        # Trim the last entries in stack array until we find the one that
+        # matches the name of this function.
+        typeset i=0
+        for (( i = ${#stack[@]} - 1; i >= 0; i-- )); do
+                [[ "${stack[i]}" == "${.sh.fun}:" ]] && break
+        done
+
+        # Print the name of the function that called this one, stripping off
+        # the [lineno] and appending any arguments provided to this function.
+        print -u2 "${stack[i-1]/\[[0-9]*\]} $*"
+        # Print the backtrace.
+        for (( i--; i >= 0; i-- )); do
+                print -u2 "\t${stack[i]%:}"
+        done
+}
+
 #
 # Given a list of disks, setup storage pools and datasets.
 #
@@ -279,6 +303,11 @@ function default_setup_noexit
 	typeset no_mountpoint=$4
 	log_note begin default_setup_noexit
 
+	# Crudely log to dmesg which test we're running for post-mortem
+	me="$(ps aux | grep zfs-tests) | head -n 1)"
+	echo "ZTS: running $me ($0)" > /dev/kmsg
+	backtrace > /dev/kmsg	
+
 	if is_global_zone; then
 		if poolexists $TESTPOOL ; then
 			destroy_pool $TESTPOOL