test: modprobe nbd at the start of autotest

This helps avoid issues with nbd not being ready when
we need it.

Still keep various "modprobe nbd" in different test
files - this ensures these test files can still be
run in isolation.  But remove the various "rmmod nbd"
to ensure that nbd always stays loaded.  There is no
harm in just keeping nbd loaded all the time.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I3597ff1f7ac53162c33a0384a33f33776cf6f182

Reviewed-on: https://review.gerrithub.io/434838
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>

autotest.sh

@@ -14,6 +14,10 @@ fi
 if [ $(uname -s) = Linux ]; then
 	# set core_pattern to a known value to avoid ABRT, systemd-coredump, etc.
 	echo "core" > /proc/sys/kernel/core_pattern
+
+	# make sure nbd (network block device) driver is loaded if it is available
+	# this ensures that when tests need to use nbd, it will be fully initialized
+	modprobe nbd || true
 fi
 
 trap "process_core; autotest_cleanup; exit 1" SIGINT SIGTERM EXIT

test/bdev/nbdjson/json_config.sh

@@ -25,6 +25,5 @@ timing_exit nbd_json_config_test
 
 $clear_config_py clear_config
 kill_targets
-rmmod nbd
 timing_exit nbd_json_config
 report_test_completion nbd_json_config

test/lvol/lvol.sh

@@ -122,7 +122,6 @@ function vhost_kill()
         sleep 1
     fi
     rm $BASE_DIR/vhost.pid || true
-    rmmod nbd || true
 }
 
 trap "vhost_kill; rm -f $BASE_DIR/aio_bdev_0 $BASE_DIR/aio_bdev_1; exit 1" SIGINT SIGTERM EXIT

test/vhost/vhost_boot/vhost_boot.sh

@@ -68,13 +68,12 @@ timing_exit create_lvol
 
 timing_enter convert_vm_image
 modprobe nbd
-trap 'nbd_stop_disks $(get_vhost_dir)/rpc.sock /dev/nbd0; rmmod nbd; err_clean "${FUNCNAME}" "${LINENO}"' ERR
+trap 'nbd_stop_disks $(get_vhost_dir)/rpc.sock /dev/nbd0; err_clean "${FUNCNAME}" "${LINENO}"' ERR
 nbd_start_disks "$(get_vhost_dir)/rpc.sock" $lvb_u /dev/nbd0
 $QEMU_PREFIX/bin/qemu-img convert $os_image -O raw /dev/nbd0
 sync
 nbd_stop_disks $(get_vhost_dir)/rpc.sock /dev/nbd0
 sleep 1
-rmmod nbd
 timing_exit convert_vm_image
 
 trap 'err_clean "${FUNCNAME}" "${LINENO}"' ERR