iotests/nbd-reconnect-on-open: Fix NBD socket path

Socket paths need to be short to avoid failures. This is why there is a
iotests.sock_dir (defaulting to /tmp) separate from the disk image base
directory.

Make use of it to fix failures in too deeply nested test directories.

Fixes: ab7f7e6
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230503165019.8867-1-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/tests/nbd-reconnect-on-open

@@ -26,7 +26,8 @@ from iotests import qemu_img_create, file_path, qemu_io_popen, qemu_nbd, \
 
 iotests.script_initialize(supported_fmts=['qcow2'])
 
-disk, nbd_sock = file_path('disk', 'nbd-sock')
+disk = file_path('disk')
+nbd_sock = file_path('nbd-sock', base_dir=iotests.sock_dir)
 
 
 def create_args(open_timeout):

tests/qemu-iotests/tests/nbd-reconnect-on-open.out

@@ -2,10 +2,10 @@ read 1048576/1048576 bytes at offset 0
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 Check fail to connect with 0 seconds of timeout
-qemu-io: can't open: Failed to connect to 'TEST_DIR/PID-nbd-sock': No such file or directory
+qemu-io: can't open: Failed to connect to 'SOCK_DIR/PID-nbd-sock': No such file or directory
 
 qemu_io finished in 0..0.2 seconds, OK
 Check fail to connect with 1 seconds of timeout
-qemu-io: can't open: Failed to connect to 'TEST_DIR/PID-nbd-sock': No such file or directory
+qemu-io: can't open: Failed to connect to 'SOCK_DIR/PID-nbd-sock': No such file or directory
 
 qemu_io finished in 1..1.2 seconds, OK