zdtm: add file_lease05 test for broken read lease restore

Add a test that exercises the broken read lease restore path. The test:

 1. Opens a file O_RDONLY and takes a read lease (F_RDLCK).
 2. Triggers the breaking sequence by attempting a conflicting
    O_WRONLY | O_NONBLOCK open (which returns EWOULDBLOCK).
 3. Forks a child to verify post-restore lease state.
 4. Calls test_daemon() / test_waitsig() to go through C/R.
 5. After restore, the child verifies that the lease type is F_UNLCK
    (the expected target type for a broken read lease), confirming
    that the breaking sequence was correctly re-established.

Without the preceding fix, restore_lease_prebreaking_state() would set a
write lease (F_WRLCK) instead of a read lease on the read-only fd,
causing either a restore failure (EACCES) or a wrong lease type
post-restore. This test fails without the fix and passes with it.

Signed-off-by: Andrei Vagin <avagin@google.com>

Author: avagin

test/zdtm/static/Makefile

@@ -366,6 +366,7 @@ TST_FILE	=				\
 		file_lease02			\
 		file_lease03			\
 		file_lease04			\
+		file_lease05			\
 		file_locks00			\
 		file_locks00_fail		\
 		file_locks01			\

test/zdtm/static/file_lease05.c

@@ -0,0 +1,89 @@
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/wait.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc = "Check broken read-lease is restored with correct type";
+const char *test_author = "Andrei Vagin <avagin@gmail.com>";
+
+char *filename;
+TEST_OPTION(filename, string, "file name", 1);
+
+static void break_sigaction(int signo, siginfo_t *info, void *ctx)
+{
+}
+
+int main(int argc, char **argv)
+{
+	struct sigaction act = {};
+	int fd;
+
+	test_init(argc, argv);
+
+	act.sa_sigaction = break_sigaction;
+	act.sa_flags = SA_SIGINFO | SA_RESTART;
+	if (sigaction(SIGIO, &act, NULL)) {
+		pr_perror("Can't set signal action");
+		return 1;
+	}
+
+	fd = open(filename, O_RDONLY | O_CREAT, 0666);
+	if (fd < 0) {
+		pr_perror("Can't open file");
+		return 1;
+	}
+
+	if (fcntl(fd, F_SETLEASE, F_RDLCK) < 0) {
+		pr_perror("Can't set read lease");
+		return 1;
+	}
+
+	if (fcntl(fd, F_SETSIG, SIGIO) < 0) {
+		pr_perror("Can't set lease signal");
+		return 1;
+	}
+
+	{
+		int fd_break = open(filename, O_WRONLY | O_NONBLOCK);
+		if (fd_break >= 0) {
+			close(fd_break);
+			pr_err("Conflicting lease not found\n");
+			return 1;
+		} else if (errno != EWOULDBLOCK) {
+			pr_perror("Can't break lease");
+			return 1;
+		}
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	{
+		int fd_check = open(filename, O_RDONLY | O_NONBLOCK);
+		if (fd_check >= 0) {
+			close(fd_check);
+		} else if (errno == EWOULDBLOCK) {
+			fail("Unexpected lease has been found");
+			return 1;
+		} else {
+			pr_perror("unexpected error");
+			return 1;
+		}
+	}
+	{
+		int fd_break = open(filename, O_WRONLY | O_NONBLOCK);
+		if (fd_break >= 0) {
+			close(fd_break);
+			fail("Conflicting lease not found");
+			return 1;
+		} else if (errno != EWOULDBLOCK) {
+			pr_perror("unexpected error");
+			return 1;
+		}
+	}
+	pass();
+	return 0;
+}

test/zdtm/static/file_lease05.desc

@@ -0,0 +1 @@
+{'feature': 'fdinfo_lock', 'opts': '--file-locks'}