[LTP] [PATCH 2/5] fcntl41: test for owner values on OFD posix locks

[Alexander Aring]

This patch adds fcntl41 to test similar owner values for OFD locks.
There was an issue been found in the gfs2 filesystem because there
can be collisions with identical owner values.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 testcases/kernel/syscalls/fcntl/.gitignore |   2 +
 testcases/kernel/syscalls/fcntl/fcntl41.c  | 178 +++++++++++++++++++++
 2 files changed, 180 insertions(+)
 create mode 100644 testcases/kernel/syscalls/fcntl/fcntl41.c

diff --git a/testcases/kernel/syscalls/fcntl/.gitignore b/testcases/kernel/syscalls/fcntl/.gitignore
index e558cfe83..4bdae1a22 100644
--- a/testcases/kernel/syscalls/fcntl/.gitignore
+++ b/testcases/kernel/syscalls/fcntl/.gitignore
@@ -76,3 +76,5 @@
 /fcntl39_64
 /fcntl40
 /fcntl40_64
+/fcntl41
+/fcntl41_64
diff --git a/testcases/kernel/syscalls/fcntl/fcntl41.c b/testcases/kernel/syscalls/fcntl/fcntl41.c
new file mode 100644
index 000000000..40d14ff02
--- /dev/null
+++ b/testcases/kernel/syscalls/fcntl/fcntl41.c
@@ -0,0 +1,178 @@
+/*
+ * [Description]
+ * Tests gfs2 dlm posix op queue handling in the kernel.
+ * It is recommended to run watch -n 0.1 "dlm_tool plocks $LS"
+ * aside to monitor dlm plock handling.
+ *
+ * [How to use it]
+ * Call it with TMPDIR=/mnt ./fcntl41 where TMPDIR is a gfs2 mountpoint.
+ * Try it on other filesystems to compare results.
+ *
+ * [What's it doing]
+ *
+ * The test shows that we currently have problems with the operation lookup
+ * functionality [0] when we using threads. The owner value is the same for two
+ * locks being in WAITING state. dlm_controld "dlm_tool plocks $LS" will show
+ * it correctly that the specific lock is not in waiting anymore. The issue
+ * begins matching the right iter->done in the kernel at dev_write() see [0].
+ *
+ * What this test does is (using dlm_controld interval range interpretation):
+ *
+ * parent:
+ *
+ * 1. lock[0-1]
+ *
+ * child:
+ *
+ * thread1:
+ *
+ * 2. lockw[1-1] - important 1-1 at first because the order of WAITING state
+ *                 locks matters
+ *
+ * thread2:
+ *
+ * 3. lockw[0-0]
+ *
+ * parent:
+ *
+ * 4. unlock[1-1] - will give a iter->done = 1 in [0] for lock at 3. and the
+ *                  application results in a deadlock
+ * 5. unlock[0-0]
+ *
+ * We have this issue also with SETLK, GETLK - it's easier to reproduce
+ * with SETLKW because dev_write() is more controlable by doing unlocks.
+ *
+ * OFD (open filedescriptor locks) are also affected and should be able
+ * to reproduce with fork() only and not threads. The owner value of [0]
+ * depends on "struct file *" pointer in this case.
+ *
+ * [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/dlm/plock.c?h=v6.3#n432
+ */
+
+#include <sys/wait.h>
+
+#include "tst_test.h"
+
+static int fd, fd2;
+
+void do_child1(void)
+{
+	const struct flock fl_0_0 = {
+		.l_type = F_WRLCK,
+		.l_whence = SEEK_SET,
+		.l_start = 0L,
+		.l_len = 1L,
+	};
+
+	tst_res(TINFO, "thread1 waits for thread2 to lock 1-1");
+	TST_CHECKPOINT_WAIT(1);
+
+	tst_res(TINFO, "thread1 lock region 0-0 - It should block");
+	SAFE_FCNTL(fd2, F_OFD_SETLKW, &fl_0_0);
+	tst_res(TINFO, "lock region 0-0 acquired");
+
+	tst_res(TPASS, "Child1 passed!");
+}
+
+void do_child2(void)
+{
+	const struct flock fl_1_1 = {
+		.l_type = F_WRLCK,
+		.l_whence = SEEK_SET,
+		.l_start = 1L,
+		.l_len = 1L,
+	};
+
+	tst_res(TINFO, "thread1 lock region 1-1 - It should block");
+	SAFE_FCNTL(fd2, F_OFD_SETLKW, &fl_1_1);
+	tst_res(TINFO, "lock region 1-1 acquired");
+
+	TST_CHECKPOINT_WAKE(2);
+	tst_res(TPASS, "Child2 passed!");
+}
+
+void do_parent(void)
+{
+	struct flock fl = {
+		.l_whence = SEEK_SET,
+	};
+
+	/* wait for 1 seconds so thread2 lock 1-1 tries to acquires at first
+	 * than thread1 lock 0-0 tries to acquired to have a specific waiting
+	 * order in dlm posix handling.
+	 */
+	sleep(1);
+	/* tell thread2 to call SETLKW for lock 0-0 */
+	TST_CHECKPOINT_WAKE(1);
+	/* wait 3 seconds for thread 1 and 2 being in waiting state */
+	sleep(3);
+
+	/* unlock 0-1, should be successful */
+	fl.l_type = F_UNLCK;
+	fl.l_start = 1;
+	fl.l_len = 1;
+	tst_res(TINFO, "unlock region 1-1 thread2");
+	SAFE_FCNTL(fd, F_OFD_SETLK, &fl);
+
+	/* wait until thread 2 got acquired and leave waiting */
+	TST_CHECKPOINT_WAIT(2);
+
+	fl.l_start = 0;
+	fl.l_len = 1;
+	fl.l_type = F_UNLCK;
+	tst_res(TINFO, "unlock region 0-0 thread2");
+	SAFE_FCNTL(fd, F_OFD_SETLK, &fl);
+}
+
+static void fcntl40_test(void)
+{
+	struct flock fl = {
+		.l_type = F_WRLCK,
+		.l_whence = SEEK_SET,
+		.l_start = 0L,
+		.l_len = 2L,
+	};
+	pid_t pid;
+
+	tst_res(TINFO, "parent lock region 0-1 - should be successful");
+	SAFE_FCNTL(fd, F_OFD_SETLK, &fl);
+	tst_res(TINFO, "parent region 0-1 locked");
+
+	pid = SAFE_FORK();
+	if (pid == 0) {
+		do_child1();
+		return;
+	}
+
+	pid = SAFE_FORK();
+	if (pid == 0) {
+		do_child2();
+		return;
+	}
+
+	do_parent();
+	wait(NULL);
+	wait(NULL);
+
+	tst_res(TPASS, "Parent passed!");
+}
+
+static void setup(void)
+{
+	fd = SAFE_OPEN("filename", O_RDWR | O_CREAT, 0700);
+	fd2 = SAFE_OPEN("filename", O_RDWR | O_CREAT, 0700);
+}
+
+static void cleanup(void)
+{
+	if (fd > -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.forks_child = 1,
+	.needs_checkpoints = 1,
+	.test_all = fcntl40_test,
+	.setup = setup,
+	.cleanup = cleanup,
+};
-- 
2.31.1