test/sqpoll-exec: add test case for file being immediately closedHEADmaster

Add test case for whether or not exec fails right after we've reaped a
CQE for the final close of a file. If the file hasn't gone through it's
final fput yet, then the exec will fail with ETXTBUSY.

Link: https://lore.kernel.org/all/313824bc-799d-414f-96b7-e6de57c7e21d@gmail.com/
Link: https://lore.kernel.org/io-uring/40c7404a-f4ce-4a7d-86f3-313a9e9ee113@kernel.dk/
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 132 insertions, 0 deletions

diff --git a/test/Makefile b/test/Makefile
index 9a65ba6c..2521e123 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -186,6 +186,7 @@ test_srcs := \
 	sq-full.c \
 	sq-full-cpp.cc \
 	sqpoll-disable-exit.c \
+	sqpoll-exec.c \
 	sq-poll-dup.c \
 	sqpoll-exit-hang.c \
 	sq-poll-kthread.c \
diff --git a/test/sqpoll-exec.c b/test/sqpoll-exec.c
new file mode 100644
index 00000000..c5beb48f
--- /dev/null
+++ b/test/sqpoll-exec.c
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Description: Check that closing a file with SQPOLL has it immediately closed
+ *		upon receiving the CQE for the close. The 6.9 kernel had a bug
+ *		where SQPOLL would not run kernel wide task_work when running the
+ *		private task_work, which would defer the close if this was the
+ *		final close of the file.
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "helpers.h"
+#include "liburing.h"
+
+static int fill_exec_target(char *dst, char *path)
+{
+	struct stat sb;
+
+	/*
+	 * Should either be ./exec-target.t or test/exec-target.t
+	 */
+	sprintf(dst, "%s", path);
+	return stat(dst, &sb);
+}
+
+static int test_exec(struct io_uring *ring, char * const argv[])
+{
+	char prog_path[PATH_MAX];
+	struct io_uring_sqe *sqe;
+	struct io_uring_cqe *cqe;
+	int ret, wstatus, fd;
+	pid_t p;
+
+	if (fill_exec_target(prog_path, "./exec-target.t") &&
+	    fill_exec_target(prog_path, "test/exec-target.t")) {
+		fprintf(stdout, "Can't find exec-target, skipping\n");
+		return 0;
+	}
+
+	sqe = io_uring_get_sqe(ring);
+	io_uring_prep_openat(sqe, AT_FDCWD, prog_path, O_WRONLY, 0);
+	sqe->user_data = 0;
+
+	io_uring_submit(ring);
+
+	ret = io_uring_wait_cqe(ring, &cqe);
+	if (ret) {
+		fprintf(stderr, "wait cqe %d\n", ret);
+		return 1;
+	}
+	if (cqe->res < 0) {
+		fprintf(stderr, "open: %d\n", cqe->res);
+		return 1;
+	}
+	fd = cqe->res;
+	io_uring_cqe_seen(ring, cqe);
+
+	sqe = io_uring_get_sqe(ring);
+	io_uring_prep_close(sqe, fd);
+	sqe->user_data = 1;
+
+	io_uring_submit(ring);
+
+	ret = io_uring_wait_cqe(ring, &cqe);
+	if (ret) {
+		fprintf(stderr, "wait cqe %d\n", ret);
+		return 1;
+	}
+	if (cqe->res < 0) {
+		fprintf(stderr, "close: %d\n", cqe->res);
+		return 1;
+	}
+	io_uring_cqe_seen(ring, cqe);
+
+	p = fork();
+	if (p == -1) {
+		fprintf(stderr, "fork() failed\n");
+		return 1;
+	}
+
+	if (p == 0) {
+		/* file should be closed, try exec'ing it */
+		ret = execve(prog_path, argv, NULL);
+		if (ret) {
+			fprintf(stderr, "exec failed: %s\n", strerror(errno));
+			exit(1);
+		}
+	}
+
+	if (waitpid(p, &wstatus, 0) == (pid_t)-1) {
+		perror("waitpid()");
+		return 1;
+	}
+	if (!WIFEXITED(wstatus) || WEXITSTATUS(wstatus))
+		return 1;
+
+	return 0;
+}
+
+int main(int argc, char * const argv[])
+{
+	struct io_uring ring;
+	int ret, i;
+
+	if (argc > 1)
+		return 0;
+
+	ret = io_uring_queue_init(8, &ring, IORING_SETUP_SQPOLL);
+	if (ret) {
+		fprintf(stderr, "ring create failed: %d\n", ret);
+		return 1;
+	}
+
+	for (i = 0; i < 20; i++) {
+		ret = test_exec(&ring, argv);
+		if (ret) {
+			fprintf(stderr, "test_exec failed\n");
+			return ret;
+		}
+	}
+
+	return 0;
+}