Merge tag 'vfs-7.3-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Bigger cleanups:

   - The lockref dead-count handling is tidied up.

     The open-coded check for a count below zero as the dead marker
     relies on information the caller should not have.

   - make put_mnt_ns() leave mounts connected. Destroying a mount
     namespace disconnected its mounts from their mount points. So a
     file descriptor still open on the parent of a mount point could be
     used to peek under it.

     Locked mounts were already kept connected to prevent exactly that.
     But a mount is only locked when its tree is copied across a user
     namespace boundary. So a mount namespace set up by a privileged
     component had no locked mounts and its mounts were disconnected.
     Passing UMOUNT_CONNECTED keeps every mount connected and prevents
     that bug.

   - vfs_prepare_mode() passes S_IFDIR for directories. I meant to fix
     that ago but didn't get to it. So now someone finally did it.

     This kills the exception where the mode could be 0 when a directory
     was created whereas every other creation operation passed it
     explicitly already.

   - move long delayed work for ufs, jffs2, hfsplus, hfs and affs from
     the per-cpu system_long_wq to the new unbound system_dfl_long_wq.

     None of that work relies on per-cpu state and the work item is
     enqueued with queue_delayed_work() whose timer is global anyway. So
     it may as well benefit from scheduler task placement.

  Smaller fixes and cleanups:

   - unlock_buffer() and journal_end_buffer_io_sync() use
     clear_and_wake_up_bit()

   - the pipe page pools are unified into a single per-pipe pool and the
     extra wake_up(rd_wait) is limited to EPOLLET consumers

   - eventpoll now computes its timer slack lazily in ep_poll()

   - shrink_dcache_for_umount() keeps making progress on busy roots

   - excess xarray nodes are freed in clear_inode()

   - romfs detects hard link cycles

   - the user path of nested backing files is fixed

   - pidfd holds exec_update_lock around the namespace ioctl

   - non-memcg-aware nr_cached_objects is skipped during memcg slab
     shrink

   - iomap_write_iter() always returns status

   - mangle_path() is renamed to seq_mangle_path()

   - inode timestamp accessors are annotated

   - new regression test for pipe->poll_usage.

   - a few documentation, kernel-doc and selftest fixes"

* tag 'vfs-7.3-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (67 commits)
  selftests/namespaces: Fix racy pipe handshake in timens and pidns_separate
  selftests/epoll: add a regression test for pipe->poll_usage
  pipe: only enable the extra wake_up(rd_wait) for EPOLLET consumers
  pidfd: hold exec_update_lock around namespace ioctl
  fs: fix user path of nested backing files
  fs: remove stale inode_insert5() kernel-doc parameter
  fs: fix switch/case indentation in sysfs() syscall
  fs: document semantics of kstat::{uid,gid} fields
  dcache: keep shrink_dcache_for_umount() making progress on busy roots
  seq_file: rename mangle_path to seq_mangle_path
  nstree: add/fix struct ns_id_req kernel-doc member fields
  dcache: use lockref routines for dead count checks
  lockref: tidy up dead count handling
  initramfs: fix typo in reserve_initrd_mem comment
  fs/pipe: unify the page pools into a single per-pipe pool
  fs: annotate inode timestamp accessors
  eventpoll: compute timer slack lazily in ep_poll()
  selftests/filesystems: add mntns cleanup test
  put_mnt_ns(): leave mounts connected
  affs: Move long delayed work on system_dfl_long_wq
  ...

8 files changed, 95 insertions, 5 deletions

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 4854a8eda449..8a4b6ddc68df 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -44,6 +44,7 @@ TARGETS += filesystems/move_mount
 TARGETS += filesystems/empty_mntns
 TARGETS += filesystems/fsmount_ns
 TARGETS += filesystems/fscontext_ns
+TARGETS += filesystems/mntns_cleanup
 TARGETS += firmware
 TARGETS += fpu
 TARGETS += ftrace
diff --git a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
index f6f1a7ff01b0..81a994943e12 100644
--- a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
+++ b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
@@ -3538,4 +3538,27 @@ TEST(epoll65)
 	close(ctx.efd[1]);
 }
 
+TEST(epoll66)
+{
+	struct epoll_event event;
+	int pfd[2], efd;
+
+	ASSERT_EQ(pipe(pfd), 0);
+
+	efd = epoll_create1(0);
+	ASSERT_GE(efd, 0);
+
+	event.events = EPOLLIN | EPOLLET;
+	ASSERT_EQ(epoll_ctl(efd, EPOLL_CTL_ADD, pfd[0], &event), 0);
+
+	for (int i = 0; i < 2; ++i) {
+		ASSERT_EQ(write(pfd[1], "", 1), 1);
+		EXPECT_EQ(epoll_wait(efd, &event, 1, 0), 1);
+	}
+
+	close(pfd[0]);
+	close(pfd[1]);
+	close(efd);
+}
+
 TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/filesystems/mntns_cleanup/.gitignore b/tools/testing/selftests/filesystems/mntns_cleanup/.gitignore
new file mode 100644
index 000000000000..493fbcf8d9ec
--- /dev/null
+++ b/tools/testing/selftests/filesystems/mntns_cleanup/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+mntns_cleanup_test
diff --git a/tools/testing/selftests/filesystems/mntns_cleanup/Makefile b/tools/testing/selftests/filesystems/mntns_cleanup/Makefile
new file mode 100644
index 000000000000..0e09e7030a5c
--- /dev/null
+++ b/tools/testing/selftests/filesystems/mntns_cleanup/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+TEST_GEN_PROGS := mntns_cleanup_test
+
+CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES)
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/filesystems/mntns_cleanup/mntns_cleanup_test.c b/tools/testing/selftests/filesystems/mntns_cleanup/mntns_cleanup_test.c
new file mode 100644
index 000000000000..5209712568b1
--- /dev/null
+++ b/tools/testing/selftests/filesystems/mntns_cleanup/mntns_cleanup_test.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "../../kselftest_harness.h"
+
+FIXTURE(mntns_cleanup) {
+};
+
+FIXTURE_SETUP(mntns_cleanup)
+{
+	if (geteuid() != 0)
+		SKIP(return, "test requires CAP_SYS_ADMIN");
+
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+	ASSERT_EQ(mount("", "/", NULL, MS_REC | MS_PRIVATE, NULL), 0);
+
+	rmdir("/mnt_dir");
+	ASSERT_EQ(mkdir("/mnt_dir", 0755), 0);
+	ASSERT_EQ(mount("tmpfs", "/mnt_dir", "tmpfs", 0, NULL), 0);
+	ASSERT_EQ(mkdir("/mnt_dir/hidden", 0755), 0);
+	ASSERT_EQ(mkdir("/mnt_dir/hidden/secret", 0755), 0);
+	ASSERT_EQ(mount("tmpfs", "/mnt_dir/hidden", "tmpfs", 0, NULL), 0);
+}
+
+FIXTURE_TEARDOWN(mntns_cleanup)
+{
+}
+
+/* Mounts must stay connected when a mount namespace is cleaned up. */
+TEST_F(mntns_cleanup, keeps_mounts_connected)
+{
+	int fd, sfd, err;
+
+	fd = open("/mnt_dir", O_PATH | O_DIRECTORY | O_CLOEXEC);
+	ASSERT_GE(fd, 0);
+
+	/* Destroy the namespace; the fd keeps /mnt_dir alive. */
+	ASSERT_EQ(unshare(CLONE_NEWNS), 0);
+
+	sfd = openat(fd, "hidden/secret", O_RDONLY);
+	err = errno;
+	if (sfd >= 0)
+		close(sfd);
+	close(fd);
+
+	ASSERT_LT(sfd, 0)
+		TH_LOG("mount namespace teardown revealed what the overmount covered");
+	ASSERT_EQ(err, ENOENT);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/filesystems/statmount/statmount_test.c b/tools/testing/selftests/filesystems/statmount/statmount_test.c
index 8dc018d47a93..60c2c544db6a 100644
--- a/tools/testing/selftests/filesystems/statmount/statmount_test.c
+++ b/tools/testing/selftests/filesystems/statmount/statmount_test.c
@@ -82,6 +82,9 @@ static void cleanup_namespace(void)
 {
 	int ret;
 
+	if (f_mountinfo)
+		fclose(f_mountinfo);
+
 	ret = fchdir(orig_root);
 	if (ret == -1)
 		ksft_perror("fchdir to original root");
@@ -515,7 +518,7 @@ static void test_statmount_mnt_opts(void)
 		return;
 	}
 
-	ksft_test_result_fail("didnt't find mount entry\n");
+	ksft_test_result_fail("didn't find mount entry\n");
 	free(sm);
 	free(line);
 }
diff --git a/tools/testing/selftests/namespaces/nsid_test.c b/tools/testing/selftests/namespaces/nsid_test.c
index 46dc838cba82..a16f31f41d38 100644
--- a/tools/testing/selftests/namespaces/nsid_test.c
+++ b/tools/testing/selftests/namespaces/nsid_test.c
@@ -649,8 +649,6 @@ TEST_F(nsid, timens_separate)
 		/* Fork a grandchild to actually enter the new namespace */
 		pid_t grandchild = fork();
 		if (grandchild == 0) {
-			/* Grandchild is in the new namespace */
-			write(pipefd[1], "Y", 1);
 			close(pipefd[1]);
 			pause();
 			_exit(0);
@@ -771,8 +769,6 @@ TEST_F(nsid, pidns_separate)
 		/* Fork a grandchild to actually enter the new namespace */
 		pid_t grandchild = fork();
 		if (grandchild == 0) {
-			/* Grandchild is in the new namespace */
-			write(pipefd[1], "Y", 1);
 			close(pipefd[1]);
 			pause();
 			_exit(0);
diff --git a/tools/testing/selftests/proc/proc-pidns.c b/tools/testing/selftests/proc/proc-pidns.c
index 25b9a2933c45..6f7c10fe97b3 100644
--- a/tools/testing/selftests/proc/proc-pidns.c
+++ b/tools/testing/selftests/proc/proc-pidns.c
@@ -6,6 +6,7 @@
 
 #include <assert.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <sched.h>
 #include <stdbool.h>
 #include <stdlib.h>