[PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[Chen Linxuan]

This patch add a simple functional test for the "abort" file
in fusectlfs (/sys/fs/fuse/connections/ID/about).

A simple fuse daemon is added for testing.

Related discussion can be found in the link below.

Link: https://lore.kernel.org/all/CAOQ4uxjKFXOKQxPpxtS6G_nR0tpw95w0GiO68UcWg_OBhmSY=Q@mail.gmail.com/
Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Co-developed-by: Miklos Szeredi <miklos@szeredi.hu>
Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
---
Changes in v4:
- Apply patch suggested by Miklos Szeredi
  - Setting up a userns environment for testing
  - Fix a EBUSY on umount/rmdir
- Link to v3: https://lore.kernel.org/all/20250610021007.2800329-2-chenlinxuan@uniontech.com/
Changes in v3:
- Apply changes suggested by Amir Goldstein
  - Rename the test subdir to filesystems/fuse
  - Verify errno when connection is aborted
- Apply changes suggested by Shuah Khan
  - Update commit message
- Link to v2: https://lore.kernel.org/all/20250517012350.10317-2-chenlinxuan@uniontech.com/
Changes in v2:
- Apply changes suggested by Amir Goldstein
   - Check errno
- Link to v1: https://lore.kernel.org/all/20250515073449.346774-2-chenlinxuan@uniontech.com/
---
 MAINTAINERS                                   |   1 +
 tools/testing/selftests/Makefile              |   1 +
 .../selftests/filesystems/fuse/.gitignore     |   3 +
 .../selftests/filesystems/fuse/Makefile       |  21 +++
 .../selftests/filesystems/fuse/fuse_mnt.c     | 146 ++++++++++++++++++
 .../selftests/filesystems/fuse/fusectl_test.c | 140 +++++++++++++++++
 6 files changed, 312 insertions(+)
 create mode 100644 tools/testing/selftests/filesystems/fuse/.gitignore
 create mode 100644 tools/testing/selftests/filesystems/fuse/Makefile
 create mode 100644 tools/testing/selftests/filesystems/fuse/fuse_mnt.c
 create mode 100644 tools/testing/selftests/filesystems/fuse/fusectl_test.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a92290fffa163..04d90432c1841 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9901,6 +9901,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git
 F:	Documentation/filesystems/fuse*
 F:	fs/fuse/
 F:	include/uapi/linux/fuse.h
+F:	tools/testing/selftests/filesystems/fuse/
 
 FUTEX SUBSYSTEM
 M:	Thomas Gleixner <tglx@linutronix.de>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 339b31e6a6b59..c37a76a8ca214 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -36,6 +36,7 @@ TARGETS += filesystems/fat
 TARGETS += filesystems/overlayfs
 TARGETS += filesystems/statmount
 TARGETS += filesystems/mount-notify
+TARGETS += filesystems/fuse
 TARGETS += firmware
 TARGETS += fpu
 TARGETS += ftrace
diff --git a/tools/testing/selftests/filesystems/fuse/.gitignore b/tools/testing/selftests/filesystems/fuse/.gitignore
new file mode 100644
index 0000000000000..3e72e742d08e8
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fuse/.gitignore
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+fuse_mnt
+fusectl_test
diff --git a/tools/testing/selftests/filesystems/fuse/Makefile b/tools/testing/selftests/filesystems/fuse/Makefile
new file mode 100644
index 0000000000000..612aad69a93aa
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fuse/Makefile
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES)
+
+TEST_GEN_PROGS := fusectl_test
+TEST_GEN_FILES := fuse_mnt
+
+include ../../lib.mk
+
+VAR_CFLAGS := $(shell pkg-config fuse --cflags 2>/dev/null)
+ifeq ($(VAR_CFLAGS),)
+VAR_CFLAGS := -D_FILE_OFFSET_BITS=64 -I/usr/include/fuse
+endif
+
+VAR_LDLIBS := $(shell pkg-config fuse --libs 2>/dev/null)
+ifeq ($(VAR_LDLIBS),)
+VAR_LDLIBS := -lfuse -pthread
+endif
+
+$(OUTPUT)/fuse_mnt: CFLAGS += $(VAR_CFLAGS)
+$(OUTPUT)/fuse_mnt: LDLIBS += $(VAR_LDLIBS)
diff --git a/tools/testing/selftests/filesystems/fuse/fuse_mnt.c b/tools/testing/selftests/filesystems/fuse/fuse_mnt.c
new file mode 100644
index 0000000000000..d12b17f30fadc
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fuse/fuse_mnt.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fusectl test file-system
+ * Creates a simple FUSE filesystem with a single read-write file (/test)
+ */
+
+#define FUSE_USE_VERSION 26
+
+#include <fuse.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+static char *content;
+static size_t content_size = 0;
+static const char test_path[] = "/test";
+
+static int test_getattr(const char *path, struct stat *st)
+{
+	memset(st, 0, sizeof(*st));
+
+	if (!strcmp(path, "/")) {
+		st->st_mode = S_IFDIR | 0755;
+		st->st_nlink = 2;
+		return 0;
+	}
+
+	if (!strcmp(path, test_path)) {
+		st->st_mode = S_IFREG | 0664;
+		st->st_nlink = 1;
+		st->st_size = content_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static int test_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+			off_t offset, struct fuse_file_info *fi)
+{
+	if (strcmp(path, "/"))
+		return -ENOENT;
+
+	filler(buf, ".", NULL, 0);
+	filler(buf, "..", NULL, 0);
+	filler(buf, test_path + 1, NULL, 0);
+
+	return 0;
+}
+
+static int test_open(const char *path, struct fuse_file_info *fi)
+{
+	if (strcmp(path, test_path))
+		return -ENOENT;
+
+	return 0;
+}
+
+static int test_read(const char *path, char *buf, size_t size, off_t offset,
+		     struct fuse_file_info *fi)
+{
+	if (strcmp(path, test_path) != 0)
+		return -ENOENT;
+
+	if (!content || content_size == 0)
+		return 0;
+
+	if (offset >= content_size)
+		return 0;
+
+	if (offset + size > content_size)
+		size = content_size - offset;
+
+	memcpy(buf, content + offset, size);
+
+	return size;
+}
+
+static int test_write(const char *path, const char *buf, size_t size,
+		      off_t offset, struct fuse_file_info *fi)
+{
+	size_t new_size;
+
+	if (strcmp(path, test_path) != 0)
+		return -ENOENT;
+
+	if(offset > content_size)
+		return -EINVAL;
+
+	new_size = MAX(offset + size, content_size);
+
+	if (new_size > content_size)
+		content = realloc(content, new_size);
+
+	content_size = new_size;
+
+	if (!content)
+		return -ENOMEM;
+
+	memcpy(content + offset, buf, size);
+
+	return size;
+}
+
+static int test_truncate(const char *path, off_t size)
+{
+	if (strcmp(path, test_path) != 0)
+		return -ENOENT;
+
+	if (size == 0) {
+		free(content);
+		content = NULL;
+		content_size = 0;
+		return 0;
+	}
+
+	content = realloc(content, size);
+
+	if (!content)
+		return -ENOMEM;
+
+	if (size > content_size)
+		memset(content + content_size, 0, size - content_size);
+
+	content_size = size;
+	return 0;
+}
+
+static struct fuse_operations memfd_ops = {
+	.getattr = test_getattr,
+	.readdir = test_readdir,
+	.open = test_open,
+	.read = test_read,
+	.write = test_write,
+	.truncate = test_truncate,
+};
+
+int main(int argc, char *argv[])
+{
+	return fuse_main(argc, argv, &memfd_ops, NULL);
+}
diff --git a/tools/testing/selftests/filesystems/fuse/fusectl_test.c b/tools/testing/selftests/filesystems/fuse/fusectl_test.c
new file mode 100644
index 0000000000000..8d124d1cacb26
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fuse/fusectl_test.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright (c) 2025 Chen Linxuan <chenlinxuan@uniontech.com>
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <sched.h>
+#include <linux/limits.h>
+
+#include "../../kselftest_harness.h"
+
+#define FUSECTL_MOUNTPOINT "/sys/fs/fuse/connections"
+#define FUSE_MOUNTPOINT "/tmp/fuse_mnt_XXXXXX"
+#define FUSE_DEVICE "/dev/fuse"
+#define FUSECTL_TEST_VALUE "1"
+
+static void write_file(struct __test_metadata *const _metadata,
+		       const char *path, const char *val)
+{
+	int fd = open(path, O_WRONLY);
+	size_t len = strlen(val);
+
+	ASSERT_GE(fd, 0);
+	ASSERT_EQ(write(fd, val, len), len);
+	ASSERT_EQ(close(fd), 0);
+}
+
+FIXTURE(fusectl){
+	char fuse_mountpoint[sizeof(FUSE_MOUNTPOINT)];
+	int connection;
+};
+
+FIXTURE_SETUP(fusectl)
+{
+	const char *fuse_mnt_prog = "./fuse_mnt";
+	int status, pid;
+	struct stat statbuf;
+	uid_t uid = getuid();
+	gid_t gid = getgid();
+	char buf[32];
+
+	/* Setup userns */
+	ASSERT_EQ(unshare(CLONE_NEWNS|CLONE_NEWUSER), 0);
+	sprintf(buf, "0 %d 1", uid);
+	write_file(_metadata, "/proc/self/uid_map", buf);
+	write_file(_metadata, "/proc/self/setgroups", "deny");
+	sprintf(buf, "0 %d 1", gid);
+	write_file(_metadata, "/proc/self/gid_map", buf);
+	ASSERT_EQ(mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL), 0);
+
+	strcpy(self->fuse_mountpoint, FUSE_MOUNTPOINT);
+
+	if (!mkdtemp(self->fuse_mountpoint))
+		SKIP(return,
+		     "Failed to create FUSE mountpoint %s",
+		     strerror(errno));
+
+	if (access(FUSECTL_MOUNTPOINT, F_OK))
+		SKIP(return,
+		     "FUSE control filesystem not mounted");
+
+	pid = fork();
+	if (pid < 0)
+		SKIP(return,
+		     "Failed to fork FUSE daemon process: %s",
+		     strerror(errno));
+
+	if (pid == 0) {
+		execlp(fuse_mnt_prog, fuse_mnt_prog, self->fuse_mountpoint, NULL);
+		exit(errno);
+	}
+
+	waitpid(pid, &status, 0);
+	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+		SKIP(return,
+		     "Failed to start FUSE daemon %s",
+		     strerror(WEXITSTATUS(status)));
+	}
+
+	if (stat(self->fuse_mountpoint, &statbuf))
+		SKIP(return,
+		     "Failed to stat FUSE mountpoint %s",
+		     strerror(errno));
+
+	self->connection = statbuf.st_dev;
+}
+
+FIXTURE_TEARDOWN(fusectl)
+{
+	umount2(self->fuse_mountpoint, MNT_DETACH);
+	rmdir(self->fuse_mountpoint);
+}
+
+TEST_F(fusectl, abort)
+{
+	char path_buf[PATH_MAX];
+	int abort_fd, test_fd, ret;
+
+	sprintf(path_buf, "/sys/fs/fuse/connections/%d/abort", self->connection);
+
+	ASSERT_EQ(0, access(path_buf, F_OK));
+
+	abort_fd = open(path_buf, O_WRONLY);
+	ASSERT_GE(abort_fd, 0);
+
+	sprintf(path_buf, "%s/test", self->fuse_mountpoint);
+
+	test_fd = open(path_buf, O_RDWR);
+	ASSERT_GE(test_fd, 0);
+
+	ret = read(test_fd, path_buf, sizeof(path_buf));
+	ASSERT_EQ(ret, 0);
+
+	ret = write(test_fd, "test", sizeof("test"));
+	ASSERT_EQ(ret, sizeof("test"));
+
+	ret = lseek(test_fd, 0, SEEK_SET);
+	ASSERT_GE(ret, 0);
+
+	ret = write(abort_fd, FUSECTL_TEST_VALUE, sizeof(FUSECTL_TEST_VALUE));
+	ASSERT_GT(ret, 0);
+
+	close(abort_fd);
+
+	ret = read(test_fd, path_buf, sizeof(path_buf));
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, ENOTCONN);
+}
+
+TEST_HARNESS_MAIN
-- 
2.43.0

Re: [PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[Shuah Khan]

On 6/12/25 03:40, Chen Linxuan wrote:
> This patch add a simple functional test for the "abort" file
> in fusectlfs (/sys/fs/fuse/connections/ID/about).
> 
> A simple fuse daemon is added for testing.
> 
> Related discussion can be found in the link below.
> 
> Link: https://lore.kernel.org/all/CAOQ4uxjKFXOKQxPpxtS6G_nR0tpw95w0GiO68UcWg_OBhmSY=Q@mail.gmail.com/
> Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
> Acked-by: Shuah Khan <skhan@linuxfoundation.org>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Co-developed-by: Miklos Szeredi <miklos@szeredi.hu>
> Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
> ---
> Changes in v4:
> - Apply patch suggested by Miklos Szeredi
>    - Setting up a userns environment for testing
>    - Fix a EBUSY on umount/rmdir
> - Link to v3: https://lore.kernel.org/all/20250610021007.2800329-2-chenlinxuan@uniontech.com/
> Changes in v3:
> - Apply changes suggested by Amir Goldstein
>    - Rename the test subdir to filesystems/fuse
>    - Verify errno when connection is aborted
> - Apply changes suggested by Shuah Khan
>    - Update commit message
> - Link to v2: https://lore.kernel.org/all/20250517012350.10317-2-chenlinxuan@uniontech.com/
> Changes in v2:
> - Apply changes suggested by Amir Goldstein
>     - Check errno
> - Link to v1: https://lore.kernel.org/all/20250515073449.346774-2-chenlinxuan@uniontech.com/

+ adding Christian to the thread

Hi Christian,

Would you like me to take this patch through my tree?

thanks,
-- Shuah

Re: [PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[Christian Brauner]

On Wed, Jun 18, 2025 at 02:52:08PM -0600, Shuah Khan wrote:
> On 6/12/25 03:40, Chen Linxuan wrote:
> > This patch add a simple functional test for the "abort" file
> > in fusectlfs (/sys/fs/fuse/connections/ID/about).
> > 
> > A simple fuse daemon is added for testing.
> > 
> > Related discussion can be found in the link below.
> > 
> > Link: https://lore.kernel.org/all/CAOQ4uxjKFXOKQxPpxtS6G_nR0tpw95w0GiO68UcWg_OBhmSY=Q@mail.gmail.com/
> > Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
> > Acked-by: Shuah Khan <skhan@linuxfoundation.org>
> > Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> > Co-developed-by: Miklos Szeredi <miklos@szeredi.hu>
> > Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
> > ---
> > Changes in v4:
> > - Apply patch suggested by Miklos Szeredi
> >    - Setting up a userns environment for testing
> >    - Fix a EBUSY on umount/rmdir
> > - Link to v3: https://lore.kernel.org/all/20250610021007.2800329-2-chenlinxuan@uniontech.com/
> > Changes in v3:
> > - Apply changes suggested by Amir Goldstein
> >    - Rename the test subdir to filesystems/fuse
> >    - Verify errno when connection is aborted
> > - Apply changes suggested by Shuah Khan
> >    - Update commit message
> > - Link to v2: https://lore.kernel.org/all/20250517012350.10317-2-chenlinxuan@uniontech.com/
> > Changes in v2:
> > - Apply changes suggested by Amir Goldstein
> >     - Check errno
> > - Link to v1: https://lore.kernel.org/all/20250515073449.346774-2-chenlinxuan@uniontech.com/
> 
> + adding Christian to the thread
> 
> Hi Christian,
> 
> Would you like me to take this patch through my tree?

I'll just take it otherwise it'll end up causing pointless merge
conflicts as I'm touching that code as well.

Re: [PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[Christian Brauner]

On Thu, 12 Jun 2025 17:40:29 +0800, Chen Linxuan wrote:
> This patch add a simple functional test for the "abort" file
> in fusectlfs (/sys/fs/fuse/connections/ID/about).
> 
> A simple fuse daemon is added for testing.
> 
> Related discussion can be found in the link below.
> 
> [...]

Applied to the vfs-6.17.selftests branch of the vfs/vfs.git tree.
Patches in the vfs-6.17.selftests branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-6.17.selftests

[1/1] selftests: filesystems: Add functional test for the abort file in fusectl
      https://git.kernel.org/vfs/vfs/c/0f505cf71c63

Re: [PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[Amir Goldstein]

On Thu, Jun 19, 2025 at 12:04 PM Christian Brauner <brauner@kernel.org> wrote:
>
> On Thu, 12 Jun 2025 17:40:29 +0800, Chen Linxuan wrote:
> > This patch add a simple functional test for the "abort" file
> > in fusectlfs (/sys/fs/fuse/connections/ID/about).

Miklos,

I see that this patch ended up in your tree.

Please fix above typo .../connections/ID/about => abort

Thanks,
Amir.

> >
> > A simple fuse daemon is added for testing.
> >
> > Related discussion can be found in the link below.
> >
> > [...]
>
> Applied to the vfs-6.17.selftests branch of the vfs/vfs.git tree.
> Patches in the vfs-6.17.selftests branch should appear in linux-next soon.
>
> Please report any outstanding bugs that were missed during review in a
> new review to the original patch series allowing us to drop it.
>
> It's encouraged to provide Acked-bys and Reviewed-bys even though the
> patch has now been applied. If possible patch trailers will be updated.
>
> Note that commit hashes shown below are subject to change due to rebase,
> trailer updates or similar. If in doubt, please check the listed branch.
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
> branch: vfs-6.17.selftests
>
> [1/1] selftests: filesystems: Add functional test for the abort file in fusectl
>       https://git.kernel.org/vfs/vfs/c/0f505cf71c63

Re: [PATCH v4] selftests: filesystems: Add functional test for the abort file in fusectl

[Miklos Szeredi]

On Thu, 17 Jul 2025 at 09:14, Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Thu, Jun 19, 2025 at 12:04 PM Christian Brauner <brauner@kernel.org> wrote:
> >
> > On Thu, 12 Jun 2025 17:40:29 +0800, Chen Linxuan wrote:
> > > This patch add a simple functional test for the "abort" file
> > > in fusectlfs (/sys/fs/fuse/connections/ID/about).
>
> Miklos,
>
> I see that this patch ended up in your tree.
>
> Please fix above typo .../connections/ID/about => abort

Okay.

Thanks,
Miklos