[RFC PATCH v3 8/8] selftests/fuse: add fuse readdir caching test

[Luis Henriques <luis@igalia.com>]

This new test will check the caching behaviour using combinations of two
opendir flags: FOPEN_KEEP_CACHE and FOPEN_CACHE_DIR.

Signed-off-by: Luis Henriques <luis@igalia.com>
---
 .../selftests/filesystems/fuse/.gitignore     |   1 +
 .../selftests/filesystems/fuse/Makefile       |   2 +
 .../fuse/fuse_readdir_cache_test.c            | 274 ++++++++++++++++++
 3 files changed, 277 insertions(+)
 create mode 100644 tools/testing/selftests/filesystems/fuse/fuse_readdir_cache_test.c

diff --git a/tools/testing/selftests/filesystems/fuse/.gitignore b/tools/testing/selftests/filesystems/fuse/.gitignore
index ebfe7133d811..ffa356f23e8c 100644
--- a/tools/testing/selftests/filesystems/fuse/.gitignore
+++ b/tools/testing/selftests/filesystems/fuse/.gitignore
@@ -4,3 +4,4 @@ fusectl_test
 write_extend_eof_test
 fuse_acl_cache_test
 fuse_symlink_cache_test
+fuse_readdir_cache_test
diff --git a/tools/testing/selftests/filesystems/fuse/Makefile b/tools/testing/selftests/filesystems/fuse/Makefile
index 3a5a557dde7a..570ced181168 100644
--- a/tools/testing/selftests/filesystems/fuse/Makefile
+++ b/tools/testing/selftests/filesystems/fuse/Makefile
@@ -6,6 +6,7 @@ TEST_GEN_PROGS := fusectl_test
 TEST_GEN_PROGS += write_extend_eof_test
 TEST_GEN_PROGS += fuse_acl_cache_test
 TEST_GEN_PROGS += fuse_symlink_cache_test
+TEST_GEN_PROGS += fuse_readdir_cache_test
 TEST_GEN_FILES := fuse_mnt
 
 include ../../lib.mk
@@ -30,5 +31,6 @@ $(OUTPUT)/fuse_mnt: LDLIBS += $(VAR_LDLIBS)
 
 $(OUTPUT)/fuse_acl_cache_test: fuse_common.c fuse_acl_cache_test.c
 $(OUTPUT)/fuse_symlink_cache_test: fuse_common.c fuse_symlink_cache_test.c
+$(OUTPUT)/fuse_readdir_cache_test: fuse_common.c fuse_readdir_cache_test.c
 
 EXTRA_CLEAN := fuse_common.o
diff --git a/tools/testing/selftests/filesystems/fuse/fuse_readdir_cache_test.c b/tools/testing/selftests/filesystems/fuse/fuse_readdir_cache_test.c
new file mode 100644
index 000000000000..7c49cc6a23e3
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fuse/fuse_readdir_cache_test.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple filesystem to test FUSE readdir cache
+ *
+ * It will simply perform readdir operations on a directory checking how many
+ * times a request is sent to user-space using all the possible caching
+ * combination setting (FOPEN_KEEP_CACHE and FOPEN_CACHE_DIR flags).
+ */
+
+#include <stdio.h>
+#include <limits.h>
+#include <dirent.h>
+
+#include "kselftest_harness.h"
+
+#include "fuse_common.h"
+
+#define DIRNAME "mydir"
+#define FILENAME "myfile"
+
+#define DIR_INO 42
+#define FILE_INO 43
+#define DOT_INO 40
+#define DOTDOT_INO 41
+
+#define TIMEOUT	86400.0f
+
+struct test_state {
+	pthread_mutex_t lock;
+	bool cache_readdir;
+	bool keep_cache;
+	int readdir_counter;
+} test_state = {
+	.lock = PTHREAD_MUTEX_INITIALIZER,
+};
+
+static void fs_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
+{
+	struct fuse_entry_param e = {};
+
+	if (parent != FUSE_ROOT_ID || strcmp(name, DIRNAME) != 0)
+		fuse_reply_err(req, ENOENT);
+	else {
+		if (!strcmp(name, DIRNAME)) {
+			e.ino = DIR_INO;
+			e.attr.st_mode = S_IFDIR | 0755;
+			e.attr.st_nlink = 1;
+		} else {
+			e.ino = FUSE_ROOT_ID;
+			e.attr.st_mode = S_IFDIR | 0755;
+			e.attr.st_nlink = 2;
+		}
+		e.attr.st_mtime = time(NULL);
+		e.attr_timeout = TIMEOUT;
+		e.entry_timeout = TIMEOUT;
+		fuse_reply_entry(req, &e);
+	}
+}
+
+static int fill_stat(fuse_ino_t ino, struct stat *st)
+{
+	int ret = 0;
+
+	st->st_ino = ino;
+	st->st_mtime = time(NULL);
+
+	switch (ino) {
+	case FUSE_ROOT_ID:
+		st->st_mode = S_IFDIR | 0755;
+		st->st_nlink = 2;
+		break;
+	case DOT_INO:
+	case DOTDOT_INO:
+	case DIR_INO:
+		st->st_mode = S_IFDIR | 0755;
+		st->st_nlink = 1;
+		break;
+	case FILE_INO:
+		st->st_mode = S_IFREG | 0444;
+		st->st_nlink = 1;
+		break;
+	default:
+		ret = -1;
+		break;
+	}
+
+	return ret;
+}
+
+static void fs_getattr(fuse_req_t req, fuse_ino_t ino,
+		       struct fuse_file_info *fi)
+{
+	struct stat st = {};
+
+	if (fill_stat(ino, &st) < 0)
+		fuse_reply_err(req, ENOENT);
+	else
+		fuse_reply_attr(req, &st, TIMEOUT);
+}
+
+static void fs_opendir(fuse_req_t req, fuse_ino_t ino,
+		       struct fuse_file_info *fi)
+{
+	pthread_mutex_lock(&test_state.lock);
+	fi->keep_cache = test_state.keep_cache;
+	fi->cache_readdir = test_state.cache_readdir;
+	pthread_mutex_unlock(&test_state.lock);
+	fuse_reply_open(req, fi);
+}
+
+static void fs_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
+		       off_t offset, struct fuse_file_info *fi)
+{
+	struct stat st = {};
+	char buf[1024];
+	char *pbuf;
+	size_t rem = size;
+	size_t sz;
+	int nextoff = 0;
+
+	if (ino != DIR_INO) {
+		fuse_reply_err(req, ENOTDIR);
+		return;
+	}
+	if (offset) {
+		fuse_reply_buf(req, NULL, 0);
+		return;
+	}
+	pbuf = buf;
+	fill_stat(DOT_INO, &st);
+	sz = fuse_add_direntry(req, pbuf, rem, ".", &st, nextoff++);
+	rem -= sz;
+	pbuf += sz;
+	fill_stat(DOTDOT_INO, &st);
+	sz = fuse_add_direntry(req, pbuf, rem, "..", &st, nextoff++);
+	rem -= sz;
+	pbuf += sz;
+	fill_stat(FILE_INO, &st);
+	sz = fuse_add_direntry(req, pbuf, rem, FILENAME, &st, nextoff++);
+	rem -= sz;
+
+	fuse_reply_buf(req, buf, size - rem);
+
+	pthread_mutex_lock(&test_state.lock);
+	test_state.readdir_counter++;
+	pthread_mutex_unlock(&test_state.lock);
+}
+
+static const struct fuse_lowlevel_ops fs_ops = {
+	.lookup		= fs_lookup,
+	.getattr	= fs_getattr,
+	.opendir	= fs_opendir,
+	.readdir	= fs_readdir,
+};
+
+FIXTURE(readdir_cache)
+{
+	struct fuse_session *se;
+	char mountpoint[MOUNTPOINT_SZ];
+	pthread_t thread;
+};
+
+FIXTURE_VARIANT(readdir_cache)
+{
+	bool cache_readdir;
+	bool keep_cache;
+};
+FIXTURE_VARIANT_ADD(readdir_cache, nocache)
+{
+	.cache_readdir = false,
+	.keep_cache = false,
+};
+FIXTURE_VARIANT_ADD(readdir_cache, cache_readdir)
+{
+	.cache_readdir = true,
+	.keep_cache = false,
+};
+FIXTURE_VARIANT_ADD(readdir_cache, keep_cache)
+{
+	.cache_readdir = false,
+	.keep_cache = true,
+};
+FIXTURE_VARIANT_ADD(readdir_cache, cache)
+{
+	.cache_readdir = true,
+	.keep_cache = true,
+};
+
+FIXTURE_SETUP(readdir_cache)
+{
+	char err[MAX_ERR_MSG];
+
+	pthread_mutex_lock(&test_state.lock);
+	test_state.readdir_counter = 0;
+	test_state.cache_readdir = variant->cache_readdir;
+	test_state.keep_cache = variant->keep_cache;
+	pthread_mutex_unlock(&test_state.lock);
+
+	if (fs_setup(&self->se, self->mountpoint, &fs_ops, &self->thread, err))
+		SKIP(return, err);
+}
+
+FIXTURE_TEARDOWN(readdir_cache)
+{
+	fs_teardown(self->se, self->thread, self->mountpoint);
+}
+
+TEST_F(readdir_cache, test_readdir_cache)
+{
+	struct dirent *dentry;
+	DIR *dir;
+	char pathname[PATH_MAX];
+	int total_counter, rewind_counter;
+	int dentrycount;
+
+	sprintf(pathname, "%s/%s", self->mountpoint, DIRNAME);
+
+	dir = opendir(pathname);
+	if (dir == NULL)
+		TH_LOG("opendir(): %s", strerror(errno));
+	ASSERT_NE(dir, NULL);
+
+	errno = 0;
+	dentrycount = 0;
+	while ((dentry = readdir(dir)))
+		dentrycount++;
+	ASSERT_EQ(errno, 0);
+	ASSERT_EQ(dentrycount, 3);
+
+	rewinddir(dir);
+	errno = 0;
+	dentrycount = 0;
+	while ((dentry = readdir(dir)))
+		dentrycount++;
+	ASSERT_EQ(errno, 0);
+	ASSERT_EQ(dentrycount, 3);
+
+	ASSERT_EQ(closedir(dir), 0);
+
+	pthread_mutex_lock(&test_state.lock);
+	rewind_counter = test_state.readdir_counter;
+	pthread_mutex_unlock(&test_state.lock);
+
+	dir = opendir(pathname);
+	if (dir == NULL)
+		TH_LOG("opendir(): %s", strerror(errno));
+	ASSERT_NE(dir, NULL);
+
+	errno = 0;
+	dentrycount = 0;
+	while ((dentry = readdir(dir)))
+		dentrycount++;
+	ASSERT_EQ(errno, 0);
+	ASSERT_EQ(dentrycount, 3);
+
+	ASSERT_EQ(closedir(dir), 0);
+
+	pthread_mutex_lock(&test_state.lock);
+	total_counter = test_state.readdir_counter;
+	pthread_mutex_unlock(&test_state.lock);
+
+	if (!variant->cache_readdir) {
+		ASSERT_EQ(rewind_counter, 2);
+		ASSERT_EQ(total_counter, 3);
+	} else if (!variant->keep_cache) {
+		ASSERT_EQ(rewind_counter, 1);
+		ASSERT_EQ(total_counter, 2);
+	} else {
+		ASSERT_EQ(rewind_counter, 1);
+		ASSERT_EQ(total_counter, 1);
+	}
+}
+
+TEST_HARNESS_MAIN