From: Filipe Manana <fdmanana@xxxxxxxx>
Test that on a fairly large directory if we keep renaming files while
holding the directory open and doing readdir(3) calls, we don't end up
in an infinite loop.
This exercise a bug that existed in btrfs and was fixed in kernel 6.5
by commit 9b378f6ad48c ("btrfs: fix infinite directory reads").
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
.gitignore | 1 +
src/Makefile | 3 +-
src/readdir-while-renames.c | 146 ++++++++++++++++++++++++++++++++++++
tests/generic/734 | 37 +++++++++
tests/generic/734.out | 2 +
5 files changed, 188 insertions(+), 1 deletion(-)
create mode 100644 src/readdir-while-renames.c
create mode 100755 tests/generic/734
create mode 100644 tests/generic/734.out
diff --git a/.gitignore b/.gitignore
index 4c32ac42..7508b6e8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -121,6 +121,7 @@ tags
/src/punch-alternating
/src/pwrite_mmap_blocked
/src/randholes
+/src/readdir-while-renames
/src/rename
/src/renameat2
/src/resvtest
diff --git a/src/Makefile b/src/Makefile
index 8160a0e8..d79015ce 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -19,7 +19,8 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \
t_ofd_locks t_mmap_collision mmap-write-concurrent \
t_get_file_time t_create_short_dirs t_create_long_dirs t_enospc \
t_mmap_writev_overlap checkpoint_journal mmap-rw-fault allocstale \
- t_mmap_cow_memory_failure fake-dump-rootino dio-buf-fault rewinddir-test
+ t_mmap_cow_memory_failure fake-dump-rootino dio-buf-fault rewinddir-test \
+ readdir-while-renames
LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \
diff --git a/src/readdir-while-renames.c b/src/readdir-while-renames.c
new file mode 100644
index 00000000..afeefb04
--- /dev/null
+++ b/src/readdir-while-renames.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 SUSE Linux Products GmbH. All Rights Reserved.
+ */
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/stat.h>
+
+/* Number of files we add to the test directory. */
+#define NUM_FILES 5000
+
+int main(int argc, char *argv[])
+{
+ struct dirent *entry;
+ DIR *dir = NULL;
+ char *dir_path = NULL;
+ int dentry_count = 0;
+ int ret = 0;
+ int i;
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s <directory>\n", argv[0]);
+ ret = 1;
+ goto out;
+ }
+
+ dir_path = malloc(strlen(argv[1]) + strlen("/testdir") + 1);
+ if (!dir_path) {
+ fprintf(stderr, "malloc failure\n");
+ ret = ENOMEM;
+ goto out;
+ }
+ i = strlen(argv[1]);
+ memcpy(dir_path, argv[1], i);
+ memcpy(dir_path + i, "/testdir", strlen("/testdir"));
+ dir_path[i + strlen("/testdir")] = '\0';
+
+ ret = mkdir(dir_path, 0700);
+ if (ret == -1) {
+ fprintf(stderr, "Failed to create test directory: %d\n", errno);
+ ret = errno;
+ goto out;
+ }
+
+ ret = chdir(dir_path);
+ if (ret == -1) {
+ fprintf(stderr, "Failed to chdir to the test directory: %d\n", errno);
+ ret = errno;
+ goto out;
+ }
+
+ /* Now create all files inside the directory. */
+ for (i = 1; i <= NUM_FILES; i++) {
+ char file_name[32];
+ FILE *f;
+
+ sprintf(file_name, "%s/%d", dir_path, i);
+ f = fopen(file_name, "w");
+ if (f == NULL) {
+ fprintf(stderr, "Failed to create file number %d: %d\n",
+ i, errno);
+ ret = errno;
+ goto out;
+ }
+ fclose(f);
+ }
+
+ dir = opendir(dir_path);
+ if (dir == NULL) {
+ fprintf(stderr, "Failed to open directory: %d\n", errno);
+ ret = errno;
+ goto out;
+ }
+
+ /*
+ * readdir(3) returns NULL when it reaches the end of the directory or
+ * when an error happens, so reset errno to 0 to distinguish between
+ * both cases later.
+ */
+ errno = 0;
+ while ((entry = readdir(dir)) != NULL) {
+ dentry_count++;
+ /*
+ * The actual number of dentries returned varies per filesystem
+ * implementation. On a 6.7-rc4 kernel, on x86_64 with default
+ * mkfs options, xfs returns 5031 dentries while ext4, f2fs and
+ * btrfs return 5002 (the 5000 files plus "." and ".."). These
+ * variations are fine and valid according to POSIX, as some of
+ * the renames may be visible or not while calling readdir(3).
+ * We only want to check we don't enter into an infinite loop,
+ * so let the maximum number of dentries be 3 * NUM_FILES, which
+ * is very reasonable.
+ */
+ if (dentry_count > 3 * NUM_FILES) {
+ fprintf(stderr,
+ "Found too many directory entries (%d)\n",
+ dentry_count);
+ ret = 1;
+ goto out;
+ }
+ /* Can't rename "." and "..", skip them. */
+ if (strcmp(entry->d_name, ".") == 0 ||
+ strcmp(entry->d_name, "..") == 0)
+ continue;
+ ret = rename(entry->d_name, "TEMPFILE");
+ if (ret == -1) {
+ fprintf(stderr,
+ "Failed to rename '%s' to TEMPFILE: %d\n",
+ entry->d_name, errno);
+ ret = errno;
+ goto out;
+ }
+ ret = rename("TEMPFILE", entry->d_name);
+ if (ret == -1) {
+ fprintf(stderr,
+ "Failed to rename TEMPFILE to '%s': %d\n",
+ entry->d_name, errno);
+ ret = errno;
+ goto out;
+ }
+ }
+
+ if (errno) {
+ fprintf(stderr, "Failed to read directory: %d\n", errno);
+ ret = errno;
+ goto out;
+ }
+
+ /* It should return at least NUM_FILES entries +2 (for "." and ".."). */
+ if (dentry_count < NUM_FILES + 2) {
+ fprintf(stderr,
+ "Found less directory entries than expected (%d but expected %d)\n",
+ dentry_count, NUM_FILES + 2);
+ ret = 2;
+ }
+out:
+ free(dir_path);
+ if (dir != NULL)
+ closedir(dir);
+
+ return ret;
+}
diff --git a/tests/generic/734 b/tests/generic/734
new file mode 100755
index 00000000..ea3dfb2d
--- /dev/null
+++ b/tests/generic/734
@@ -0,0 +1,37 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2023 SUSE Linux Products GmbH. All Rights Reserved.
+#
+# FS QA Test 734
+#
+# Test that on a fairly large directory if we keep renaming files while holding
+# the directory open and doing readdir(3) calls, we don't end up in an infinite
+# loop.
+#
+. ./common/preamble
+_begin_fstest auto quick dir
+
+_cleanup()
+{
+ cd /
+ rm -fr $tmp.*
+ rm -fr $target_dir
+}
+
+_supported_fs generic
+_require_test
+_require_test_program readdir-while-renames
+
+[ $FSTYP == "btrfs" ] && _fixed_by_kernel_commit 9b378f6ad48c \
+ "btrfs: fix infinite directory reads"
+
+target_dir="$TEST_DIR/test-$seq"
+rm -fr $target_dir
+mkdir $target_dir
+
+$here/src/readdir-while-renames $target_dir
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/generic/734.out b/tests/generic/734.out
new file mode 100644
index 00000000..4299839b
--- /dev/null
+++ b/tests/generic/734.out
@@ -0,0 +1,2 @@
+QA output created by 734
+Silence is golden
--
2.40.1
