On Tue, Dec 05, 2023 at 04:39:20PM +0000, fdmanana@xxxxxxxxxx wrote:
> 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>
> ---
This patch looks good to me, I'll add this case into "rename" group too
when I merge it.
Reviewed-by: Zorro Lang <zlang@xxxxxxxxxx>
> .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
>
>
