From: Filipe Manana <fdmanana@xxxxxxxx>
Test that doing a direct IO append write to a file when the input buffer
was not yet faulted in, does not result in an incorrect file size.
This exercises a bug on btrfs reported by users and which is fixed by
the following kernel patch:
"btrfs: fix corruption after buffer fault in during direct IO append write"
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
V2: Deal with partial writes by looping and writing any remaining data.
Don't exit when the first test fails, instead let the second test
run as well.
.gitignore | 1 +
src/Makefile | 2 +-
src/dio-append-buf-fault.c | 145 +++++++++++++++++++++++++++++++++++++
tests/generic/362 | 28 +++++++
tests/generic/362.out | 2 +
5 files changed, 177 insertions(+), 1 deletion(-)
create mode 100644 src/dio-append-buf-fault.c
create mode 100755 tests/generic/362
create mode 100644 tests/generic/362.out
diff --git a/.gitignore b/.gitignore
index b5f15162..97c7e001 100644
--- a/.gitignore
+++ b/.gitignore
@@ -72,6 +72,7 @@ tags
/src/deduperace
/src/detached_mounts_propagation
/src/devzero
+/src/dio-append-buf-fault
/src/dio-buf-fault
/src/dio-interleaved
/src/dio-invalidate-cache
diff --git a/src/Makefile b/src/Makefile
index 99796137..559209be 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -20,7 +20,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \
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 \
- readdir-while-renames
+ readdir-while-renames dio-append-buf-fault
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/dio-append-buf-fault.c b/src/dio-append-buf-fault.c
new file mode 100644
index 00000000..72c23265
--- /dev/null
+++ b/src/dio-append-buf-fault.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 SUSE Linux Products GmbH. All Rights Reserved.
+ */
+
+/*
+ * Test a direct IO write in append mode with a buffer that was not faulted in
+ * (or just partially) before the write.
+ */
+
+/* Get the O_DIRECT definition. */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+static ssize_t do_write(int fd, const void *buf, size_t count)
+{
+ while (count > 0) {
+ ssize_t ret;
+
+ ret = write(fd, buf, count);
+ if (ret < 0) {
+ if (errno == EINTR)
+ continue;
+ return ret;
+ }
+ count -= ret;
+ buf += ret;
+ }
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ struct stat stbuf;
+ int fd;
+ long pagesize;
+ void *buf;
+ ssize_t ret;
+
+ if (argc != 2) {
+ fprintf(stderr, "Use: %s <file path>\n", argv[0]);
+ return 1;
+ }
+
+ /*
+ * First try an append write against an empty file of a buffer with a
+ * size matching the page size. The buffer is not faulted in before
+ * attempting the write.
+ */
+
+ fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT | O_APPEND, 0666);
+ if (fd == -1) {
+ perror("Failed to open/create file");
+ return 2;
+ }
+
+ pagesize = sysconf(_SC_PAGE_SIZE);
+ if (pagesize == -1) {
+ perror("Failed to get page size");
+ return 3;
+ }
+
+ buf = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (buf == MAP_FAILED) {
+ perror("Failed to allocate first buffer");
+ return 4;
+ }
+
+ ret = do_write(fd, buf, pagesize);
+ if (ret < 0) {
+ perror("First write failed");
+ return 5;
+ }
+
+ ret = fstat(fd, &stbuf);
+ if (ret < 0) {
+ perror("First stat failed");
+ return 6;
+ }
+
+ /* Don't exit on failure so that we run the second test below too. */
+ if (stbuf.st_size != pagesize)
+ fprintf(stderr,
+ "Wrong file size after first write, got %jd expected %ld\n",
+ (intmax_t)stbuf.st_size, pagesize);
+
+ munmap(buf, pagesize);
+ close(fd);
+
+ /*
+ * Now try an append write against an empty file of a buffer with a
+ * size matching twice the page size. Only the first page of the buffer
+ * is faulted in before attempting the write, so that the second page
+ * should be faulted in during the write.
+ */
+ fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT | O_APPEND, 0666);
+ if (fd == -1) {
+ perror("Failed to open/create file");
+ return 7;
+ }
+
+ buf = mmap(NULL, pagesize * 2, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (buf == MAP_FAILED) {
+ perror("Failed to allocate second buffer");
+ return 8;
+ }
+
+ /* Fault in first page of the buffer before the write. */
+ memset(buf, 0, 1);
+
+ ret = do_write(fd, buf, pagesize * 2);
+ if (ret < 0) {
+ perror("Second write failed");
+ return 9;
+ }
+
+ ret = fstat(fd, &stbuf);
+ if (ret < 0) {
+ perror("Second stat failed");
+ return 10;
+ }
+
+ if (stbuf.st_size != pagesize * 2)
+ fprintf(stderr,
+ "Wrong file size after second write, got %jd expected %ld\n",
+ (intmax_t)stbuf.st_size, pagesize * 2);
+
+ munmap(buf, pagesize * 2);
+ close(fd);
+
+ return 0;
+}
diff --git a/tests/generic/362 b/tests/generic/362
new file mode 100755
index 00000000..2c127347
--- /dev/null
+++ b/tests/generic/362
@@ -0,0 +1,28 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2024 SUSE Linux Products GmbH. All Rights Reserved.
+#
+# FS QA Test 362
+#
+# Test that doing a direct IO append write to a file when the input buffer was
+# not yet faulted in, does not result in an incorrect file size.
+#
+. ./common/preamble
+_begin_fstest auto quick
+
+_require_test
+_require_odirect
+_require_test_program dio-append-buf-fault
+
+[ $FSTYP == "btrfs" ] && \
+ _fixed_by_kernel_commit xxxxxxxxxxxx \
+ "btrfs: fix corruption after buffer fault in during direct IO append write"
+
+# On error the test program writes messages to stderr, causing a golden output
+# mismatch and making the test fail.
+$here/src/dio-append-buf-fault $TEST_DIR/dio-append-buf-fault
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/generic/362.out b/tests/generic/362.out
new file mode 100644
index 00000000..0ff40905
--- /dev/null
+++ b/tests/generic/362.out
@@ -0,0 +1,2 @@
+QA output created by 362
+Silence is golden
--
2.43.0
