* [RFC PATCH] generic: test race between appending AIO DIO and fallocate
[not found] <20191029034850.8212-1-david@fromorbit.com>
@ 2019-10-29 20:23 ` Darrick J. Wong
0 siblings, 0 replies; only message in thread
From: Darrick J. Wong @ 2019-10-29 20:23 UTC (permalink / raw)
To: Dave Chinner; +Cc: linux-xfs, Brian Foster, Eric Sandeen, fstests
From: Darrick J. Wong <darrick.wong@oracle.com>
Dave Chinner reports[1] that an appending AIO DIO write to the second
block of a zero-length file and an fallocate request to the first block
of the same file can race to set isize, with the user-visible end result
that the file size is set incorrectly to one block long. Write a small
test to reproduce the results.
[1] https://lore.kernel.org/linux-xfs/20191029100342.GA41131@bfoster/T/
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
.../aio-dio-append-write-fallocate-race.c | 212 ++++++++++++++++++++
tests/generic/722 | 44 ++++
tests/generic/722.out | 2
tests/generic/group | 1
4 files changed, 259 insertions(+)
create mode 100644 src/aio-dio-regress/aio-dio-append-write-fallocate-race.c
create mode 100755 tests/generic/722
create mode 100644 tests/generic/722.out
diff --git a/src/aio-dio-regress/aio-dio-append-write-fallocate-race.c b/src/aio-dio-regress/aio-dio-append-write-fallocate-race.c
new file mode 100644
index 00000000..091b047d
--- /dev/null
+++ b/src/aio-dio-regress/aio-dio-append-write-fallocate-race.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-or-newer
+/*
+ * Copyright (c) 2019 Oracle.
+ * All Rights Reserved.
+ *
+ * Race appending aio dio and fallocate to make sure we get the correct file
+ * size afterwards.
+ */
+#include <stdio.h>
+#include <pthread.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <libaio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <limits.h>
+
+static int fd;
+static int blocksize;
+
+static void *
+falloc_thread(
+ void *p)
+{
+ int ret;
+
+ ret = fallocate(fd, 0, 0, blocksize);
+ if (ret)
+ perror("falloc");
+
+ return NULL;
+}
+
+static int
+test(
+ const char *fname,
+ unsigned int iteration,
+ unsigned int *passed)
+{
+ struct stat sbuf;
+ pthread_t thread;
+ io_context_t ioctx = 0;
+ struct iocb iocb;
+ struct iocb *iocbp = &iocb;
+ struct io_event event;
+ char *buf;
+ bool wait_thread = false;
+ int ret;
+
+ /* Truncate file, allocate resources for doing IO. */
+ fd = open(fname, O_DIRECT | O_RDWR | O_TRUNC | O_CREAT, 0644);
+ if (fd < 0) {
+ perror(fname);
+ return -1;
+ }
+
+ ret = fstat(fd, &sbuf);
+ if (ret) {
+ perror(fname);
+ goto out;
+ }
+ blocksize = sbuf.st_blksize;
+
+ ret = posix_memalign((void **)&buf, blocksize, blocksize);
+ if (ret) {
+ errno = ret;
+ perror("buffer");
+ goto out;
+ }
+ memset(buf, 'X', blocksize);
+ memset(&event, 0, sizeof(event));
+
+ ret = io_queue_init(1, &ioctx);
+ if (ret) {
+ errno = -ret;
+ perror("io_queue_init");
+ goto out_buf;
+ }
+
+ /*
+ * Set ourselves up to race fallocate(0..blocksize) with aio dio
+ * pwrite(blocksize..blocksize * 2). This /should/ give us a file
+ * with length (2 * blocksize).
+ */
+ io_prep_pwrite(&iocb, fd, buf, blocksize, blocksize);
+
+ ret = pthread_create(&thread, NULL, falloc_thread, NULL);
+ if (ret) {
+ errno = ret;
+ perror("pthread");
+ goto out_io;
+ }
+ wait_thread = true;
+
+ ret = io_submit(ioctx, 1, &iocbp);
+ if (ret != 1) {
+ errno = -ret;
+ perror("io_submit");
+ goto out_join;
+ }
+
+ ret = io_getevents(ioctx, 1, 1, &event, NULL);
+ if (ret != 1) {
+ errno = -ret;
+ perror("io_getevents");
+ goto out_join;
+ }
+
+ if (event.res < 0) {
+ errno = -event.res;
+ perror("io_event.res");
+ goto out_join;
+ }
+
+ if (event.res2 < 0) {
+ errno = -event.res2;
+ perror("io_event.res2");
+ goto out_join;
+ }
+
+ wait_thread = false;
+ ret = pthread_join(thread, NULL);
+ if (ret) {
+ errno = ret;
+ perror("join");
+ goto out_io;
+ }
+
+ /* Make sure we actually got a file of size (2 * blocksize). */
+ ret = fstat(fd, &sbuf);
+ if (ret) {
+ perror(fname);
+ goto out_buf;
+ }
+
+ if (sbuf.st_size != 2 * blocksize) {
+ fprintf(stderr, "[%u]: sbuf.st_size=%llu, expected %llu.\n",
+ iteration,
+ (unsigned long long)sbuf.st_size,
+ (unsigned long long)2 * blocksize);
+ } else {
+ printf("[%u]: passed.\n", iteration);
+ (*passed)++;
+ }
+
+out_join:
+ if (wait_thread) {
+ ret = pthread_join(thread, NULL);
+ if (ret) {
+ errno = ret;
+ perror("join");
+ goto out_io;
+ }
+ }
+out_io:
+ ret = io_queue_release(ioctx);
+ if (ret) {
+ errno = -ret;
+ perror("io_queue_release");
+ }
+
+out_buf:
+ free(buf);
+out:
+ ret = close(fd);
+ fd = -1;
+ if (ret) {
+ perror("close");
+ return -1;
+ }
+
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ int ret;
+ long l;
+ unsigned int i;
+ unsigned int passed = 0;
+
+ if (argc != 3) {
+ printf("Usage: %s filename iterations\n", argv[0]);
+ return 1;
+ }
+
+ errno = 0;
+ l = strtol(argv[2], NULL, 0);
+ if (errno) {
+ perror(argv[2]);
+ return 1;
+ }
+ if (l < 1 || l > UINT_MAX) {
+ fprintf(stderr, "%ld: must be between 1 and %u.\n",
+ l, UINT_MAX);
+ return 1;
+ }
+
+ for (i = 0; i < l; i++) {
+ ret = test(argv[1], i, &passed);
+ if (ret)
+ return 1;
+ }
+
+ printf("pass rate: %u/%u (%.2f%%)\n", passed, i, 100.0 * passed / i);
+
+ return 0;
+}
diff --git a/tests/generic/722 b/tests/generic/722
new file mode 100755
index 00000000..307e3b77
--- /dev/null
+++ b/tests/generic/722
@@ -0,0 +1,44 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2019, Oracle and/or its affiliates. All Rights Reserved.
+#
+# FS QA Test No. 722
+#
+# Race an appending aio dio write to the second block of a file while
+# simultaneously fallocating to the first block. Make sure that we end up
+# with a two-block file.
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1 # failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+ cd /
+ rm -f $tmp.* $testfile
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+
+# real QA test starts here
+_supported_os Linux
+_supported_fs generic
+_require_aiodio "aiocp"
+_require_test
+AIO_TEST=$here/src/aio-dio-regress/aio-dio-append-write-fallocate-race
+
+rm -f $seqres.full
+
+testfile=$TEST_DIR/test-$seq
+$AIO_TEST $testfile 100 >> $seqres.full
+
+echo Silence is golden.
+# success, all done
+status=0
+exit
diff --git a/tests/generic/722.out b/tests/generic/722.out
new file mode 100644
index 00000000..8621a87d
--- /dev/null
+++ b/tests/generic/722.out
@@ -0,0 +1,2 @@
+QA output created by 722
+Silence is golden.
diff --git a/tests/generic/group b/tests/generic/group
index a252f424..20df0964 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -591,3 +591,4 @@
716 dangerous_norepair
720 dangerous_norepair
721 auto quick atime
+722 auto quick rw falloc
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