[PATCH] fstests: add generic/609 to test O_DIRECT|O_DSYNC

* [PATCH] fstests: add generic/609 to test O_DIRECT|O_DSYNC
@ 2020-09-02 15:00 Josef Bacik
  2020-09-02 15:03 ` Johannes Thumshirn
                   ` (3 more replies)
  0 siblings, 4 replies; 7+ messages in thread
From: Josef Bacik @ 2020-09-02 15:00 UTC (permalink / raw)
  To: linux-btrfs, fstests

We had a problem recently where btrfs would deadlock with
O_DIRECT|O_DSYNC because of an unexpected dependency on ->fsync in
iomap.  This was only caught by chance with aiostress, because weirdly
we don't actually test this particular configuration anywhere in
xfstests.  Fix this by adding a basic test that just does
O_DIRECT|O_DSYNC writes.  With this test the box deadlocks right away
with Btrfs, which would have been helpful in finding this issue before
the patches were merged.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 .gitignore                      |  1 +
 src/aio-dio-regress/dio-dsync.c | 61 +++++++++++++++++++++++++++++++++
 tests/generic/609               | 44 ++++++++++++++++++++++++
 tests/generic/group             |  1 +
 4 files changed, 107 insertions(+)
 create mode 100644 src/aio-dio-regress/dio-dsync.c
 create mode 100755 tests/generic/609

diff --git a/.gitignore b/.gitignore
index 5f5c4a0f..07c8014b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -175,6 +175,7 @@
 /src/aio-dio-regress/aio-last-ref-held-by-io
 /src/aio-dio-regress/aiocp
 /src/aio-dio-regress/aiodio_sparse2
+/src/aio-dio-regress/dio-dsync
 /src/log-writes/replay-log
 /src/perf/*.pyc
 
diff --git a/src/aio-dio-regress/dio-dsync.c b/src/aio-dio-regress/dio-dsync.c
new file mode 100644
index 00000000..53cda9ac
--- /dev/null
+++ b/src/aio-dio-regress/dio-dsync.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-or-newer
+/*
+ * Copyright (c) 2020 Facebook.
+ * All Rights Reserved.
+ *
+ * Do some O_DIRECT writes with O_DSYNC to exercise this path.
+ */
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+
+int main(int argc, char **argv)
+{
+	struct stat st;
+	char *buf;
+	ssize_t ret;
+	int fd, i;
+	int bufsize;
+
+	if (argc != 2) {
+		printf("Usage: %s filename\n", argv[0]);
+		return 1;
+	}
+
+	fd = open(argv[1], O_DIRECT | O_RDWR | O_TRUNC | O_CREAT | O_DSYNC,
+		  0644);
+	if (fd < 0) {
+		perror(argv[1]);
+		return 1;
+	}
+
+	if (fstat(fd, &st)) {
+		perror(argv[1]);
+		return 1;
+	}
+	bufsize = st.st_blksize * 10;
+
+	ret = posix_memalign((void **)&buf, st.st_blksize, bufsize);
+	if (ret) {
+		errno = ret;
+		perror("allocating buffer");
+		return 1;
+	}
+
+	memset(buf, 'a', bufsize);
+	for (i = 0; i < 10; i++) {
+		ret = write(fd, buf, bufsize);
+		if (ret < 0) {
+			perror("writing");
+			return 1;
+		}
+	}
+	free(buf);
+	close(fd);
+	return 0;
+}
diff --git a/tests/generic/609 b/tests/generic/609
new file mode 100755
index 00000000..8a888eb9
--- /dev/null
+++ b/tests/generic/609
@@ -0,0 +1,44 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2020 Josef Bacik.  All Rights Reserved.
+#
+# FS QA Test 609
+#
+# iomap can call generic_write_sync() if we're O_DSYNC, so write a basic test to
+# exercise O_DSYNC so any unsuspecting file systems will get lockdep warnings if
+# they're locking isn't compatible.
+#
+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.*
+	rm -rf $TEST_DIR/file
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# Modify as appropriate.
+_supported_fs generic
+_supported_os Linux
+_require_test
+_require_aiodio dio-dsync
+
+$AIO_TEST $TEST_DIR/file
+
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/generic/group b/tests/generic/group
index aa969bcb..ae2567a0 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -611,3 +611,4 @@
 606 auto attr quick dax
 607 auto attr quick dax
 608 auto attr quick dax
+609 auto quick
-- 
2.26.2


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