[PATCH v2] xfstests: pwrite hang when writing from mmaped buffer of the same page

[PATCH v2] xfstests: pwrite hang when writing from mmaped buffer of the same page

[Zhong, Xin]

The problem is found in meego testing on btrfs:
http://bugs.meego.com/show_bug.cgi?id=6672

Reviewed-by: Hellwig, Christoph <hch@infradead.org>
Signed-off-by: Zhong, Xin <xin.zhong@intel.com>
---
 248                       |   58 +++++++++++++++++++++++++++++++++
 248.out                   |    2 +
 group                     |    1 +
 src/Makefile              |    2 +-
 src/pwrite_mmap_blocked.c |   78 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 140 insertions(+), 1 deletions(-)
 create mode 100755 248
 create mode 100644 248.out
 create mode 100644 src/pwrite_mmap_blocked.c

diff --git a/248 b/248
new file mode 100755
index 0000000..a4664d9
--- /dev/null
+++ b/248
@@ -0,0 +1,58 @@
+#! /bin/bash
+# FS QA Test No. 248
+#
+# Test for pwrite hang problem when writing from mmaped buffer of the same page 
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2010 YOUR NAME HERE.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+# creator
+owner=xin.zhong@intel.com
+
+seq=`basename $0`
+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 $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs generic
+_supported_os Linux
+
+TESTFILE=$TEST_DIR/test_file
+TEST_PROG=$here/src/pwrite_mmap_blocked
+
+$TEST_PROG $TESTFILE
+rm -f $TESTFILE
+
+# success, all done
+status=0
+exit
diff --git a/248.out b/248.out
new file mode 100644
index 0000000..d02c1ac
--- /dev/null
+++ b/248.out
@@ -0,0 +1,2 @@
+QA output created by 248
+pwrite 1 bytes from 2 to 3
diff --git a/group b/group
index 0f94dd9..ddda26c 100644
--- a/group
+++ b/group
@@ -361,3 +361,4 @@ deprecated
 245 auto quick dir
 246 auto quick rw
 247 auto quick rw
+248 other quick rw 
diff --git a/src/Makefile b/src/Makefile
index b827bd0..47d7334 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -17,7 +17,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \
 	preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \
 	locktest unwritten_mmap bulkstat_unlink_test t_stripealign \
 	bulkstat_unlink_test_modified t_dir_offset t_futimens t_immutable \
-	stale_handle
+	stale_handle pwrite_mmap_blocked
 
 SUBDIRS =
 
diff --git a/src/pwrite_mmap_blocked.c b/src/pwrite_mmap_blocked.c
new file mode 100644
index 0000000..288a62f
--- /dev/null
+++ b/src/pwrite_mmap_blocked.c
@@ -0,0 +1,78 @@
+/*    Copyright (c) 2010 Intel Corporation
+ *
+ *    This program is free software; you can redistribute it and/or modify it
+ *    under the terms of the GNU General Public License as published by the Free
+ *    Software Foundation; version 2 of the License
+ *
+ *    This program is distributed in the hope that it will be useful, but
+ *    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ *    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *    for more details.
+ *
+ *    You should have received a copy of the GNU General Public License along
+ *    with this program; if not, write to the Free Software Foundation, Inc., 59
+ *    Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/mman.h>
+#include <sys/signal.h>
+#include <sys/stat.h>
+
+char *progname;
+loff_t size;
+int fd;
+void *mapped_mem;
+
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	progname = argv[0];
+	size = 5;
+	fd = open(argv[1], O_RDWR|O_TRUNC|O_CREAT, 0666);
+	if (fd < 0) {
+		fprintf(stderr, "%s: Cannot open `%s': %s\n",
+			progname, argv[1], strerror(errno));
+		exit(1);
+	}
+
+	char *cc = "01234";
+	if ((ret = pwrite(fd, (const char *)cc,
+				size, 0)) != size) {
+		fprintf(stderr, "%s: pwrite returned %d\n",
+			__FUNCTION__, ret);
+		perror("pwrite");
+		exit(1);
+	}
+
+	mapped_mem = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (mapped_mem == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+	loff_t amount = 1;
+	loff_t from = 2;
+	loff_t to = 3;
+	printf("pwrite %Ld bytes from %Ld to %Ld\n", amount, from, to);
+	if ((ret = pwrite(fd, (char *)mapped_mem + from, amount, to)) != amount) {
+		printf("%s: pwrite returned %d, not %Ld\n",
+					__FUNCTION__, ret, amount);
+		if (errno == EFAULT) {
+			printf("pwrite: EFAULT\n");
+		} else if (ret < 0) {
+			perror("pwrite");
+			exit(1);
+		}
+	}
+	munmap(mapped_mem,0);
+	close(fd);
+	exit(0);
+}
-- 
1.6.2.2

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Re: [PATCH v2] xfstests: pwrite hang when writing from mmaped buffer of the same page

[Dave Chinner]

On Tue, Dec 14, 2010 at 11:00:52AM +0800, Zhong, Xin wrote:
> The problem is found in meego testing on btrfs:
> http://bugs.meego.com/show_bug.cgi?id=6672
> 
> Reviewed-by: Hellwig, Christoph <hch@infradead.org>
> Signed-off-by: Zhong, Xin <xin.zhong@intel.com>
> ---
>  248                       |   58 +++++++++++++++++++++++++++++++++
>  248.out                   |    2 +
>  group                     |    1 +
>  src/Makefile              |    2 +-
>  src/pwrite_mmap_blocked.c |   78 +++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 140 insertions(+), 1 deletions(-)
>  create mode 100755 248
>  create mode 100644 248.out
>  create mode 100644 src/pwrite_mmap_blocked.c
> 
> diff --git a/248 b/248
> new file mode 100755
> index 0000000..a4664d9
> --- /dev/null
> +++ b/248
> @@ -0,0 +1,58 @@
> +#! /bin/bash
> +# FS QA Test No. 248
> +#
> +# Test for pwrite hang problem when writing from mmaped buffer of the same page 
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2010 YOUR NAME HERE.  All Rights Reserved.
                        ^^^^^^^^^^^^^^

Needs updating, I think. ;)

While I'm here, a two minute review...

....

> +_cleanup()
> +{
> +    cd /
> +    rm -f $tmp.*
> +}
> +
> +# get standard environment, filters and checks
> +. ./common.rc
> +. ./common.filter
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs generic
> +_supported_os Linux
> +
> +TESTFILE=$TEST_DIR/test_file
> +TEST_PROG=$here/src/pwrite_mmap_blocked
> +
> +$TEST_PROG $TESTFILE
> +rm -f $TESTFILE

This rm should be in the _cleanup() function so that it is removed
even when the test is aborted.

.....

> diff --git a/group b/group
> index 0f94dd9..ddda26c 100644
> --- a/group
> +++ b/group
> @@ -361,3 +361,4 @@ deprecated
>  245 auto quick dir
>  246 auto quick rw
>  247 auto quick rw
> +248 other quick rw 

Why not the auto group?

> +char *progname;
> +loff_t size;
> +int fd;
> +void *mapped_mem;

None of these need to be global.

> +
> +
> +int main(int argc, char *argv[])
> +{
> +	int ret;
> +
> +	progname = argv[0];
> +	size = 5;
> +	fd = open(argv[1], O_RDWR|O_TRUNC|O_CREAT, 0666);
> +	if (fd < 0) {
> +		fprintf(stderr, "%s: Cannot open `%s': %s\n",
> +			progname, argv[1], strerror(errno));
> +		exit(1);
> +	}
> +
> +	char *cc = "01234";

Don't mix declarations in the the code. Better would be:

	int ret;
	char *cc = "01234";

	progname = argv[0];
	size = strlen(cc);
	....


> +	if ((ret = pwrite(fd, (const char *)cc,
> +				size, 0)) != size) {

	ret = pwrite(fd, cc, size, 0);
	if (ret != size) {

> +		fprintf(stderr, "%s: pwrite returned %d\n",
> +			__FUNCTION__, ret);
> +		perror("pwrite");
> +		exit(1);
> +	}

No need for both fprintf and perror calls.

> +
> +	mapped_mem = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
> +	if (mapped_mem == MAP_FAILED) {
> +		perror("mmap");
> +		exit(1);
> +	}
> +	loff_t amount = 1;
> +	loff_t from = 2;
> +	loff_t to = 3;
> +	printf("pwrite %Ld bytes from %Ld to %Ld\n", amount, from, to);
> +	if ((ret = pwrite(fd, (char *)mapped_mem + from, amount, to)) != amount) {

	ret = pwrite(fd, (char *)mapped_mem + from, amount, to));
	if (ret != amount) {

> +		printf("%s: pwrite returned %d, not %Ld\n",
> +					__FUNCTION__, ret, amount);
> +		if (errno == EFAULT) {
> +			printf("pwrite: EFAULT\n");
> +		} else if (ret < 0) {
> +			perror("pwrite");
> +			exit(1);
> +		}

A single call to perror() will be sufficient here...

> +	}
> +	munmap(mapped_mem,0);
> +	close(fd);
> +	exit(0);
> +}

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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