[PATCH] nfs: test files written size as expected

[Zorro Lang <zlang@kernel.org>]

Test nfs and its underlying fs, make sure file size as expected
after writting a file, and the speculative allocation space can
be shrunken.

Signed-off-by: Zorro Lang <zlang@kernel.org>
---

Hi,

The original bug reproducer is:
1. mount nfs3 backed by xfs
2. dd if=/dev/zero of=/nfs/10M bs=1M count=10
3. du -sh /nfs/10M                           
16M	/nfs/10M 

As this was a xfs issue, so cc linux-xfs@ to get review.

Thanks,
Zorro

 tests/nfs/002     | 43 +++++++++++++++++++++++++++++++++++++++++++
 tests/nfs/002.out |  2 ++
 2 files changed, 45 insertions(+)
 create mode 100755 tests/nfs/002
 create mode 100644 tests/nfs/002.out

diff --git a/tests/nfs/002 b/tests/nfs/002
new file mode 100755
index 00000000..3d29958d
--- /dev/null
+++ b/tests/nfs/002
@@ -0,0 +1,43 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022 Red Hat, Inc.  All Rights Reserved.
+#
+# FS QA Test 002
+#
+# Make sure nfs gets expected file size after writting a big sized file. It's
+# not only testing nfs, test its underlying fs too. For example a known old bug
+# on xfs (underlying fs) caused nfs get larger file size (e.g. 16M) after
+# writting 10M data to a file. It's fixed by a series of patches around
+# 579b62faa5fb16 ("xfs: add background scanning to clear eofblocks inodes")
+#
+. ./common/preamble
+_begin_fstest auto rw
+
+# real QA test starts here
+_supported_fs nfs
+_require_test
+
+localfile=$TEST_DIR/testfile.$seq
+rm -rf $localfile
+
+$XFS_IO_PROG -f -t -c "pwrite 0 10m" -c "fsync" $localfile >>$seqres.full 2>&1
+block_size=`stat -c '%B' $localfile`
+iblocks_expected=$((10 * 1024 * 1024 / $block_size))
+# Try several times for the speculative allocated file size can be shrunken
+res=1
+for ((i=0; i<10; i++));do
+	iblocks_real=`stat -c '%b' $localfile`
+	if [ "$iblocks_expected" = "$iblocks_real" ];then
+		res=0
+		break
+	fi
+	sleep 10
+done
+if [ $res -ne 0 ];then
+	echo "Write $iblocks_expected blocks, but get $iblocks_real blocks"
+fi
+
+echo "Silence is golden"
+# success, all done
+status=0
+exit
diff --git a/tests/nfs/002.out b/tests/nfs/002.out
new file mode 100644
index 00000000..61705c7c
--- /dev/null
+++ b/tests/nfs/002.out
@@ -0,0 +1,2 @@
+QA output created by 002
+Silence is golden
-- 
2.31.1