[PATCH V4 07/11] xfs: Check for extent overflow when writing to unwritten extent

[Chandan Babu R <chandanrlinux@gmail.com>]

This test verifies that XFS does not cause inode fork's extent count to
overflow when writing to an unwritten extent.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 tests/xfs/527     | 89 +++++++++++++++++++++++++++++++++++++++++++++++
 tests/xfs/527.out | 11 ++++++
 tests/xfs/group   |  1 +
 3 files changed, 101 insertions(+)
 create mode 100755 tests/xfs/527
 create mode 100644 tests/xfs/527.out

diff --git a/tests/xfs/527 b/tests/xfs/527
new file mode 100755
index 00000000..cd67bce4
--- /dev/null
+++ b/tests/xfs/527
@@ -0,0 +1,89 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2020 Chandan Babu R.  All Rights Reserved.
+#
+# FS QA Test 527
+#
+# Verify that XFS does not cause inode fork's extent count to overflow when
+# writing to an unwritten extent.
+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.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/inject
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+_supported_fs xfs
+_require_scratch
+_require_xfs_debug
+_require_xfs_io_command "falloc"
+_require_xfs_io_error_injection "reduce_max_iextents"
+
+echo "Format and mount fs"
+_scratch_mkfs_sized $((1024 * 1024 * 1024)) >> $seqres.full
+_scratch_mount >> $seqres.full
+
+bsize=$(_get_file_block_size $SCRATCH_MNT)
+
+testfile=${SCRATCH_MNT}/testfile
+
+echo "Inject reduce_max_iextents error tag"
+_scratch_inject_error reduce_max_iextents 1
+
+nr_blks=15
+
+for io in Buffered Direct; do
+	echo "* $io write to unwritten extent"
+
+	echo "Fallocate $nr_blks blocks"
+	$XFS_IO_PROG -f -c "falloc 0 $((nr_blks * bsize))" $testfile >> $seqres.full
+
+	if [[ $io == "Buffered" ]]; then
+		xfs_io_flag=""
+	else
+		xfs_io_flag="-d"
+	fi
+
+	echo "$io write to every other block of fallocated space"
+	for i in $(seq 1 2 $((nr_blks - 1))); do
+		$XFS_IO_PROG -f -s $xfs_io_flag -c "pwrite $((i * bsize)) $bsize" \
+		       $testfile >> $seqres.full 2>&1
+		[[ $? != 0 ]] && break
+	done
+
+	echo "Verify \$testfile's extent count"
+	nextents=$($XFS_IO_PROG -c 'stat' $testfile | grep nextents)
+	nextents=${nextents##fsxattr.nextents = }
+	if (( $nextents > 10 )); then
+		echo "Extent count overflow check failed: nextents = $nextents"
+		exit 1
+	fi
+
+	rm $testfile
+done
+
+# super_block->s_wb_err will have a newer seq value when compared to "/"'s
+# file->f_sb_err. Consume it here so that xfs_scrub can does not error out.
+$XFS_IO_PROG -c syncfs $SCRATCH_MNT >> $seqres.full 2>&1
+
+# success, all done
+status=0
+exit
diff --git a/tests/xfs/527.out b/tests/xfs/527.out
new file mode 100644
index 00000000..3597ad92
--- /dev/null
+++ b/tests/xfs/527.out
@@ -0,0 +1,11 @@
+QA output created by 527
+Format and mount fs
+Inject reduce_max_iextents error tag
+* Buffered write to unwritten extent
+Fallocate 15 blocks
+Buffered write to every other block of fallocated space
+Verify $testfile's extent count
+* Direct write to unwritten extent
+Fallocate 15 blocks
+Direct write to every other block of fallocated space
+Verify $testfile's extent count
diff --git a/tests/xfs/group b/tests/xfs/group
index d089797b..627813fe 100644
--- a/tests/xfs/group
+++ b/tests/xfs/group
@@ -524,3 +524,4 @@
 524 auto quick punch zero insert collapse
 525 auto quick attr
 526 auto quick dir hardlink symlink
+527 auto quick
-- 
2.29.2