xfs: Check for extent overflow when punching a hole

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

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>

tests/xfs/531

@@ -0,0 +1,83 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021 Chandan Babu R.  All Rights Reserved.
+#
+# FS QA Test 531
+#
+# Verify that XFS does not cause inode fork's extent count to overflow when
+# punching out an 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 "fpunch"
+_require_xfs_io_command "finsert"
+_require_xfs_io_command "fcollapse"
+_require_xfs_io_command "fzero"
+_require_xfs_io_error_injection "reduce_max_iextents"
+
+echo "Format and mount fs"
+_scratch_mkfs >> $seqres.full
+_scratch_mount >> $seqres.full
+
+bsize=$(_get_file_block_size $SCRATCH_MNT)
+nr_blks=30
+
+testfile=$SCRATCH_MNT/testfile
+
+echo "Inject reduce_max_iextents error tag"
+_scratch_inject_error reduce_max_iextents 1
+
+for op in fpunch finsert fcollapse fzero; do
+	echo "* $op regular file"
+
+	echo "Create \$testfile"
+	$XFS_IO_PROG -f -s \
+		     -c "pwrite -b $((nr_blks * bsize)) 0 $((nr_blks * bsize))" \
+		     $testfile  >> $seqres.full
+
+	echo "$op alternating blocks"
+	for i in $(seq 1 2 $((nr_blks - 1))); do
+		$XFS_IO_PROG -f -c "$op $((i * bsize)) $bsize" $testfile \
+		       >> $seqres.full 2>&1
+		[[ $? != 0 ]] && break
+	done
+
+	echo "Verify \$testfile's extent count"
+
+	nextents=$(_xfs_get_fsxattr nextents $testfile)
+	if (( $nextents > 10 )); then
+		echo "Extent count overflow check failed: nextents = $nextents"
+		exit 1
+	fi
+
+	rm $testfile
+done
+
+# success, all done
+status=0
+exit

tests/xfs/531.out

@@ -0,0 +1,19 @@
+QA output created by 531
+Format and mount fs
+Inject reduce_max_iextents error tag
+* fpunch regular file
+Create $testfile
+fpunch alternating blocks
+Verify $testfile's extent count
+* finsert regular file
+Create $testfile
+finsert alternating blocks
+Verify $testfile's extent count
+* fcollapse regular file
+Create $testfile
+fcollapse alternating blocks
+Verify $testfile's extent count
+* fzero regular file
+Create $testfile
+fzero alternating blocks
+Verify $testfile's extent count

tests/xfs/group

@@ -507,3 +507,4 @@
 528 auto quick rw realtime
 529 auto quick quota
 530 auto quick realtime growfs
+531 auto quick punch zero insert collapse