--- /dev/null
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021 Chandan Babu R. All Rights Reserved.
+#
+# FS QA Test 534
+#
+# 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_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
--- /dev/null
+QA output created by 534
+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