[PATCH V4 08/11] xfs: Check for extent overflow when moving extent from cow to data fork

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

This test verifies that XFS does not cause inode fork's extent count to
overflow when writing to/funshare-ing a shared extent.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 tests/xfs/528     | 110 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/xfs/528.out |  12 +++++
 tests/xfs/group   |   1 +
 3 files changed, 123 insertions(+)
 create mode 100755 tests/xfs/528
 create mode 100644 tests/xfs/528.out

diff --git a/tests/xfs/528 b/tests/xfs/528
new file mode 100755
index 00000000..269d368d
--- /dev/null
+++ b/tests/xfs/528
@@ -0,0 +1,110 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2020 Chandan Babu R.  All Rights Reserved.
+#
+# FS QA Test 528
+#
+# Verify that XFS does not cause inode fork's extent count to overflow when
+# writing to a shared 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/reflink
+. ./common/inject
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+_supported_fs xfs
+_require_scratch
+_require_scratch_reflink
+_require_xfs_debug
+_require_xfs_io_command "reflink"
+_require_xfs_io_command "funshare"
+_require_xfs_io_error_injection "reduce_max_iextents"
+
+echo "Format and mount fs"
+_scratch_mkfs_sized $((512 * 1024 * 1024)) >> $seqres.full
+_scratch_mount >> $seqres.full
+
+bsize=$(_get_block_size $SCRATCH_MNT)
+
+nr_blks=15
+
+srcfile=${SCRATCH_MNT}/srcfile
+dstfile=${SCRATCH_MNT}/dstfile
+
+echo "Inject reduce_max_iextents error tag"
+_scratch_inject_error reduce_max_iextents 1
+
+echo "Create a \$srcfile having an extent of length $nr_blks blocks"
+$XFS_IO_PROG -f -c "pwrite -b $((nr_blks * bsize))  0 $((nr_blks * bsize))" \
+       -c fsync $srcfile  >> $seqres.full
+
+echo "* Write to shared extent"
+
+echo "Share the extent with \$dstfile"
+$XFS_IO_PROG -f -c "reflink $srcfile" $dstfile >> $seqres.full
+
+echo "Buffered write to every other block of \$dstfile's shared extent"
+for i in $(seq 1 2 $((nr_blks - 1))); do
+	$XFS_IO_PROG -f -s -c "pwrite $((i * bsize)) $bsize" $dstfile \
+	       >> $seqres.full 2>&1
+	[[ $? != 0 ]] && break
+done
+
+echo "Verify \$dstfile's extent count"
+nextents=$($XFS_IO_PROG -c 'stat' $dstfile | grep nextents)
+nextents=${nextents##fsxattr.nextents = }
+if (( $nextents > 10 )); then
+	echo "Extent count overflow check failed: nextents = $nextents"
+	exit 1
+fi
+
+rm $dstfile
+
+echo "* Funshare shared extent"
+
+echo "Share the extent with \$dstfile"
+$XFS_IO_PROG -f -c "reflink $srcfile" $dstfile >> $seqres.full
+
+echo "Funshare every other block of \$dstfile's shared extent"
+for i in $(seq 1 2 $((nr_blks - 1))); do
+	$XFS_IO_PROG -f -s -c "funshare $((i * bsize)) $bsize" $dstfile \
+	       >> $seqres.full 2>&1
+	[[ $? != 0 ]] && break
+done
+
+echo "Verify \$dstfile's extent count"
+nextents=$($XFS_IO_PROG -c 'stat' $dstfile | grep nextents)
+nextents=${nextents##fsxattr.nextents = }
+if (( $nextents > 10 )); then
+	echo "Extent count overflow check failed: nextents = $nextents"
+	exit 1
+fi
+
+# super_block->s_wb_err will have a newer seq value when compared to "/"'s
+# file->f_sb_err. Consume it here so that xfs_scrub can does not error out.
+$XFS_IO_PROG -c syncfs $SCRATCH_MNT >> $seqres.full 2>&1
+
+# success, all done
+status=0
+exit
+ 
diff --git a/tests/xfs/528.out b/tests/xfs/528.out
new file mode 100644
index 00000000..d0f2c878
--- /dev/null
+++ b/tests/xfs/528.out
@@ -0,0 +1,12 @@
+QA output created by 528
+Format and mount fs
+Inject reduce_max_iextents error tag
+Create a $srcfile having an extent of length 15 blocks
+* Write to shared extent
+Share the extent with $dstfile
+Buffered write to every other block of $dstfile's shared extent
+Verify $dstfile's extent count
+* Funshare shared extent
+Share the extent with $dstfile
+Funshare every other block of $dstfile's shared extent
+Verify $dstfile's extent count
diff --git a/tests/xfs/group b/tests/xfs/group
index 627813fe..c85aac6b 100644
--- a/tests/xfs/group
+++ b/tests/xfs/group
@@ -525,3 +525,4 @@
 525 auto quick attr
 526 auto quick dir hardlink symlink
 527 auto quick
+528 auto quick reflink
-- 
2.29.2