xfs: Check for extent overflow when trivally adding a new extent

This test verifies that XFS does not cause inode fork's extent count to
overflow when adding a single extent while there's no possibility of splitting
an existing mapping.

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/529

@@ -0,0 +1,171 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021 Chandan Babu R.  All Rights Reserved.
+#
+# FS QA Test 529
+#
+# Verify that XFS does not cause inode fork's extent count to overflow when
+# adding a single extent while there's no possibility of splitting an existing
+# mapping.
+
+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/quota
+. ./common/inject
+. ./common/populate
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+_supported_fs xfs
+_require_scratch
+_require_xfs_quota
+_require_xfs_debug
+_require_test_program "punch-alternating"
+_require_xfs_io_command "falloc"
+_require_xfs_io_error_injection "reduce_max_iextents"
+_require_xfs_io_error_injection "bmap_alloc_minlen_extent"
+
+echo "Format and mount fs"
+_scratch_mkfs_sized $((512 * 1024 * 1024)) >> $seqres.full
+_scratch_mount -o uquota >> $seqres.full
+
+bsize=$(_get_file_block_size $SCRATCH_MNT)
+
+echo "* Delalloc to written extent conversion"
+
+testfile=$SCRATCH_MNT/testfile
+
+echo "Inject reduce_max_iextents error tag"
+_scratch_inject_error reduce_max_iextents 1
+
+nr_blks=$((15 * 2))
+
+echo "Create fragmented file"
+for i in $(seq 0 2 $((nr_blks - 1))); do
+	$XFS_IO_PROG -f -s -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
+
+echo "* Fallocate unwritten extents"
+
+echo "Fallocate fragmented file"
+for i in $(seq 0 2 $((nr_blks - 1))); do
+	$XFS_IO_PROG -f -c "falloc $((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
+
+echo "* Directio write"
+
+echo "Create fragmented file via directio writes"
+for i in $(seq 0 2 $((nr_blks - 1))); do
+	$XFS_IO_PROG -d -s -f -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 $testfile
+
+# Check if XFS gracefully returns with an error code when we try to increase
+# extent count of user quota inode beyond the pseudo max extent count limit.
+echo "* Extend quota inodes"
+
+echo "Disable reduce_max_iextents error tag"
+_scratch_inject_error reduce_max_iextents 0
+
+echo "Consume free space"
+fillerdir=$SCRATCH_MNT/fillerdir
+nr_free_blks=$(stat -f -c '%f' $SCRATCH_MNT)
+nr_free_blks=$((nr_free_blks * 90 / 100))
+
+_fill_fs $((bsize * nr_free_blks)) $fillerdir $bsize 0 >> $seqres.full 2>&1
+
+echo "Create fragmented filesystem"
+for dentry in $(ls -1 $fillerdir/); do
+	$here/src/punch-alternating $fillerdir/$dentry >> $seqres.full
+done
+
+echo "Inject reduce_max_iextents error tag"
+_scratch_inject_error reduce_max_iextents 1
+
+echo "Inject bmap_alloc_minlen_extent error tag"
+_scratch_inject_error bmap_alloc_minlen_extent 1
+
+nr_blks=20
+
+# This is a rough calculation; It doesn't take block headers into
+# consideration.
+# gdb -batch vmlinux -ex 'print sizeof(struct xfs_dqblk)'
+# $1 = 136
+nr_quotas_per_block=$((bsize / 136))
+nr_quotas=$((nr_quotas_per_block * nr_blks))
+
+echo "Extend uquota file"
+for i in $(seq 0 $nr_quotas_per_block $nr_quotas); do
+	chown $i $testfile >> $seqres.full 2>&1
+	[[ $? != 0 ]] && break
+done
+
+_scratch_unmount >> $seqres.full
+
+echo "Verify uquota inode's extent count"
+uquotino=$(_scratch_xfs_get_metadata_field 'uquotino' 'sb 0')
+
+nextents=$(_scratch_get_iext_count $uquotino data || \
+		   _fail "Unable to obtain inode fork's extent count")
+if (( $nextents > 10 )); then
+	echo "Extent count overflow check failed: nextents = $nextents"
+	exit 1
+fi
+
+# success, all done
+status=0
+exit

tests/xfs/529.out

@@ -0,0 +1,20 @@
+QA output created by 529
+Format and mount fs
+* Delalloc to written extent conversion
+Inject reduce_max_iextents error tag
+Create fragmented file
+Verify $testfile's extent count
+* Fallocate unwritten extents
+Fallocate fragmented file
+Verify $testfile's extent count
+* Directio write
+Create fragmented file via directio writes
+Verify $testfile's extent count
+* Extend quota inodes
+Disable reduce_max_iextents error tag
+Consume free space
+Create fragmented filesystem
+Inject reduce_max_iextents error tag
+Inject bmap_alloc_minlen_extent error tag
+Extend uquota file
+Verify uquota inode's extent count

tests/xfs/group

@@ -505,3 +505,4 @@
 526 auto quick mkfs
 527 auto quick quota
 528 auto quick rw realtime
+529 auto quick quota