diff --git a/common/rc b/common/rc
index c016673..474fa84 100644
--- a/common/rc
+++ b/common/rc
@@ -101,7 +101,7 @@ _mwrite_byte() {
 	mmap_len="$4"
 	file="$5"
 
-	"$XFS_IO_PROG" -f -c "mmap -rw 0 $mmap_len" -c "pwrite -S $pattern $offset $len" "$file"
+	"$XFS_IO_PROG" -f -c "mmap -rw 0 $mmap_len" -c "mwrite -S $pattern $offset $len" "$file"
 }
 
 # ls -l w/ selinux sometimes puts a dot at the end:
diff --git a/tests/generic/842 b/tests/generic/842
new file mode 100755
index 0000000..5eda56b
--- /dev/null
+++ b/tests/generic/842
@@ -0,0 +1,107 @@
+#! /bin/bash
+# FS QA Test No. 842
+#
+# Reflink a file, use up the rest of the space, then try to observe ENOSPC
+# while copy-on-writing the file via the page cache.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015, Oracle and/or its affiliates.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+
+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 -rf "$tmp".* "$TESTDIR1"
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/attr
+. ./common/reflink
+
+# real QA test starts here
+_supported_os Linux
+_require_scratch_reflink
+_require_cp_reflink
+
+rm -f "$seqres.full"
+
+echo "Format and mount"
+_scratch_mkfs > "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+
+TESTDIR="$SCRATCH_MNT/test-$seq"
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Reformat with appropriate size"
+BLKSZ="$(stat -f "$TESTDIR" -c '%S')"
+NR_BLKS=10240
+umount "$SCRATCH_MNT"
+SZ_BYTES=$((NR_BLKS * 8 * BLKSZ))
+if [ $SZ_BYTES -lt $((32 * 1048576)) ]; then
+	SZ_BYTES=$((32 * 1048576))
+fi
+_scratch_mkfs_sized $SZ_BYTES >> "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Create a big file and reflink it"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" >> "$seqres.full" 2>&1
+_cp_reflink "$TESTDIR/bigfile" "$TESTDIR/clonefile"
+sync
+
+echo "Allocate the rest of the space"
+NR_FREE="$(stat -f -c '%f' "$TESTDIR")"
+touch "$TESTDIR/file0" "$TESTDIR/file1"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_FREE)) "$TESTDIR/eat_my_space" >> "$seqres.full" 2>&1
+sync
+
+echo "CoW the big file"
+out="$(_pwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" 2>&1)"
+echo "${out}" | grep -q "No space left on device" || echo "CoW should have failed with ENOSPC"
+echo "${out}" >> "$seqres.full" 2>&1
+echo "${out}"
+
+echo "Remount and try CoW again"
+_scratch_remount
+
+out="$(_pwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" 2>&1)"
+echo "${out}" | grep -q "No space left on device" || echo "CoW should have failed with ENOSPC"
+echo "${out}" >> "$seqres.full" 2>&1
+echo "${out}"
+
+#filefrag -v $TESTDIR/bigfile
+#filefrag -v $TESTDIR/clonefile
+
+echo "Check scratch fs"
+umount "$SCRATCH_MNT"
+_check_scratch_fs
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/842.out b/tests/generic/842.out
new file mode 100644
index 0000000..df58025
--- /dev/null
+++ b/tests/generic/842.out
@@ -0,0 +1,10 @@
+QA output created by 842
+Format and mount
+Reformat with appropriate size
+Create a big file and reflink it
+Allocate the rest of the space
+CoW the big file
+pwrite64: No space left on device
+Remount and try CoW again
+pwrite64: No space left on device
+Check scratch fs
diff --git a/tests/generic/843 b/tests/generic/843
new file mode 100755
index 0000000..03dc570
--- /dev/null
+++ b/tests/generic/843
@@ -0,0 +1,107 @@
+#! /bin/bash
+# FS QA Test No. 843
+#
+# Reflink a file that uses more than half of the space, then try to observe
+# ENOSPC while copy-on-writing the file via the page cache.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015, Oracle and/or its affiliates.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+
+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 -rf "$tmp".* "$TESTDIR1"
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/attr
+. ./common/reflink
+
+# real QA test starts here
+_supported_os Linux
+_require_scratch_reflink
+_require_cp_reflink
+
+rm -f "$seqres.full"
+
+echo "Format and mount"
+_scratch_mkfs > "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+
+TESTDIR="$SCRATCH_MNT/test-$seq"
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Reformat with appropriate size"
+BLKSZ="$(stat -f "$TESTDIR" -c '%S')"
+NR_BLKS=10240
+umount "$SCRATCH_MNT"
+SZ_BYTES=$((NR_BLKS * 3 / 2 * BLKSZ))
+if [ $SZ_BYTES -lt $((32 * 1048576)) ]; then
+	SZ_BYTES=$((32 * 1048576))
+fi
+_scratch_mkfs_sized $SZ_BYTES >> "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Create a big file and reflink it"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" >> "$seqres.full" 2>&1
+_cp_reflink "$TESTDIR/bigfile" "$TESTDIR/clonefile"
+sync
+
+echo "Allocate the rest of the space"
+NR_FREE="$(stat -f -c '%f' "$TESTDIR")"
+touch "$TESTDIR/file0" "$TESTDIR/file1"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_FREE)) "$TESTDIR/eat_my_space" >> "$seqres.full" 2>&1
+sync
+
+echo "CoW the big file"
+out="$(_pwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" 2>&1)"
+echo "${out}" | grep -q "No space left on device" || echo "CoW should have failed with ENOSPC"
+echo "${out}" >> "$seqres.full" 2>&1
+echo "${out}"
+
+echo "Remount and try CoW again"
+_scratch_remount
+
+out="$(_pwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" 2>&1)"
+echo "${out}" | grep -q "No space left on device" || echo "CoW should have failed with ENOSPC"
+echo "${out}" >> "$seqres.full" 2>&1
+echo "${out}"
+
+#filefrag -v $TESTDIR/bigfile
+#filefrag -v $TESTDIR/clonefile
+
+echo "Check scratch fs"
+umount "$SCRATCH_MNT"
+_check_scratch_fs
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/843.out b/tests/generic/843.out
new file mode 100644
index 0000000..43c1cf6
--- /dev/null
+++ b/tests/generic/843.out
@@ -0,0 +1,10 @@
+QA output created by 843
+Format and mount
+Reformat with appropriate size
+Create a big file and reflink it
+Allocate the rest of the space
+CoW the big file
+pwrite64: No space left on device
+Remount and try CoW again
+pwrite64: No space left on device
+Check scratch fs
diff --git a/tests/generic/844 b/tests/generic/844
new file mode 100755
index 0000000..70bc235
--- /dev/null
+++ b/tests/generic/844
@@ -0,0 +1,109 @@
+#! /bin/bash
+# FS QA Test No. 844
+#
+# Reflink a file, use up the rest of the space, then try to observe ENOSPC
+# while copy-on-writing the file via mmap.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015, Oracle and/or its affiliates.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+
+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 -rf "$tmp".* "$TESTDIR1"
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/attr
+. ./common/reflink
+
+# real QA test starts here
+_supported_os Linux
+_require_scratch_reflink
+_require_cp_reflink
+
+rm -f "$seqres.full"
+
+echo "Format and mount"
+_scratch_mkfs > "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+
+TESTDIR="$SCRATCH_MNT/test-$seq"
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Reformat with appropriate size"
+BLKSZ="$(stat -f "$TESTDIR" -c '%S')"
+NR_BLKS=10240
+umount "$SCRATCH_MNT"
+SZ_BYTES=$((NR_BLKS * 8 * BLKSZ))
+if [ $SZ_BYTES -lt $((32 * 1048576)) ]; then
+	SZ_BYTES=$((32 * 1048576))
+fi
+_scratch_mkfs_sized $SZ_BYTES >> "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Create a big file and reflink it"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" >> "$seqres.full" 2>&1
+_cp_reflink "$TESTDIR/bigfile" "$TESTDIR/clonefile"
+sync
+
+echo "Allocate the rest of the space"
+NR_FREE="$(stat -f -c '%f' "$TESTDIR")"
+touch "$TESTDIR/file0" "$TESTDIR/file1"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_FREE)) "$TESTDIR/eat_my_space" >> "$seqres.full" 2>&1
+sync
+
+echo "mmap CoW the big file"
+out="$(_mwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" 2>&1)"
+err="$?"
+if [ "$err" -lt 128 ]; then
+	echo "mmap CoW should have failed with SIGBUS, got SIG$(kill -l $err)"
+fi
+
+echo "Remount and try CoW again"
+_scratch_remount
+
+out="$(_mwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" 2>&1)"
+err="$?"
+if [ "$err" -lt 128 ]; then
+	echo "mmap CoW should have failed with SIGBUS, got SIG$(kill -l $err)"
+fi
+
+#filefrag -v $TESTDIR/bigfile
+#filefrag -v $TESTDIR/clonefile
+
+echo "Check scratch fs"
+umount "$SCRATCH_MNT"
+_check_scratch_fs
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/844.out b/tests/generic/844.out
new file mode 100644
index 0000000..130afc1
--- /dev/null
+++ b/tests/generic/844.out
@@ -0,0 +1,8 @@
+QA output created by 844
+Format and mount
+Reformat with appropriate size
+Create a big file and reflink it
+Allocate the rest of the space
+mmap CoW the big file
+Remount and try CoW again
+Check scratch fs
diff --git a/tests/generic/845 b/tests/generic/845
new file mode 100755
index 0000000..5efaf38
--- /dev/null
+++ b/tests/generic/845
@@ -0,0 +1,107 @@
+#! /bin/bash
+# FS QA Test No. 845
+#
+# Reflink a file, use up the rest of the space, then try to observe ENOSPC
+# while copy-on-writing the file via direct-io.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015, Oracle and/or its affiliates.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+
+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 -rf "$tmp".* "$TESTDIR1"
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/attr
+. ./common/reflink
+
+# real QA test starts here
+_supported_os Linux
+_require_scratch_reflink
+_require_cp_reflink
+
+rm -f "$seqres.full"
+
+echo "Format and mount"
+_scratch_mkfs > "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+
+TESTDIR="$SCRATCH_MNT/test-$seq"
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Reformat with appropriate size"
+BLKSZ="$(stat -f "$TESTDIR" -c '%S')"
+NR_BLKS=10240
+umount "$SCRATCH_MNT"
+SZ_BYTES=$((NR_BLKS * 8 * BLKSZ))
+if [ $SZ_BYTES -lt $((32 * 1048576)) ]; then
+	SZ_BYTES=$((32 * 1048576))
+fi
+_scratch_mkfs_sized $SZ_BYTES >> "$seqres.full" 2>&1
+_scratch_mount >> "$seqres.full" 2>&1
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Create a big file and reflink it"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" >> "$seqres.full" 2>&1
+_cp_reflink "$TESTDIR/bigfile" "$TESTDIR/clonefile"
+sync
+
+echo "Allocate the rest of the space"
+NR_FREE="$(stat -f -c '%f' "$TESTDIR")"
+touch "$TESTDIR/file0" "$TESTDIR/file1"
+_pwrite_byte 0x61 0 $((BLKSZ * NR_FREE)) "$TESTDIR/eat_my_space" >> "$seqres.full" 2>&1
+sync
+
+echo "CoW the big file"
+out="$(_pwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" -d 2>&1)"
+echo "${out}" | grep -q "No space left on device" || echo "CoW should have failed with ENOSPC"
+echo "${out}" >> "$seqres.full" 2>&1
+echo "${out}"
+
+echo "Remount and try CoW again"
+_scratch_remount
+
+out="$(_pwrite_byte 0x62 0 $((BLKSZ * NR_BLKS)) "$TESTDIR/bigfile" -d 2>&1)"
+echo "${out}" | grep -q "No space left on device" || echo "CoW should have failed with ENOSPC"
+echo "${out}" >> "$seqres.full" 2>&1
+echo "${out}"
+
+#filefrag -v $TESTDIR/bigfile
+#filefrag -v $TESTDIR/clonefile
+
+echo "Check scratch fs"
+umount "$SCRATCH_MNT"
+_check_scratch_fs
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/845.out b/tests/generic/845.out
new file mode 100644
index 0000000..d367a73
--- /dev/null
+++ b/tests/generic/845.out
@@ -0,0 +1,10 @@
+QA output created by 845
+Format and mount
+Reformat with appropriate size
+Create a big file and reflink it
+Allocate the rest of the space
+CoW the big file
+pwrite64: No space left on device
+Remount and try CoW again
+pwrite64: No space left on device
+Check scratch fs
diff --git a/tests/generic/group b/tests/generic/group
index eef608f..e184473 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -249,4 +249,8 @@
 839 auto quick clone
 840 clone_stress
 841 clone_stress
+842 auto quick clone
+843 auto quick clone
+844 auto quick clone
+845 auto quick clone
 846 auto quick clone
