Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

14 files changed, 2816 insertions, 0 deletions

diff --git a/qa/rbd/common.sh b/qa/rbd/common.sh
new file mode 100644
index 00000000..232cf45a
--- /dev/null
+++ b/qa/rbd/common.sh
@@ -0,0 +1,103 @@
+#!/usr/bin/env bash
+
+die() {
+	echo "$*"
+	exit 1
+}
+
+cleanup() {
+    rm -rf $TDIR
+    TDIR=""
+}
+
+set_variables() {
+    # defaults
+    [ -z "$bindir" ] && bindir=$PWD       # location of init-ceph
+    if [ -z "$conf" ]; then
+        conf="$basedir/ceph.conf"
+        [ -e $conf ] || conf="/etc/ceph/ceph.conf"
+    fi
+    [ -e $conf ] || die "conf file not found"
+
+    CCONF="ceph-conf -c $conf"
+
+    [ -z "$mnt" ] && mnt="/c"
+    if [ -z "$monhost" ]; then
+        $CCONF -t mon -i 0 'mon addr' > $TDIR/cconf_mon
+        if [ $? -ne 0 ]; then
+            $CCONF -t mon.a -i 0 'mon addr' > $TDIR/cconf_mon
+            [ $? -ne 0 ] && die "can't figure out \$monhost"
+        fi
+        read monhost < $TDIR/cconf_mon
+    fi
+
+    [ -z "$imgsize" ] && imgsize=1024
+    [ -z "$user" ] && user=admin
+    [ -z "$keyring" ] && keyring="`$CCONF keyring`"
+    [ -z "$secret" ] && secret="`ceph-authtool $keyring -n client.$user -p`"
+
+    monip="`echo $monhost | sed 's/:/ /g' | awk '{print $1}'`"
+    monport="`echo $monhost | sed 's/:/ /g' | awk '{print $2}'`"
+
+    [ -z "$monip" ] && die "bad mon address"
+
+    [ -z "$monport" ] && monport=6789
+
+    set -e
+
+    mydir=`hostname`_`echo $0 | sed 's/\//_/g'`
+
+    img_name=test.`hostname`.$$
+}
+
+rbd_load() {
+	modprobe rbd
+}
+
+rbd_create_image() {
+	id=$1
+	rbd create $img_name.$id --size=$imgsize
+}
+
+rbd_add() {
+	id=$1
+	echo "$monip:$monport name=$user,secret=$secret rbd $img_name.$id" \
+	    > /sys/bus/rbd/add
+
+	pushd /sys/bus/rbd/devices &> /dev/null
+	[ $? -eq 0 ] || die "failed to cd"
+	devid=""
+	rm -f "$TDIR/rbd_devs"
+	for f in *; do echo $f >> "$TDIR/rbd_devs"; done
+	sort -nr "$TDIR/rbd_devs" > "$TDIR/rev_rbd_devs"
+	while read f < "$TDIR/rev_rbd_devs"; do
+	  read d_img_name < "$f/name"
+	  if [ "x$d_img_name" == "x$img_name.$id" ]; then
+	    devid=$f
+	    break
+	  fi
+	done
+	popd &> /dev/null
+
+	[ "x$devid" == "x" ] && die "failed to find $img_name.$id"
+
+	export rbd$id=$devid
+	while [ ! -e /dev/rbd$devid ]; do sleep 1; done
+}
+
+rbd_test_init() {
+	rbd_load
+}
+
+rbd_remove() {
+	echo $1 > /sys/bus/rbd/remove
+}
+
+rbd_rm_image() {
+	id=$1
+	rbd rm $imgname.$id
+}
+
+TDIR=`mktemp -d`
+trap cleanup INT TERM EXIT
+set_variables
diff --git a/qa/rbd/krbd_blkroset.t b/qa/rbd/krbd_blkroset.t
new file mode 100644
index 00000000..bbbd26aa
--- /dev/null
+++ b/qa/rbd/krbd_blkroset.t
@@ -0,0 +1,364 @@
+
+Setup
+=====
+
+  $ RO_KEY=$(ceph auth get-or-create-key client.ro mon 'profile rbd' mgr 'profile rbd' osd 'profile rbd-read-only')
+  $ rbd create --size 10 img
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd create --size 1 imgpart
+  $ DEV=$(sudo rbd map imgpart)
+  $ cat <<EOF | sudo sfdisk $DEV >/dev/null 2>&1
+  > unit: sectors
+  > /dev/rbd0p1 : start=        512, size=    512, Id=83
+  > /dev/rbd0p2 : start=       1024, size=    512, Id=83
+  > EOF
+  $ sudo rbd unmap $DEV
+  $ rbd snap create imgpart@snap
+
+
+Image HEAD
+==========
+
+R/W, unpartitioned:
+
+  $ DEV=$(sudo rbd map img)
+  $ blockdev --getro $DEV
+  0
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  $ blkdiscard $DEV
+  $ blockdev --setro $DEV
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setro $DEV
+  $ blockdev --getro $DEV
+  1
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?': Operation not permitted (glob)
+  [1]
+  $ blkdiscard $DEV
+  blkdiscard: /dev/rbd?: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ blockdev --setrw $DEV
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw $DEV
+  $ blockdev --getro $DEV
+  0
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  $ blkdiscard $DEV
+  $ sudo rbd unmap $DEV
+
+R/W, partitioned:
+
+  $ DEV=$(sudo rbd map imgpart)
+  $ udevadm settle
+  $ blockdev --getro ${DEV}p1
+  0
+  $ blockdev --getro ${DEV}p2
+  0
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p1
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p2
+  $ blockdev --setro ${DEV}p1
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setro ${DEV}p1
+  $ blockdev --getro ${DEV}p1
+  1
+  $ blockdev --getro ${DEV}p2
+  0
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p1': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p1
+  blkdiscard: /dev/rbd?p1: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p2
+  $ blockdev --setrw ${DEV}p1
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw ${DEV}p1
+  $ blockdev --getro ${DEV}p1
+  0
+  $ blockdev --getro ${DEV}p2
+  0
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p1
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p2
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map imgpart)
+  $ udevadm settle
+  $ blockdev --getro ${DEV}p1
+  0
+  $ blockdev --getro ${DEV}p2
+  0
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p1
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p2
+  $ blockdev --setro ${DEV}p2
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setro ${DEV}p2
+  $ blockdev --getro ${DEV}p1
+  0
+  $ blockdev --getro ${DEV}p2
+  1
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p1
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p2': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p2
+  blkdiscard: /dev/rbd?p2: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ blockdev --setrw ${DEV}p2
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw ${DEV}p2
+  $ blockdev --getro ${DEV}p1
+  0
+  $ blockdev --getro ${DEV}p2
+  0
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p1
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  $ blkdiscard ${DEV}p2
+  $ sudo rbd unmap $DEV
+
+R/O, unpartitioned:
+
+  $ DEV=$(sudo rbd map --read-only img)
+  $ blockdev --getro $DEV
+  1
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?': Operation not permitted (glob)
+  [1]
+  $ blkdiscard $DEV
+  blkdiscard: /dev/rbd?: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ blockdev --setrw $DEV
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw $DEV
+  .*BLKROSET: Read-only file system (re)
+  [1]
+  $ blockdev --getro $DEV
+  1
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?': Operation not permitted (glob)
+  [1]
+  $ blkdiscard $DEV
+  blkdiscard: /dev/rbd?: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ sudo rbd unmap $DEV
+
+R/O, partitioned:
+
+  $ DEV=$(sudo rbd map --read-only imgpart)
+  $ udevadm settle
+  $ blockdev --getro ${DEV}p1
+  1
+  $ blockdev --getro ${DEV}p2
+  1
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p1': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p1
+  blkdiscard: /dev/rbd?p1: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p2': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p2
+  blkdiscard: /dev/rbd?p2: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ blockdev --setrw ${DEV}p1
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw ${DEV}p1
+  .*BLKROSET: Read-only file system (re)
+  [1]
+  $ blockdev --setrw ${DEV}p2
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw ${DEV}p2
+  .*BLKROSET: Read-only file system (re)
+  [1]
+  $ blockdev --getro ${DEV}p1
+  1
+  $ blockdev --getro ${DEV}p2
+  1
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p1': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p1
+  blkdiscard: /dev/rbd?p1: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p2': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p2
+  blkdiscard: /dev/rbd?p2: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ sudo rbd unmap $DEV
+
+
+Image snapshot
+==============
+
+Unpartitioned:
+
+  $ DEV=$(sudo rbd map img@snap)
+  $ blockdev --getro $DEV
+  1
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?': Operation not permitted (glob)
+  [1]
+  $ blkdiscard $DEV
+  blkdiscard: /dev/rbd?: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ blockdev --setrw $DEV
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw $DEV
+  .*BLKROSET: Read-only file system (re)
+  [1]
+  $ blockdev --getro $DEV
+  1
+  $ dd if=/dev/urandom of=$DEV bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?': Operation not permitted (glob)
+  [1]
+  $ blkdiscard $DEV
+  blkdiscard: /dev/rbd?: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ sudo rbd unmap $DEV
+
+Partitioned:
+
+  $ DEV=$(sudo rbd map imgpart@snap)
+  $ udevadm settle
+  $ blockdev --getro ${DEV}p1
+  1
+  $ blockdev --getro ${DEV}p2
+  1
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p1': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p1
+  blkdiscard: /dev/rbd?p1: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p2': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p2
+  blkdiscard: /dev/rbd?p2: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ blockdev --setrw ${DEV}p1
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw ${DEV}p1
+  .*BLKROSET: Read-only file system (re)
+  [1]
+  $ blockdev --setrw ${DEV}p2
+  .*BLKROSET: Permission denied (re)
+  [1]
+  $ sudo blockdev --setrw ${DEV}p2
+  .*BLKROSET: Read-only file system (re)
+  [1]
+  $ blockdev --getro ${DEV}p1
+  1
+  $ blockdev --getro ${DEV}p2
+  1
+  $ dd if=/dev/urandom of=${DEV}p1 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p1': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p1
+  blkdiscard: /dev/rbd?p1: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ dd if=/dev/urandom of=${DEV}p2 bs=1k seek=1 count=1 status=none
+  dd: error writing '/dev/rbd?p2': Operation not permitted (glob)
+  [1]
+  $ blkdiscard ${DEV}p2
+  blkdiscard: /dev/rbd?p2: BLKDISCARD ioctl failed: Operation not permitted (glob)
+  [1]
+  $ sudo rbd unmap $DEV
+
+
+read-only OSD caps
+==================
+
+R/W:
+
+  $ DEV=$(sudo rbd map --id ro --key $(echo $RO_KEY) img)
+  rbd: sysfs write failed
+  rbd: map failed: (1) Operation not permitted
+  [1]
+
+R/O:
+
+  $ DEV=$(sudo rbd map --id ro --key $(echo $RO_KEY) --read-only img)
+  $ blockdev --getro $DEV
+  1
+  $ sudo rbd unmap $DEV
+
+Snapshot:
+
+  $ DEV=$(sudo rbd map --id ro --key $(echo $RO_KEY) img@snap)
+  $ blockdev --getro $DEV
+  1
+  $ sudo rbd unmap $DEV
+
+R/W, clone:
+
+  $ DEV=$(sudo rbd map --id ro --key $(echo $RO_KEY) cloneimg)
+  rbd: sysfs write failed
+  rbd: map failed: (1) Operation not permitted
+  [1]
+
+R/O, clone:
+
+  $ DEV=$(sudo rbd map --id ro --key $(echo $RO_KEY) --read-only cloneimg)
+  $ blockdev --getro $DEV
+  1
+  $ sudo rbd unmap $DEV
+
+
+rw -> ro with open_count > 0
+============================
+
+  $ DEV=$(sudo rbd map img)
+  $ { sleep 10; sudo blockdev --setro $DEV; } &
+  $ dd if=/dev/urandom of=$DEV bs=1k oflag=direct status=noxfer
+  dd: error writing '/dev/rbd?': Operation not permitted (glob)
+  [1-9]\d*\+0 records in (re)
+  [1-9]\d*\+0 records out (re)
+  [1]
+  $ sudo rbd unmap $DEV
+
+
+"-o rw --read-only" should result in read-only mapping
+======================================================
+
+  $ DEV=$(sudo rbd map -o rw --read-only img)
+  $ blockdev --getro $DEV
+  1
+  $ sudo rbd unmap $DEV
+
+
+Teardown
+========
+
+  $ rbd snap purge imgpart >/dev/null 2>&1
+  $ rbd rm imgpart >/dev/null 2>&1
+  $ rbd rm cloneimg >/dev/null 2>&1
+  $ rbd snap unprotect img@snap
+  $ rbd snap purge img >/dev/null 2>&1
+  $ rbd rm img >/dev/null 2>&1
+
diff --git a/qa/rbd/krbd_deep_flatten.t b/qa/rbd/krbd_deep_flatten.t
new file mode 100644
index 00000000..7235f003
--- /dev/null
+++ b/qa/rbd/krbd_deep_flatten.t
@@ -0,0 +1,329 @@
+
+Write:
+
+  $ rbd create --size 12M --image-feature layering,deep-flatten img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -w 0 12M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd snap create cloneimg@snap
+  $ DEV=$(sudo rbd map cloneimg)
+  $ xfs_io -c 'pwrite -S 0xab -w 6M 1k' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0600000 abab abab abab abab abab abab abab abab
+  *
+  0600400 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd flatten --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0600000 abab abab abab abab abab abab abab abab
+  *
+  0600400 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd snap rm --no-progress cloneimg@snap
+  $ rbd rm --no-progress cloneimg
+
+Write, whole object:
+
+  $ rbd create --size 12M --image-feature layering,deep-flatten img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -w 0 12M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd snap create cloneimg@snap
+  $ DEV=$(sudo rbd map cloneimg)
+  $ xfs_io -d -c 'pwrite -b 4M -S 0xab 4M 4M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000 abab abab abab abab abab abab abab abab
+  *
+  0800000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd flatten --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000 abab abab abab abab abab abab abab abab
+  *
+  0800000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd snap rm --no-progress cloneimg@snap
+  $ rbd rm --no-progress cloneimg
+
+Zeroout:
+
+  $ rbd create --size 12M --image-feature layering,deep-flatten img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -w 0 12M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd snap create cloneimg@snap
+  $ DEV=$(sudo rbd map cloneimg)
+  $ fallocate -z -o 6M -l 1k $DEV
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0600000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0600400 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd flatten --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0600000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0600400 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd snap rm --no-progress cloneimg@snap
+  $ rbd rm --no-progress cloneimg
+
+Zeroout, whole object:
+
+  $ rbd create --size 12M --image-feature layering,deep-flatten img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -w 0 12M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd snap create cloneimg@snap
+  $ DEV=$(sudo rbd map cloneimg)
+  $ fallocate -z -o 4M -l 4M $DEV
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0800000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd flatten --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0800000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd snap rm --no-progress cloneimg@snap
+  $ rbd rm --no-progress cloneimg
+
+Discard, whole object, empty clone:
+
+  $ rbd create --size 12M --image-feature layering,deep-flatten img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -w 0 12M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd snap create cloneimg@snap
+  $ DEV=$(sudo rbd map cloneimg)
+  $ blkdiscard -o 4M -l 4M $DEV
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd flatten --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd snap rm --no-progress cloneimg@snap
+  $ rbd rm --no-progress cloneimg
+
+Discard, whole object, full clone:
+
+  $ rbd create --size 12M --image-feature layering,deep-flatten img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -w 0 12M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd snap create cloneimg@snap
+  $ DEV=$(sudo rbd map cloneimg)
+  $ xfs_io -c 'pwrite -S 0xab -w 0 12M' $DEV >/dev/null
+  $ blkdiscard -o 4M -l 4M $DEV
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0800000 abab abab abab abab abab abab abab abab
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd flatten --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0800000 abab abab abab abab abab abab abab abab
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg@snap)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+
+  $ rbd snap rm --no-progress cloneimg@snap
+  $ rbd rm --no-progress cloneimg
diff --git a/qa/rbd/krbd_discard.t b/qa/rbd/krbd_discard.t
new file mode 100644
index 00000000..99f7261f
--- /dev/null
+++ b/qa/rbd/krbd_discard.t
@@ -0,0 +1,398 @@
+
+  $ rbd create --size 4M img
+  $ DEV=$(sudo rbd map img)
+
+Zero, < 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 156672 -l 512 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 64512 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 65024 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 65024 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 65536 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 66048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 66048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 66560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, < 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 163840 -l 65536 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 130048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 130560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0030000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 130560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 131072 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 131584 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 131584 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 132096 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 37 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 589824 -l 2424832 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0090000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02e0000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 589312 -l 2424832 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0090000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02d0000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 590336 -l 2424832 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  00a0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02e0000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Truncate:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4193792 -l 512 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4129280 -l 65024 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4128768 -l 65536 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4128256 -l 66048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4063744 -l 130560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4063232 -l 131072 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4062720 -l 131584 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 512 -l 4193792 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0010000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Delete:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Empty clone:
+
+  $ xfs_io -c 'pwrite -S 0xab -w 0 4M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+
+  $ rbd clone img@snap cloneimg1
+  $ DEV=$(sudo rbd map cloneimg1)
+  $ blkdiscard -o 720896 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg2
+  $ DEV=$(sudo rbd map cloneimg2)
+  $ blkdiscard -o 1474560 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg3
+  $ DEV=$(sudo rbd map cloneimg3)
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+Full clone:
+
+  $ rbd clone img@snap cloneimg4
+  $ DEV=$(sudo rbd map cloneimg4)
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 720896 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  00b0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0340000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 1474560 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0170000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ sudo rbd unmap $DEV
+
+Multiple object requests:
+
+  $ rbd create --size 50M --stripe-unit 16K --stripe-count 5 fancyimg
+  $ DEV=$(sudo rbd map fancyimg)
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 143360 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 286720 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0008000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0014000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  001c000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0028000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  003c000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0044000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 573440 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0050000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ sudo rbd unmap $DEV
+
+  $ rbd rm --no-progress fancyimg
+  $ rbd rm --no-progress cloneimg4
+  $ rbd rm --no-progress cloneimg3
+  $ rbd rm --no-progress cloneimg2
+  $ rbd rm --no-progress cloneimg1
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_discard_4M.t b/qa/rbd/krbd_discard_4M.t
new file mode 100644
index 00000000..6c3d7cc7
--- /dev/null
+++ b/qa/rbd/krbd_discard_4M.t
@@ -0,0 +1,330 @@
+
+  $ rbd create --size 4M img
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 img)
+
+Zero, < 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 156672 -l 512 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 64512 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 65024 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 65024 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 65536 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 66048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 66048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 66560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, < 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 163840 -l 65536 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 130048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 130560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 130560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 131072 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 131584 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 131584 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 132096 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 37 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 589824 -l 2424832 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 589312 -l 2424832 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 590336 -l 2424832 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Truncate:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4193792 -l 512 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03ffe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4129280 -l 65024 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4128768 -l 65536 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4128256 -l 66048 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03efe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4063744 -l 130560 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4063232 -l 131072 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4062720 -l 131584 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03dfe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 512 -l 4193792 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0000200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Delete:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Empty clone:
+
+  $ xfs_io -c 'pwrite -S 0xab -w 0 4M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+
+  $ rbd clone img@snap cloneimg1
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 cloneimg1)
+  $ blkdiscard -o 720896 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg2
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 cloneimg2)
+  $ blkdiscard -o 1474560 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg3
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 cloneimg3)
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+Full clone:
+
+  $ rbd clone img@snap cloneimg4
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 cloneimg4)
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 720896 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 1474560 -l 2719744 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0168000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ sudo rbd unmap $DEV
+
+Multiple object requests:
+
+  $ rbd create --size 50M --stripe-unit 16K --stripe-count 5 fancyimg
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 fancyimg)
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 143360 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 286720 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 573440 $DEV
+  $ dd if=$DEV iflag=direct bs=4M status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ sudo rbd unmap $DEV
+
+  $ rbd rm --no-progress fancyimg
+  $ rbd rm --no-progress cloneimg4
+  $ rbd rm --no-progress cloneimg3
+  $ rbd rm --no-progress cloneimg2
+  $ rbd rm --no-progress cloneimg1
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_discard_512b.t b/qa/rbd/krbd_discard_512b.t
new file mode 100644
index 00000000..b3a7c447
--- /dev/null
+++ b/qa/rbd/krbd_discard_512b.t
@@ -0,0 +1,416 @@
+
+  $ rbd create --size 4M img
+  $ DEV=$(sudo rbd map -o alloc_size=512 img)
+
+Zero, < 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 156672 -l 512 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0026400 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0026600 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 64512 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  002fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 65024 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 65024 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  002fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 65536 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 66048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 66048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 66560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, < 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 163840 -l 65536 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0028000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0038000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 130048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  003fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131584 -l 130560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 130560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  003fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 131072 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 131072 -l 131584 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 131584 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 130560 -l 132096 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 37 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 589824 -l 2424832 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0090000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02e0000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 589312 -l 2424832 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  008fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02dfe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 590336 -l 2424832 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0090200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02e0200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Truncate:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4193792 -l 512 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03ffe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4129280 -l 65024 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4128768 -l 65536 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4128256 -l 66048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03efe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4063744 -l 130560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4063232 -l 131072 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 4062720 -l 131584 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03dfe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 512 -l 4193792 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0000200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Delete:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Empty clone:
+
+  $ xfs_io -c 'pwrite -S 0xab -w 0 4M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+
+  $ rbd clone img@snap cloneimg1
+  $ DEV=$(sudo rbd map -o alloc_size=512 cloneimg1)
+  $ blkdiscard -o 720896 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg2
+  $ DEV=$(sudo rbd map -o alloc_size=512 cloneimg2)
+  $ blkdiscard -o 1474560 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg3
+  $ DEV=$(sudo rbd map -o alloc_size=512 cloneimg3)
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+Full clone:
+
+  $ rbd clone img@snap cloneimg4
+  $ DEV=$(sudo rbd map -o alloc_size=512 cloneimg4)
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 720896 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  00b0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0348000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 1474560 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0168000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 4194304 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ sudo rbd unmap $DEV
+
+Multiple object requests:
+
+  $ rbd create --size 50M --stripe-unit 16K --stripe-count 5 fancyimg
+  $ DEV=$(sudo rbd map -o alloc_size=512 fancyimg)
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 143360 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0023000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 286720 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0046000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ blkdiscard -o 0 -l 573440 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  008c000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ sudo rbd unmap $DEV
+
+  $ rbd rm --no-progress fancyimg
+  $ rbd rm --no-progress cloneimg4
+  $ rbd rm --no-progress cloneimg3
+  $ rbd rm --no-progress cloneimg2
+  $ rbd rm --no-progress cloneimg1
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_discard_granularity.t b/qa/rbd/krbd_discard_granularity.t
new file mode 100644
index 00000000..844643ba
--- /dev/null
+++ b/qa/rbd/krbd_discard_granularity.t
@@ -0,0 +1,40 @@
+
+  $ rbd create --size 20M img
+
+  $ DEV=$(sudo rbd map img)
+  $ blockdev --getiomin $DEV
+  65536
+  $ blockdev --getioopt $DEV
+  65536
+  $ cat /sys/block/${DEV#/dev/}/queue/discard_granularity
+  65536
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map -o alloc_size=512 img)
+  $ blockdev --getiomin $DEV
+  512
+  $ blockdev --getioopt $DEV
+  512
+  $ cat /sys/block/${DEV#/dev/}/queue/discard_granularity
+  512
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map -o alloc_size=4194304 img)
+  $ blockdev --getiomin $DEV
+  4194304
+  $ blockdev --getioopt $DEV
+  4194304
+  $ cat /sys/block/${DEV#/dev/}/queue/discard_granularity
+  4194304
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map -o alloc_size=8388608 img)
+  $ blockdev --getiomin $DEV
+  4194304
+  $ blockdev --getioopt $DEV
+  4194304
+  $ cat /sys/block/${DEV#/dev/}/queue/discard_granularity
+  4194304
+  $ sudo rbd unmap $DEV
+
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_get_features.t b/qa/rbd/krbd_get_features.t
new file mode 100644
index 00000000..b3abf3ce
--- /dev/null
+++ b/qa/rbd/krbd_get_features.t
@@ -0,0 +1,31 @@
+
+journaling makes the image only unwritable, rather than both unreadable
+and unwritable:
+
+  $ rbd create --size 1 --image-feature layering,exclusive-lock,journaling img
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone --image-feature layering,exclusive-lock,journaling img@snap cloneimg
+
+  $ DEV=$(sudo rbd map img)
+  rbd: sysfs write failed
+  rbd: map failed: (6) No such device or address
+  [6]
+  $ DEV=$(sudo rbd map --read-only img)
+  $ blockdev --getro $DEV
+  1
+  $ sudo rbd unmap $DEV
+
+  $ DEV=$(sudo rbd map cloneimg)
+  rbd: sysfs write failed
+  rbd: map failed: (6) No such device or address
+  [6]
+  $ DEV=$(sudo rbd map --read-only cloneimg)
+  $ blockdev --getro $DEV
+  1
+  $ sudo rbd unmap $DEV
+
+  $ rbd rm --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_huge_image.t b/qa/rbd/krbd_huge_image.t
new file mode 100644
index 00000000..9fff1d9d
--- /dev/null
+++ b/qa/rbd/krbd_huge_image.t
@@ -0,0 +1,41 @@
+
+  $ get_field() {
+  >     rbd info --format=json $1 | python -c "import sys, json; print json.load(sys.stdin)['$2']"
+  > }
+
+Write to first and last sectors and make sure we hit the right objects:
+
+  $ ceph osd pool create hugeimg 12 >/dev/null 2>&1
+  $ rbd pool init hugeimg
+  $ rbd create --size 4E --object-size 4K --image-feature layering hugeimg/img
+  $ DEV=$(sudo rbd map hugeimg/img)
+  $ xfs_io -c 'pwrite 0 512' $DEV >/dev/null # first sector
+  $ xfs_io -c 'pwrite 4611686018427387392 512' $DEV >/dev/null # last sector
+  $ sudo rbd unmap $DEV
+
+  $ get_field hugeimg/img size
+  4611686018427387904
+  $ get_field hugeimg/img objects
+  1125899906842624
+  $ rados -p hugeimg ls | grep $(get_field hugeimg/img block_name_prefix) | sort
+  .*\.0000000000000000 (re)
+  .*\.0003ffffffffffff (re)
+
+Dump first and last megabytes:
+
+  $ DEV=$(sudo rbd map hugeimg/img)
+  $ dd if=$DEV bs=1M count=1 status=none | hexdump
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0000200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0100000
+  $ dd if=$DEV bs=1M skip=4398046511103 status=none | hexdump
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  00ffe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0100000
+  $ sudo rbd unmap $DEV
+
+  $ ceph osd pool delete hugeimg hugeimg --yes-i-really-really-mean-it >/dev/null 2>&1
diff --git a/qa/rbd/krbd_msgr_segments.t b/qa/rbd/krbd_msgr_segments.t
new file mode 100644
index 00000000..c373af5a
--- /dev/null
+++ b/qa/rbd/krbd_msgr_segments.t
@@ -0,0 +1,85 @@
+
+  $ get_block_name_prefix() {
+  >     rbd info --format=json $1 | python -c "import sys, json; print json.load(sys.stdin)['block_name_prefix']"
+  > }
+
+Short segments:
+
+  $ rbd create --size 12M img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -d -c 'pwrite 5120 512' $DEV >/dev/null
+  $ xfs_io -d -c 'pwrite 12577280 512' $DEV >/dev/null
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0001400 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0001600 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0bfea00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0bfec00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ rbd rm --no-progress img
+
+Short segment, ceph_msg_data_bio_cursor_init():
+
+  $ rbd create --size 12M img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -d -c 'pwrite 0 512' $DEV >/dev/null
+  $ rados -p rbd stat $(get_block_name_prefix img).0000000000000000
+  .* size 512 (re)
+  $ xfs_io -d -c 'pread -b 2M 0 2M' $DEV >/dev/null
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0000200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ rbd rm --no-progress img
+
+Short segment, ceph_msg_data_bio_advance():
+
+  $ rbd create --size 12M img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -d -c 'pwrite 0 1049088' $DEV >/dev/null
+  $ rados -p rbd stat $(get_block_name_prefix img).0000000000000000
+  .* size 1049088 (re)
+  $ xfs_io -d -c 'pread -b 2M 0 2M' $DEV >/dev/null
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0100200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0c00000
+  $ sudo rbd unmap $DEV
+  $ rbd rm --no-progress img
+
+Cloned bios (dm-snapshot.ko, based on generic/081):
+
+  $ rbd create --size 300M img
+  $ DEV=$(sudo rbd map img)
+  $ sudo vgcreate vg_img $DEV
+    Physical volume "/dev/rbd?" successfully created* (glob)
+    Volume group "vg_img" successfully created
+  $ sudo lvcreate -L 256M -n lv_img vg_img
+    Logical volume "lv_img" created.
+  $ udevadm settle
+  $ sudo mkfs.ext4 -q /dev/mapper/vg_img-lv_img
+  $ sudo lvcreate -L 4M --snapshot -n lv_snap vg_img/lv_img | grep created
+    Logical volume "lv_snap" created.
+  $ udevadm settle
+  $ sudo mount /dev/mapper/vg_img-lv_snap /mnt
+  $ sudo xfs_io -f -c 'pwrite 0 5M' /mnt/file1 >/dev/null
+  $ sudo umount /mnt
+  $ sudo vgremove -f vg_img
+    Logical volume "lv_snap" successfully removed
+    Logical volume "lv_img" successfully removed
+    Volume group "vg_img" successfully removed
+  $ sudo pvremove $DEV
+    Labels on physical volume "/dev/rbd?" successfully wiped* (glob)
+  $ sudo rbd unmap $DEV
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_parent_overlap.t b/qa/rbd/krbd_parent_overlap.t
new file mode 100644
index 00000000..47deda90
--- /dev/null
+++ b/qa/rbd/krbd_parent_overlap.t
@@ -0,0 +1,64 @@
+
+For reads, only the object extent needs to be reverse mapped:
+
+  $ rbd create --size 20M img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite 0 20M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd resize --no-progress --size 5M --allow-shrink cloneimg
+  $ rbd resize --no-progress --size 20M cloneimg
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0500000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  1400000
+  $ sudo rbd unmap $DEV
+  $ rbd rm --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
+
+For writes, the entire object needs to be reverse mapped:
+
+  $ rbd create --size 2M img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite 0 1M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+  $ rbd clone img@snap cloneimg
+  $ rbd resize --no-progress --size 8M cloneimg
+  $ DEV=$(sudo rbd map cloneimg)
+  $ xfs_io -c 'pwrite -S 0xef 3M 1M' $DEV >/dev/null
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0100000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0300000 efef efef efef efef efef efef efef efef
+  *
+  0400000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0800000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0100000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0300000 efef efef efef efef efef efef efef efef
+  *
+  0400000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0800000
+  $ sudo rbd unmap $DEV
+  $ rbd rm --no-progress cloneimg
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_whole_object_zeroout.t b/qa/rbd/krbd_whole_object_zeroout.t
new file mode 100644
index 00000000..3530f93e
--- /dev/null
+++ b/qa/rbd/krbd_whole_object_zeroout.t
@@ -0,0 +1,143 @@
+
+  $ get_block_name_prefix() {
+  >     rbd info --format=json $1 | python -c "import sys, json; print json.load(sys.stdin)['block_name_prefix']"
+  > }
+
+  $ rbd create --size 200M img
+  $ DEV=$(sudo rbd map img)
+  $ xfs_io -c 'pwrite -b 4M 0 200M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+
+cloneimg1:
+1 object in an object set, 4M
+25 full object sets
+25 objects in total
+
+  $ rbd clone img@snap cloneimg1
+  $ DEV=$(sudo rbd map cloneimg1)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ fallocate -z -l 100M $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg1)
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+
+cloneimg2:
+7 objects in an object set, 28M
+3 full object sets
+min((100M % 28M) / 512K, 7) = 7 objects in the last object set
+28 objects in total
+
+  $ rbd clone --stripe-unit 512K --stripe-count 7 img@snap cloneimg2
+  $ DEV=$(sudo rbd map cloneimg2)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ fallocate -z -l 100M $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg2)
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+
+cloneimg3:
+23 objects in an object set, 92M
+1 full object set
+min((100M % 92M) / 512K, 23) = 16 objects in the last object set
+39 objects in total
+
+  $ rbd clone --stripe-unit 512K --stripe-count 23 img@snap cloneimg3
+  $ DEV=$(sudo rbd map cloneimg3)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ fallocate -z -l 100M $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg3)
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+
+cloneimg4:
+65 objects in an object set, 260M
+0 full object sets
+min((100M % 260M) / 512K, 65) = 65 objects in the last object set
+65 objects in total
+
+  $ rbd clone --stripe-unit 512K --stripe-count 65 img@snap cloneimg4
+  $ DEV=$(sudo rbd map cloneimg4)
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ fallocate -z -l 100M $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+  $ DEV=$(sudo rbd map cloneimg4)
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  6400000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  c800000
+  $ sudo rbd unmap $DEV
+
+  $ rados -p rbd ls | grep -c $(get_block_name_prefix cloneimg1)
+  25
+  $ rados -p rbd ls | grep -c $(get_block_name_prefix cloneimg2)
+  28
+  $ rados -p rbd ls | grep -c $(get_block_name_prefix cloneimg3)
+  39
+  $ rados -p rbd ls | grep -c $(get_block_name_prefix cloneimg4)
+  65
+
+  $ rbd rm --no-progress cloneimg4
+  $ rbd rm --no-progress cloneimg3
+  $ rbd rm --no-progress cloneimg2
+  $ rbd rm --no-progress cloneimg1
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/krbd_zeroout.t b/qa/rbd/krbd_zeroout.t
new file mode 100644
index 00000000..33c8e9d9
--- /dev/null
+++ b/qa/rbd/krbd_zeroout.t
@@ -0,0 +1,422 @@
+
+  $ rbd create --size 4M img
+  $ DEV=$(sudo rbd map img)
+
+Zero, < 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 156672 -l 512 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0026400 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0026600 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131584 -l 64512 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  002fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131584 -l 65024 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131072 -l 65024 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  002fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 1 block:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131072 -l 65536 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131072 -l 66048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 130560 -l 66048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 130560 -l 66560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0030200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, < 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 163840 -l 65536 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0028000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0038000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131584 -l 130048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  003fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131584 -l 130560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131072 -l 130560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  003fe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 2 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131072 -l 131072 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 131072 -l 131584 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0020000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 130560 -l 131584 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 130560 -l 132096 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  001fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0040200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Zero, 37 blocks:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 589824 -l 2424832 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0090000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02e0000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 589312 -l 2424832 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  008fe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02dfe00 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 590336 -l 2424832 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0090200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  02e0200 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+Truncate:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4193792 -l 512 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03ffe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4129280 -l 65024 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4128768 -l 65536 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03f0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4128256 -l 66048 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03efe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4063744 -l 130560 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4063232 -l 131072 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03e0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 4062720 -l 131584 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  03dfe00 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 512 -l 4193792 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0000200 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Delete:
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 0 -l 4194304 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+Empty clone:
+
+  $ xfs_io -c 'pwrite -S 0xab -w 0 4M' $DEV >/dev/null
+  $ sudo rbd unmap $DEV
+  $ rbd snap create img@snap
+  $ rbd snap protect img@snap
+
+  $ rbd clone img@snap cloneimg1
+  $ DEV=$(sudo rbd map cloneimg1)
+  $ fallocate -z -o 720896 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  00b0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0348000 abab abab abab abab abab abab abab abab
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg2
+  $ DEV=$(sudo rbd map cloneimg2)
+  $ fallocate -z -o 1474560 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 abab abab abab abab abab abab abab abab
+  *
+  0168000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+  $ rbd clone img@snap cloneimg3
+  $ DEV=$(sudo rbd map cloneimg3)
+  $ fallocate -z -o 0 -l 4194304 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+  $ sudo rbd unmap $DEV
+
+Full clone:
+
+  $ rbd clone img@snap cloneimg4
+  $ DEV=$(sudo rbd map cloneimg4)
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 720896 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  00b0000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0348000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 1474560 -l 2719744 $DEV
+  $ hexdump $DEV
+  0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  0168000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ xfs_io -c 'pwrite -w 0 4M' $DEV >/dev/null
+  $ fallocate -z -o 0 -l 4194304 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0400000
+
+  $ sudo rbd unmap $DEV
+
+Multiple object requests:
+
+  $ rbd create --size 50M --stripe-unit 16K --stripe-count 5 fancyimg
+  $ DEV=$(sudo rbd map fancyimg)
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ fallocate -z -o 0 -l 143360 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0023000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ fallocate -z -o 0 -l 286720 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  0046000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ xfs_io -c 'pwrite -b 4M -w 0 50M' $DEV >/dev/null
+  $ fallocate -z -o 0 -l 573440 $DEV
+  $ hexdump $DEV
+  0000000 0000 0000 0000 0000 0000 0000 0000 0000
+  *
+  008c000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
+  *
+  3200000
+
+  $ sudo rbd unmap $DEV
+
+  $ rbd rm --no-progress fancyimg
+  $ rbd rm --no-progress cloneimg4
+  $ rbd rm --no-progress cloneimg3
+  $ rbd rm --no-progress cloneimg2
+  $ rbd rm --no-progress cloneimg1
+  $ rbd snap unprotect img@snap
+  $ rbd snap rm --no-progress img@snap
+  $ rbd rm --no-progress img
diff --git a/qa/rbd/rbd.sh b/qa/rbd/rbd.sh
new file mode 100755
index 00000000..2b7ce8ee
--- /dev/null
+++ b/qa/rbd/rbd.sh
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+set -x
+
+basedir=`echo $0 | sed 's/[^/]*$//g'`.
+. $basedir/common.sh
+
+rbd_test_init
+
+
+create_multiple() {
+	for i in `seq 1 10`; do
+		rbd_create_image $i
+	done
+
+	for i in `seq 1 10`; do
+		rbd_add $i
+	done
+	for i in `seq 1 10`; do
+		devname=/dev/rbd`eval echo \\$rbd$i`
+		echo $devname
+	done
+	for i in `seq 1 10`; do
+		devid=`eval echo \\$rbd$i`
+		rbd_remove $devid
+	done
+	for i in `seq 1 10`; do
+		rbd_rm_image $i
+	done
+}
+
+test_dbench() {
+	rbd_create_image 0
+	rbd_add 0
+
+	devname=/dev/rbd$rbd0
+
+	mkfs -t ext3 $devname
+	mount -t ext3 $devname $mnt
+
+	dbench -D $mnt -t 30 5
+	sync
+
+	umount $mnt
+	rbd_remove $rbd0
+	rbd_rm_image 0
+}
+
+create_multiple
+test_dbench
+