Adding upstream version 4.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

tests/05r1-re-add

@@ -0,0 +1,39 @@
+
+#
+# create a raid1, remove a drive, and readd it.
+# resync should be instant.
+# Then do some IO first.  Resync should still be very fast
+#
+
+mdadm -CR $md0 -l1 -n2 -binternal --bitmap-chunk=4 -d1 $dev1 $dev2
+check resync
+check wait
+testdev $md0 1 $mdsize1a 64
+sleep 4
+
+mdadm $md0 -f $dev2
+sleep 1
+mdadm $md0 -r $dev2
+mdadm $md0 -a $dev2
+#cat /proc/mdstat
+check nosync
+
+mdadm $md0 -f $dev2
+sleep 1
+mdadm $md0 -r $dev2
+testdev $md0 1 $mdsize1a 64
+mdadm $md0 -a $dev2
+check wait
+blockdev --flushbufs $dev1 $dev2
+cmp --ignore-initial=$[64*512] --bytes=$[$mdsize0*1024] $dev1 $dev2
+
+mdadm $md0 -f $dev2; sleep 1
+mdadm $md0 -r $dev2
+if dd if=/dev/zero of=$md0 ; then : ; fi
+blockdev --flushbufs $md0 # ensure writes have been sent.
+mdadm $md0 -a $dev2
+check recovery
+check wait
+blockdev --flushbufs $dev1 $dev2
+cmp --ignore-initial=$[64*512] --bytes=$[$mdsize0*1024] $dev1 $dev2
+mdadm -S $md0