[Qemu-devel] [PATCH] Fix block migration bug

[Vladimir Sementsov-Ogievskiy]

Because of wrong return value of .save_live_pending() in
block-migration, migration finishes before the whole disk
is transferred. Such situation occures when the migration
process is fast enouth, for example when source and dest 
are on the same host.

It's easy to test this with the following:

bug.sh
=====================================================================
#!/bin/sh

size=$1
addr=$2

rm /tmp/fifo-mig /tmp/a /tmp/b /tmp/sock-mig

./qemu-img create -f qcow2 /tmp/a $size
./qemu-img create -f qcow2 /tmp/b $size

./qemu-io -c "write -P 0x22 $addr 512" /tmp/a

mkfifo /tmp/fifo-mig

./x86_64-softmmu/qemu-system-x86_64 -drive file=/tmp/b,id=disk\
    -qmp unix:/tmp/sock-mig,server,nowait\
    -incoming "exec: cat /tmp/fifo-mig" &

echo 'migrate -b exec:cat>/tmp/fifo-mig\nquit\n' |\
./x86_64-softmmu/qemu-system-x86_64 -drive file=/tmp/a,id=disk\
    -monitor stdio

./scripts/qmp/qmp --path=/tmp/sock-mig quit
sleep 3

echo checking
./qemu-io -c "read -P 0x22 $addr 512" /tmp/b
=====================================================================

For './bug.sh 1G 1M' qemu-io check finishes successfully,
but for './bug.sh 1G 1022M' it finishes with 'Pattern verification
failed' status.

The following patch fixes this bug.

Vladimir Sementsov-Ogievskiy (1):
  block-migration: fix pending() return value

 block-migration.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
1.9.1