[Xen-changelog] [qemu-upstream-unstable] migration/block: fix pending() return value

[patchbot@xxxxxxx]

commit 83dbd88b5ce280e26a40a22aa473a248f9bb0f5e
Author:     Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
AuthorDate: Tue Dec 30 13:04:16 2014 +0300
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Sun Feb 22 12:27:50 2015 -0600

    migration/block: fix pending() return value
    
    Because of wrong return value of .save_live_pending() in
    migration/block.c, migration finishes before the whole disk is
    transferred. Such situation occurs when the migration process is fast
    enough, for example when source and dest are on the same host.
    
    If in the bulk phase we return something < max_size, we will skip
    transferring the tail of the device. Currently we have "set pending to
    BLOCK_SIZE if it is zero" for bulk phase, but there no guarantee, that
    it will be < max_size.
    
    True approach is to return, for example, max_size+1 when we are in the
    bulk phase.
    
    Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
    Message-id: 1419933856-4018-2-git-send-email-vsementsov@xxxxxxxxxxxxx
    Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
    (cherry picked from commit 04636dc410b163c2243e66c3813dd4900a50a4ed)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 block-migration.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/block-migration.c b/block-migration.c
index 74d9eb1..2e92605 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -765,8 +765,8 @@ static uint64_t block_save_pending(QEMUFile *f, void 
*opaque, uint64_t max_size)
                        block_mig_state.read_done * BLOCK_SIZE;
 
     /* Report at least one block pending during bulk phase */
-    if (pending == 0 && !block_mig_state.bulk_completed) {
-        pending = BLOCK_SIZE;
+    if (pending <= max_size && !block_mig_state.bulk_completed) {
+        pending = max_size + BLOCK_SIZE;
     }
     blk_mig_unlock();
     qemu_mutex_unlock_iothread();
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

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