[Xen-changelog] [qemu-xen master] block: Call .drain_begin only once in bdrv_drain_all_begin()

[patchbot@xxxxxxx]

commit 2b0c34cf61dbf9fa2d3ab78f0c43609cb781c5a9
Author:     Kevin Wolf <kwolf@xxxxxxxxxx>
AuthorDate: Tue Dec 5 13:53:35 2017 +0100
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue Jan 9 10:49:13 2018 -0600

    block: Call .drain_begin only once in bdrv_drain_all_begin()
    
    bdrv_drain_all_begin() used to call the .bdrv_co_drain_begin() driver
    callback inside its polling loop. This means that how many times it got
    called for each node depended on long it had to poll the event loop.
    
    This is obviously not right and results in nodes that stay drained even
    after bdrv_drain_all_end(), which calls .bdrv_co_drain_begin() once per
    node.
    
    Fix bdrv_drain_all_begin() to call the callback only once, too.
    
    Cc: qemu-stable@xxxxxxxxxx
    Signed-off-by: Kevin Wolf <kwolf@xxxxxxxxxx>
    Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
    (cherry picked from commit 2da9b7d456278bccc6ce889ae350f2867155d7e8)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 block/io.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/block/io.c b/block/io.c
index 096468b..603f5b0 100644
--- a/block/io.c
+++ b/block/io.c
@@ -355,6 +355,7 @@ void bdrv_drain_all_begin(void)
         aio_context_acquire(aio_context);
         bdrv_parent_drained_begin(bs);
         aio_disable_external(aio_context);
+        bdrv_drain_invoke(bs, true);
         aio_context_release(aio_context);
 
         if (!g_slist_find(aio_ctxs, aio_context)) {
@@ -377,8 +378,6 @@ void bdrv_drain_all_begin(void)
             aio_context_acquire(aio_context);
             for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
                 if (aio_context == bdrv_get_aio_context(bs)) {
-                    /* FIXME Calling this multiple times is wrong */
-                    bdrv_drain_invoke(bs, true);
                     waited |= bdrv_drain_recurse(bs, true);
                 }
             }
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master

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