block: only call aio_poll on the current thread's AioContext
aio_poll is not thread safe; for example bdrv_drain can hang if
the last in-flight I/O operation is completed in the I/O thread after
the main thread has checked bs->in_flight.
The bug remains latent as long as all of it is called within
aio_context_acquire/aio_context_release, but this will change soon.
To fix this, if bdrv_drain is called from outside the I/O thread,
signal the main AioContext through a dummy bottom half. The event
loop then only runs in the I/O thread.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-18-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
diff --git a/block/nfs.c b/block/nfs.c
index 7474fbc..88c60a9 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -505,6 +505,7 @@
error_report("NFS Error: %s", nfs_get_error(nfs));
}
task->complete = 1;
+ bdrv_wakeup(task->bs);
}
static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
