From 986c28d655dc9196c9c426c667c1764bd3d6d5bd Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Mon, 15 Jun 2009 13:52:27 +0200 Subject: [PATCH] fix qemu_aio_flush qemu_aio_wait by invoking the bh or one of the aio completion callbacks, could end up submitting new pending aio, breaking the invariant that qemu_aio_flush returns only when no pending aio is outstanding (possibly a problem for migration as such). Signed-off-by: Andrea Arcangeli Signed-off-by: Christoph Hellwig Acked-by: Kevin Wolf --- aio.c | 8 ++++++-- qemu-aio.h | 7 ++++--- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/aio.c b/aio.c index 11fbb6c..dc9b85d 100644 --- a/aio.c +++ b/aio.c @@ -103,11 +103,15 @@ void qemu_aio_flush(void) do { ret = 0; + /* + * If there are pending emulated aio start them now so flush + * will be able to return 1. + */ + qemu_aio_wait(); + LIST_FOREACH(node, &aio_handlers, node) { ret |= node->io_flush(node->opaque); } - - qemu_aio_wait(); } while (ret > 0); } diff --git a/qemu-aio.h b/qemu-aio.h index 7967829..f262344 100644 --- a/qemu-aio.h +++ b/qemu-aio.h @@ -24,9 +24,10 @@ typedef int (AioFlushHandler)(void *opaque); * outstanding AIO operations have been completed or cancelled. */ void qemu_aio_flush(void); -/* Wait for a single AIO completion to occur. This function will until a - * single AIO opeartion has completed. It is intended to be used as a looping - * primative when simulating synchronous IO based on asynchronous IO. */ +/* Wait for a single AIO completion to occur. This function will wait + * until a single AIO event has completed and it will ensure something + * has moved before returning. This can issue new pending aio as + * result of executing I/O completion or bh callbacks. */ void qemu_aio_wait(void); /* Register a file descriptor and associated callbacks. Behaves very similarly -- 1.7.9.5