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authorAndrea Arcangeli <aarcange@redhat.com>2009-06-15 13:52:27 +0200
committerChristoph Hellwig <hch@brick.lst.de>2009-06-15 13:52:27 +0200
commit986c28d655dc9196c9c426c667c1764bd3d6d5bd (patch)
treec617fd5bc12a7c417b0827af64cb016f718934ad
parentmigrate_fd_close: delete associated io-handler before closing the fd (diff)
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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 <aarcange@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--aio.c8
-rw-r--r--qemu-aio.h7
2 files changed, 10 insertions, 5 deletions
diff --git a/aio.c b/aio.c
index 11fbb6c0c..dc9b85d16 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 79678293e..f262344af 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