f29602ca0e
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).
(cherry picked from commit 986c28d655)
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kevin Wolf <kwolf@redhat.com>
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/*
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* QEMU aio implementation
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*
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* Copyright IBM, Corp. 2008
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef QEMU_AIO_H
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#define QEMU_AIO_H
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#include "qemu-common.h"
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#include "qemu-char.h"
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/* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
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typedef int (AioFlushHandler)(void *opaque);
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/* Flush any pending AIO operation. This function will block until all
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* outstanding AIO operations have been completed or cancelled. */
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void qemu_aio_flush(void);
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/* Wait for a single AIO completion to occur. This function will wait
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* until a single AIO event has completed and it will ensure something
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* has moved before returning. This can issue new pending aio as
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* result of executing I/O completion or bh callbacks. */
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void qemu_aio_wait(void);
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/* Register a file descriptor and associated callbacks. Behaves very similarly
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* to qemu_set_fd_handler2. Unlike qemu_set_fd_handler2, these callbacks will
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* be invoked when using either qemu_aio_wait() or qemu_aio_flush().
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*
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* Code that invokes AIO completion functions should rely on this function
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* instead of qemu_set_fd_handler[2].
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*/
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int qemu_aio_set_fd_handler(int fd,
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IOHandler *io_read,
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IOHandler *io_write,
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AioFlushHandler *io_flush,
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void *opaque);
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#endif
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