block: document semantics of bdrv_co_preadv|pwritev
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170831105456.9558-1-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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@ -146,12 +146,43 @@ struct BlockDriver {
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int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
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/**
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* @offset: position in bytes to read at
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* @bytes: number of bytes to read
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* @qiov: the buffers to fill with read data
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* @flags: currently unused, always 0
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*
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* @offset and @bytes will be a multiple of 'request_alignment',
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* but the length of individual @qiov elements does not have to
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* be a multiple.
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*
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* @bytes will always equal the total size of @qiov, and will be
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* no larger than 'max_transfer'.
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*
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* The buffer in @qiov may point directly to guest memory.
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*/
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int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs,
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uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
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int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
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int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags);
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/**
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* @offset: position in bytes to write at
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* @bytes: number of bytes to write
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* @qiov: the buffers containing data to write
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* @flags: zero or more bits allowed by 'supported_write_flags'
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*
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* @offset and @bytes will be a multiple of 'request_alignment',
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* but the length of individual @qiov elements does not have to
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* be a multiple.
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*
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* @bytes will always equal the total size of @qiov, and will be
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* no larger than 'max_transfer'.
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*
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* The buffer in @qiov may point directly to guest memory.
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*/
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int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
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uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
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