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>
This commit is contained in:
Daniel P. Berrange 2017-08-31 11:54:56 +01:00 committed by Stefan Hajnoczi
parent 921a32179b
commit b461151ff3

View File

@ -146,12 +146,43 @@ struct BlockDriver {
int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
/**
* @offset: position in bytes to read at
* @bytes: number of bytes to read
* @qiov: the buffers to fill with read data
* @flags: currently unused, always 0
*
* @offset and @bytes will be a multiple of 'request_alignment',
* but the length of individual @qiov elements does not have to
* be a multiple.
*
* @bytes will always equal the total size of @qiov, and will be
* no larger than 'max_transfer'.
*
* The buffer in @qiov may point directly to guest memory.
*/
int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags);
/**
* @offset: position in bytes to write at
* @bytes: number of bytes to write
* @qiov: the buffers containing data to write
* @flags: zero or more bits allowed by 'supported_write_flags'
*
* @offset and @bytes will be a multiple of 'request_alignment',
* but the length of individual @qiov elements does not have to
* be a multiple.
*
* @bytes will always equal the total size of @qiov, and will be
* no larger than 'max_transfer'.
*
* The buffer in @qiov may point directly to guest memory.
*/
int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);