From 64182a6b8bc78a4a11902fc0c019b2092e9a9d28 Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Thu, 31 Aug 2017 11:54:56 +0100 Subject: [PATCH] block: document semantics of bdrv_co_preadv|pwritev Reviewed-by: Stefan Hajnoczi Reviewed-by: Eric Blake Signed-off-by: Daniel P. Berrange Signed-off-by: Kevin Wolf --- include/block/block_int.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/include/block/block_int.h b/include/block/block_int.h index 223801e4fb..ba4c383393 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -150,12 +150,43 @@ 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);