[Qemu-devel] [PATCH v2] block: document semanatics of bdrv_co_preadv|pwritev

[Qemu-devel] [PATCH v2] block: document semanatics of bdrv_co_preadv|pwritev

[Daniel P. Berrange]

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---

Changed in v2:

 - Document 'flags' parameter too (Eric)

 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 d4f4ea7584..4fe3081742 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -147,12 +147,43 @@ 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 may be less than the total sizeof @iov, 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 of 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 may be less than the total sizeof @iov, 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);
 
-- 
2.13.3