tree 7701c3c369c7c9e03e17e84aca651c679b8d67ac
parent a90d411e63ef29bb99b984e0fdb7796aeee1c724
author Fam Zheng <famz@redhat.com> 1410415796 +0800
committer Stefan Hajnoczi <stefanha@redhat.com> 1411382363 +0100

block: Introduce "null" drivers

This is an analogue to Linux null_blk. It can be used for testing or
benchmarking block device emulation and general block layer
functionalities such as coroutines and throttling, where disk IO is not
necessary or wanted.

Use null-aio:// for AIO version, and null-co:// for coroutine version.

[Resolved conflict with Fam's async bdrv_aio_cancel() series:
1. Drop .bdrv_aio_cancel() since it is now done by block.c
2. Rename qemu_aio_release() to qemu_aio_unref()
--Stefan]

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1410415798-20673-2-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>