[Qemu-devel] Re: [PATCH 0/3] Remove ->bdrv_pread() internal block layer API (v2)

[Anthony Liguori <aliguori@us.ibm.com>]

Avi Kivity wrote:
> The internal block layer API has a wart in the form of the
> ->bdrv_pread() and ->bdrv_pwrite() methods.  These duplicate
> bdrv_read() and bdrv_write(), and are unnatural for a block
> device in that they are not sector oriented.
>
> One of the reasons for their existence is the scsi-generic host support.
> That is also a wart, as scsi-generic is really a packet (command/response)
> rather than a block (random access to sectors) API.  There is also the
> wierd negative sector count == byte count thing.
>
> This patchset addresses these warts by adding a new API for scsi-generic
> and dropping ->bdrv_pread() and bdrv_pwrite().  While the improvement
> falls short of spectacular, it does make further hacking on the block
> layer easier as there are fewer callbacks to worry about.
>   

Applied all.  Thanks.

Regards,

Anthony Liguori

> ---
>
> Changes since v1:
> - rebased against trunk
> - performance testing: tested 'rm -rf *; tar xjf ../linux-2.6.22.tar.bz2'
>   with a vm snapshot.  While there are significant variances among runs
>   (15-25sec), likely due to different ext3 allocation decisions and different
>   host caching decisions, there seems to be no regression due to this patchset.
>
> Avi Kivity (3):
>   Add specialized block driver scsi generic API
>   Add internal scsi generic block API
>   Drop internal bdrv_pread()/bdrv_pwrite() APIs
>
>  block-raw-posix.c |   50 ++++++++++++++++++++++++--
>  block-raw-win32.c |   20 ++++++----
>  block.c           |  101 +++++++++++++++--------------------------------------
>  block.h           |    8 ++++
>  block_int.h       |   14 +++++--
>  hw/scsi-generic.c |   39 +++++++++++---------
>  6 files changed, 126 insertions(+), 106 deletions(-)
>
>
>