Re: [Qemu-devel] [PATCH v5 00/10] Clean up around bdrv_getlength()

[Stefan Hajnoczi]

On Thu, Jun 26, 2014 at 01:23:15PM +0200, Markus Armbruster wrote:
> Issues addressed in this series:
> 
> * BlockDriver method bdrv_getlength() generally returns -errno, but
>   some implementations return -1 instead.  Fix them [PATCH 1].
> 
> * Frequent conversions between sectors and bytes complicate the code
>   needlessly.  Clean up some [PATCH 2-7].
> 
> * bdrv_getlength() always returns a multiple of BDRV_SECTOR_SIZE, but
>   some places appear to be confused about that, and align the result
>   up or down.  Don't [PATCH 8].
> 
> * bdrv_get_geometry() hides errors.  Don't use it in places where
>   errors should be detected [PATCH 9+10].
> 
> Issues not addressed:
> 
> * We want to move away from counting in arbitrary units of 512 bytes
>   we call "sector", even though it's not really related to either
>   guest or host sector size.  My patches mostly move sideways:
> 
>   - Sector-based bdrv_get_geometry() gets partly replaced by new
>     bdrv_nb_sectors(), still sector-based.
> 
>   - Some sector-based places get converted from bdrv_getlength() to
>     bdrv_nb_sectors().  At least, this de-duplicates the conversion
>     from bytes to sectors.
> 
>   - Two places get converted from bdrv_get_geometry() to
>     bdrv_getlength().  Two baby steps forward.
> 
> * There are quite a few literals left in the code where
>   BDRV_SECTOR_SIZE, BDRV_SECTOR_BITS or BDRV_SECTOR_MASK should be
>   used instead.
> 
> * Error handling is missing in places, but it's not always obvious
>   whether errors can actually happen, and if yes, how to handle them.
> 
> * Several calls of bdrv_get_geometry() remain in hw/.  I wanted to
>   replace them all, but ran out of steam.
> 
> v5:
> * Straightforward rebase, only 10/10 conflicted
> v4:
> * Trivially rebased
> * Set ret on error paths in img_compare() and img_rebase() in PATCH 10
>   [Benoît]
> v3:
> * Trivially rebased
> * Correct silly g_new() vs. g_new0() mistake in PATCH 09 [Max]
> v2:
> * Trivially rebased
> * Correct silly bdrv_getlength() vs. bdrv_nb_sectors() mistake in
>   PATCH 03
> * Split PATCH 03 into 03-07 [Kevin]
> * Conversion of bs_sectors to array in PATCH 05 had a subscript off by
>   one, fix [Kevin]
> * Split PATCH 05 into 09-10 [Kevin]
> 
> Markus Armbruster (10):
>   raw-posix: Fix raw_getlength() to always return -errno on error
>   block: New bdrv_nb_sectors()
>   block: Use bdrv_nb_sectors() in bdrv_make_zero()
>   block: Use bdrv_nb_sectors() in bdrv_aligned_preadv()
>   block: Use bdrv_nb_sectors() in bdrv_co_get_block_status()
>   block: Use bdrv_nb_sectors() in img_convert()
>   block: Use bdrv_nb_sectors() where sectors, not bytes are wanted
>   block: Drop superfluous aligning of bdrv_getlength()'s value
>   qemu-img: Make img_convert() get image size just once per image
>   block: Avoid bdrv_get_geometry() where errors should be detected
> 
>  block-migration.c     |  9 +++--
>  block.c               | 81 +++++++++++++++++++++++-------------------
>  block/qapi.c          | 14 +++++---
>  block/qcow2.c         |  3 +-
>  block/raw-posix.c     | 28 +++++++++++----
>  block/vmdk.c          |  5 ++-
>  include/block/block.h |  1 +
>  qemu-img.c            | 98 
> +++++++++++++++++++++++++++++++++++----------------
>  8 files changed, 152 insertions(+), 87 deletions(-)

Thanks, applied Patches 2-10 to my block-next tree:
https://github.com/stefanha/qemu/commits/block-next

Stefan

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