On 17.08.19 19:53, Nir Soffer wrote:
> Replace instances of:
>
> (n & (BDRV_SECTOR_SIZE - 1)) == 0)
>
> With:
>
> QEMU_IS_ALIGNED(n, BDRV_SECTOR_SIZE)
>
> Which reveals the intent of the code better, and makes it easier to
> locate the code checking alignment.
>
> QEMU_IS_ALIGNED is implemented using %, which may be less efficient but
> it is used only in assert() except one instance, so it should not
> matter.
>
> Signed-off-by: Nir Soffer <address@hidden>
> ---
> block/bochs.c | 4 ++--
> block/cloop.c | 4 ++--
> block/dmg.c | 4 ++--
> block/io.c | 8 ++++----
> block/qcow2.c | 4 ++--
> block/vvfat.c | 8 ++++----
> qemu-img.c | 2 +-
> 7 files changed, 17 insertions(+), 17 deletions(-)
Because John was speaking about a magical incantation, I found
BDRV_SECTOR_MASK. There are two places in block/qcow2-cluster.c that
use that to check alignment, I think those should be amended as well.
$ git grep BDRV_SECTOR_MASK
block/qcow2-cluster.c: assert((offset_in_cluster & ~BDRV_SECTOR_MASK) == 0);
block/qcow2-cluster.c: assert((bytes & ~BDRV_SECTOR_MASK) == 0);
Right, should use QEMU_IS_ALIGNED
include/block/block.h:#define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1)
include/block/block.h:#define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK
migration/block.c: flags = addr & ~BDRV_SECTOR_MASK;
This could use (BDRV_SECTOR_SIZE - 1).
In Linux SECTOR_MASK is defined as:
drivers/block/null_blk_main.c:#define SECTOR_MASK (PAGE_SECTORS - 1)
It seems that qemu use use the same.
I will try to handle these in v2.
Nir