On Thu, Apr 13, 2017 at 6:06 PM, Ming Lei <ming.lei@xxxxxxxxxx> wrote:
> Now commit 729204ef49ec("block: relax check on sg gap")
> allows us to merge bios if both are physically contiguous,
> this change can merge huge of small bios in use case of mkfs,
> for example, mkfs.ntfs running time can be decreased to ~1/10.
>
> But if one rq starts with non-aligned buffer(the 1st bvec's
> bv_offset isn't zero) and if we allow to merge, it is quite
> difficult to respect sg gap limit, especially the segment
> can't be at maximum segment size, otherwise the segment
> ends in unaligned virt boundary. This patch trys to avoid the
> issue by not allowing to merge if the req starts with non-aligned
> buffer.
>
> Also add comments to explain why the merged segment can't
> end in unaligned virt boundary.
>
> Fixes: 729204ef49ec ("block: relax check on sg gap")
> Tested-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
Hi Jens and Omar,
I know Jens is currently on vacation, but can maybe Omar get this fix to Linus
before v4.11? This would be highly appreciated.
Thanks a lot,
Johannes
