From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35835) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGKv5-0003c9-6y for qemu-devel@nongnu.org; Fri, 24 Jun 2016 02:48:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bGKv0-0002BL-U7 for qemu-devel@nongnu.org; Fri, 24 Jun 2016 02:48:50 -0400 Date: Fri, 24 Jun 2016 14:48:31 +0800 From: Fam Zheng Message-ID: <20160624064831.GE13266@ad.usersys.redhat.com> References: <1466721446-27737-1-git-send-email-eblake@redhat.com> <1466721446-27737-20-git-send-email-eblake@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466721446-27737-20-git-send-email-eblake@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 19/22] block: Split bdrv_merge_limits() from bdrv_refresh_limits() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, kwolf@redhat.com, stefanha@redhat.com, Max Reitz On Thu, 06/23 16:37, Eric Blake wrote: > During bdrv_merge_limits(), we were computing initial limits > based on another BDS in two places. At first glance, the two > computations are not identical (one is doing straight copying, > the other is doing merging towards or away from zero) - but > when you realize that the first round is starting with all-0 > memory, all of the merging happens to work. Factoring out the > merging makes it easier to track how two BDS limits are merged, > in case we have future reasons to merge in even more limits. > > Signed-off-by: Eric Blake > > --- > v3: Split raw block driver changes to its own patch, make new > function static > v2: new patch > --- > block/io.c | 31 +++++++++++++------------------ > 1 file changed, 13 insertions(+), 18 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 0f15d05..69dbbd3 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -67,6 +67,17 @@ static void bdrv_parent_drained_end(BlockDriverState *bs) > } > } > > +static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src) > +{ > + dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer); > + dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer); > + dst->opt_mem_alignment = MAX(dst->opt_mem_alignment, > + src->opt_mem_alignment); > + dst->min_mem_alignment = MAX(dst->min_mem_alignment, > + src->min_mem_alignment); > + dst->max_iov = MIN_NON_ZERO(dst->max_iov, src->max_iov); > +} > + > void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) > { > BlockDriver *drv = bs->drv; > @@ -88,11 +99,7 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) > error_propagate(errp, local_err); > return; > } > - bs->bl.opt_transfer = bs->file->bs->bl.opt_transfer; > - bs->bl.max_transfer = bs->file->bs->bl.max_transfer; > - bs->bl.min_mem_alignment = bs->file->bs->bl.min_mem_alignment; > - bs->bl.opt_mem_alignment = bs->file->bs->bl.opt_mem_alignment; > - bs->bl.max_iov = bs->file->bs->bl.max_iov; > + bdrv_merge_limits(&bs->bl, &bs->file->bs->bl); > } else { > bs->bl.min_mem_alignment = 512; > bs->bl.opt_mem_alignment = getpagesize(); > @@ -107,19 +114,7 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) > error_propagate(errp, local_err); > return; > } > - bs->bl.opt_transfer = MAX(bs->bl.opt_transfer, > - bs->backing->bs->bl.opt_transfer); > - bs->bl.max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, > - bs->backing->bs->bl.max_transfer); > - bs->bl.opt_mem_alignment = > - MAX(bs->bl.opt_mem_alignment, > - bs->backing->bs->bl.opt_mem_alignment); > - bs->bl.min_mem_alignment = > - MAX(bs->bl.min_mem_alignment, > - bs->backing->bs->bl.min_mem_alignment); > - bs->bl.max_iov = > - MIN(bs->bl.max_iov, > - bs->backing->bs->bl.max_iov); > + bdrv_merge_limits(&bs->bl, &bs->backing->bs->bl); > } > > /* Then let the driver override it */ > -- > 2.5.5 > Reviewed-by: Fam Zheng