From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48031) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGJbH-0000AN-41 for qemu-devel@nongnu.org; Fri, 24 Jun 2016 01:24:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bGJbE-0007bO-Vx for qemu-devel@nongnu.org; Fri, 24 Jun 2016 01:24:18 -0400 Date: Fri, 24 Jun 2016 13:24:04 +0800 From: Fam Zheng Message-ID: <20160624052404.GB11920@ad.usersys.redhat.com> References: <1466721446-27737-1-git-send-email-eblake@redhat.com> <1466721446-27737-9-git-send-email-eblake@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466721446-27737-9-git-send-email-eblake@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 08/22] block: Give nonzero result to blk_get_max_transfer_length() 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 , "Michael S. Tsirkin" , Paolo Bonzini On Thu, 06/23 16:37, Eric Blake wrote: > Making all callers special-case 0 as unlimited is awkward, > and we DO have a hard maximum of BDRV_REQUEST_MAX_SECTORS given > our current block layer API limits. > > In the case of scsi, this means that we now always advertise a > limit to the guest, even in cases where the underlying layers > previously use 0 for no inherent limit beyond the block layer. > > Signed-off-by: Eric Blake > Reviewed-by: Kevin Wolf > > --- > v3: rebase to scsi limits fix > v2: new patch > --- > block/block-backend.c | 7 ++++--- > hw/block/virtio-blk.c | 3 +-- > hw/scsi/scsi-generic.c | 12 ++++++------ > 3 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/block/block-backend.c b/block/block-backend.c > index 34500e6..1fb070b 100644 > --- a/block/block-backend.c > +++ b/block/block-backend.c > @@ -1303,15 +1303,16 @@ int blk_get_flags(BlockBackend *blk) > } > } > > +/* Returns the maximum transfer length, in sectors; guaranteed nonzero */ > int blk_get_max_transfer_length(BlockBackend *blk) > { > BlockDriverState *bs = blk_bs(blk); > + int max = 0; > > if (bs) { > - return bs->bl.max_transfer_length; > - } else { > - return 0; > + max = bs->bl.max_transfer_length; > } > + return MIN_NON_ZERO(max, BDRV_REQUEST_MAX_SECTORS); > } > > int blk_get_max_iov(BlockBackend *blk) > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index 284e646..1d2792e 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -382,7 +382,7 @@ static int multireq_compare(const void *a, const void *b) > void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb) > { > int i = 0, start = 0, num_reqs = 0, niov = 0, nb_sectors = 0; > - int max_xfer_len = 0; > + int max_xfer_len; > int64_t sector_num = 0; > > if (mrb->num_reqs == 1) { > @@ -392,7 +392,6 @@ void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb) > } > > max_xfer_len = blk_get_max_transfer_length(mrb->reqs[0]->dev->blk); > - max_xfer_len = MIN_NON_ZERO(max_xfer_len, BDRV_REQUEST_MAX_SECTORS); > > qsort(mrb->reqs, mrb->num_reqs, sizeof(*mrb->reqs), > &multireq_compare); > diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c > index 75e227d..0cb8568 100644 > --- a/hw/scsi/scsi-generic.c > +++ b/hw/scsi/scsi-generic.c > @@ -227,12 +227,12 @@ static void scsi_read_complete(void * opaque, int ret) > r->req.cmd.buf[2] == 0xb0) { > uint32_t max_xfer_len = blk_get_max_transfer_length(s->conf.blk) / > (s->blocksize / BDRV_SECTOR_SIZE); > - if (max_xfer_len) { > - stl_be_p(&r->buf[8], max_xfer_len); > - /* Also take care of the opt xfer len. */ > - if (ldl_be_p(&r->buf[12]) > max_xfer_len) { > - stl_be_p(&r->buf[12], max_xfer_len); > - } > + > + assert(max_xfer_len); > + stl_be_p(&r->buf[8], max_xfer_len); > + /* Also take care of the opt xfer len. */ > + if (ldl_be_p(&r->buf[12]) > max_xfer_len) { > + stl_be_p(&r->buf[12], max_xfer_len); > } > } > scsi_req_data(&r->req, len); > -- > 2.5.5 > Reviewed-by: Fam Zheng