From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53330) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dddGy-0001oc-7y for qemu-devel@nongnu.org; Fri, 04 Aug 2017 10:08:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dddGl-0002ke-KC for qemu-devel@nongnu.org; Fri, 04 Aug 2017 10:08:16 -0400 Date: Fri, 4 Aug 2017 15:06:30 +0100 From: "Daniel P. Berrange" Message-ID: <20170804140630.GC14504@redhat.com> Reply-To: "Daniel P. Berrange" References: <20170804105059.11941-1-berrange@redhat.com> <20170804140210.GD4108@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170804140210.GD4108@localhost.localdomain> Subject: Re: [Qemu-devel] [PATCH] block: document semanatics of bdrv_co_preadv|pwritev List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Stefan Hajnoczi , Fam Zheng , Max Reitz On Fri, Aug 04, 2017 at 04:02:10PM +0200, Kevin Wolf wrote: > Am 04.08.2017 um 12:50 hat Daniel P. Berrange geschrieben: > > Signed-off-by: Daniel P. Berrange > > --- > > include/block/block_int.h | 29 +++++++++++++++++++++++++++++ > > 1 file changed, 29 insertions(+) > > > > diff --git a/include/block/block_int.h b/include/block/block_int.h > > index d4f4ea7584..deb81a58bd 100644 > > --- a/include/block/block_int.h > > +++ b/include/block/block_int.h > > @@ -147,12 +147,41 @@ struct BlockDriver { > > > > int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs, > > int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); > > + > > + /** > > + * @offset: position in bytes to read at > > + * @bytes: number of bytes to read > > + * @qiov: the buffers to fill with read data > > + * > > + * @offset and @bytes will be a multiple of 'request_alignment', > > + * but the length of individual @qiov elements does not have to > > + * be a multiple. > > + * > > + * @bytes may be less than the total sizeof @iov, and will be > > + * no larger than 'max_transfer'. > > Really? We are asserting that they match in bdrv_aligned_preadv(): > > assert(!qiov || bytes == qiov->size); Hmm, why do we pass @bytes at all then ? If they're always the same, how about deleting it and just letting everyone read qiov->size directly. > Also, s/sizeof @iov/size of @qiov/ > > > + * > > + * The buffer in @qiov may point directly to guest memory. > > + */ > > int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs, > > uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags); > > int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs, > > int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); > > int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs, > > int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags); > > + /** > > + * @offset: position in bytes to write at > > + * @bytes: number of bytes to write > > + * @qiov: the buffers containing data to write > > + * > > + * @offset and @bytes will be a multiple of 'request_alignment', > > + * but the length of individual @qiov elements does not have to > > + * be a multiple. > > + * > > + * @bytes may be less than the total sizeof @iov, and will be > > + * no larger than 'max_transfer'. > > The same assertion exists in bdrv_aligned_pwritev() (and the same typo > in your comment). > > > + * The buffer in @qiov may point directly to guest memory. > > + */ > > int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs, > > uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags); > > Kevin Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|