From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4108DC636D4 for ; Fri, 10 Feb 2023 16:59:25 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pQWj2-0003Y1-JM; Fri, 10 Feb 2023 11:58:16 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pQWj0-0003XZ-M6 for qemu-devel@nongnu.org; Fri, 10 Feb 2023 11:58:14 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pQWiy-0003zB-LB for qemu-devel@nongnu.org; Fri, 10 Feb 2023 11:58:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676048291; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QiLNcLWwnmtJI9QLCDi1/ww3J50XSemCDDUDadzNGBQ=; b=QiTtX3yjgO4aB4IiDLT8X6CfPLmBJgF09sq/ouQFKYu75jNydwleviNHAhgIHBKn7McUVN b7sY1ZWwv0GvtMRfyy7kSMiLr4U/1IP9Xqnlo5SvqVX21AVuLi/HktaoNIF4B7SBj8M3vp zhuOd8KV08qZwDsZQwvTY5veTMT6ets= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-382-9n4dNUsXOOmsehk_HCJsFw-1; Fri, 10 Feb 2023 11:58:10 -0500 X-MC-Unique: 9n4dNUsXOOmsehk_HCJsFw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A554F1C08797; Fri, 10 Feb 2023 16:58:09 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.76]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4DE0440CF8F0; Fri, 10 Feb 2023 16:58:08 +0000 (UTC) Date: Fri, 10 Feb 2023 16:58:04 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Nikolay Borisov , dgilbert@redhat.com, qemu-devel@nongnu.org, jfehlig@suse.com, Claudio.Fontana@suse.com, dfaggioli@suse.com Subject: Re: [PATCH v3 04/14] io: Add generic pwritev/preadv interface Message-ID: References: <20221028103914.908728-1-nborisov@suse.com> <20221028103914.908728-5-nborisov@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Feb 10, 2023 at 04:26:22PM +0000, Daniel P. Berrangé wrote: > On Fri, Oct 28, 2022 at 01:39:04PM +0300, Nikolay Borisov wrote: > > Introduce basic pwriteve/preadv support in the generic channel layer. > > SPecific implementation will follow for the file channel as this is > > required in order to support migration streams with fixed location of > > each ram page. > > > > Signed-off-by: Nikolay Borisov > > --- > > include/io/channel.h | 49 ++++++++++++++++++++++++++++++++++++++++++++ > > io/channel.c | 26 +++++++++++++++++++++++ > > 2 files changed, 75 insertions(+) > > > > diff --git a/include/io/channel.h b/include/io/channel.h > > index c680ee748021..6b10bce8bbdf 100644 > > --- a/include/io/channel.h > > +++ b/include/io/channel.h > > @@ -124,6 +124,16 @@ struct QIOChannelClass { > > Error **errp); > > > > /* Optional callbacks */ > > + ssize_t (*io_pwritev)(QIOChannel *ioc, > > + const struct iovec *iov, > > + size_t niov, > > + off_t offset, > > + Error **errp); > > + ssize_t (*io_preadv)(QIOChannel *ioc, > > + const struct iovec *iov, > > + size_t niov, > > + off_t offset, > > + Error **errp); > > nit-pick the alignment of the 2nd line of parameters onwards, > needs to be indented by 3 more spaces. > > > > +/** > > + * qio_channel_io_pwritev > > + * @ioc: the channel object > > + * @iov: the array of memory regions to write data from > > + * @niov: the length of the @iov array > > + * @offset: offset in the channel where writes should begin > > + * @errp: pointer to a NULL-initialized error object > > + * > > + * Not all implementations will support this facility, so may report an error. > > + * To avoid errors, the caller may check for the feature flag > > + * QIO_CHANNEL_FEATURE_SEEKABLE prior to calling this method. > > + * > > + * Behaves as qio_channel_writev_full, apart from not supporting sending of file > > Given this, we should have "_full" suffix on these methods > too for consistent naming policy. > > > + * handles as well as beginning the write at the passed @offset > > + * > > + */ > > +ssize_t qio_channel_io_pwritev(QIOChannel *ioc, const struct iovec *iov, > > + size_t niov, off_t offset, Error **errp); In addition to giving this method the '_full' suffix, we should also add the qio_channel_io_pwritev entrypoint which takes a single buffer instead of iovec. The migration code in QEMUFile that is added in a later patch in this series doesn't actually want to use iovecs in the first place. So having the non-iov entrypoints in QIOChannel will simplify the migration code. > > + > > + > > +/** > > + * qio_channel_io_preadv > > + * @ioc: the channel object > > + * @iov: the array of memory regions to read data into > > + * @niov: the length of the @iov array > > + * @offset: offset in the channel where writes should begin > > + * @errp: pointer to a NULL-initialized error object > > + * > > + * Not all implementations will support this facility, so may report an error. > > + * To avoid errors, the caller may check for the feature flag > > + * QIO_CHANNEL_FEATURE_SEEKABLE prior to calling this method. > > + * > > + * Behaves as qio_channel_readv_full, apart from not supporting receiving of file > > + * handles as well as beginning the read at the passed @offset > > + * > > + */ > > +ssize_t qio_channel_io_preadv(QIOChannel *ioc, const struct iovec *iov, > > + size_t niov, off_t offset, Error **errp); > > /** > > * qio_channel_shutdown: > > * @ioc: the channel object > > diff --git a/io/channel.c b/io/channel.c > > index 0640941ac573..f5ac9499a7ad 100644 > > --- a/io/channel.c > > +++ b/io/channel.c > > @@ -437,6 +437,32 @@ GSource *qio_channel_add_watch_source(QIOChannel *ioc, > > } > > > > > > +ssize_t qio_channel_io_pwritev(QIOChannel *ioc, const struct iovec *iov, > > + size_t niov, off_t offset, Error **errp) > > +{ > > + QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc); > > + > > + if (!klass->io_pwritev) { > > + error_setg(errp, "Channel does not support pwritev"); > > + return -1; > > + } > > This also possibly benefits from a validation check > > if (!qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_SEEKABLE)) { > error_setg_errno(errp, EINVAL, > "Requested channel is not seekable") > return -1; > } > > because the QIOChannelFile impl will support io_pwritev callback, > but not all the FDs it can use will support seeking. > > Same check for preadv > > > + > > + return klass->io_pwritev(ioc, iov, niov, offset, errp); > > +} > > + > > +ssize_t qio_channel_io_preadv(QIOChannel *ioc, const struct iovec *iov, > > + size_t niov, off_t offset, Error **errp) > > +{ > > + QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc); > > + > > + if (!klass->io_preadv) { > > + error_setg(errp, "Channel does not support preadv"); > > + return -1; > > + } > > + > > + return klass->io_preadv(ioc, iov, niov, offset, errp); > > +} > > + > > int qio_channel_shutdown(QIOChannel *ioc, > > QIOChannelShutdown how, > > Error **errp) > > -- > > 2.34.1 > > > > With 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 :| > > With 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 :|