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Fri, 10 Feb 2023 16:26:26 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.76]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0EA451731B; Fri, 10 Feb 2023 16:26:24 +0000 (UTC) Date: Fri, 10 Feb 2023 16:26:22 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Nikolay Borisov Cc: 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 In-Reply-To: <20221028103914.908728-5-nborisov@suse.com> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 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, 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); > + > + > +/** > + * 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 :|