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Thu, 29 Feb 2024 16:08:32 -0800 (PST) X-Google-Smtp-Source: AGHT+IHkl8zueJAcWAocpKjDft17adkwwl/pUsdwZZRwpou511+jiFQ4fRays4TFcTT1sJmf5eXUnQ== X-Received: by 2002:a17:90a:f68e:b0:29b:10c1:a7d1 with SMTP id cl14-20020a17090af68e00b0029b10c1a7d1mr158291pjb.4.1709251712347; Thu, 29 Feb 2024 16:08:32 -0800 (PST) Received: from x1n ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id c19-20020a17090aa61300b0029a54e43073sm2043515pjq.30.2024.02.29.16.08.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Feb 2024 16:08:31 -0800 (PST) Date: Fri, 1 Mar 2024 08:08:24 +0800 From: Peter Xu To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Fabiano Rosas , qemu-devel@nongnu.org, armbru@redhat.com, Claudio Fontana Subject: Re: [PATCH v5 17/23] migration/multifd: Add outgoing QIOChannelFile support Message-ID: References: <20240228152127.18769-1-farosas@suse.de> <20240228152127.18769-18-farosas@suse.de> <87msrjz6ov.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.096, 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, T_SCC_BODY_TEXT_LINE=-0.01 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Feb 29, 2024 at 02:34:13PM +0000, Daniel P. Berrangé wrote: > On Thu, Feb 29, 2024 at 11:27:44AM -0300, Fabiano Rosas wrote: > > Peter Xu writes: > > > > > On Thu, Feb 29, 2024 at 10:44:21AM +0800, Peter Xu wrote: > > >> On Wed, Feb 28, 2024 at 12:21:21PM -0300, Fabiano Rosas wrote: > > >> > Allow multifd to open file-backed channels. This will be used when > > >> > enabling the mapped-ram migration stream format which expects a > > >> > seekable transport. > > >> > > > >> > The QIOChannel read and write methods will use the preadv/pwritev > > >> > versions which don't update the file offset at each call so we can > > >> > reuse the fd without re-opening for every channel. > > >> > > > >> > Contrary to the socket migration, the file migration doesn't need an > > >> > asynchronous channel creation process, so expose > > >> > multifd_channel_connect() and call it directly. > > >> > > > >> > Note that this is just setup code and multifd cannot yet make use of > > >> > the file channels. > > >> > > > >> > Signed-off-by: Fabiano Rosas > > >> > --- > > >> > - moved flags change to another patch > > >> > - removed channels_created assert > > >> > --- > > >> > migration/file.c | 41 +++++++++++++++++++++++++++++++++++++++-- > > >> > migration/file.h | 4 ++++ > > >> > migration/multifd.c | 18 +++++++++++++++--- > > >> > migration/multifd.h | 1 + > > >> > 4 files changed, 59 insertions(+), 5 deletions(-) > > >> > > > >> > diff --git a/migration/file.c b/migration/file.c > > >> > index 22d052a71f..83328a7a1b 100644 > > >> > --- a/migration/file.c > > >> > +++ b/migration/file.c > > >> > @@ -12,12 +12,17 @@ > > >> > #include "channel.h" > > >> > #include "file.h" > > >> > #include "migration.h" > > >> > +#include "multifd.h" > > >> > #include "io/channel-file.h" > > >> > #include "io/channel-util.h" > > >> > #include "trace.h" > > >> > > > >> > #define OFFSET_OPTION ",offset=" > > >> > > > >> > +static struct FileOutgoingArgs { > > >> > + char *fname; > > >> > +} outgoing_args; > > >> > + > > >> > /* Remove the offset option from @filespec and return it in @offsetp. */ > > >> > > > >> > int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp) > > >> > @@ -37,6 +42,36 @@ int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp) > > >> > return 0; > > >> > } > > >> > > > >> > +void file_cleanup_outgoing_migration(void) > > >> > +{ > > >> > + g_free(outgoing_args.fname); > > >> > + outgoing_args.fname = NULL; > > >> > +} > > >> > + > > >> > +bool file_send_channel_create(gpointer opaque, Error **errp) > > >> > +{ > > >> > + QIOChannelFile *ioc; > > >> > + int flags = O_WRONLY; > > >> > + bool ret = true; > > >> > + > > >> > + ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp); > > >> > + if (!ioc) { > > >> > + ret = false; > > >> > + goto out; > > >> > + } > > >> > + > > >> > + multifd_channel_connect(opaque, QIO_CHANNEL(ioc)); > > >> > + > > >> > +out: > > >> > + /* > > >> > + * File channel creation is synchronous. However posting this > > >> > + * semaphore here is simpler than adding a special case. > > >> > + */ > > >> > + multifd_send_channel_created(); > > >> > + > > >> > + return ret; > > >> > +} > > >> > + > > >> > void file_start_outgoing_migration(MigrationState *s, > > >> > FileMigrationArgs *file_args, Error **errp) > > >> > { > > >> > @@ -47,12 +82,14 @@ void file_start_outgoing_migration(MigrationState *s, > > >> > > > >> > trace_migration_file_outgoing(filename); > > >> > > > >> > - fioc = qio_channel_file_new_path(filename, O_CREAT | O_WRONLY | O_TRUNC, > > >> > - 0600, errp); > > >> > + fioc = qio_channel_file_new_path(filename, O_CREAT | O_TRUNC | O_WRONLY, > > >> > + 0660, errp); > > >> > > >> It seems this is still leftover? > > >> > > >> > if (!fioc) { > > >> > return; > > >> > } > > >> > > > >> > + outgoing_args.fname = g_strdup(filename); > > >> > + > > >> > ioc = QIO_CHANNEL(fioc); > > >> > if (offset && qio_channel_io_seek(ioc, offset, SEEK_SET, errp) < 0) { > > >> > return; > > >> > diff --git a/migration/file.h b/migration/file.h > > >> > index 37d6a08bfc..4577f9efdd 100644 > > >> > --- a/migration/file.h > > >> > +++ b/migration/file.h > > >> > @@ -9,10 +9,14 @@ > > >> > #define QEMU_MIGRATION_FILE_H > > >> > > > >> > #include "qapi/qapi-types-migration.h" > > >> > +#include "io/task.h" > > >> > +#include "channel.h" > > >> > > > >> > void file_start_incoming_migration(FileMigrationArgs *file_args, Error **errp); > > >> > > > >> > void file_start_outgoing_migration(MigrationState *s, > > >> > FileMigrationArgs *file_args, Error **errp); > > >> > int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp); > > >> > +void file_cleanup_outgoing_migration(void); > > >> > +bool file_send_channel_create(gpointer opaque, Error **errp); > > >> > #endif > > >> > diff --git a/migration/multifd.c b/migration/multifd.c > > >> > index 3574fd3953..f155223303 100644 > > >> > --- a/migration/multifd.c > > >> > +++ b/migration/multifd.c > > >> > @@ -17,6 +17,7 @@ > > >> > #include "exec/ramblock.h" > > >> > #include "qemu/error-report.h" > > >> > #include "qapi/error.h" > > >> > +#include "file.h" > > >> > #include "ram.h" > > >> > #include "migration.h" > > >> > #include "migration-stats.h" > > >> > @@ -28,6 +29,7 @@ > > >> > #include "threadinfo.h" > > >> > #include "options.h" > > >> > #include "qemu/yank.h" > > >> > +#include "io/channel-file.h" > > >> > #include "io/channel-socket.h" > > >> > #include "yank_functions.h" > > >> > > > >> > @@ -694,6 +696,7 @@ static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp) > > >> > { > > >> > if (p->c) { > > >> > migration_ioc_unregister_yank(p->c); > > >> > + qio_channel_close(p->c, NULL); > > >> > > >> s/NULL/&error_abort/? > > > > > > Or we can drop this line? IIUC iochannel finalize() will always close it, > > > or it could be a separate bug. > > > > > > > We need it so the fsync happens. The finalize() will be a noop because > > the qio_channel_file_close() will clear the fd. Not the cleanest, but it > > works. > > It is always wise to explicitly call 'close'. > > If something still has a GSource watch registered against > the QIOChannel, that GSource will be holding a reference > on the QIOChannel and will thus prevent finalize() ever > running. > > By calling close() you guarantee the channel is closed, > even if you've mistakenly leaked a GSource somewhere. > Finalize still won't run in that case, but at least the > FD is gone, and the HUP might cause the GSource callback > to trigger correct cleanup; I see. Let's add a comment to explain why we do this explicit close(), then? It wasn't that clear, and we also don't do that on recv side. It seems also only useful for "file:", we can mention that in the comment if so. Thanks, -- Peter Xu