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Tue, 16 Jan 2024 13:37:51 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id zm3QDq+GpmUbYAAAD6G6ig (envelope-from ); Tue, 16 Jan 2024 13:37:51 +0000 From: Fabiano Rosas To: Peter Xu Cc: qemu-devel@nongnu.org, berrange@redhat.com, armbru@redhat.com, Juan Quintela , Leonardo Bras , Claudio Fontana Subject: Re: [RFC PATCH v3 13/30] migration/multifd: Add outgoing QIOChannelFile support In-Reply-To: References: <20231127202612.23012-1-farosas@suse.de> <20231127202612.23012-14-farosas@suse.de> Date: Tue, 16 Jan 2024 10:37:48 -0300 Message-ID: <87bk9lxutv.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain Authentication-Results: smtp-out2.suse.de; none X-Spamd-Result: default: False [-3.10 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; BAYES_HAM(-3.00)[100.00%]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_SEVEN(0.00)[7]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:2; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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 Peter Xu writes: > On Mon, Nov 27, 2023 at 05:25:55PM -0300, Fabiano Rosas wrote: >> Allow multifd to open file-backed channels. This will be used when >> enabling the fixed-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. >> >> Note that this is just setup code and multifd cannot yet make use of >> the file channels. >> >> Signed-off-by: Fabiano Rosas >> --- >> - open multifd channels with O_WRONLY and no mode >> - stop cancelling migration and propagate error via qio_task >> --- >> migration/file.c | 47 +++++++++++++++++++++++++++++++++++++++++-- >> migration/file.h | 5 +++++ >> migration/multifd.c | 14 +++++++++++-- >> migration/options.c | 7 +++++++ >> migration/options.h | 1 + >> migration/qemu-file.h | 1 - >> 6 files changed, 70 insertions(+), 5 deletions(-) >> >> diff --git a/migration/file.c b/migration/file.c >> index 5d4975f43e..67d6f42da7 100644 >> --- a/migration/file.c >> +++ b/migration/file.c >> @@ -17,6 +17,10 @@ >> >> #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) >> @@ -36,6 +40,42 @@ int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp) >> return 0; >> } >> >> +static void qio_channel_file_connect_worker(QIOTask *task, gpointer opaque) >> +{ >> + /* noop */ >> +} >> + >> +int file_send_channel_destroy(QIOChannel *ioc) >> +{ >> + if (ioc) { >> + qio_channel_close(ioc, NULL); >> + object_unref(OBJECT(ioc)); >> + } >> + g_free(outgoing_args.fname); >> + outgoing_args.fname = NULL; >> + >> + return 0; >> +} >> + >> +void file_send_channel_create(QIOTaskFunc f, void *data) >> +{ >> + QIOChannelFile *ioc; >> + QIOTask *task; >> + Error *err = NULL; >> + int flags = O_WRONLY; >> + >> + ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, &err); >> + >> + task = qio_task_new(OBJECT(ioc), f, (gpointer)data, NULL); >> + if (!ioc) { >> + qio_task_set_error(task, err); >> + return; >> + } >> + >> + qio_task_run_in_thread(task, qio_channel_file_connect_worker, >> + (gpointer)data, NULL, NULL); > > This is pretty weird. This invokes a thread, but it'll run a noop. It > seems meaningless to me. > That's QIOTask weirdness isn't it? It will run the worker in the thread, but it also schedules the completion function as a glib event. So that's when multifd_new_send_channel_async() will run. The crucial aspect here is that it gets dispatched by glib on the main loop. I'm just keeping the model, except that I don't have work to do during the "connection" phase. > I assume you wanted to keep using the same async model as the socket typed > multifd, but I don't think that works anyway, because file open blocks at > qio_channel_file_new_path() so it's sync anyway. It's async regarding multifd_channel_connect(). The connections will be happening while multifd_save_setup() continues execution, IIUC. > > AFAICT we still share the code, as long as the file path properly invokes > multifd_channel_connect() after the iochannel is setup. > I don't see the point in moving any of that logic into the URI implementation. We already have the TLS handshake code which can also call multifd_channel_connect() and that is a mess. IMO we should be keeping the interface between multifd and the frontends as boilerplate as possible. >> +} >> + >> void file_start_outgoing_migration(MigrationState *s, >> FileMigrationArgs *file_args, Error **errp) >> { >> @@ -43,15 +83,18 @@ void file_start_outgoing_migration(MigrationState *s, >> g_autofree char *filename = g_strdup(file_args->filename); >> uint64_t offset = file_args->offset; >> QIOChannel *ioc; >> + int flags = O_CREAT | O_TRUNC | O_WRONLY; >> + mode_t mode = 0660; >> >> 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, flags, mode, errp); >> 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..511019b319 100644 >> --- a/migration/file.h >> +++ b/migration/file.h >> @@ -9,10 +9,15 @@ >> #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_send_channel_create(QIOTaskFunc f, void *data); >> +int file_send_channel_destroy(QIOChannel *ioc); >> #endif >> diff --git a/migration/multifd.c b/migration/multifd.c >> index 123ff0dec0..427740aab6 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" >> >> @@ -511,7 +513,11 @@ static void multifd_send_terminate_threads(Error *err) >> >> static int multifd_send_channel_destroy(QIOChannel *send) >> { >> - return socket_send_channel_destroy(send); >> + if (migrate_to_file()) { >> + return file_send_channel_destroy(send); >> + } else { >> + return socket_send_channel_destroy(send); >> + } >> } >> >> void multifd_save_cleanup(void) >> @@ -904,7 +910,11 @@ static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque) >> >> static void multifd_new_send_channel_create(gpointer opaque) >> { >> - socket_send_channel_create(multifd_new_send_channel_async, opaque); >> + if (migrate_to_file()) { >> + file_send_channel_create(multifd_new_send_channel_async, opaque); >> + } else { >> + socket_send_channel_create(multifd_new_send_channel_async, opaque); >> + } >> } >> >> int multifd_save_setup(Error **errp) >> diff --git a/migration/options.c b/migration/options.c >> index 10730b13ba..f671e24758 100644 >> --- a/migration/options.c >> +++ b/migration/options.c >> @@ -409,6 +409,13 @@ bool migrate_tls(void) >> return s->parameters.tls_creds && *s->parameters.tls_creds; >> } >> >> +bool migrate_to_file(void) >> +{ >> + MigrationState *s = migrate_get_current(); >> + >> + return qemu_file_is_seekable(s->to_dst_file); >> +} > > Would this migrate_to_file() == migrate_multifd_packets()? > > Maybe we can keep using the other one and drop migrate_to_file? > Possibly the other way around as you mention. I'll take a look. >> + >> typedef enum WriteTrackingSupport { >> WT_SUPPORT_UNKNOWN = 0, >> WT_SUPPORT_ABSENT, >> diff --git a/migration/options.h b/migration/options.h >> index 8a19d6939c..84628a76e8 100644 >> --- a/migration/options.h >> +++ b/migration/options.h >> @@ -60,6 +60,7 @@ bool migrate_multifd_packets(void); >> bool migrate_postcopy(void); >> bool migrate_rdma(void); >> bool migrate_tls(void); >> +bool migrate_to_file(void); >> >> /* capabilities helpers */ >> >> diff --git a/migration/qemu-file.h b/migration/qemu-file.h >> index 32fd4a34fd..78ea21ab98 100644 >> --- a/migration/qemu-file.h >> +++ b/migration/qemu-file.h >> @@ -83,5 +83,4 @@ size_t qemu_get_buffer_at(QEMUFile *f, const uint8_t *buf, size_t buflen, >> off_t pos); >> >> QIOChannel *qemu_file_get_ioc(QEMUFile *file); >> - >> #endif >> -- >> 2.35.3 >>