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Thu, 11 Jan 2024 18:46:13 +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 KxmtFXU3oGWWeQAAD6G6ig (envelope-from ); Thu, 11 Jan 2024 18:46:13 +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 04/30] io: fsync before closing a file channel In-Reply-To: References: <20231127202612.23012-1-farosas@suse.de> <20231127202612.23012-5-farosas@suse.de> Date: Thu, 11 Jan 2024 15:46:02 -0300 Message-ID: <87wmsfn1xx.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain Authentication-Results: smtp-out2.suse.de; none X-Spamd-Result: default: False [-1.30 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; BAYES_HAM(-0.00)[31.30%]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; 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]; NEURAL_HAM_SHORT(-0.20)[-0.978]; RCPT_COUNT_SEVEN(0.00)[7]; 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 05:25:46PM -0300, Fabiano Rosas wrote: >> Make sure the data is flushed to disk before closing file >> channels. This will ensure data is on disk at the end of a migration >> to file. > > Looks reasonable, but just two (possibly naive) questions: > > (1) Does this apply to all io channel users, or only migration? All file channel users. > > (2) Why metadata doesn't matter (v.s. fsync(), when CONFIG_FDATASYNC=y)? Syncing the inode information is not critical, it's mostly timestamp information (man inode). And fdatasync makes sure to sync any metadata that would be relevant for the retrieval of the data. > > Thanks,