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Mon, 9 Nov 2026 18:47:21 +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 R38wFDkV8mrldAAAD6G6ig (envelope-from ); Mon, 09 Nov 2026 18:47:21 +0000 Date: Mon, 9 Nov 2026 19:47:12 +0100 From: David Sterba To: Qu Wenruo Cc: Cheng Yongkang , David Sterba , Chris Mason , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] btrfs: reject refs=0 subvolume without DEAD in SUBVOL_SYNC_WAIT Message-ID: <20261109184712.GF4186782@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <20261101062539.1744605-1-teel4res@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Spamd-Result: default: False [-13.21 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; HAS_REPLYTO(0.30)[dsterba@suse.cz]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_TRACE(0.00)[suse.cz:+]; RCVD_TLS_ALL(0.00)[]; REPLYTO_ADDR_EQ_FROM(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[gmail.com,suse.com,kernel.org,vger.kernel.org]; RCVD_COUNT_TWO(0.00)[2]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_SEVEN(0.00)[7]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:replyto,suse.cz:dkim,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -13.21 X-Spam-Level: X-Rspamd-Queue-Id: CBA8A2212E On Sun, Nov 01, 2026 at 05:48:21PM +1030, Qu Wenruo wrote: > With that said, there are more problems with the ioctl. > > - No real user > No one is utilizing BTRFS_SUBVOL_SYNC* flags. Btrfs-progs itself > doesn't even bother it. > > So all these fixes are very low priority, unless there are some wild > programs utilizing this. > > But even btrfs-progs doesn't utilize them, the possibility are very > low. Obviously the ioctl was added so progs 'subvol sync' can use it for non-root users. I started working on it but there's a problem with the behaviour change between the user types. Root has full access and reports the progress while with this ioctl there were some problems I don't remember. The ioctl was designed to emulate all modes that root can do so it should be possible to get 1:1 output.