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Thu, 02 May 2024 23:29:10 +0200 Message-ID: Date: Fri, 3 May 2024 06:59:03 +0930 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] btrfs: automatically remove the subvolume qgroup To: dsterba@suse.cz Cc: Boris Burkov , Qu Wenruo , linux-btrfs@vger.kernel.org References: <598907d6-77e0-4134-b709-51106dcfb2f8@gmx.com> <20240425123450.GP3492@twin.jikos.cz> <9df817bc-f3a8-4096-aabc-12044447a900@gmx.com> <20240429131333.GC21573@zen.localdomain> <20240429163136.GG2585@suse.cz> <20240430105938.GM2585@suse.cz> <4a83b326-9cde-45f5-8a53-da7b62c45619@gmx.com> <20240430221839.GA51927@zen.localdomain> <20240502150332.GS2585@twin.jikos.cz> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00iVQUJDToH pgAKCRDCPZHzoSX+qNKACACkjDLzCvcFuDlgqCiS4ajHAo6twGra3uGgY2klo3S4JespWifr BLPPak74oOShqNZ8yWzB1Bkz1u93Ifx3c3H0r2vLWrImoP5eQdymVqMWmDAq+sV1Koyt8gXQ XPD2jQCrfR9nUuV1F3Z4Lgo+6I5LjuXBVEayFdz/VYK63+YLEAlSowCF72Lkz06TmaI0XMyj jgRNGM2MRgfxbprCcsgUypaDfmhY2nrhIzPUICURfp9t/65+/PLlV4nYs+DtSwPyNjkPX72+ LdyIdY+BqS8cZbPG5spCyJIlZonADojLDYQq4QnufARU51zyVjzTXMg5gAttDZwTH+8LbNI4 mm2YzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00ibgUJDToHvwAK CRDCPZHzoSX+qK6vB/9yyZlsS+ijtsvwYDjGA2WhVhN07Xa5SBBvGCAycyGGzSMkOJcOtUUf tD+ADyrLbLuVSfRN1ke738UojphwkSFj4t9scG5A+U8GgOZtrlYOsY2+cG3R5vjoXUgXMP37 INfWh0KbJodf0G48xouesn08cbfUdlphSMXujCA8y5TcNyRuNv2q5Nizl8sKhUZzh4BascoK DChBuznBsucCTAGrwPgG4/ul6HnWE8DipMKvkV9ob1xJS2W4WJRPp6QdVrBWJ9cCdtpR6GbL iQi22uZXoSPv/0oUrGU+U5X4IvdnvT+8viPzszL5wXswJZfqfy8tmHM85yjObVdIG6AlnrrD In-Reply-To: <20240502150332.GS2585@twin.jikos.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:MuagGtsdrIDMs3wb3JrWINj+c41O3q1vimfLGlTNojN9xFGnhHV OWPtQCQy8WwkSD/vZCpvt/+m+DnTbp3HafnJSUvD0SS8s2griIXex1AFn3swVcrf/QzOmwR 9aTtwwr5EFd9Ko2NXDswK5688k6yOnO7Guii2hPluvjNNueUC64zPZPFMGAS0FXUoOUNjv3 wKmZvEGgmmcdj7as6WXxA== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:mV6IOOL6FWY=;GnpqtbCceJ6erUbjrkWfXhLcOHx yBoP6b40k7imkxp+NEj9Z/9gTWBzQhOwPLbKbWXHhpRP+DfTQKzWeP5ihSbUB7KAsDjjABe4H /aa4LDPyV/3/Ze2+ESjnG7/uttgJUqEtVAyDrNbx4wuxm9sqVOijHoclfI/I3wTKu8klQ3/TB qzQ4vxtfsMY6eUDt5kEg8OESN07PThgB12Puj8lRTkIku0mIy9mGIVgSlFsjjJ+Qs4gWyGuat oRNmM766EH/H6koyTokn/8i4J4njTHXpDV04I54hTbecCmp3lQ9t9VouoTvDLpz8ybthtmf9N JzyzqfS+Rhvt5JOzVsiVZRaPhLwiyHxOVLMX++SQRXOhTMO+VIwAuack2PPALpcvgzkhfedsn rw9ZQnqxBaMllbHdwU0Thckdc+EcDu+gi86Saiz3HgFbYVEKebRRNPUhoAWd+L0qD6124Nh5K sXp9VztxVjtVdicBysypD7kbMO50Q1DAHUKvQTMw387qo2gvaHGkk+F6RvTSag8QVSLbmezPX ftnxwx87JWHt5pU9zo22rolbnqwaRH5yojlgroZZphtZZYzsGswLsCGbY8e1kIB2X4rXN+Tf5 tpUoSb+QmXBEAyz+OsYWk76n3UY9uEe9qFB8xXAYWA0dWNfndw256EqyCZe7+jPknKM0/tgl2 uMF8EPdkqjrMMkLgfAqoikAafcVS/ueIsSJPOXeHmzSIErDYdWeePNVavzs5JNXqCjZLDMeT7 gF34DDQFQO7j0tDECC6BGCal+MzmXfkfD7pO3JIbOe8gETwLrVdii1HaZgdVhVlrxpA6eLb6h OCOXKJrNLuHzuxTI1l6lU/TcFcXZfSPX1jnsuJUAHOWCM= =E5=9C=A8 2024/5/3 00:33, David Sterba =E5=86=99=E9=81=93: > On Wed, May 01, 2024 at 07:57:08AM +0930, Qu Wenruo wrote: >> >> >> =E5=9C=A8 2024/5/1 07:48, Boris Burkov =E5=86=99=E9=81=93: >>> On Wed, May 01, 2024 at 07:35:09AM +0930, Qu Wenruo wrote: >> [...] >>>>> >>>>> I don't see how a compat bit would work here, we use them for featur= e >>>>> compatibility and for general access to data (full or read-only). Wh= at >>>>> we do with individual behavioral changes are sysfs files. They're >>>>> detectable by scripts and can be also used for configuration. In thi= s >>>>> case enabling/disabling autoclean of the qgroups. >>> >>> This was my initial thought too, but your compat bit idea is interesti= ng >>> since it persists? I vote sysfs since it has good >>> infrastructure/momentum already for similar config. >> >> Sysfs is another way which we are already utilizing for qgroups, like >> drop_subtree_threshold. >> >> The problem is as mentioned already, it's not persistent, thus it needs >> a user space daemon to set it for every fs after mount. > > My idea of using sysfs is to export the information that the > autocleaning feature is present and if we make it on by default then > there's no need for additional step to enable it. The feedback about > that was that it should have been default so we're going to make that > change, but with sysfs export also provide a fallback to disable it in > case it breaks things for somebody. > >> I'm totally fine to go sysfs for now, but I really hope to a persistent >> solution. >> Maybe a dedicated config tree? > > No, we already have a way to store data in the trees or in the > properties so no new tree. That means a on-disk format change. IIRC everytime we introduce a new TEMP objectid, it should at least be compat or compat_ro bit change. Or older kernel won't understand nor follow the new TEMP key. Thanks, Qu