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Wed, 01 May 2024 00:27:14 +0200 Message-ID: Date: Wed, 1 May 2024 07:57:08 +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: Boris Burkov Cc: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org References: <07e54de6747a5bf1e6a422cba80cbb06ba832cf4.1713519718.git.wqu@suse.com> <20240424124156.GO3492@twin.jikos.cz> <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> 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: <20240430221839.GA51927@zen.localdomain> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:KwafYg1+LNHe/gl+zQJ/ZWGDxALi1Pa2cn3feg3eNadCKn6SVvQ 67M9CeTKVl9WEev9fgVpNHsKNL1ZtsCFZPIEfF2GeM00fPsMu/jBQAncMf8ZoVHZAofWc6A ap524WlQBS84lIlYedx4azTfgY9t1tMXSFIzMZgh8KG9ScQlDKN5UPgBJhHjQE90DOHa4Zh nW/+gI1SOtXS/Spln0ozw== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:NSbqUC9cpcE=;o36t+29jQv69d8DCGo/3MKBX9kN Kl2gWGFSwNOMTv6So/yZGeeG7r9/cIMIbfSJzsSipEYw2S3SA942xjooGlU/UBZj7u1/AxWh0 zdV0Tyaugg7cimcoGwe5xtmV0dGl0UwKhEwihmFGZR2Xd7oCA70EpXtokVx4cgzPO+q9J8I/i A7UatAxdo2/cZ1XOcs9UY9DQGkoc5DFyR+2mxt6fONKzqjEWujoE1fMkEseRIEL2BhtKYwrqw ROGTzKPgX7U+dQJadWtyTDg+HG83PwFUhG+r9J+XW1mHnMaJQAOBJm9aAves97BRpv1LWtWDP L2xo0YWI+8+BKdW88bVUa0v4CaKyy+ehKd5CE84Rx4hGb0eAuRXVk1gHFxmsvjKcZF7zPvpEC XbWVl07ZgGX3zKtuJ7ek1UsWIxL8aRkOiYly1ASk39Mti08ZEKTmxryRhBsgEob3x1Kia/jz/ ZlXJdq68h8t/8o+1vmMuEMTXA5Mi3Vg4VBWgFj0eAp3bxnnMIxlimOh7t+/YcvQ2hdZ2MmWgV dq6cu5Kk6L4GwcwUQ73s+nwEymHiMqsJuSz1FD8UNfKxENYL5ugGUTrTMnRiFeNPViEICnirU Z6pslNlvsr+V40CiwJEC9nPnevGF9w5jugQpYRok1IATICb5/Snu38qH5d1rYxEJVjRl9zG8U 6oYpHqwT2r2Gn1brtIFTYC3GYs9JHsV44E2k/wkFhJvZloyW5EVO+iygZHRbe/R3NWNIJpU/E 0ONitVDZkvzaXdaKW4uhGUZRnVCP4sWH3qN4JZJzBjENelHJ4hYhhDgdNKd7AzuqCQUsATUzK 5U7f2ChkahXBE7WavIWB6UyNCUp8wlCpq/Naspm1xzvvc= =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 feature >>> compatibility and for general access to data (full or read-only). What >>> we do with individual behavioral changes are sysfs files. They're >>> detectable by scripts and can be also used for configuration. In this >>> case enabling/disabling autoclean of the qgroups. > > This was my initial thought too, but your compat bit idea is interesting > 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. I'm totally fine to go sysfs for now, but I really hope to a persistent solution. Maybe a dedicated config tree? Thanks, Qu > >>> >> >> I mean the compat bit, which is fully empty now. >> >> The new bit would be something like BTRFS_QGROUP_AUTO_REMOVAL, with tha= t >> set, btrfs would auto remove any stale qgroups (for regular qgroups tho= ugh). >> >> Without that, it would be as usual (no auto removal). >> >> Since this doesn't cause any on-disk change, it does not needs compat-r= o >> nor incompat. >> >> Thanks, >> Qu