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Mon, 08 Jul 2024 07:20:12 +0200 Message-ID: Date: Mon, 8 Jul 2024 14:50:07 +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 v4 3/7] btrfs: split RAID stripes on deletion To: Johannes Thumshirn , Johannes Thumshirn , Chris Mason , Josef Bacik , David Sterba Cc: "linux-btrfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20240705-b4-rst-updates-v4-0-f3eed3f2cfad@kernel.org> <20240705-b4-rst-updates-v4-3-f3eed3f2cfad@kernel.org> 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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:HPL/K+hCXncaMbuI5AbXTGUtBZX6CYPY7mmBYaMYTMHcq9AIG29 tCThzsFrBY3hXlzVM6PA0r1NfPsdT15xClFkkbeyIo6R+cOh/cs94T9G/+LSBHYl6OyFR2v H+jf4M4gtZz7FJWQ28MX95DCDKVo+V4H4y3jadjjBbN185i6B5WhEzYs+oAHqI2uwrwZui9 3CLuMTDeeAE2dcLaZ3vmQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:P916Mzac2hU=;rC7JTAKPnmwG/lw2OzdT/9ij7JG vxg+0+YNZScE+aB87UUiLzkw3X9Ga0mzdgE2XmlEXR/iyRA7aWEyAFXXWXC3/EC0xwrBE1RwJ R7dJ9AlDfW5zI+DP8pb9B84Uo07kCNa+4JeZxzhGswtVScKCeRBpctU4oyLE1YI0VYvr6etFc w5P+Eut9Z1Dh2xGnD3RMihM/wzIdTIVpMaOt9q8OP/58YV9hEc0QWnMltzbv6GVPjpJvXRGtn q5LHR8qlXpjN4U3FysIm3+EVwuo25DrPeD5/q34ThqNVzNaC2Od73XM52S/UM3R24LwzK+c1L PjUqVOxVxWq+nFLVuNsN6g5pX80m3BVgFgouEPzcNtLJ82b/ivAa0r6u8kOVBijPZoInFgeMa WlPYuy/BwJmupNlQn0kU8dWHQ0Wa24NrGppKzmnAcI1k8I0W7Fb4iJ8pNp6+oReBDXP1rMVDe 8MeGn4Y5mQCTTEhhcYhbRZwH5SUP9DqMdTF7N4VM++dRIfZnKc76Tw8Mc0pF9H3IKZk/N4flq jrALpRZVVJTos5k0NsewZ8wmcSx4N6cEPdVfnA0ARvKlsGAa7y9P+C1KGgIki6aXjfxOnAO+N xZJg0mprVtYzfX/kMMjIxYTESXaX2UpaJpKSw/pkP4iSv7DGWHaZ0311E6fe/0i0Pke8zxHby WyihQVUftJIcqZWjh4z5Ks84PsBpVU/uEgx58HIWe6zYz7b+0QBERRak0tQunDWTMBivSDYnq 92IGGTGbokOSuNQuR1MDE3rnSg0sbBIRm4fxRtZGiR7P3m991UccVFU8RsTAdOIcW5GTufOQL ePcVLaYgzWKI7Nt87tv7FDTAgBd92BbnJqUgaAg25OCy0= =E5=9C=A8 2024/7/8 14:26, Johannes Thumshirn =E5=86=99=E9=81=93: > On 06.07.24 01:26, Qu Wenruo wrote: >> >> >> =E5=9C=A8 2024/7/6 00:43, Johannes Thumshirn =E5=86=99=E9=81=93: >>> From: Johannes Thumshirn >>> >>> The current RAID stripe code assumes, that we will always remove a >>> whole stripe entry. >>> >>> But if we're only removing a part of a RAID stripe we're hitting the >>> ASSERT()ion checking for this condition. >>> >>> Instead of assuming the complete deletion of a RAID stripe, split the >>> stripe if we need to. >> >> Sorry to be so critical, but if I understand correctly, >> btrfs_insert_one_raid_extent() does not do any merge of stripe extent. > > No problem at all. I want to solve bugs, not increase my patch count ;). > >> >> Thus one stripe extent always means part of a data extent. >> >> In that case a removal of a data extent should always remove all its >> stripe extents. >> >> Furthermore due to the COW nature on zoned/rst devices, the space of a >> deleted data extent should not be re-allocated until a transaction >> commitment. >> >> Thus I'm wonder if this split is masking some bigger problems. > > Hmm now that you're saying it. The reason I wrote this path is, that I > did hit the following ASSERT() in my testing: > >>> - ASSERT(found_start >=3D start && found_end <=3D end); > > This indicates a partial delete of a stripe extent. But I agree as > stripe extents are tied to extent items, this shouldn't really happen. > > So maybe most of this series (apart from the deadlock fix) masks problem= s? > > I'm back to the drawing board :(. Can the ASSERT() be reproduced without a zoned device? (I'm really not a fan of the existing tcmu emulated solution, meanwhile libvirt still doesn't support ZNS devices) If it can be reproduced just with RST feature, I may provide some help digging into the ASSERT(). Thanks, Qu