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Wed, 27 Mar 2024 20:35:29 +0100 Message-ID: <700d7bf5-2ffa-4ff6-9ca1-2497bb700d56@gmx.com> Date: Thu, 28 Mar 2024 06:05:24 +1030 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 1/7] btrfs: correctly model root qgroup rsv in convert To: Boris Burkov , Qu Wenruo Cc: linux-btrfs@vger.kernel.org, kernel-team@fb.com References: <71f49d2923b8bff3a06006abfcb298b10e7a0683.1711488980.git.boris@bur.io> <245057c8-e7fb-4ad0-9e88-d21ae31cf375@suse.com> <20240327172031.GA2470028@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: <20240327172031.GA2470028@zen.localdomain> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:9SybuEdRYX/Vrgw43QSGYfJtHKa/0CFL8UvwFOpw7DJCAu+NjNR I6+eJyCEoXRSN18XV14rgBGS/8dosNj2+SzytQe899ulX1alGUtQo/uDQpzvnYSbj+iKgkL rrP7cyyF1nNXWKykf7k9X1F+qEt0DAJshBbn3GVoi/4JEvy8otkNKLGAhWPrICkCwPOTpTi JWRGBIL+BbeenEtK9tEOg== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:oKweKNiaEnk=;qBFyBVgW6XNuzsvDRTUsv5p41nj 1ww57v9Eb/iAjYzfZIgAsr4HjE3WVpoLH0oGxR+MDN/rKN+V/U4PHmjA0+ySZZ4fFf46lOUny kA7SB8GexFB1gHF0u00thBzIB7HusrplNdC6aol2QkbEyXRcbk+FCs03fpZtprk/a3QvncT8y GpRGgg9lo5ySjbbBCGRRU+7jMIga8TwK6o8Ia+ihPkjWjWA4/3db7AhhykymgLRUKZ7C1Ux+a QTzHsIl9D8eUMB/SpWwayrFSHIXFRwpJRUYcBNvPD9XxNGsSO2g+hNbwM1IvxE9SfS+wpbeev 9gRsZ1G3Yw1FtFUMJqsm0m56QPNFiS78ulmPL6B5RpWFBK/a1wpW5Ou1M6ofydyaX3I9Ucm3/ P+F5rIMooOdd3oD39tgMlQ+MrDV8G1uijPvn/iY2ltJxaStRIL130iFDrMDELgl15mpSowV0C eF/NzyGSpDFBqlM7wlUnOvjla4A1MImdqur4HhIQ3CR3DUSVCnhqsHtksJvJGqLBRmuFBaOee 9GVsIPwX9EhCn2S9e5SlreLWWBsDo1hh+CMc5V8gGuiYPovvoGckJjkW+RIO8+LtY3W9Lb45L KyQAKE+CUX8EVV7zZgsVXTFGgwwRJTb7LIEMY/yUfg3xUMQ9THzOSPgCm1rxYquQsqT37sLfI 8EaApIo4nF2nV8hPlcKWuIw/VP43R79ZVESIS097EGpQ+ukRc/Zej+t6EAYaPs84bvhoyLYNZ Kswdz/f12Sk0LrslCvw7Op1YDSLdiHjxB2e89BiV+q4vb1Vh6ggCwk4QIRpaZFDgmh2uhYwn7 CB3u2u4WuS0yxhna6Tk1/zkDDpjlc19y9WzJzhWHg9k2k= =E5=9C=A8 2024/3/28 03:50, Boris Burkov =E5=86=99=E9=81=93: > On Wed, Mar 27, 2024 at 08:30:47AM +1030, Qu Wenruo wrote: >> >> >> =E5=9C=A8 2024/3/27 08:09, Boris Burkov =E5=86=99=E9=81=93: >>> We use add_root_meta_rsv and sub_root_meta_rsv to track prealloc and >>> pertrans reservations for subvols when quotas are enabled. The convert >>> function does not properly increment pertrans after decrementing >>> prealloc, so the count is not accurate. >>> >>> Note: we check that the fs is not read-only to mirror the logic in >>> qgroup_convert_meta, which checks that before adding to the pertrans r= sv. >>> >>> Fixes: 8287475a2055 ("btrfs: qgroup: Use root::qgroup_meta_rsv_* to re= cord qgroup meta reserved space") >>> Signed-off-by: Boris Burkov >>> --- >>> fs/btrfs/qgroup.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c >>> index a8197e25192c..2cba6451d164 100644 >>> --- a/fs/btrfs/qgroup.c >>> +++ b/fs/btrfs/qgroup.c >>> @@ -4492,6 +4492,8 @@ void btrfs_qgroup_convert_reserved_meta(struct b= trfs_root *root, int num_bytes) >>> BTRFS_QGROUP_RSV_META_PREALLOC); >>> trace_qgroup_meta_convert(root, num_bytes); >>> qgroup_convert_meta(fs_info, root->root_key.objectid, num_bytes); >>> + if (!sb_rdonly(fs_info->sb)) >>> + add_root_meta_rsv(root, num_bytes, BTRFS_QGROUP_RSV_META_PERTRANS); >> >> Don't we already call qgroup_rsv_add() inside qgroup_convert_meta()? >> This sounds like a double add here. > > qgroup_rsv_add doesn't call add_root_meta_rsv. AFAICT, this is the > separate accounting in root->qgroup_meta_rsv_pertrans to fixup underflow > errors as we free. My bad, it's true that we have extra per-root accounting that's not the same as qgroup rsv. > >> >> And if you have any example to show the problem in a more detailed way,= it >> would be great help. > > I don't have a reproducer for this, it was just something I noticed. I'm > fine to drop this patch if you don't think it's worth the churn (and > certainly if I'm just a dummy and didn't see where we already call it) In that case, I think you're correct and the patch looks good to me. Reviewed-by: Qu Wenruo Thanks, Qu > > In fact, this counter only exists to avoid underflow, but PERTRANS is > cleared by exact amount, and not via btrfs_qgroup_free_meta_pertrans, so > it might just be moot to track it at all in this way. > >> >> Thanks, >> Qu >>> } >>> /* >