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Fri, 26 Jan 2024 00:09:17 +0100 Message-ID: Date: Fri, 26 Jan 2024 09:39:14 +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 03/20] btrfs: handle block group lookup error when it's being removed Content-Language: en-US To: dsterba@suse.cz Cc: David Sterba , linux-btrfs@vger.kernel.org References: <20240125161252.GN31555@twin.jikos.cz> 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: <20240125161252.GN31555@twin.jikos.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:gBHZmow5MmUMIjAqUN/q8ECdN8iu+gMtwxBB+ZOs7wKaHWMx/Zw kPQgiUPVC3hPa16sWK6jRhkquAYCVsHd3CW/KOcAcwC3FZX/e7qimWRVQbAZOXnxAAyJckG expKDWcI1Fw6dAWsajZ9W/5/ieNhLDG9PlM5Iasz1uI1u/+nOAWVcS0Jr9Biw04gs3BRvsj +iYfd1fYL6qASIVVQcjTw== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:gk4utkAASOM=;6+Hs2QzBqGx/6ZBxDmjRzSsl2rK 07BUgXQH8ewd6JIqPHMIVZKV9LA8m4ePHzI+g+zUJxPJF/SWOUXW6sstTgP9pgD9r7NVT3m+v gNZjaC/ESgleNkMCiB1bzz1mWaha6++AS8lGZbdTx4wt6LUOYCx28crapc16VvmJSmQh2xK0w SCbaULdfo4jVhVvtMcvKXUFk4vkEmtYQNgYyEWOA3jaDqBledHYxpBJgjW0qgehIqwohz9f5U /xkbogzmgHDCwj0luemToZGOjHjRpcGTNoTpEAZ0i6VeABs0qznKVpktsRVtqzVbZnsg70eNV RLAYxX2/NdSPQzWcdP9mIq9DScI8Y1DKqohEW3w2u+ORaLArbHsUcoacVmqHJzS2CZKJv3aAD +GxufJpHZL1R0Np5Vu8NxNZD4iZJJ5nVTBGMgNAfEYh0pDpAGR364Rea+U3lHlragkmxHxlvi IbzSKjLOdYXzzTPv/sahIWuIPU0XKHvw2WT0JQl/f4rWnSHQ9ZXqyDvfu12W5J2k9IsUizBo8 UtJ4DylEPltwuguymGtrYxdlfUWqgtChPUr4YmZXUO/M+54RBf8KhYs2t3utMYCx6mM1qZIcG sYS7EZXHeBnXp3jgw4aMJMLTLKbeV8IBw/66giuM1kmovHjZjCRTsfzlp+znen4MGqF5e454E KtgnStAPDJ/b9AfT0szwp8JC3ZSGBYHJC1hBUB84I2KHZXx02XWq/ZBp8MxQ9OlvFkz26S6oy VOYPojF7GyMhVK5uJLQ+D8Xq+bYyiDEDnatKGCfbKS2TXvMfsYpKu5r/oYXgCZ87Y+CtQ2I0y +h8M46+J9r2/o588N2VM9RPElFTIHaYnT7MlbOVi1aKTLsOnfv+IMd5q7y1K6v/nuP20x1rUt TU38XAAenoSs9XHKb6P3XoBtONHu4BOLL7claj9akBZQaRGlU12Lg+KhmkN3ORr5sp8JptXZU r/Jxh4OuX0IjXlMydJOSC2RpAVI= On 2024/1/26 02:42, David Sterba wrote: > On Thu, Jan 25, 2024 at 02:28:02PM +1030, Qu Wenruo wrote: >> >> >> On 2024/1/25 07:47, David Sterba wrote: >>> The unlikely case of lookup error in btrfs_remove_block_group() can be >>> handled properly, in its caller this would lead to a transaction abort= . >>> We can't do anything else, a block group must have been loaded first. >>> >>> Signed-off-by: David Sterba >>> --- >>> fs/btrfs/block-group.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c >>> index 1905d76772a9..16a2b8609989 100644 >>> --- a/fs/btrfs/block-group.c >>> +++ b/fs/btrfs/block-group.c >>> @@ -1063,7 +1063,9 @@ int btrfs_remove_block_group(struct btrfs_trans_= handle *trans, >>> bool remove_rsv =3D false; >>> >>> block_group =3D btrfs_lookup_block_group(fs_info, map->start); >>> - BUG_ON(!block_group); >>> + if (!block_group) >>> + return -ENOENT; >> >> This -ENOENT return value is fine, as the only caller would call >> btrfs_abort_transaction() to be noisy enough. >> >> And talking about btrfs_abort_transaction(), I think we can call it >> early to make debug a little easierly. > > There are several patterns, one is that transaction abort is called by > the function that started it. It's not consistent but as a hint abort > can be used anywhere if things go so bad that it's impossible to roll > back, eg. in a middle of a big loop setting up block groups and such. In this case, I don't think we can do anything to really rollback, thus aborting early would help debug and provide a better call trace. Thanks, Qu > >>> + >>> BUG_ON(!block_group->ro); >> >> But shouldn't we also handle the RO case? > > Of course but it's fixing a different problem with tracking of read-only > status of a bg and I will not mix that to that patch. >