From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA88318F2FC for ; Wed, 9 Oct 2024 23:11:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=212.227.15.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728515477; cv=none; b=llAmV8QYQpNzvNe8S34rZRF0ogaZeFakC++sn37kCgmyhFlapF7oTqoK/K6t3BnN+5gPik0aevv9geM8Zu7lcyg5Sn6gHeVSk6jDjG94bJ8BFHs+/m9d0FyHCrMijaiPmIc2aJIsQssQrKPNOEKK+eycVTCndxwKGL8AEkgxpxI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728515477; c=relaxed/simple; bh=H4hJAQD9rCClvuLVK8dzaZ8iwDBBaj8E3b3e9W2x8Pg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GhyQ8Zf3VgPHDLK+4c9QvYpqDwoUegaCdD0LLlTJSb4k9mFWSZtqqB6ZsUEANSKQ1TTFv4IDVPMsaeseD8U5ljhpCV1xIWZt3BV0Qou2HBKoSDIH/+6RRDMo6+56naOkRXJqRIkzRI/QCr+krx/ei9+l0eYsb4mcOyxMMAqAszk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gmx.com; spf=pass smtp.mailfrom=gmx.com; dkim=pass (2048-bit key) header.d=gmx.com header.i=quwenruo.btrfs@gmx.com header.b=rjznHWpd; arc=none smtp.client-ip=212.227.15.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gmx.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmx.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmx.com header.i=quwenruo.btrfs@gmx.com header.b="rjznHWpd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmx.com; s=s31663417; t=1728515468; x=1729120268; i=quwenruo.btrfs@gmx.com; bh=H4hJAQD9rCClvuLVK8dzaZ8iwDBBaj8E3b3e9W2x8Pg=; h=X-UI-Sender-Class:Message-ID:Date:MIME-Version:Subject:To:Cc: References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding:cc:content-transfer-encoding: content-type:date:from:message-id:mime-version:reply-to:subject: to; b=rjznHWpd6iJqNpkAbt6bwC7f4C4KRgQAZ6tb0aJA/9495KSiDHbE6ESWIsbDN5Gk B1XtWwplzoXNNKknrAKD4eIfxa0Vc+SWPKgdyjWHpK3bYfba5KIxchrR/BjhILsEX Mjmt23eta1H4cpi0BQt/X7y3/mUEblJtI7NUXPA/kXFNrzDdGl57EPqbcW5+cJ3jB dR5ExLHIxpy5ROJvZCRu2PC0uZCvRj4lE4t5EkCwT493qTQDtSEaAuWXW81lg9B6Y NbiG2ewC6cH4A/kQFLuyAuucRYNAqXvu4JbrS3hp3jCD/270y7Ym7+eBwmHH5aeLd zy51R6kOJmgG5aYYFA== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from [172.16.0.191] ([159.196.52.54]) by mail.gmx.net (mrgmx005 [212.227.17.184]) with ESMTPSA (Nemesis) id 1MfpOd-1teLB43DZ3-00cGle; Thu, 10 Oct 2024 01:11:08 +0200 Message-ID: <8f76a524-aa49-46b2-aa44-33f92fcd00a5@gmx.com> Date: Thu, 10 Oct 2024 09:41:04 +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] btrfs: fix error propagation of split bios To: Naohiro Aota , linux-btrfs@vger.kernel.org Cc: wqu@suse.com, hch@lst.de References: <1865ebe2-ab9b-4db0-84bd-9f4f6309eb7a@gmx.com> <5c363f14-c3d3-4d5d-bc46-8b38d2bcd08e@gmx.com> 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: <5c363f14-c3d3-4d5d-bc46-8b38d2bcd08e@gmx.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:zV+jaoDfI10k83mVm9WDPjAQLYkMLa5uIfMudVvpSMUtyMT/lUZ +M+dBa4n5z5cYlhAR7PiubHVN1Vyyn5+vkveiH2kCvYlTAE4XyP5xvlcQLCw9AzedcIsH+P pDJymOmYfxdEMFtaNMdkfWUbMVP0TmeUyHzdKDgw/lYjAeOJ/Gk4Emi6pV6m2uCw3jS3Wfz dBCHL8Z4GI2ellF0aeC3w== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:OyJc8M4o/5g=;Q90u9BfztvLya7h5nq5rzkXRw/T Hs9F77yHiUY9uE8YtjFVTiKUv+FMVu88Op1gGIIQDZ1tZlRmSKqZpSo2cYH7plr+mZh828l9p Y2tXWlGbVpMGG13F5zsp5CnnZDCJVmPdfuCKFO2HJU2/GwGmw0eCQjfYEd36wkw5nLb9dzK6O rTVYSegqGQBHV1maoosZK7rwKqXps31lhKCmaUHiSMz5s+8DggtUe//WYLe6wFoH2NhQ7JXWk n8pCMAkrtzbNLl2Jr50H5SdAIvumeB/biImOW/YV0soABEpxawEa/IrG4eHx/LhxwmGUqMOWJ Cl3wKlkQ/e3H9Z8RnUNb8bFWJfN8z0LjUjOd1cQmszewpKc1ybsLQrDkIvPVbmg43aV9aVUx0 3KNQhe9MgGpRT8ocAjqnfFwVaDJFCZoKGSwrAeLrD41RbRwaRmswxjoq9Eo+NG1a0IbEO0AWw koCO7eLgFnY0Bw5ynRypGA7TG5+Y8rsH6XHWe2CrDTkYY+mP7WTB67ddOvcBZFJgiw45w97Dn vBF93VIV8Jofu7n1w+JltIwJcu8UtiIWapt+ed857FPitklRkIN1b2TDQG9OGneiyGxGnbRW3 ywZc0BP1HMji8iPuUnROx/qmxm6EjoX7mtmKBleiRG9wk8kgHUICr0ZziGo9IUvfSPiYmf3qw TdQfTpusUWye7f0SSwmxaLnpp6B7NdkvoiX1LM6/wrKmaS1942NzHriSRsMgQoRCXUPj4Vki1 /+eUJI+BWMMhUt4ulzN73j8dMA8uKCo3xJK4PlEJEYtxLghk6DKdty5qOBrqwcLSiYG104Bzc Ls2s3H8O4D5n2JborNGxywZw== =E5=9C=A8 2024/10/10 08:28, Qu Wenruo =E5=86=99=E9=81=93: > > > =E5=9C=A8 2024/10/10 08:08, Qu Wenruo =E5=86=99=E9=81=93: [...] >> And __bi_remaining is only decreased when the cloned or the original bi= o >> get its endio function called (bio_endio()). >> >> For cloned bios, it's mostly the same chained bio behavior, with extra >> btrfs write tolerance added. > > OK, I see the point. For the cloned ones we can have the following case: > > The profile is DUP/RAID1. > > For stripe 0, we cloned the original bio, increased > orig_bio->__bi_remaining. > > Then submitted the cloned bio. > > But before submitting the original one, cloned one get finished first, > it call the cloned endio function, which calls back to the endio of the > original bio. > > Then the endio function decrease the __bi_remaining to 0 of the original > bio, thus it continue to call the endio of the original bio, which freed > the original bio. My bad, this is not possible. The original bio will have 1 as __bi_remaining as the initial value. So even if the cloned one is finished first, the __bi_remaining will only stay at 1, not reaching 0, so the original bio will not finish, thus impossible to free the original bio. I need to dig further deeper to find out why the NULL pointer dereference happens. Thanks, Qu