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Fri, 15 Feb 2019 08:18:31 +0100 Subject: Re: [PATCH v4 04/12] btrfs: extent_io: Move the BUG_ON() in flush_write_bio() one level up To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org References: <20190125050925.30754-1-wqu@suse.com> <20190125050925.30754-5-wqu@suse.com> <20190130151914.GU2900@twin.jikos.cz> <3893155e-d3c3-5fd0-6f61-ae067d341d81@gmx.com> <20190131143637.GF2900@twin.jikos.cz> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0IlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT6JAVQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWCnQUJCWYC bgAKCRDCPZHzoSX+qAR8B/94VAsSNygx1C6dhb1u1Wp1Jr/lfO7QIOK/nf1PF0VpYjTQ2au8 ihf/RApTna31sVjBx3jzlmpy+lDoPdXwbI3Czx1PwDbdhAAjdRbvBmwM6cUWyqD+zjVm4RTG rFTPi3E7828YJ71Vpda2qghOYdnC45xCcjmHh8FwReLzsV2A6FtXsvd87bq6Iw2axOHVUax2 FGSbardMsHrya1dC2jF2R6n0uxaIc1bWGweYsq0LXvLcvjWH+zDgzYCUB0cfb+6Ib/ipSCYp 3i8BevMsTs62MOBmKz7til6Zdz0kkqDdSNOq8LgWGLOwUTqBh71+lqN2XBpTDu1eLZaNbxSI ilaVuQENBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAGJATwEGAEIACYWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWBrwIbDAUJA8JnAAAK CRDCPZHzoSX+qA3xB/4zS8zYh3Cbm3FllKz7+RKBw/ETBibFSKedQkbJzRlZhBc+XRwF61mi f0SXSdqKMbM1a98fEg8H5kV6GTo62BzvynVrf/FyT+zWbIVEuuZttMk2gWLIvbmWNyrQnzPl mnjK4AEvZGIt1pk+3+N/CMEfAZH5Aqnp0PaoytRZ/1vtMXNgMxlfNnb96giC3KMR6U0E+siA 4V7biIoyNoaN33t8m5FwEwd2FQDG9dAXWhG13zcm9gnk63BN3wyCQR+X5+jsfBaS4dvNzvQv h8Uq/YGjCoV1ofKYh3WKMY8avjq25nlrhzD/Nto9jHp8niwr21K//pXVA81R2qaXqGbql+zo Message-ID: Date: Fri, 15 Feb 2019 15:18:18 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190131143637.GF2900@twin.jikos.cz> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="os45etS1G8Zgd7mFnlCPz15pNgnUmIaPR" X-Provags-ID: V03:K1:3ERQOb2+OoKAFKnlCW5wiCNq+cRs6J1molRuFTFs2MiB1pkQJxZ HuUB+0UrjCTHwBrFKzhUS1StBoPF5t/+4il2B+vE3S8lG5qA9yOU7NFbX1vUxwo4VgX7aTz k+u5GBcIEysNa1K1iG18DSImEKVy+Ni5OtCo1AxsuH6VLHDRBRNe/IHQcMaOhNT9BS8K3dY iLU0pL6rQS8VpSJOVWLwg== X-UI-Out-Filterresults: notjunk:1;V03:K0:7d9YMnK6cjU=:6CIjOeuW5KGeF66XLBVgTM OwLBpXUjhMvqLMhvMaq2jc2n53uiES4Fws4sg/leeLkMvnBSGKHQYGeK2zTV9v0DFb0pBdeKL wfzJ1h9GgT/NnhE5xPw1e4SgH+CDAk/2pW9zFo3O9UXEXg7INNxtPD9ZTBbckbwlYckLqQmYV QdviBo+qu5H0n2BOJfAMGddU1ol+fbIrrTFjt1HhEMmqAJawCIwDMSSQk6PYfZTQ02qljURNl pTOollGsdc7io7H13+792NtemJ4gRzar+6R/A/XHDNX6QzxSvDroz0GyAIihI9/PT1sPU43vZ HkFtRSnvjlk9gR4kmBJG7aN798yFag7BvIv+7okt4vJIIp4j8vrmB8Rkpzq/om+c0uB4UhgCc eZPjA/2Ee0VXDR2x7rcvbzbsD+l/y19DzoyyYmoJki4N8t9TeV9C4xRJ+eyiJdrnGh6DuNTkd X9DISL5do80sudlpc/KdKrei4w+E3tMubmx3/JHChjl5xtvGVJnNBCOKlrPKjA+ko370N3S7G T7RSK/zvg0JahkoiAiz6b6WJHImXjtZwxKP97i80ac52iRFE+QH4yRxIrVbiNtXeSxMx8pfil uOh8/CjNVMUeOWmqFRyO9hp04lZpZwahMbH7/2Q6rvoXZutOLZ9N6EGVfcNfUyii5m5fPWEcl XV2TxUnC36NCpe80XP5/DeODr7G4A5Dp8p2EkkKpG1kCy5r8L/LEFmmG9sjP58ODZDPJTYji+ uxW97r2rdNEvbPgEJA1nyHcQxukmD37c8/6LKtyingyRzq1XXbab3+fPbacQzVznnI638wtf3 0Ar8Dd4bFhIqX5irpnEr9sBcDsr8CX1OFjmOrxBQLRhkHFmP2/mw+GHBCYWugkHTLAmcyMXhq x/k1ycnBSoshTy+/tOcvlynYZ+0Mjkm4Bi/A6v8n1MmXYQ8D8Ry3k5LIf6b9LM Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --os45etS1G8Zgd7mFnlCPz15pNgnUmIaPR Content-Type: multipart/mixed; boundary="379uqfBFk35ghDyL5aZSYOTpO6ZFWRrHy"; protected-headers="v1" From: Qu Wenruo To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org Message-ID: Subject: Re: [PATCH v4 04/12] btrfs: extent_io: Move the BUG_ON() in flush_write_bio() one level up References: <20190125050925.30754-1-wqu@suse.com> <20190125050925.30754-5-wqu@suse.com> <20190130151914.GU2900@twin.jikos.cz> <3893155e-d3c3-5fd0-6f61-ae067d341d81@gmx.com> <20190131143637.GF2900@twin.jikos.cz> In-Reply-To: <20190131143637.GF2900@twin.jikos.cz> --379uqfBFk35ghDyL5aZSYOTpO6ZFWRrHy Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2019/1/31 =E4=B8=8B=E5=8D=8810:36, David Sterba wrote: > On Thu, Jan 31, 2019 at 08:45:42AM +0800, Qu Wenruo wrote: >> >> >> On 2019/1/30 =E4=B8=8B=E5=8D=8811:19, David Sterba wrote: >>> On Fri, Jan 25, 2019 at 01:09:17PM +0800, Qu Wenruo wrote: >>>> +static int __must_check flush_write_bio(struct extent_page_data *ep= d) >>>> { >>>> - if (epd->bio) { >>>> - int ret; >>>> + int ret =3D 0; >>>> =20 >>>> + if (epd->bio) { >>>> ret =3D submit_one_bio(epd->bio, 0, 0); >>>> - BUG_ON(ret < 0); /* -ENOMEM */ >>>> epd->bio =3D NULL; >>> >>> I'm not sure if resetting epd->bio to NULL is all that needs to be do= ne >>> here. With the BUG_ON the error case never happens so if all goes fin= e >>> it's also ok to set it to NULL and continue. But the callers might ne= ed >>> to send the flush again. >> >> If flush_write_bio() get called again on the failed one, it will just >> get skipped as epd->bio is NULL, submit_one_bio() will not be trigger= ed. >=20 > Yes that's clear, but what is the state of the bio that went to > flush_write_bio and submit_one_bio failed? >=20 You got me. In fact current simple "epd->bio =3D NULL" on failure will just leak epd-= >bio. We need to at least call "bio_put(epd->bio);" before setting "epd->bio =3D= NULL;" Thanks for pointing this problem out, Qu --379uqfBFk35ghDyL5aZSYOTpO6ZFWRrHy-- --os45etS1G8Zgd7mFnlCPz15pNgnUmIaPR Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlxmZ7sACgkQwj2R86El /qj7fQf/SoRShlEcR/05ZwRaYcGhwvsPt9jkjCuAnOWHipgSSpvVTAFrZEfgU8ly ge5nRG8jzQ110qLLxQWqXwtyQbf+5TDEcYA0kum5C8LZ5/OrNTChoNsnbrMhnd3z bzMyzB1kYF45wsT+yrj3tvdOqGSLBlHBu+0T/BGWEsmYcH5mBRpPUPhOa+MzuKWw wtgY2AVFu7Jnq+8aNdZi/zhHq9jS+4bTb+xi9FZXryXLLKzycYCUuCwylPuq/Pdh Htub1WRd1FhwmzOhU7wxoP4YOzpOWe/pmzJI6mdmvkU+ClpnLtWOO1xTCvl2ane4 GJ1sbhAO01Cc0r1fNBMfbblrLJkxLg== =Tn6N -----END PGP SIGNATURE----- --os45etS1G8Zgd7mFnlCPz15pNgnUmIaPR--