From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B8631C10F14 for ; Tue, 23 Apr 2019 12:12:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E544214AE for ; Tue, 23 Apr 2019 12:12:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="FEFomVWQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727656AbfDWMM6 (ORCPT ); Tue, 23 Apr 2019 08:12:58 -0400 Received: from mout.gmx.net ([212.227.17.22]:36661 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726033AbfDWMM5 (ORCPT ); Tue, 23 Apr 2019 08:12:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1556021572; bh=+Mx0eEky0/LMVkge2fPqP9YqmvEjX1Bm4zBYxeXYrrM=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=FEFomVWQGeU8FnAWDcloHptutwk5ZBha1PbqqvsawLXvpyS+ZkeS23mTLg2Aoet0n FRyfqH0pfedpLhDgJ1lxXfQFbUqilfXa9Jmjthc2zee2bJjHj20XSJ9LDMnpDbOBxx Vg4L3ZofUiwTpPsGJZ/s+vRfnybXRkIfKYAFJnaA= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx103 [212.227.17.174]) with ESMTPSA (Nemesis) id 0Lskr7-1gqHZF0A37-012FZh; Tue, 23 Apr 2019 14:12:52 +0200 Subject: Re: fallocate does not prevent ENOSPC on write To: dsterba@suse.cz, Jakob Unterwurzacher , linux-btrfs@vger.kernel.org References: <20190423113302.GS20156@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: Tue, 23 Apr 2019 20:12:42 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190423113302.GS20156@twin.jikos.cz> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="1NSDDD2NzzqlQ51F4ieaz3ns6xdBR7LMO" X-Provags-ID: V03:K1:uMiXBfnks6j6epiyfC6HNyEwRkDhWdVAidWjItN0hHQpz7azuj2 rdGpD5FioEgmYfvKGg56NJ0CSy7drT8suvltVaLZuwUqzhNdMeaOombT7xaMcA0IyQSJl2U ohXx3i07+f5ep0+nej5t5UMY3LcAxjK1QUAzwbqBZ05A2ohINhHSxPA5EENc2P5Ew3MaSXI r4sQi/Op+ZolFV8IdRiIA== X-UI-Out-Filterresults: notjunk:1;V03:K0:BNrHffoxdMk=:osMFb+fTMAI4crfhNU1qC6 /wIyDglCrYPZWETTVu2C3owOx9VBHziTSECkQN+++FQ5Jm9+4x9awC1wD/ajsXOXg4qXMWuwX wFveyfswcqOi4H1xM2tA1PsrHQVV/qA0QwooJ762fDaEXr0BRMHxAhTRTAjA0YPQFdLq/9bs8 mJjbHx9/Ph9cLDbHavS3FFnyQnLLIAH4t0l/QFhlGFJThRxU3gtxdShSfcPB/A+LBlfc4ccU0 qmHkLqQMRsRhTFLup96P3jcsRr4ud5y3CjicCoTFKD13YQPK4RMeYpUKIJClxR5dK7QNufmda IbN2Ht6CqpGQlGW6wdPRNQ6TvS4Vf8/2Wi/COQVHw1pS0jr0gvokkde/ZaEGRlhhaK2XE48Xd 2Y6smiRNzirQ5iWNLYJuvBmHwwedy77Oq9/EVmwSFUHhP/3uaj/vIA4k22crg/phHcPQEa0XR oSks/VNuhQuf3aeQRidAd/OquJsHxPelF3ZCW5WcPP80yunCpEvUE+n9KhA5PtRilbcqBse4K mYbte+vowXMsdHm89rSBfao8NeJmsfb7JGjEFdX/5SQcE0U8VBZq0JG014r5Qjvv90AMpvVK6 Vvp45z6zJfKkOr84P8Qhv31ys9p7lGokrRWCVnlOi4JbFFvCzoGHEBqhOFe4PU6HCIJ751TVD KS/s2adOB8orTQtCCEV1G/CrLjuMaZjIOHE/XyYeKIz63OK8gt3GXVs9b3WnBehcuGhrrNpDM 9iyCO8YYhY16a9y85AjYF/KB9d9UcGICdmfzqLFSorVwvHq163iaTtdPKLrLkI3RVF2VBvQ/X OO9RxfUuM3ondhCYmC6KO7Mom+OgS9wCNr6Om7oa6QLVjUWjpO3HSApzbXgj3/M71NdAOg5gu cMuyuNSxJZC5WJJ/21+SAOGxh/HmTGdBY27SX65ljntwJnuy5ppeEw2MXdKfeE 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) --1NSDDD2NzzqlQ51F4ieaz3ns6xdBR7LMO Content-Type: multipart/mixed; boundary="JA28Yj4IPgontlvOshIIikMDccIRSdvF5"; protected-headers="v1" From: Qu Wenruo To: dsterba@suse.cz, Jakob Unterwurzacher , linux-btrfs@vger.kernel.org Message-ID: Subject: Re: fallocate does not prevent ENOSPC on write References: <20190423113302.GS20156@twin.jikos.cz> In-Reply-To: <20190423113302.GS20156@twin.jikos.cz> --JA28Yj4IPgontlvOshIIikMDccIRSdvF5 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2019/4/23 =E4=B8=8B=E5=8D=887:33, David Sterba wrote: > On Tue, Apr 23, 2019 at 10:16:32AM +0800, Qu Wenruo wrote: >> On 2019/4/23 =E4=B8=8A=E5=8D=885:09, Jakob Unterwurzacher wrote: >>> I have a user who is reporting ENOSPC errors when running gocryptfs o= n >>> top of btrfs (ticket: https://github.com/rfjakob/gocryptfs/issues/395= ). >>> >>> What is interesting is that the error gets thrown at write time. This= >>> is not supposed to happen, because gocryptfs does >>> >>> fallocate(..., FALLOC_FL_KEEP_SIZE, ...) >>> >>> before writing. >>> >>> I wrote a minimal reproducer in C: https://github.com/rfjakob/falloca= te_write >>> This is what it looks like on ext4: >>> >>> $ ../fallocate_write/fallocate_write >>> reading from /dev/urandom >>> writing to ./blob.379Q8P >>> writing blocks of 132096 bytes each >>> [...] >>> fallocate failed: No space left on device >>> >>> On btrfs, it will instead look like this: >>> >>> [...] >>> pwrite failed: No space left on device >>> >>> Is this a bug in btrfs' fallocate implementation or am I reading the >>> guarantees that fallocate gives me wrong? >> >> Since v4.7, this commit changed the how btrfs do NodataCOW check: >> c6887cd11149 ("Btrfs: don't do nocow check unless we have to"). >> >> Before that commit, btrfs always check if they need to reserve space f= or >> COW, while after that patch, btrfs never checks unless we have no spac= e. >> >> However this screws up other nodatacow space check. >> And due to its age and deep changeset, it's pretty hard to fix it. >> I have tried several times, but it will only cause more problems. >=20 > What if the commit is reverted, if the problem is otherwise hard to fix= ? Tried reverted, but all other problems came up. E.g. reserved space underflow. I'll find the old thread and retry again. Thanks, Qu > This seems to break the semantics of fallocate so the performance shoul= d > not the main concern here. >=20 --JA28Yj4IPgontlvOshIIikMDccIRSdvF5-- --1NSDDD2NzzqlQ51F4ieaz3ns6xdBR7LMO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAly/AToACgkQwj2R86El /qhSbAf/S1kSEDzWi8mTMmNXMhF6Weku8u35eMqHE6Z3StQ2+zwo6HWiFg307KWh Ij7H2B08tkVqHvGdq/CDZwR6DhxlGsF71sLwRey8oDrp5yF4PVb+OwXlpfKIBY86 U/Ji+DWnggQU4E4uUl6M2bdTJ0tFLRJwD1BMoPmzURo2hhq7Zm1mSZxDf4dMUj9v DDaoJKwgw9MIBsvIPcgADNaOCUYcdKxIlaDDNaXI92mf0PU7LDdAu+wo/4aqfBLO Il6dfdDrL09gupX0j+iAfkSTxju+Ri7iz5tnnBcpvkgUbCi7FbY4DFpHqmUQ9csv NRhDHaQzfFRQODh5DEl/HES3WjhClw== =521o -----END PGP SIGNATURE----- --1NSDDD2NzzqlQ51F4ieaz3ns6xdBR7LMO--