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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFBA8C6FA82 for ; Tue, 13 Sep 2022 04:52:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229889AbiIMEwu (ORCPT ); Tue, 13 Sep 2022 00:52:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229728AbiIMEws (ORCPT ); Tue, 13 Sep 2022 00:52:48 -0400 Received: from mail-pf1-x435.google.com (mail-pf1-x435.google.com [IPv6:2607:f8b0:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D604B21E1F for ; Mon, 12 Sep 2022 21:52:46 -0700 (PDT) Received: by mail-pf1-x435.google.com with SMTP id j12so10617408pfi.11 for ; Mon, 12 Sep 2022 21:52:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date; bh=JLF2I4wOwXauDOEb5+Sh8J70kOC65ivJWEGZB27Sv0g=; b=7dTZTr4FYIktraDjKfcf82VDAwiKwQ9io1MDq8z8uKJytwJm6fYshMdfMlhRY8GgHe 3fDCxLXATEjYBLmNGd0dJg7/5KTNHgeT6O8qaLU/05BXymesEDIzEecRwAlDkwIZxLxQ nFUe1rTAB7CG3WrDKzjXnHkke7NvZ0x8tZqW7+8hr6I9rz7PK3o1GQrg3W//Ge3EF365 h8Le6mRlItymgSZJ778jtK7oBIelM1VMXuPSn50g5nS1cqQFRUoKori3HVcwh1ZxEur6 MQLbzVK8wF3rWnuSErZ24/5MIRwwXRIX1DN1fN6M5TsgqqX2MdV3jmy+BDvBpeMI1k7u 6+GA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date; bh=JLF2I4wOwXauDOEb5+Sh8J70kOC65ivJWEGZB27Sv0g=; b=vjeV6UAwk/Fxo+esfy1UF24HtaJKsf/3RJOKID8b6tw+rX0hN48ME2agAYbarYyqw4 K/D3uRmGDalD9Y8Xoq8qqJ+U0fXqNY9d7/crkF0M/eTHfIQcVc4biQB46OZcrb8gNazm h/KvYMxD5+5icSYdflvgGwHBL++XVFiP7s8EHyYJLPQLMF2v4F1F3TtoMleZdvHn0yAm c963n7aM0OzphD0dvOSbPagVpkJyWNbixA4dpVyQhtD/GpTjWgc/1fBaEo1hBMvoCX8Q Xzg6tb0Th1PpMLDnz0GfvO+52TSJ2uc+nInYhy1Hwqz1PVnvLbw3peMRMC6E/Lp6RGkp 0pew== X-Gm-Message-State: ACgBeo1xhXEcFYizwfsUMYf1CzdYNFLpuD7mMLfN3x8pDoNBaME3wrjn qzCeXai7n4N22kJ1Bv+ZPQ8lkz+f1FdTww== X-Google-Smtp-Source: AA6agR5dV5R2BRbUXES4VtsugHRQDiNuiv2o2I1g/ph2SiQRoaG6a1nGMpB/RzAH04YkM8Dye47NnA== X-Received: by 2002:a05:6a00:e8a:b0:535:cc5c:3d87 with SMTP id bo10-20020a056a000e8a00b00535cc5c3d87mr31153288pfb.24.1663044766321; Mon, 12 Sep 2022 21:52:46 -0700 (PDT) Received: from [10.76.37.214] ([61.213.176.12]) by smtp.gmail.com with ESMTPSA id x92-20020a17090a38e500b002008b7c9764sm6109658pjb.50.2022.09.12.21.52.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Sep 2022 21:52:45 -0700 (PDT) Message-ID: <27143c70-906e-a575-ef58-ac9f3c5ab080@bytedance.com> Date: Tue, 13 Sep 2022 12:52:41 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [External] Re: [PATCH V2 4/5] erofs: remove duplicated unregister_cookie To: JeffleXu , linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, yinxin.x@bytedance.com, huyue2@coolpad.com References: <20220902105305.79687-1-zhujia.zj@bytedance.com> <20220902105305.79687-5-zhujia.zj@bytedance.com> <3f75d266-7ccd-be6d-657c-fe0633b25687@linux.alibaba.com> <8a239157-de28-44ae-edef-336092c34a15@linux.alibaba.com> From: Jia Zhu In-Reply-To: <8a239157-de28-44ae-edef-336092c34a15@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/9/9 18:28, JeffleXu 写道: > > > On 9/9/22 5:55 PM, JeffleXu wrote: >> >> >> On 9/2/22 6:53 PM, Jia Zhu wrote: >>> In erofs umount scenario, erofs_fscache_unregister_cookie() is called >>> twice in kill_sb() and put_super(). >>> >>> It works for original semantics, cause 'ctx' will be set to NULL in >>> put_super() and will not be unregister again in kill_sb(). >>> However, in shared domain scenario, we use refcount to maintain the >>> lifecycle of cookie. Unregister the cookie twice will cause it to be >>> released early. > > Sorry, why can't we also set sbi->s_fscache to NULL after decrementing > the refcount in shared domain mode, to avoid the refcount being > decremented twice? > In below case: 1. mount -t erofs none -o fsid=bootstrap.img -o device=blob.img -o domain_id=1 mnt 2. mount -t erofs none -o fsid=bootstrap.img -o device=blob.img -o domain_id=1 mnt2 3. Procedure 2 will fail since we can't mount erofs with the same sysfs entry. 4. Mount()'s error handling path will step into put_super(). 5. Domain's refcnt will be decremented even if it has not yet been incremented. >>> >>> For the above reasons, this patch removes duplicate unregister_cookie >>> and move fscache_unregister_* before shotdown_super() to prevent busy >>> inode(ctx->inode) when umount. >>> >>> Signed-off-by: Jia Zhu >>> --- >>> fs/erofs/super.c | 16 ++++++++-------- >>> 1 file changed, 8 insertions(+), 8 deletions(-) >>> >>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c >>> index 69de1731f454..667a78f0ee70 100644 >>> --- a/fs/erofs/super.c >>> +++ b/fs/erofs/super.c >>> @@ -919,19 +919,20 @@ static void erofs_kill_sb(struct super_block *sb) >>> kill_litter_super(sb); >>> return; >>> } >>> - if (erofs_is_fscache_mode(sb)) >>> - generic_shutdown_super(sb); >>> - else >>> - kill_block_super(sb); >>> - >>> sbi = EROFS_SB(sb); >>> if (!sbi) >>> return; >>> >>> + if (erofs_is_fscache_mode(sb)) { >>> + erofs_fscache_unregister_cookie(&sbi->s_fscache); >>> + erofs_fscache_unregister_fs(sb); >>> + generic_shutdown_super(sb); >> >> Generally we can't do clean ups before generic_shutdown_super(), since >> generic_shutdown_super() may trigger IO, e.g. in sync_filesystem(), >> though it's not the case for erofs (read-only). >> >> How about embedding erofs_fscache_unregister_cookie() into >> erofs_fscache_unregister_fs(), and thus we can check domain_id in >> erofs_fscache_unregister_fs()? >> >>> + } else { >>> + kill_block_super(sb); >>> + } >>> + >>> erofs_free_dev_context(sbi->devs); >>> fs_put_dax(sbi->dax_dev, NULL); >>> - erofs_fscache_unregister_cookie(&sbi->s_fscache); >>> - erofs_fscache_unregister_fs(sb); >>> kfree(sbi->opt.fsid); >>> kfree(sbi->opt.domain_id); >>> kfree(sbi); >>> @@ -951,7 +952,6 @@ static void erofs_put_super(struct super_block *sb) >>> iput(sbi->managed_cache); >>> sbi->managed_cache = NULL; >>> #endif >>> - erofs_fscache_unregister_cookie(&sbi->s_fscache); >>> } >>> >>> struct file_system_type erofs_fs_type = { >> >