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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 80EA3C54FC9 for ; Sun, 19 Apr 2020 22:58:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4D13C2074B for ; Sun, 19 Apr 2020 22:58:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4D13C2074B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=acm.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EA9698E0005; Sun, 19 Apr 2020 18:58:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E5ABD8E0003; Sun, 19 Apr 2020 18:58:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D48828E0005; Sun, 19 Apr 2020 18:58:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0068.hostedemail.com [216.40.44.68]) by kanga.kvack.org (Postfix) with ESMTP id BABCD8E0003 for ; Sun, 19 Apr 2020 18:58:02 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 669D7181AEF32 for ; Sun, 19 Apr 2020 22:58:02 +0000 (UTC) X-FDA: 76726119204.06.cats16_bf1822fa8133 X-HE-Tag: cats16_bf1822fa8133 X-Filterd-Recvd-Size: 4623 Received: from mail-pf1-f196.google.com (mail-pf1-f196.google.com [209.85.210.196]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Sun, 19 Apr 2020 22:58:01 +0000 (UTC) Received: by mail-pf1-f196.google.com with SMTP id y25so4028132pfn.5 for ; Sun, 19 Apr 2020 15:58:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=WeNfqqul/V3m4dCr3fDBJiD7q3+RqFqQXCZmIH0aZiQ=; b=bBeUrjD5UQIq19uQFNWDE0fC1yT+iTcKfX2Kt2wU75Z68v5cd+rUKD980POy0G7iwc I2x3khf0Rmt1Kt9FxXcLS0J1yQa8hVnLX/MftDVw9aKLIuegZQqMWCcV8n2LEY3VORj1 Sci3y17/uWTd1GfocbIYShdNdl6tseKfaLJr5TxuwKPHuaWdcMoNBIMFQ9cp98lXLRQN iCAmhaFSzQ60Qw9rcDejFaKsZxhPiC6K+9uftHxGXoXUhFZdThugj5WffPeX7chziUCs OiS0zXPHWkjf0ZulCnS7e47MZCbIVI++tI629WMVri+6fTcgKErHpIKHDwnlELbPTsXg bE+Q== X-Gm-Message-State: AGi0PubxIZ0XTp4TF7XmSMpU26ch6hLisyjtzS6ehZLWS8DaZzgQCw3I z3qZRXBz0Xu2ZGeTghuOEiI= X-Google-Smtp-Source: APiQypK3Dfc0+33A+/ZdM0DiJzbhdXOT2T6zI92OuybLuYpFMQsRiH8HjeTGYxZmN/hnAY3YB78k3g== X-Received: by 2002:a63:d90c:: with SMTP id r12mr13564924pgg.158.1587337081070; Sun, 19 Apr 2020 15:58:01 -0700 (PDT) Received: from [100.124.11.78] ([104.129.198.64]) by smtp.gmail.com with ESMTPSA id l15sm24246102pgk.59.2020.04.19.15.57.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 19 Apr 2020 15:58:00 -0700 (PDT) Subject: Re: [PATCH v2 08/10] blktrace: add checks for created debugfs files on setup To: Luis Chamberlain , axboe@kernel.dk, viro@zeniv.linux.org.uk, gregkh@linuxfoundation.org, rostedt@goodmis.org, mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com, nstange@suse.de, akpm@linux-foundation.org Cc: mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20200419194529.4872-1-mcgrof@kernel.org> <20200419194529.4872-9-mcgrof@kernel.org> From: Bart Van Assche Message-ID: <38240225-e48e-3035-0baa-4929948b23a3@acm.org> Date: Sun, 19 Apr 2020 15:57:58 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200419194529.4872-9-mcgrof@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/19/20 12:45 PM, Luis Chamberlain wrote: > Even though debugfs can be disabled, enabling BLK_DEV_IO_TRACE will > select DEBUG_FS, and blktrace exposes an API which userspace uses > relying on certain files created in debugfs. If files are not created > blktrace will not work correctly, so we do want to ensure that a > blktrace setup creates these files properly, and otherwise inform > userspace. > > Signed-off-by: Luis Chamberlain > --- > kernel/trace/blktrace.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index 9cc0153849c3..fc32a8665ce8 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -552,17 +552,19 @@ static int blk_trace_create_debugfs_files(struct blk_user_trace_setup *buts, > struct dentry *dir, > struct blk_trace *bt) > { > - int ret = -EIO; > - > bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, > &blk_dropped_fops); > + if (!bt->dropped_file) > + return -ENOMEM; > > bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops); > + if (!bt->msg_file) > + return -ENOMEM; > > bt->rchan = relay_open("trace", dir, buts->buf_size, > buts->buf_nr, &blk_relay_callbacks, bt); > if (!bt->rchan) > - return ret; > + return -EIO; > > return 0; > } I should have had a look at this patch before I replied to the previous patch. Do you agree that the following code can be triggered by debugfs_create_file() and also that debugfs_create_file() never returns NULL? static struct dentry *failed_creating(struct dentry *dentry) { inode_unlock(d_inode(dentry->d_parent)); dput(dentry); simple_release_fs(&debugfs_mount, &debugfs_mount_count); return ERR_PTR(-ENOMEM); } Thanks, Bart.