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[209.85.220.41]) by mx.google.com with SMTPS id 102sor20469043plb.0.2019.02.12.11.07.34 for (Google Transport Security); Tue, 12 Feb 2019 11:07:34 -0800 (PST) Received-SPF: pass (google.com: domain of hughd@google.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=nXwzCRB2; spf=pass (google.com: domain of hughd@google.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=OpyY+rWGCRjCWIcHJBnUa587hFsQzOCB56va24AW1sA=; b=nXwzCRB20IcaOH6u9s6yP3zgt1SGf3oSlamcc6rIBa+zTCjN8F8wxDnSJHxgpoUmBe aEBVuobGX9CsTsYo0UpQuNZnjdFlSpVo0gEq/UmDQp7v6q3hXOEI8E7pxzm9ityCAySw KfupLnTJm/qL26PkWGs4pVfV34ZfxiEQsTcWm77K6LvtfXgjBK7/6C+dMYyCtGDue3u5 0wZcSD4zNTtzGDZax2tp1ybb5fZdm7Lkl5D9hJF5rWPdiH8VqrKDJse8GcwRBbvb2RS7 sYnUqnEwLI8xnOmkQOoFpgkNzkrrpI0vIYNNRCnsWthJNSdogqCbJY79/kPQvzhkbM6k WnAA== X-Google-Smtp-Source: AHgI3IZly9Yr8ptRK7gT1k/BsvVpZtBQyuyHNcQJoC23Cm5pF5l+J4mVKgCH+63VX8FgpINv2H6PeQ== X-Received: by 2002:a17:902:2966:: with SMTP id g93mr5312125plb.11.1549998453457; Tue, 12 Feb 2019 11:07:33 -0800 (PST) Received: from [100.112.89.103] ([104.133.8.103]) by smtp.gmail.com with ESMTPSA id e9sm61911867pfh.42.2019.02.12.11.07.32 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 12 Feb 2019 11:07:32 -0800 (PST) Date: Tue, 12 Feb 2019 11:07:19 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Matej Kupljen cc: Hugh Dickins , linux-mm@kvack.org Subject: Re: Fwd: tmpfs inode leakage when opening file with O_TMP_FILE In-Reply-To: Message-ID: References: User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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 Tue, 12 Feb 2019, Matej Kupljen wrote: > Hi all, > > I sent this mail yesterday to kernel mailing list, but I got no reply. > So, I checked the MAINTAINERS file and I have found these emails. > I hope this is the right address for this issue. Yes, thanks: I'll look into it (not this moment), and reply to you and both lists when I've got something. Hugh > > Thanks and BR, > Matej > > ---------- Forwarded message --------- > From: Matej Kupljen > Date: Mon, Feb 11, 2019 at 3:18 PM > Subject: tmpfs inode leakage when opening file with O_TMP_FILE > To: > > > Hi, > > it seems that when opening file on file system that is mounted on > tmpfs with the O_TMPFILE flag and using linkat call after that, it > uses 2 inodes instead of 1. > > This is simple test case: > > #include > #include > #include > #include > #include > #include > #include > #include > #include > > #define TEST_STRING "Testing\n" > > #define TMP_PATH "/tmp/ping/" > #define TMP_FILE "file.txt" > > > int main(int argc, char* argv[]) > { > char path[PATH_MAX]; > int fd; > int rc; > > fd = open(TMP_PATH, __O_TMPFILE | O_RDWR, > S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | > S_IROTH | S_IWOTH); > > rc = write(fd, TEST_STRING, strlen(TEST_STRING)); > > snprintf(path, PATH_MAX, "/proc/self/fd/%d", fd); > linkat(AT_FDCWD, path, AT_FDCWD, TMP_PATH TMP_FILE, AT_SYMLINK_FOLLOW); > close(fd); > > return 0; > } > > I have checked indoes with "df -i" tool. The first inode is used when > the call to open is executed and the second one when the call to > linkat is executed. > It is not decreased when close is executed. > > I have also tested this on an ext4 mounted fs and there only one inode is used. > > I tested this on: > $ cat /etc/lsb-release > DISTRIB_ID=Ubuntu > DISTRIB_RELEASE=18.04 > DISTRIB_CODENAME=bionic > DISTRIB_DESCRIPTION="Ubuntu 18.04.1 LTS" > > $ uname -a > Linux Orion 4.15.0-43-generic #46-Ubuntu SMP Thu Dec 6 14:45:28 UTC > 2018 x86_64 x86_64 x86_64 GNU/Linux > > If you need any more information, please let me know. > > And please CC me when replying, I am not subscribed to the list. > > Thanks and BR, > Matej >