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=-9.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 74AB6C433E4 for ; Sun, 26 Jul 2020 02:12:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D3B9206D8 for ; Sun, 26 Jul 2020 02:12:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tfz-net.20150623.gappssmtp.com header.i=@tfz-net.20150623.gappssmtp.com header.b="KWW7XRvn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728207AbgGZCL4 (ORCPT ); Sat, 25 Jul 2020 22:11:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727101AbgGZCLz (ORCPT ); Sat, 25 Jul 2020 22:11:55 -0400 Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89A65C0619D2 for ; Sat, 25 Jul 2020 19:11:55 -0700 (PDT) Received: by mail-wr1-x443.google.com with SMTP id 88so11562999wrh.3 for ; Sat, 25 Jul 2020 19:11:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tfz-net.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=2BY5Poqr2fA3RRuOzlPlb22Tg24jxGxBQVUUxrbzh/M=; b=KWW7XRvnNCgZsnxgTX9/6O5WphsFCiJ5rLsriaFFCjo0w89hIZa98KECDv1RbTuJsB OwKi4lc2CXeYWMG/TPbEpfad9Wc9R2wKh3+FpYWffG0Vj2ymqxzWsqtD2oe6xw1lPfPU wY0u30YQLtGsFu3Ld/o0DcVKmZaLrdeMWiG2h4ItCsaC8aTXj/vbt6L39CVpNkLxuo2i l2AI4Ddif5Z4Nm3HM5K6pJUACvOMOX3lTuVi4NvMtjLOr5UYjtUy+fiRH2e1+hykOBxi H5RKk/F7BWjL+NkminG2g9cQeJ10xBI5HZ/CuDaCqKhKGTNVfotpQNpwHjMKXkne3blx N9HQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=2BY5Poqr2fA3RRuOzlPlb22Tg24jxGxBQVUUxrbzh/M=; b=pbDBF/0H87clPtIY5+1APrSo5IhfI9M/yb1KtSoG3yB4hKgv9J3wR2UjVhvj7AJurg 3rzYfsXbd+CghPEAohQ7fqGV4VB+kkelzlcp5j5u0ihFAvDrlVPoHblXfgpYZ0zFHMj1 mddt1Kl4Sp2dxEFXWogFlI/KvjylXm80OSHSnIdSyBxaRmU0ijejABlkXGaIBtm2eVAx Lpl8ilSNAHoCx79QReCP82K9PVdpw0FRAHyMxZY+rLzak43iPudyb7CViY8yYmFkReZi NX9L0jUOpHOxukaHOjkDnpqY/gODpSdptWWOIvcECdwDuEWBa39i0I9Ql5HvEZi1NIYF 5tvw== X-Gm-Message-State: AOAM530s/+OjEzBMp+y2pqjg2rSMIF8ZTDqkIe6M3+TUZsuWZE5bE8dA LtT44nDI5RpUIztXDOXl0Y55od6X6n1+BVWCKG6V9Q== X-Google-Smtp-Source: ABdhPJzYjq53hix8vYV6O/NEWrQvf44oV97N5I8qZhQjdzG/xJ+YJAaus2rch7JC6PFRpE1E4F7UxrZeV8/91/vPRjk= X-Received: by 2002:a05:6000:141:: with SMTP id r1mr10897990wrx.69.1595729514257; Sat, 25 Jul 2020 19:11:54 -0700 (PDT) MIME-Version: 1.0 References: <20200725045921.2723-1-kalou@tfz.net> <20200725051547.3718-1-kalou@tfz.net> In-Reply-To: <20200725051547.3718-1-kalou@tfz.net> From: Pascal Bouchareine Date: Sat, 25 Jul 2020 19:11:43 -0700 Message-ID: Subject: Re: [PATCH v3] This command attaches a description to a file descriptor for troubleshooting purposes. The free string is displayed in the process fdinfo file for that fd /proc/pid/fdinfo/fd. To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Alexey Dobriyan , Al Viro , Jeff Layton , "J. Bruce Fields" Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Sorry about all the noise, please disregard this one. On Sat, Jul 25, 2020 at 7:04 PM Pascal Bouchareine wrote: > > One intended usage is to allow processes to self-document sockets > for netstat and friends to report > > Signed-off-by: Pascal Bouchareine > --- > Documentation/filesystems/proc.rst | 3 +++ > fs/fcntl.c | 19 +++++++++++++++++++ > fs/file_table.c | 2 ++ > fs/proc/fd.c | 5 +++++ > include/linux/fs.h | 3 +++ > include/uapi/linux/fcntl.h | 5 +++++ > 6 files changed, 37 insertions(+) > > diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst > index 996f3cfe7030..ae8045650836 100644 > --- a/Documentation/filesystems/proc.rst > +++ b/Documentation/filesystems/proc.rst > @@ -1918,6 +1918,9 @@ A typical output is:: > flags: 0100002 > mnt_id: 19 > > +An optional 'desc' is set if the process documented its usage of > +the file via the fcntl command F_SET_DESCRIPTION. > + > All locks associated with a file descriptor are shown in its fdinfo too:: > > lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF > diff --git a/fs/fcntl.c b/fs/fcntl.c > index 2e4c0fa2074b..c1ef724a906e 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -319,6 +319,22 @@ static long fcntl_rw_hint(struct file *file, unsigned int cmd, > } > } > > +static long fcntl_set_description(struct file *file, char __user *desc) > +{ > + char *d; > + > + d = strndup_user(desc, MAX_FILE_DESC_SIZE); > + if (IS_ERR(d)) > + return PTR_ERR(d); > + > + spin_lock(&file->f_lock); > + kfree(file->f_description); > + file->f_description = d; > + spin_unlock(&file->f_lock); > + > + return 0; > +} > + > static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, > struct file *filp) > { > @@ -426,6 +442,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, > case F_SET_FILE_RW_HINT: > err = fcntl_rw_hint(filp, cmd, arg); > break; > + case F_SET_DESCRIPTION: > + err = fcntl_set_description(filp, argp); > + break; > default: > break; > } > diff --git a/fs/file_table.c b/fs/file_table.c > index 656647f9575a..6673a48d2ea1 100644 > --- a/fs/file_table.c > +++ b/fs/file_table.c > @@ -272,6 +272,8 @@ static void __fput(struct file *file) > eventpoll_release(file); > locks_remove_file(file); > > + kfree(file->f_description); > + > ima_file_free(file); > if (unlikely(file->f_flags & FASYNC)) { > if (file->f_op->fasync) > diff --git a/fs/proc/fd.c b/fs/proc/fd.c > index 81882a13212d..60b3ff971b2b 100644 > --- a/fs/proc/fd.c > +++ b/fs/proc/fd.c > @@ -57,6 +57,11 @@ static int seq_show(struct seq_file *m, void *v) > (long long)file->f_pos, f_flags, > real_mount(file->f_path.mnt)->mnt_id); > > + spin_lock(&file->f_lock); > + if (file->f_description) > + seq_printf(m, "desc:\t%s\n", file->f_description); > + spin_unlock(&file->f_lock); > + > show_fd_locks(m, file, files); > if (seq_has_overflowed(m)) > goto out; > diff --git a/include/linux/fs.h b/include/linux/fs.h > index f5abba86107d..09717bfa4e3b 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -980,6 +980,9 @@ struct file { > struct address_space *f_mapping; > errseq_t f_wb_err; > errseq_t f_sb_err; /* for syncfs */ > + > +#define MAX_FILE_DESC_SIZE 256 > + char *f_description; > } __randomize_layout > __attribute__((aligned(4))); /* lest something weird decides that 2 is OK */ > > diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h > index 2f86b2ad6d7e..f86ff6dc45c7 100644 > --- a/include/uapi/linux/fcntl.h > +++ b/include/uapi/linux/fcntl.h > @@ -55,6 +55,11 @@ > #define F_GET_FILE_RW_HINT (F_LINUX_SPECIFIC_BASE + 13) > #define F_SET_FILE_RW_HINT (F_LINUX_SPECIFIC_BASE + 14) > > +/* > + * Set file description > + */ > +#define F_SET_DESCRIPTION (F_LINUX_SPECIFIC_BASE + 15) > + > /* > * Valid hint values for F_{GET,SET}_RW_HINT. 0 is "not set", or can be > * used to clear any hints previously set. > -- > 2.25.1 >