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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCA4EC433F5 for ; Tue, 22 Mar 2022 23:58:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1E3B76B0073; Tue, 22 Mar 2022 19:58:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 192466B0074; Tue, 22 Mar 2022 19:58:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 033806B0075; Tue, 22 Mar 2022 19:58:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0082.hostedemail.com [216.40.44.82]) by kanga.kvack.org (Postfix) with ESMTP id E9CD66B0073 for ; Tue, 22 Mar 2022 19:58:19 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 99A88A4DCF for ; Tue, 22 Mar 2022 23:58:19 +0000 (UTC) X-FDA: 79273688718.27.11E11D4 Received: from mail-oa1-f52.google.com (mail-oa1-f52.google.com [209.85.160.52]) by imf10.hostedemail.com (Postfix) with ESMTP id 2FB08C0028 for ; Tue, 22 Mar 2022 23:58:19 +0000 (UTC) Received: by mail-oa1-f52.google.com with SMTP id 586e51a60fabf-de2cb87f6aso109126fac.10 for ; Tue, 22 Mar 2022 16:58:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9vUVk/dhLiB155bUOvch7vh6le5Az932UZy2a3V1Wso=; b=SnVVlXv+vVQWOpu6S8pxeRjqAqL9xosoIjT7GXzkOqKYDdN5+7EHDolhRT7reiVera fZUR5oZTnj3wvRBhawomMWcJ4IFwVRMb5J0xluAFekR/5uUFdTvweYcfFQxG5dodKQnU mkEqGUOjpJXAo+dAd+gy+sF3KwXZfvJAnQYHV3QhqzGJghnryLWiRCWg9W5tJLIGlIip DvtMQ/6/6oVzPQGWNBl0C2IqaCeX2TNLm5wSRvXpMgrkwk9jfGg6qA+Z8JvTs6azn6EU q1Ewt9ZaqtnMV8jm09mdntJDy2xwA7AHHBhDMF/2iQSPVSAIMirthY4gjsArDVP2LzUs 57JQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9vUVk/dhLiB155bUOvch7vh6le5Az932UZy2a3V1Wso=; b=YMf0y8zXN5uUjxw06zgDjoHw5eHAZdFpXRD6fCYjyBv/79V2sgkAmbpfbOpa1EJVqr Y2K6eg1Kfnrr8Im4d/Qomyojcw7R8V9YlyZIfcpuR7ntOqw06EwWitdzEFGSx490nVe4 Jbtd/lGJijH+EEiOY50vQ44wVJwNHo6KjcGJyolRYUdIXwiGyamk34XRyrWY/2bGZ7p8 6Qg5PypsCtHcN6rQPScbWz3AQs4xK5d2TRR06pRtsaDJU6dmcYLwYDjDU22OhDOea0Ga rj0sK/PkqbZLP0BAlNwbNz6iEcrVWEWxXZCx9yn0PsVB5gsGLNn6lLdQLsuNHCHFsg98 Z5Gw== X-Gm-Message-State: AOAM532n+JXSGkFgbebtu9Gn0oDEL+TTzbtVMppu8HJW3TH+yS/lwQKw 404epz7lEN2MqkQJRkTf6GiGXc5Q4ailECkEPj8= X-Google-Smtp-Source: ABdhPJx1R+hFPdecpLkNdEYr4Pf2lULkUM+icjWjv4HQr+ek9QcLIWnB3CF6tRcTn28F4B2PRa43uCgq9FLttu9kGF4= X-Received: by 2002:a05:6870:7393:b0:dd:9a31:96d1 with SMTP id z19-20020a056870739300b000dd9a3196d1mr2883939oam.98.1647993498406; Tue, 22 Mar 2022 16:58:18 -0700 (PDT) MIME-Version: 1.0 References: <20220322222738.182974-1-krisman@collabora.com> <20220322222738.182974-3-krisman@collabora.com> In-Reply-To: <20220322222738.182974-3-krisman@collabora.com> From: Amir Goldstein Date: Wed, 23 Mar 2022 01:58:07 +0200 Message-ID: Subject: Re: [PATCH 2/3] shmem: Introduce /sys/fs/tmpfs support To: Gabriel Krisman Bertazi Cc: Hugh Dickins , Andrew Morton , Khazhismel Kumykov , Linux MM , kernel@collabora.com, linux-fsdevel Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 3fwwyz54cpz1pddugbxgch3nfc3f1wru X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2FB08C0028 Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=SnVVlXv+; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf10.hostedemail.com: domain of amir73il@gmail.com designates 209.85.160.52 as permitted sender) smtp.mailfrom=amir73il@gmail.com X-Rspam-User: X-HE-Tag: 1647993499-599105 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: [+fsdevel please CC on next versions] On Wed, Mar 23, 2022 at 12:27 AM Gabriel Krisman Bertazi wrote: > > In order to expose tmpfs statistics on sysfs, add the boilerplate code > to create the /sys/fs/tmpfs structure. Other filesystems usually do > /sys/fs//, but since this is a nodev filesystem, I'm proposing > to use fsid as . I am proposing st_dev minor. > > This takes care of not exposing SB_NOUSER mounts. I don't think we have > a usecase for showing them and, since they don't appear elsewhere, they > might be confusing to users. > > Signed-off-by: Gabriel Krisman Bertazi > --- > include/linux/shmem_fs.h | 4 +++ > mm/shmem.c | 73 +++++++++++++++++++++++++++++++++++++++- > 2 files changed, 76 insertions(+), 1 deletion(-) > [...] > +static int shmem_register_sysfs(struct super_block *sb) > +{ > + int err; > + struct shmem_sb_info *sbinfo = SHMEM_SB(sb); > + __kernel_fsid_t fsid = uuid_to_fsid(sb->s_uuid.b); > + > + init_completion(&sbinfo->s_kobj_unregister); > + err = kobject_init_and_add(&sbinfo->s_kobj, &tmpfs_sb_ktype, shmem_root, > + "%x%x", fsid.val[0], fsid.val[1]); uuid (and fsid) try to be unique across tmpfs instances from different times. You don't need that. I think you'd rather use s_dev (minor number) which is unique among all tmpfs instances at a given time and also much easier from user scripts to read from (e.g. stat or /proc/self/mountinfo). That's btw the same number is used as an entry in /sys/fs/fuse/connections (fusectl pseudo fs). Thanks, Amir.