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From:   Gabriel Krisman Bertazi <krisman@collabora.com>
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     Hugh Dickins <hughd@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Khazhismel Kumykov <khazhy@google.com>,
        Linux MM <linux-mm@kvack.org>, kernel@collabora.com,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 2/3] shmem: Introduce /sys/fs/tmpfs support
Organization: Collabora
References: <20220322222738.182974-1-krisman@collabora.com>
        <20220322222738.182974-3-krisman@collabora.com>
        <CAOQ4uxhLQp4ujuR8k16k9EfeOC2TiwwiCeVGYOzpViwRpa5oqw@mail.gmail.com>
Date:   Wed, 23 Mar 2022 14:04:21 -0400
In-Reply-To: <CAOQ4uxhLQp4ujuR8k16k9EfeOC2TiwwiCeVGYOzpViwRpa5oqw@mail.gmail.com>
        (Amir Goldstein's message of "Wed, 23 Mar 2022 01:58:07 +0200")
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Amir Goldstein <amir73il@gmail.com> writes:

>> +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).

Hi Amir, thanks for the review.

Sounds good.  I will follow up with a new version that uses
MINOR(sb->s_dev).

Thank you,


-- 
Gabriel Krisman Bertazi