From: Anand Jain <anajain.sg@gmail.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Theodore Tso <tytso@mit.edu>,
"Darrick J. Wong" <djwong@kernel.org>,
linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org,
linux-xfs@vger.kernel.org, Anand Jain <asj@kernel.org>,
dsterba@suse.com
Subject: Re: [PATCH v2 3/3] ext4: derive f_fsid from block device to avoid collisions
Date: Mon, 27 Apr 2026 18:16:19 +0800 [thread overview]
Message-ID: <a7df722a-834a-44f0-87ad-d0da5a813e6b@gmail.com> (raw)
In-Reply-To: <aempTb5TyKG0vPL0@infradead.org>
On 23/4/26 13:08, Christoph Hellwig wrote:
> On Wed, Apr 22, 2026 at 07:39:57PM +0800, Anand Jain wrote:
>>> No, T10 does not actually mandate unique identifiers, NVMe does, but the
>>> implementations are often totally broken.
>>
>> Right. Newer SPC-3 (and above) compliant devices must support
>> the Inquiry CDB EVPD flag and provide page 0x83 for identification,
>> which is what we typically use for multipathing.
>
> But there is no requirement for it to contain something useful.
>
>> These are globally unique. And, we can overlook legacy
>> drives, as they've probably been past their EOSL for a while now.
>
> We have absolutely no useful identifiers for most USB devices.
> NVMe devices have broken identifiers all the time as well.
>
> So no, you can't.
Agreed. I have dropped the plan to rely on hardware identifiers;
the lack of consistency in USB/NVMe firmware makes them a
non-starter for a stable identifier.
The updated patch set, excluding the ext4 changes, has been
submitted to the mailing list. Fstests test case updated as well.
Thanks, Anand
prev parent reply other threads:[~2026-04-27 10:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-21 11:55 [PATCH v2 0/3] fix s_uuid and f_fsid consistency for cloned filesystems Anand Jain
2026-03-21 11:55 ` [PATCH v2 1/3] btrfs: use on-disk uuid for s_uuid in temp_fsid mounts Anand Jain
2026-03-21 11:55 ` [PATCH v2 2/3] btrfs: derive f_fsid from on-disk fsuuid and dev_t Anand Jain
2026-03-21 11:55 ` [PATCH v2 3/3] ext4: derive f_fsid from block device to avoid collisions Anand Jain
2026-03-23 4:16 ` Theodore Tso
2026-03-23 15:29 ` Darrick J. Wong
2026-03-23 16:44 ` Darrick J. Wong
2026-03-25 10:02 ` Andreas Dilger
2026-03-25 10:59 ` Anand Jain
2026-03-25 12:59 ` Theodore Tso
2026-04-02 7:33 ` Anand Jain
2026-03-23 15:41 ` Anand Jain
2026-04-04 8:59 ` Anand Jain
2026-04-07 5:22 ` Christoph Hellwig
2026-04-07 14:47 ` Theodore Tso
2026-04-08 22:28 ` Anand Jain
2026-04-09 4:10 ` Theodore Tso
2026-04-09 9:45 ` Anand Jain
2026-04-09 13:12 ` Theodore Tso
2026-04-16 15:21 ` Anand Jain
2026-04-17 7:34 ` Christoph Hellwig
2026-04-22 11:39 ` Anand Jain
2026-04-23 5:08 ` Christoph Hellwig
2026-04-27 10:16 ` Anand Jain [this message]
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