From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f51.google.com (mail-pj1-f51.google.com [209.85.216.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8070927603C for ; Mon, 27 Apr 2026 10:16:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777284985; cv=none; b=dGd4cAkKmwE5E6K2iIZpFK/lYWMfUAAZrYqUmBnp7NcEqRxDDGMO5drZQFPPvHhCL2HWmfb6nwiK1jH2WGq72wWXdq3zclLs7SomKi/0+i/ryuwSQ3Gxub9IJiGA9Kfq1VP2cEJk4Dje/PrqCFhQSit058NEE/9e1dUDCh2x8FM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777284985; c=relaxed/simple; bh=MVzRp4OGUxMMdWcsFlN4qWeIX4Qazp+n6VnfWzrAamk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QN6bP5zw9wFosFhyZkc/YJJYkpmEgzr4wYifGPEkq4xwHmpg7TN9FuWrj6iCSfI9dzGNV7evRqi3FMryt/XdaYQzBPrjIRci68vW1iLwhrpBUOgdL8SZqkYBnu8B4snGQDRnNZbgD8cdjmdmN4iOu+1xvSYeshbE39Buehv5PM0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ipf/P+mJ; arc=none smtp.client-ip=209.85.216.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ipf/P+mJ" Received: by mail-pj1-f51.google.com with SMTP id 98e67ed59e1d1-35d94f4ee36so6000849a91.3 for ; Mon, 27 Apr 2026 03:16:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777284984; x=1777889784; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=pdggqY40OkypkTlyFCDPbQJ5t8fWVIZTWFDYfO2J5OM=; b=ipf/P+mJXMFbjUJOYSs6xDia98wvHxaAjL40BuOuATATeYYLy8jD4ZwaXBY/oAKIdh zjaj0NamCDeLhyrr5M+LMwmeI1uVFnx7/08SowVtFlhKSBTVTWKKTUEZ8KNcgBmPROTy ldoe5bO5NygjFrhfyuf2aOV3hoTanFTK7pfmuMrUReOGmcZqGSEvIWFtMZ7VqCcRlYfB buyXAsmV20TiqYI8RdE1yjWNDGSbd43ejYakfLlhhqPXZC++Uo8JY1+ZvmYBGf+W9W40 2w0mh6cOUOWUVi9x/Ds2eWSE+fyZdBjt2mFX+6raVVEnv6+VfUyLQ163UOJ3LRyDC0qz dleA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777284984; x=1777889784; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=pdggqY40OkypkTlyFCDPbQJ5t8fWVIZTWFDYfO2J5OM=; b=stwP3yKQbEtmV9YPFOoBt0yrIYvTqlC3KjJ5mWHXoryblSw1O2I/FgbeOwVX9rkNu+ yonqkmcWL7GMj0nFuJEQ7ABOcIFN0OGqHGMTwBBBdig8Z3/HeSWhMiVWecC+JSavXt5J sADEQZfaSstvNJft3kOIANBSNwbnjObrGvm6fU91KSHazAtLziRCgCRXl+9SWBYQkE/3 7LGRCVd+UPhmP2gyO1viWFXOX5Ce/9g9RUHR+52Nrl2z0FmPldzTRxpsveBZgC614iKv O2VosZRtHt1plZyOjA9s5QEoaf3msWGyvJ3epMbB83aZhhs4Sj96yboHfumqxgOesDcY Wd4A== X-Forwarded-Encrypted: i=1; AFNElJ/X31kGCMuh8qaylAkdjVP0YjLrSAEkbzldZusEMFEFDHBvAJ+oqqdFQoQBExNWYjlnDWFngxCrxjg=@vger.kernel.org X-Gm-Message-State: AOJu0YyKWYlMwWLzPDTV+OaEPbTn5PUnpZQeJxT0p3tlHG/8OuhA3ExG a1qWR0NoLWGTuqOA9c9n/kL3yu+gwi2JC6YUs52yyO2l50dZGJTQNZ+U X-Gm-Gg: AeBDiesGtHS4+fzg0eVRa4qj4FAhpe2mpk8MPvGbk83askkPQbeYRSXGpsjX1WfP344 a5GBJnTRgjfuTNvy6f2R3JAJ1uIgyz4RWmzCgA1s2W4nfFA5423RUWpyLWXVgLrs6NpdJJvbbdC RaZG3pflI7MQ62S0LGMq2F6HoreuZS8OyMnet8XBNwCbaY0MGCKKFRMOfu/Eyp/PgKVgSEuA/02 wbZsRQl3XbFhtNjdY7ys3HyroO6y+/xPf6MRG+Ioxu1ZBRKdGpjz5sAmCOiW52N/6V5/3rYYgOo /0V5OJUzVReneU0OwFEoJ8G0o35x5lx8MAKstBczv86WL+JwlqMRdKzFnw+6v8nx0XNOrv5DcPm U/AJt499ti4k2gQ9jq6kSLLhP02rLqMw1m6VY8pEt33FRQX83WH+K2iNWrSnMGT3aefEucZFgcJ jokrtMeWx5T61vJhVjbleQ7Hw7Y8K/9TmS9bFTzA== X-Received: by 2002:a17:90b:5544:b0:35b:90e7:c44f with SMTP id 98e67ed59e1d1-361403e1016mr40055142a91.7.1777284983849; Mon, 27 Apr 2026 03:16:23 -0700 (PDT) Received: from [192.168.50.90] ([116.87.14.48]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3613f56ecbesm11872541a91.0.2026.04.27.03.16.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Apr 2026 03:16:23 -0700 (PDT) Message-ID: Date: Mon, 27 Apr 2026 18:16:19 +0800 Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] ext4: derive f_fsid from block device to avoid collisions To: Christoph Hellwig Cc: Theodore Tso , "Darrick J. Wong" , linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, Anand Jain , dsterba@suse.com References: <5bda3d00-df35-4ea1-b313-2fef6e5c5682@gmail.com> <20260407144709.GA81690@macsyma-wired.lan> <3c9e478a-42ef-446f-a8cc-1b4ac970d2ef@gmail.com> <20260409041035.GC99725@macsyma-wired.lan> <22cfbf8d-af9b-462e-b240-67a1de24764f@gmail.com> <20260409131238.GC18443@macsyma-wired.lan> Content-Language: en-US From: Anand Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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