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(2403-580d-fda1--299.ip6.aussiebb.net. [2403:580d:fda1::299]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7992d9932edsm13435303b3a.73.2025.10.13.22.13.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Oct 2025 22:14:00 -0700 (PDT) Message-ID: Date: Tue, 14 Oct 2025 15:43:54 +1030 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/1] ovl: Use fsid as unique identifier for trusted origin To: Christoph Hellwig , =?UTF-8?Q?Andr=C3=A9_Almeida?= Cc: linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-dev@igalia.com, Miklos Szeredi , Amir Goldstein , Chris Mason , David Sterba , Anand Jain , "Guilherme G . Piccoli" References: <20251014015707.129013-1-andrealmeid@igalia.com> <20251014015707.129013-2-andrealmeid@igalia.com> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=wqu@suse.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNGFF1IFdlbnJ1byA8d3F1QHN1c2UuY29tPsLAlAQTAQgAPgIbAwULCQgHAgYVCAkKCwIE FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXVgBQkQ/lqxAAoJEMI9kfOh Jf6o+jIH/2KhFmyOw4XWAYbnnijuYqb/obGae8HhcJO2KIGcxbsinK+KQFTSZnkFxnbsQ+VY fvtWBHGt8WfHcNmfjdejmy9si2jyy8smQV2jiB60a8iqQXGmsrkuR+AM2V360oEbMF3gVvim 2VSX2IiW9KERuhifjseNV1HLk0SHw5NnXiWh1THTqtvFFY+CwnLN2GqiMaSLF6gATW05/sEd V17MdI1z4+WSk7D57FlLjp50F3ow2WJtXwG8yG8d6S40dytZpH9iFuk12Sbg7lrtQxPPOIEU rpmZLfCNJJoZj603613w/M8EiZw6MohzikTWcFc55RLYJPBWQ+9puZtx1DopW2jOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXWBBQkQ/lrSAAoJEMI9kfOhJf6o cakH+QHwDszsoYvmrNq36MFGgvAHRjdlrHRBa4A1V1kzd4kOUokongcrOOgHY9yfglcvZqlJ qfa4l+1oxs1BvCi29psteQTtw+memmcGruKi+YHD7793zNCMtAtYidDmQ2pWaLfqSaryjlzR /3tBWMyvIeWZKURnZbBzWRREB7iWxEbZ014B3gICqZPDRwwitHpH8Om3eZr7ygZck6bBa4MU o1XgbZcspyCGqu1xF/bMAY2iCDcq6ULKQceuKkbeQ8qxvt9hVxJC2W3lHq8dlK1pkHPDg9wO JoAXek8MF37R8gpLoGWl41FIUb3hFiu3zhDDvslYM4BmzI18QgQTQnotJH8= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2025/10/14 15:09, Christoph Hellwig 写道: > On Mon, Oct 13, 2025 at 10:57:07PM -0300, André Almeida wrote: >> Some filesystem have non-persistent UUIDs, that can change between >> mounting, even if the filesystem is not modified. To prevent >> false-positives when mounting overlayfs with index enabled, use the fsid >> reported from statfs that is persistent across mounts. > > Please fix btrfs to not change uuids, as that completely defeats the > point of uuids. > That is the temp-fsid feature from Anand, introduced by commit a5b8a5f9f835 ("btrfs: support cloned-device mount capability"). I'm not 100% sure if it's really that important to support mounting cloned devices in the first place, as LVM will reject activating any LVs if there is even conflicting VGs names, not to mention conflicting UUIDs. If temp-fsid is causing problems with overlayfs, I'm happy to remove it, as this really looks like a niche that no one is asking. Yes, mounting cloned devices can be useful for certain cases, but with metadata_uuid changing the uuid should not even take a second, or one can just unregister the previously scanned device. I'd say we paid too much cost for a niche that is not worthy. Thanks, Qu