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Mon, 09 Nov 2026 12:30:41 -0800 (PST) Received: from [172.16.0.229] ([159.196.52.54]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b16769b589sm831706a91.5.2026.11.09.12.30.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Nov 2026 12:30:41 -0800 (PST) Message-ID: <70aa1a4e-895b-416f-a3cb-195af489b55e@suse.com> Date: Tue, 10 Nov 2026 07:00:34 +1030 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] btrfs: reject refs=0 subvolume without DEAD in SUBVOL_SYNC_WAIT To: dsterba@suse.cz Cc: Cheng Yongkang , David Sterba , Chris Mason , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261101062539.1744605-1-teel4res@gmail.com> <20261109184712.GF4186782@twin.jikos.cz> 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 FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJq3ujyBQkUpLw5AAoJEMI9kfOh Jf6o8OIH/0mqW+TQM4m2x3hCsnK+oB4yJH1qnGvIhFF/Lhs48wI02sGh6/4aA0hkCDfd9LHQ +ci4FUepZ9y4VS01+oIExbg/8ytzGYTzLtb44jK2GBOBVSJkMiha6jp22XFt7WUkT/tvbreu WWdGsaJIRQaZChy7xsMI8lqQ2WdmluZJ4LT0wD3l/l6QU1ZseMGySebdY9sVOQEOJNV7Qj92 /KOAFNmeZshV/qDI8Iw1RTs6TvLqCcqmlZLCmJkYSVhT1RonWRren8xIRcFEgMe004IDnt7V qdQhk/nhTS9x9MBAhMRl0TTE1VKDLvVALsud3iZLrmmtYvwPApzGJk052f0m28vOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJq3ukKBQkUzDspAAoJEMI9kfOhJf6o SNsH/1ysUWOKmzY0rGS3ZdS61QgqMGhSWD/EJ4UiPw+xO4l4+GtX0fOAqxqsmBKqje3vyhBa Z5o/1Y+gNiN+E6RBcSz4b1TAd78sQ2bvT5DWOvBjeeVxHdiuQMIn4S8xk5ZpySBw5ifjoiuL 0M33UVtJOzM8yfAeL+d/Rp4leJw72SutjkLyZTG/gJIp4pJGD/kFHn24OLL0IxEcO0gOekNZ os5e1R6jAJ2ILk7+MDnvU8wXHcCiVzuDhJLI1tih1uUIE50muHQJWbYuVBbdJeu8WlIDDssx UOCxLylNG3gDXV5MhLubPTOpp9OiFc/XC37nvkgEcrlmlOFBv4/NJCbECpo= In-Reply-To: <20261109184712.GF4186782@twin.jikos.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/11/10 05:17, David Sterba 写道: > On Sun, Nov 01, 2026 at 05:48:21PM +1030, Qu Wenruo wrote: >> With that said, there are more problems with the ioctl. >> >> - No real user >> No one is utilizing BTRFS_SUBVOL_SYNC* flags. Btrfs-progs itself >> doesn't even bother it. >> >> So all these fixes are very low priority, unless there are some wild >> programs utilizing this. >> >> But even btrfs-progs doesn't utilize them, the possibility are very >> low. > > Obviously the ioctl was added so progs 'subvol sync' can use it for > non-root users. I started working on it but there's a problem with the > behaviour change between the user types. Root has full access and > reports the progress while with this ioctl there were some problems I > don't remember. The ioctl was designed to emulate all modes that root > can do so it should be possible to get 1:1 output. Are you still planning to implement the full root-less subvolume wait in progs? Or is this feature deprecated and we can eventually remove it to reduce LLM bug reports?