From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E9C2E19E7E2; Fri, 22 Aug 2025 23:39:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=212.227.15.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755905962; cv=none; b=ZvYwTc+t+zqPIy9vFXfavVNY7FDSL+/fmm92/NVSLKfMvtJDdNktY2p5cnI84bWltWdQN/aCcZxNzFVrU75t2/PDJpqjmYLB25BQqmzyVD98IujSma0f5FIrS6wcAHZLMb78MjJ9Ay9rrXn2f9xXHq2dPjv72HXqtRc3M9ZRAfE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755905962; c=relaxed/simple; bh=R2/ct0PKs2GPBIiPOE+cpYWQQo6AmiLxuIp2chwI34c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EfgML3O8WijhTjtpBKd6/QXKl/2Ljy5PpOMo/jsOiGkxM9lOvS3L6Xu5pCyzhPFQz2L+Od4TlvZhAeXmpP4C4FUpfOhmT12dNsl4vN+U28ytUQb3GDj15R+HukZqCIWt9ebdtzQxfZWAdoH+TQCpKM753Vtra4QB26i/3reKAn0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gmx.com; spf=pass smtp.mailfrom=gmx.com; dkim=pass (2048-bit key) header.d=gmx.com header.i=quwenruo.btrfs@gmx.com header.b=bGv5IN/A; arc=none smtp.client-ip=212.227.15.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gmx.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmx.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmx.com header.i=quwenruo.btrfs@gmx.com header.b="bGv5IN/A" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmx.com; s=s31663417; t=1755905951; x=1756510751; i=quwenruo.btrfs@gmx.com; bh=3TpI1WJGDbhCoG9ooDv0D78R4NOBKu2kp+Bk6NNmHoA=; h=X-UI-Sender-Class:Message-ID:Date:MIME-Version:Subject:To:Cc: References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding:cc:content-transfer-encoding: content-type:date:from:message-id:mime-version:reply-to:subject: to; b=bGv5IN/AkCF8TOIdNy4ElJ8jp7Txo7J1jhYHLUhgCiKAdElApJo2qGLeq8D6yl3A VSuwYKoqx2Wm45Qj8kLeLV1RYAorlfJeCD3sBzMGGjhwiBvKWEF/6lByH3/zaN9XY rEHgANevEpNpqSrrx3ATpyAOwmV+oEEvvVbx48tLJuLSF5KD1FdoiJxvzw+Rb7aD0 I3K5KCDpzFIR3UHYxQJzS7K3K+2T2zcvDHenlND1SeafnrJhHs8SfbPM9yfEQ57gj AxL9WzzsVPj9fqDutSrlmemN2ppFPcdmhRl1oladAhydOZfxqxJACo2Ncl54AwzAo LaYPw6u3TpPrj3DZzw== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from [172.16.0.229] ([159.196.52.54]) by mail.gmx.net (mrgmx005 [212.227.17.184]) with ESMTPSA (Nemesis) id 1M2wL0-1uoULq3P36-000Ctb; Sat, 23 Aug 2025 01:39:11 +0200 Message-ID: <9cacdafc-98ec-4ad2-99a8-dfb077e4a5fb@gmx.com> Date: Sat, 23 Aug 2025 09:09:06 +0930 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] btrfs: Accept and ignore compression level for lzo To: Calvin Owens Cc: Sun YangKai , clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, neelx@suse.com References: <2022221.PYKUYFuaPT@saltykitkat> <810d2b19-47ed-4902-bd8d-eb69bacbf0c6@gmx.com> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCZxF1YAUJEP5a sQAKCRDCPZHzoSX+qF+mB/9gXu9C3BV0omDZBDWevJHxpWpOwQ8DxZEbk9b9LcrQlWdhFhyn xi+l5lRziV9ZGyYXp7N35a9t7GQJndMCFUWYoEa+1NCuxDs6bslfrCaGEGG/+wd6oIPb85xo naxnQ+SQtYLUFbU77WkUPaaIU8hH2BAfn9ZSDX9lIxheQE8ZYGGmo4wYpnN7/hSXALD7+oun tZljjGNT1o+/B8WVZtw/YZuCuHgZeaFdhcV2jsz7+iGb+LsqzHuznrXqbyUQgQT9kn8ZYFNW 7tf+LNxXuwedzRag4fxtR+5GVvJ41Oh/eygp8VqiMAtnFYaSlb9sjia1Mh+m+OBFeuXjgGlG VvQFzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCZxF1gQUJEP5a0gAK CRDCPZHzoSX+qHGpB/kB8A7M7KGL5qzat+jBRoLwB0Y3Zax0QWuANVdZM3eJDlKJKJ4HKzjo B2Pcn4JXL2apSan2uJftaMbNQbwotvabLXkE7cPpnppnBq7iovmBw++/d8zQjLQLWInQ5kNq Vmi36kmq8o5c0f97QVjMryHlmSlEZ2Wwc1kURAe4lsRG2dNeAd4CAqmTw0cMIrR6R/Dpt3ma +8oGXJOmwWuDFKNV4G2XLKcghqrtcRf2zAGNogg3KulCykHHripG3kPKsb7fYVcSQtlt5R6v HZStaZBzw4PcDiaAF3pPDBd+0fIKS6BlpeNRSFG94RYrt84Qw77JWDOAZsyNfEIEE0J6LSR/ In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:6UQf6AMpa/Kdg769ftIkpTv67MVMrF8U52jg0eXN7HaDPMhL5lF BssB4zlX7tYEE6wwwRuGFnDDO3myGnxaggV2THThuG/Zckptnq0hzoRyGm3/RR8IhQUZT0+ KuCJjbFcI4/q/4qR3EQQEz+YNHpNzH10TEkuH/G9s8D0uJT+NShXY863F0XpDnpf7U196hu Kalucf+IHQXBaF8vkAN5Q== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:F4a+SGPlL6M=;mow3pfuw8PvXuYe7EXhmaj5KPhy oh+wdzHeilchE8YtlyvBXld+PL9z++Za9ypUkiXsF2/mYjK/puQjmMUgNqSGg3KN23wSkwuJC T3Lt6jNJuZxBQTplop2QAel95VsQP9AG1cu+y0XeblHXllNN1xMBjRXzyJbzwIN9FE84MGm0G ITEp5nVZobsRfhHBGVG3gaCW7S0ztylGlLmRYELpDlDDyl3cvlpsP2JlgEj0pOlRpQ1Aod55e 57Y2cWi+U6tFXeWu+4I5xaJRQjfYBZZ5ViTp9PGuqvyjmyOp2KLrQuKbwS6MczdlypCLQbI26 Lsy2sCPLKJHD2Siy8GT5j34NXNJuGECSSogxq46q3VRYZ0KFZIU1HJBAXY7MXgkzzt5kz29/W O97DJdS+L+zX/VyabSS7HACtO62/h+epoXjVGOKgWzz2JRsZCSBXhb5xhL+YB8BeFokHRiD4e nJscyRzVynmPm+UcOdmdN5FLYe/Ma2NJ4GUWN5LK/O2u+KNy0UyfFm+seK5ab+MmOUxDq94mp Q/b4ug1mXBPbF+Fc86r2ftqCYXoOrPRFTD9eyjbIqFn+SSBSrQWP1XlWlmmmDyxEVHKoiyADn wzd6A/UVq2k9Pfw8K6/VD1M6c3Nrc8usjScz9JLcWldYCaAyKaOcfy97EIezxU7vd7Z1/ptWR Ct2bKZIeprxqdEd6GY1BluJkeUFQ+PUv5eq2poLiHBgCORGHEjW+28oPlWN1k4T0gKntf3eQU O28hPckMuxycpEWCJUgcRQPcfbHLPJ+jAYi/t8Cv+AYkcSKBPoTakGF77DvEt8PIxujBuvY4T Ua1I07287K7qt6rucbXUZOPxbVIVaiq49X4Wdx//lWCzUBmJPN8uVTtIsSuKwReKH53u/K6bD 6hXbgkux18WmT1YpfDGBpI+p0vHe8CGurArht8SCHD47xejUzYVKLlKtw0ZASUf/6dXiXCWw3 fVlau3j/MCQ5p+xQL+zWI2NkkROhD2iztkEa8NpCyetO+oMZMQMrzYu7cPGg7c14QjZLUJnvM hBG9cwaNT4Slh2Vxh6H0Kt0WGAuzOp7qwurU5ZZhQHkuPYPchSk2/7XgDOmh7xvYOEKI5W796 4TMxEH4B7zKAoqcXbcfzX/sNZRpNaGW+2LLmSlpcTdBYGgA9GMesED1eT461izQbn2Ra0plz+ lMxtSDKlw/W2dVQRJ7cHeVix0hBneZbtQDtsJcV9xEj8ptcWc4fkP81qYKPMnMUD+fqAqrRKs D6R5581O3ozV5vtthmr99y8jp2P2O03l/VudsYJVKpPZT5H6Vney4nGvM5/TOepJIHVsi1VIm K4WCM6KLeY1vMkrTYsv2LPbJ0wmFB05r06818J1YF94nNiWk045OkjoKw33DoyDBwKFOIVZ13 qaqK04zLm/VelXRbjBKCexVmSjnA6AJ6YNxiaSmqP5oz2vrkW2pEjGeQKGs1GkQSK6FxkYnIB fmGz03BLQwpKNYKYax1ym0ygejLWPSu382KUarA1kiB/oNTXwL5uLCKTnWoU+djI1veiD3ruo 3r7HyP9Cxjsm+DZ0hDObWbUJLnR1h5YEF+JlvkdzUHQY5+5VD0COzrTan+WTQsEkOt+0KXE5F PvdmUgKNb2YUcccO5xh62FIjXj5Z5GUyg3zgIufHzkVd2rBQ4woZCMK64pfTzdXiXxC/RatFX PmAqJcAFoDRR5/sdJY+UHcnqpjZAWelzo5wSScH2QyvVUk2S+rFqjtjCN2VnH6AoQKKb+SLA+ ERp0SSZvnYno9jgOCFh6+6oA8YKZokwUhnUCaZZcJPLUzrQ8/dOyYle0R/fMxjGC28wxVE1Kf zJ7fotqpTaJe8b36PkVy5agiAQWBH5t/cJ4MWL6oyllYSmOX13a97RMF2a2eDh3xME6djxpP3 qeO25P6F07Uo0S9gPkfUn4gcw3uB6ALBqwDIoZF+IwF8jZMiHIEg5/DsJHdkXa5gw4S/RGqVq tIUUXKd/e4V+3wwbS75nVyetCznAwfH9QJbijDm8frHP6jZMo72/Q8Lu/MFEjhKT3f17QhGxF 9KmF9qngHc6Fn7ZfSqmMv4KN2NlbRQWhXIkDSRKVCfV78tqJ9fIAm10feazXJMvAFM/41EcCD 9wNIeAjdIHpssNj45PR+s7pE3PLhaX3YIEUyouILy+rGxzlxNY8W02b6SiOrgaWGRtf6YNhG2 NtsfPUArf3JO9518JzHJGLupcFrB7fc1WVFXT1ptPmB+yVFRlukBBbpUFJG8dphoCnaKvCZx5 2CzYY4eBen22L9Tvh3vE+vpOEqQlrrOAHLs/U1glluKCYAGglBcOUj9yCz6sXAb6EfzO23je9 6EgeOFBTAZvEByQ8rKCApULbr1PY9aeFRbt6AVyVfmAbTi+8LG2/ZKRmOXmB5KpScL5Q/BcMW OZLOoJVvBzQaLEiOlMaPLfrvTWP29BfuqcNtpiqYplNW3w7dQlgbwKDHgn1UB4gQMMKjUO7wH 5z64BKH4cBqlySGdRGvEnqGMiqpLXAEWgfj7kDdijp0mt6NMbhBeo0fD6VvY34ZUNYp72LhZL P62jB6jhyGpBTymtT65f7k3plWPHFnlCzx8HKS/k+wzGxel7IWp8nF1y2APHVXfGCGegzJ/Z5 VhwLPVqYjtxx4oSg2sWILN+TlzKlKylZqJjnB0dQc2zS1LApHZ8mYn1/9awIw2yumeuwPCX7h TSAym33U8SPcsAfhsirVYwGqY7g2lLw386vQAlV+FKNrpfYpcZ+L3SYucSSdya7YezjTjTiPP EyNgtACU4Fjzk1vEOX7vvEGHx6EVmQAc0YnUzd1OAO/n9xqv+SVafWPgnWX7R/Ia/5opOd8eh DRs8V/wNFMFXl32PZPzHE2PCMb7yAeX9BKryLZGtY6CNIBRKzY+gjD8ytv8KQpYXeKiyOr8Ox ATicFVKr7igYMhqJNi9/qA36WfXtETG6mdULXXIJJsCIuHYROMjQQ4YFTQs1d4OLMCYGON2tZ ahd5KWhUUnxUa8z91KXr/gIObPpZnvVD13COFWZhtl4iYtQ8FmnFXBDFREe4UoatcrRR2+0RD a6cesBQGRJzzkw0vVrtZl+/hy7gDWKzz5sCwaFW9zvwvax/fdgjO3+kPoxCaBLM5At9j/SiZP 0FVl53V8eVTiPK5R2U+1DyLqV6wCeQf2FrMP4vMuIuWmWT/hyBuRNv8r7qLWMSHBmxDcu7Cxu sDMs3ZrHxqKrIzZ1xCtVblwqktN+bafbkreBYHXq967/RkCFW5k7lJDKlwVfhP97Kr1hLi4YB MUOBqPOG68mrn89u0dXjczZ/IXejO31D5/KFkJweWsvLsSAsCQI0VtTBryH5Uzdyl1KQkXp7r c7MhYJt7+gt0HiRg/yqLymDfbDwrHtHnHvlzFF1XsksZ+j7EiR38nMaUfu5zcfX2XFIP2t5b+ nd1Ef0EUxlqbRzHXULx6Mp5S+U8mRbh84W4RMo9jHkB8jQyGxq9YWkyEXZJm0mY+LYQCergBB yjWmSqYdprvctTB2hcUOMeU+cYyXefv5PpFYe/HQhIj5gEx6QymzqJ7ot2IVagj4LF/t88P6u g9B+OriTBInIyb5bpPH56NixsFX8noERMntvN0bwafaKV9va46+bbQS0VnNK6KfPrbJCnD55g xk0o7EcVY7/WH9VltCVGeh0vrcNV+0LkvsnxpajvtrYAde4wS7HDFdOECMChZ2htZiJk7d+sK pxBQNOfEFv/pi8BckC3GUMELg2u6Lvo09JFDfc3yKYweDMv6CXpofxrqUQOr+phYL4Zd1aJMg jdlAgcy9/8O3/IK87IiIBTKstxHCiMf60slUaHx56Hxpz3sNVcpk/P9AuTALQRgUIyfVpOvdp JFo7H2/7mka2z7V8fS+3mpJDhyT6/3plWAKjaH1JnJ2Dr0O2AyfhS4SvJbLMokA6SNqUO3Ttu fSs/RwOVv83MTpdT/ZSP0BemJWA3uHUyX3RfMzqKzvAHzU9r8CQGHsE+u+SSC8pFb22uuMUt7 0cDX28LAfnQ3doSI2lMK0gn4g7zfPZXEI5oyxjHSs4BURau5egY44dyf2iyYAiF7x/kUmyw4p woeYGoXlBcVRAshi1pylW7CvX/juaZJQeMX+f2vbpBP2kqEGkZSsnL/VhSrttxIb4ozOjqPIm YgRbVhKcvJZkIKZ9T5Ypv70cbrzvP8vyT1GQzlvBx/v4rSdY5QFnetal113Awt797hKwhgYjP f2AKn4Yocn3LWFJ2XGr/OuIK+V1xdLKq/46mTQaxWO/PoDkjNdkF9l6YOPeNdi4EU6E2FXTw8 XUHRX5vfcSThionXIcWDu4L0X+DH8UKC1jwkHFBqoIQAhxDf2AvscFEaG6GpVG3Ns7DkMM7h2 eY2QHoqDWBdDm0LaZzgX770mx6DqEJF4zqRm0gQ/YkJlvbjnEUbca3grPh2lzpCxuqlUcDZV1 dcy+wRPqwAHidQwWh71qO7kSJ/SsphU0OdLv5ItVM4UeX8QP6BtEkFEBHom/G0OLGWrZ3JiP9 EOUX5gw0pvVkdtcAsihdy6j/I3nSFOk1xAWqlnKEUlzZXOmO221oNHKa3ObAA1ai9UvARRMZz AdT5MBYRVC1wnzFrIhqOR8PSBLic9hz7xvNgEdZUgyprcMaHuDowcdVRyrHhtf1yIYuY2guS4 M8ZjeDMjCyJu7cof904UNjqvt5RQaz22rCjq93Haw+bWtFy0QvgFVpXFeJj/P/XeTR3tmVsbI +2N+eJ24JOjCuTyNckWf55sZ1exGy8MbXpwbN9OWgggMW1tT50ig62aP2Ke/h17eOEDUtt0= =E5=9C=A8 2025/8/23 08:54, Calvin Owens =E5=86=99=E9=81=93: > On Saturday 08/23 at 07:14 +0930, Qu Wenruo wrote: >> =E5=9C=A8 2025/8/23 01:24, Calvin Owens =E5=86=99=E9=81=93: >>> On Friday 08/22 at 19:53 +0930, Qu Wenruo wrote: >>>> =E5=9C=A8 2025/8/22 19:50, Sun YangKai =E5=86=99=E9=81=93: >>>>>> The compression level is meaningless for lzo, but before commit >>>>>> 3f093ccb95f30 ("btrfs: harden parsing of compression mount options"= ), >>>>>> it was silently ignored if passed. >>>>>> >>>>>> After that commit, passing a level with lzo fails to mount: >>>>>> BTRFS error: unrecognized compression value lzo:1 >>>>>> >>>>>> Restore the old behavior, in case any users were relying on it. >>>>>> >>>>>> Fixes: 3f093ccb95f30 ("btrfs: harden parsing of compression mount o= ptions") >>>>>> Signed-off-by: Calvin Owens >>>>>> --- >>>>>> >>>>>> fs/btrfs/super.c | 2 +- >>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c >>>>>> index a262b494a89f..7ee35038c7fb 100644 >>>>>> --- a/fs/btrfs/super.c >>>>>> +++ b/fs/btrfs/super.c >>>>>> @@ -299,7 +299,7 @@ static int btrfs_parse_compress(struct btrfs_fs= _context >>>>>> *ctx,> >>>>>> btrfs_set_opt(ctx->mount_opt, COMPRESS); >>>>>> btrfs_clear_opt(ctx->mount_opt, NODATACOW); >>>>>> btrfs_clear_opt(ctx->mount_opt, NODATASUM); >>>>>> >>>>>> - } else if (btrfs_match_compress_type(string, "lzo", false)) { >>>>>> + } else if (btrfs_match_compress_type(string, "lzo", true)) { >>>>>> >>>>>> ctx->compress_type =3D BTRFS_COMPRESS_LZO; >>>>>> ctx->compress_level =3D 0; >>>>>> btrfs_set_opt(ctx->mount_opt, COMPRESS); >>>>>> >>>>>> -- >>>>>> 2.47.2 >>>>> >>>>> A possible improvement would be to emit a warning in >>>>> btrfs_match_compress_type() when @may_have_level is false but a >>>>> level is still provided. And the warning message can be something li= ke >>>>> "Providing a compression level for {compression_type} is not support= ed, the >>>>> level is ignored." >>>>> >>>>> This way: >>>>> 1. users receive a clearer hint about what happened, >>>> >>>> I'm fine with the extra warning, but I do not believe those kind of u= sers >>>> who provides incorrect mount option will really read the dmesg. >>>> >>>>> 2. existing setups relying on this behavior continue to work, >>>> >>>> Or let them fix the damn incorrect mount option. >>> >>> You're acting like I'm asking for "compress=3Dlzo:iamafancyboy" to kee= p >>> working here. I think what I proposed is a lot more reasonable than >>> that, I'm *really* surprised you feel so strongly about this. >> >> Because there are too many things in btrfs that are being abused when i= t was >> never supposed to work. >> >> You are not aware about how damaging those damn legacies are. >> >> Thus I strongly opposite anything that is only to keep things working w= hen >> it is not supposed to be in the first place. >> >> I'm already so tired of fixing things we should have not implemented a >> decade ago, and those things are still popping here and there. >> >> If you feel offended, then I'm sorry but I just don't want bad examples >> anymore, even it means regression. >=20 > I'm not offended Qu. I empathize with your point of view, I apologize if > I came across as dismissive earlier. >=20 > I think trivial regression fixes like this can actually save you pain in > the long term, when they're caught as quickly as this one was. I think > this will prevent a steady trickle of user complaints over the next five > years from happening. >=20 > I can't speak for anybody else, but I'm *always* willing to do extra > work to deal with breaking changes if the end result is that things are > better or simpler. This just seems to me like a case where nothing > tangible is gained by breaking compatibility, and nothing is lost by > keeping it. >=20 > I'm absolutely not arguing that the mount options should be backwards > compatible with any possible abuse, this is a specific exception. Would > clarifying that in the commit message help? I understand if you're > concerned about the "precedent". Then I'm fine with a such patch, but still prefer a warning (not WARN(),= =20 just much simpler btrfs_warn()) line to be shown when a level is=20 provided for lzo. Furthermore, since we already have something like btrfs_lzo_compress=20 indicating the supported level, setting to the proper default value=20 would be better. (Already done by btrfs_compress_set_level() call in=20 your v2 patch). BTW, since you mentioned something like "compress=3Dlzo:asdf",=20 btrfs_compress_set_level() just ignores any kstrtoint() error, allowing=20 things like "compress=3Dzstd:invalid" to pass the option parsing. I can definitely send out something to enhance that check, but just want= =20 to be sure, would you opposite such extra sanity checks? Thanks, Qu >=20 >>> In my case it was actually little ARM boards with an /etc/fstab >>> generated by templating code that didn't understand lzo is special. >>> >>> I'm not debating that it's incorrect (I've already fixed it). But give= n >>> that passing the level has worked forever, I'm sure this thing sitting >>> on my desk right now is not the only thing in the world that assumed i= t >>> would keep working... >>> >>>> I'm fine with warning, but the mount should still fail. >>>> Or those people will never learn to read the doc. >>> >>> The warning is pointless IMHO, it's already obvious why it failed. My >>> only goal was to avoid breaking existing systems in the real world whe= n >>> they upgrade the kernel. >>> >>> If you'd take a patch that makes it work with a WARN(), I'll happily >>> send you that. But I'm not going to add the WARN() and keep it failing= : >>> if that's all you'll accept, let's just drop it. >>> >>> Thanks, >>> Calvin >>> >>>>> 3. the @may_have_level semantics remain consistent. >>>>> >>>>> >>> >> >=20