From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f172.google.com ([209.85.213.172]:37331 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754071AbbK3O7w (ORCPT ); Mon, 30 Nov 2015 09:59:52 -0500 Received: by igcto18 with SMTP id to18so72431704igc.0 for ; Mon, 30 Nov 2015 06:59:51 -0800 (PST) Subject: Re: Bug/regression: Read-only mount not read-only To: Hugo Mills , Btrfs mailing list References: <20151128134634.GF24333@carfax.org.uk> From: Austin S Hemmelgarn Message-ID: <565C645C.5030608@gmail.com> Date: Mon, 30 Nov 2015 09:59:40 -0500 MIME-Version: 1.0 In-Reply-To: <20151128134634.GF24333@carfax.org.uk> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms060800060808080807050002" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms060800060808080807050002 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-11-28 08:46, Hugo Mills wrote: > We've just had someone on IRC with a problem mounting their FS. The= > main problem is that they've got a corrupt log tree. That isn't the > subject of this email, though. > > The issue I'd like to raise is that even with -oro as a point > option, the FS is trying to replay the log tree. The dmesg output from > mount -oro is at the end of the email. > > Now, my memory, experience and understanding is that the FS > doesn't, and shouldn't replay the log tree on a RO mount, because the > FS should still be consistent even without the reply, and > RO-means-actually-RO is possible and desirable. (Compared to a > journalling FS, where journal replay is required for a consistent, > usable FS). This is exactly how it should behave (being able to say that a RO mount=20 is really RO (if atimes aren't enabled) is a huge selling point). On a=20 side note, a properly designed journaling filesystem _can_ be made to=20 behave like this, but it makes the filesystem _really_ slow if you don't = have enough RAM to cache all the blocks modified by the journal (because = each block access has to check the journal for modifications). > > So, this looks to me like a regression that's come in somewhere. I'm not sure that this ever worked the way it should. It should be=20 fixed regardless of what state things were however. --------------ms060800060808080807050002 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgMFADCABgkqhkiG9w0BBwEAAKCC Brgwgga0MIIEnKADAgECAgMRLfgwDQYJKoZIhvcNAQENBQAweTEQMA4GA1UEChMHUm9vdCBD QTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNp Z25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcwHhcN MTUwOTIxMTEzNTEzWhcNMTYwMzE5MTEzNTEzWjBjMRgwFgYDVQQDEw9DQWNlcnQgV29UIFVz ZXIxIzAhBgkqhkiG9w0BCQEWFGFoZmVycm9pbjdAZ21haWwuY29tMSIwIAYJKoZIhvcNAQkB FhNhaGVtbWVsZ0BvaGlvZ3QuY29tMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEA nQ/81tq0QBQi5w316VsVNfjg6kVVIMx760TuwA1MUaNQgQ3NyUl+UyFtjhpkNwwChjgAqfGd LIMTHAdObcwGfzO5uI2o1a8MHVQna8FRsU3QGouysIOGQlX8jFYXMKPEdnlt0GoQcd+BtESr pivbGWUEkPs1CwM6WOrs+09bAJP3qzKIr0VxervFrzrC5Dg9Rf18r9WXHElBuWHg4GYHNJ2V Ab8iKc10h44FnqxZK8RDN8ts/xX93i9bIBmHnFfyNRfiOUtNVeynJbf6kVtdHP+CRBkXCNRZ qyQT7gbTGD24P92PS2UTmDfplSBcWcTn65o3xWfesbf02jF6PL3BCrVnDRI4RgYxG3zFBJuG qvMoEODLhHKSXPAyQhwZINigZNdw5G1NqjXqUw+lIqdQvoPijK9J3eijiakh9u2bjWOMaleI SMRR6XsdM2O5qun1dqOrCgRkM0XSNtBQ2JjY7CycIx+qifJWsRaYWZz0aQU4ZrtAI7gVhO9h pyNaAGjvm7PdjEBiXq57e4QcgpwzvNlv8pG1c/hnt0msfDWNJtl3b6elhQ2Pz4w/QnWifZ8E BrFEmjeeJa2dqjE3giPVWrsH+lOvQQONsYJOuVb8b0zao4vrWeGmW2q2e3pdv0Axzm/60cJQ haZUv8+JdX9ZzqxOm5w5eUQSclt84u+D+hsCAwEAAaOCAVkwggFVMAwGA1UdEwEB/wQCMAAw VgYJYIZIAYb4QgENBEkWR1RvIGdldCB5b3VyIG93biBjZXJ0aWZpY2F0ZSBmb3IgRlJFRSBo ZWFkIG92ZXIgdG8gaHR0cDovL3d3dy5DQWNlcnQub3JnMA4GA1UdDwEB/wQEAwIDqDBABgNV HSUEOTA3BggrBgEFBQcDBAYIKwYBBQUHAwIGCisGAQQBgjcKAwQGCisGAQQBgjcKAwMGCWCG SAGG+EIEATAyBggrBgEFBQcBAQQmMCQwIgYIKwYBBQUHMAGGFmh0dHA6Ly9vY3NwLmNhY2Vy dC5vcmcwMQYDVR0fBCowKDAmoCSgIoYgaHR0cDovL2NybC5jYWNlcnQub3JnL3Jldm9rZS5j cmwwNAYDVR0RBC0wK4EUYWhmZXJyb2luN0BnbWFpbC5jb22BE2FoZW1tZWxnQG9oaW9ndC5j b20wDQYJKoZIhvcNAQENBQADggIBADMnxtSLiIunh/TQcjnRdf63yf2D8jMtYUm4yDoCF++J jCXbPQBGrpCEHztlNSGIkF3PH7ohKZvlqF4XePWxpY9dkr/pNyCF1PRkwxUURqvuHXbu8Lwn 8D3U2HeOEU3KmrfEo65DcbanJCMTTW7+mU9lZICPP7ZA9/zB+L0Gm1UNFZ6AU50N/86vjQfY WgkCd6dZD4rQ5y8L+d/lRbJW7ZGEQw1bSFVTRpkxxDTOwXH4/GpQfnfqTAtQuJ1CsKT12e+H NSD/RUWGTr289dA3P4nunBlz7qfvKamxPymHeBEUcuICKkL9/OZrnuYnGROFwcdvfjGE5iLB kjp/ttrY4aaVW5EsLASNgiRmA6mbgEAMlw3RwVx0sVelbiIAJg9Twzk4Ct6U9uBKiJ8S0sS2 8RCSyTmCRhJs0vvva5W9QUFGmp5kyFQEoSfBRJlbZfGX2ehI2Hi3U2/PMUm2ONuQG1E+a0AP u7I0NJc/Xil7rqR0gdbfkbWp0a+8dAvaM6J00aIcNo+HkcQkUgtfrw+C2Oyl3q8IjivGXZqT 5UdGUb2KujLjqjG91Dun3/RJ/qgQlotH7WkVBs7YJVTCxfkdN36rToPcnMYOI30FWa0Q06gn F6gUv9/mo6riv3A5bem/BdbgaJoPnWQD9D8wSyci9G4LKC+HQAMdLmGoeZfpJzKHMYIE0TCC BM0CAQEwgYAweTEQMA4GA1UEChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNl cnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcN AQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DANBglghkgBZQMEAgMFAKCCAiEwGAYJKoZI hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUxMTMwMTQ1OTQwWjBPBgkq hkiG9w0BCQQxQgRAHmIz1/Y24ZTR+CwUKZwYHVuINrNEAG5t2OU5pryqHo1iNUKoqMiAhO3e dskh/Zx1XWmZYvF3goQdhdGIJwmQ3DBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxEt+DCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DAN BgkqhkiG9w0BAQEFAASCAgAuFCqm4pH3MXDQb1iBq24rboaWqtEOWw9BQAV6RKkwWiDZNQbV u3aFphrlGNY0oprS+D4CpwQ+l1OJ1cxxPwbDSBhKKDJf8upTS0sjRgX5atLmr4RZwrt96d6e fkqhY1Zi3YchWGzFQjigbhtRnpPBWs9EZzqM7OOsq8s+OQ2QCMC+5Z7ZyawYaeKXrt8K4Xui KTw1CHn/kcLK02mnKvVZxD4adbqa6qpEZU7DCDG2aXqusLEAh2pv2X0LyBmjvomZk+BcgykE zD8ojrUt+igcGSuTpWd/Hj8IAS4DQdOSS+06PUNbi8b3TaDaBFhGf42jJ64/pkhg5RyIQ5Ys PxwqPMA0Evrm2RG+7KNEBOTU5slFv1VBJHZzPVp453+XtpSzIosUcbr91P/V/rhvRBRwNh6J RaKabqX4Akiep/ucPoWb/l63Km6evcU8jmRaEHjfa7jm+dMTpgW1FeyLgeVMo2XIT5KalfKf qxsAAe/p6D9EzkTufHzth5b/7z+/deSVQa0iZ9tFmv4RC1HIq2bmqMvNw8lQ1oMw6Cu4pf1e oAr3SI0iS+DSc+2/iX+ZC2/tYUigHp55+1SWn809HoPqbJ5nnx733/Kv7KojUr1Uh4TNJBCg tSv6RhDY8/sS8OdtpPk+9z39qZ/tBZTJs3vXm36xpgvmWA/rzJNDca9c8QAAAAAAAA== --------------ms060800060808080807050002--