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Mon, 24 Dec 2018 14:02:48 +0100 Subject: Re: Mount issue, mount /dev/sdc2: can't read superblock To: =?UTF-8?B?VG9tw6HFoSBNZXRlbGth?= Cc: Peter Chant , Chris Murphy , Btrfs BTRFS References: <1aa82e28-3331-bc64-071c-6cf87b08ad94@petezilla.co.uk> <3b4d0ed3-4151-50b9-b1da-6be240bb58b3@petezilla.co.uk> <99716398-e99c-6ee9-e256-6d05fdc48122@petezilla.co.uk> <0024a4b2-7117-8d76-45c5-240e23edc29b@gmx.com> <5670f5ac-b9e9-8bed-67ee-d113a385a304@metaliza.cz> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0IlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT6JAVQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWCnQUJCWYC bgAKCRDCPZHzoSX+qAR8B/94VAsSNygx1C6dhb1u1Wp1Jr/lfO7QIOK/nf1PF0VpYjTQ2au8 ihf/RApTna31sVjBx3jzlmpy+lDoPdXwbI3Czx1PwDbdhAAjdRbvBmwM6cUWyqD+zjVm4RTG rFTPi3E7828YJ71Vpda2qghOYdnC45xCcjmHh8FwReLzsV2A6FtXsvd87bq6Iw2axOHVUax2 FGSbardMsHrya1dC2jF2R6n0uxaIc1bWGweYsq0LXvLcvjWH+zDgzYCUB0cfb+6Ib/ipSCYp 3i8BevMsTs62MOBmKz7til6Zdz0kkqDdSNOq8LgWGLOwUTqBh71+lqN2XBpTDu1eLZaNbxSI ilaVuQENBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAGJATwEGAEIACYWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWBrwIbDAUJA8JnAAAK CRDCPZHzoSX+qA3xB/4zS8zYh3Cbm3FllKz7+RKBw/ETBibFSKedQkbJzRlZhBc+XRwF61mi f0SXSdqKMbM1a98fEg8H5kV6GTo62BzvynVrf/FyT+zWbIVEuuZttMk2gWLIvbmWNyrQnzPl mnjK4AEvZGIt1pk+3+N/CMEfAZH5Aqnp0PaoytRZ/1vtMXNgMxlfNnb96giC3KMR6U0E+siA 4V7biIoyNoaN33t8m5FwEwd2FQDG9dAXWhG13zcm9gnk63BN3wyCQR+X5+jsfBaS4dvNzvQv h8Uq/YGjCoV1ofKYh3WKMY8avjq25nlrhzD/Nto9jHp8niwr21K//pXVA81R2qaXqGbql+zo Message-ID: Date: Mon, 24 Dec 2018 21:02:42 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <5670f5ac-b9e9-8bed-67ee-d113a385a304@metaliza.cz> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="sVu9HiNKMOQqLHxyr5kIpnuo3bX9xoEDl" X-Provags-ID: V03:K1:Wo8vIsZw+LF2qLz0rhR60ov3uLHsoqcfSE5ComILPOStoF+FGtl 3wkvGTKwG9fKjEbsL9wZ8YGf1vXd7TFMAlI3Tv+9CWcT/zMJMlmg69gFy+Bh/E9HKS1Jfxw 2OqDlSThtAEeW7SV2FxApdATOZWBnUKl0cA/g3ndTLt18GXjfMbMJBfbdfPyKODjfj7glxZ h91Uj3k2RBbbYm13k06cw== X-UI-Out-Filterresults: notjunk:1;V03:K0:6mrQvRh5Uh0=:L+jp4OsYHZ9akjS55fKfNF HLGZOTq3Di2QFQJrTR1NKk95G9lT3KnGFrympaMwaCEL8LZ/kUaxDmsEx154z4ezzHuGmCIcF 86F4ArWfIkBsQMtOSrUBQqRtflPpmvjLRBFLIM80tCK2ZQsChBiz/9WJSBpm0jrqbndRj7lns QmpqL3r4a8UkP17nrWC5tK1JI+Ep9rmdkQbDFcW2+F7cz2WK0YZMjn25JNeu93gSiC0+PIhb1 nAz189BKMJs8SYuVIvk2SJ+Kj+k8JmpKRKAxRHGZaj4zKXlGR0kzsAh5QtZKxyqi9F+jvqLVe nn/43rO5TLXdXmlkc5Ouwb8b377CW9am0k2b1UisAlzS9WNqJVLd0Egn/JM1+gd67dmfZBVcT NtC+e0nXg9L5GduhMlWB6v+93K7dzNaHklj2qqoLUQSq+FgAqbxrm12yrjAGtE5Jg247KAQOz a5jrRVGqyf8wQANQriRmwJddRraQbi72+5mn8w89uHEtjVfR0dSZxTgtOZxabhSljuYDqi01Y P96p7sypNgvDkH/I8fgwvu0ol7SFtIswfW6QigvukrEqxL6QP9xzshBBJLv7nk4U5QcbEQzSF XIKokfjzc8JKjwm72Cij1y8k+LfXV3RD78SWjIJ2BGvNkqaDYHhtZTcIUoWGjneTScQUWYIac hRzQTYJrX1pizmIGb5BTxWBeyt4ALoyDcthHO/v24Cm+UbfFm94ZOi+1RzT2RLaNQMnrXFMuh XHuLpPfx0MNzE6lHHwoweHyRRsyQ3RW4JNbovazkhkq6vvxJgCxGpy79MkYRB/NutaIkGkhlh a0Y/llCxvyxwUAJkPWsSNLXeR110gEZig3jkjUU5g3+hQI4XIqnOHAU5D3LH81WhJxMnmiJvp j5GUVuqWV5A0X99fYp+vney0ZT4JE3t4CTFR62lXXkwoM/gVxrZRGi7NXRs7kE Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --sVu9HiNKMOQqLHxyr5kIpnuo3bX9xoEDl Content-Type: multipart/mixed; boundary="p0LC1ianXcgTBD6xztXFcRCt4dEAtw1as"; protected-headers="v1" From: Qu Wenruo To: =?UTF-8?B?VG9tw6HFoSBNZXRlbGth?= Cc: Peter Chant , Chris Murphy , Btrfs BTRFS Message-ID: Subject: Re: Mount issue, mount /dev/sdc2: can't read superblock References: <1aa82e28-3331-bc64-071c-6cf87b08ad94@petezilla.co.uk> <3b4d0ed3-4151-50b9-b1da-6be240bb58b3@petezilla.co.uk> <99716398-e99c-6ee9-e256-6d05fdc48122@petezilla.co.uk> <0024a4b2-7117-8d76-45c5-240e23edc29b@gmx.com> <5670f5ac-b9e9-8bed-67ee-d113a385a304@metaliza.cz> In-Reply-To: <5670f5ac-b9e9-8bed-67ee-d113a385a304@metaliza.cz> --p0LC1ianXcgTBD6xztXFcRCt4dEAtw1as Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2018/12/24 =E4=B8=8B=E5=8D=888:48, Tom=C3=A1=C5=A1 Metelka wrote: > Hi Qu, >=20 > just 1 curious question (maybe 2) about your statement "log_root is 0":= >=20 > What does it mean when log_root is non-zero? This means there are some dirty log, namely caused by fsync(). You could consider log tree as some kind of journal used in ext/xfs. Btrfs doesn't rely on log tree to keep its metadata consistent, but uses it as a faster way to implement fsync(). For fs with dirty log, btrfs itself should be consistent no matter if we replay the log or not. The only certain thing a non-zero log tree shows is, there is definitely an unexpected powerloss happened. (But not vice verse, it's completely possible to hit a unexpected powerloss without a dirty log, either it's lucky that no fsync() called during that trans, or notreelog mount option is used) > Because I have similar > problem (unmountable FS ... I don't know how much but I know there's > corrupted 2 subsequent items in chunk tree node) Then the problem is not related to log root. But either chunk tree get corrupted or metadata cow get exploited. > and when I have made > "btrfs inspect-internal dump-super": >=20 > superblock: bytenr=3D65536, device=3D/dev/sda4 > ... > generation=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 2488742 > root=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = 232408301568 > sys_array_size=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 97 > chunk_root_generation=C2=A0=C2=A0=C2=A0 2487902 > root_level=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 1 > chunk_root=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 242098421760 > chunk_root_level=C2=A0=C2=A0=C2=A0 1 > log_root=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 232433811456 log_root is only recorded in the primary super block. So it's fine that your backup super block doesn't contain log root. It's the designed behavior. > log_root_transid=C2=A0=C2=A0=C2=A0 0 > log_root_level=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 0 >=20 > superblock: bytenr=3D67108864, device=3D/dev/sda4 > ... > generation=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 2488742 > root=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = 232408301568 > sys_array_size=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 97 > chunk_root_generation=C2=A0=C2=A0=C2=A0 2487902 > root_level=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 1 > chunk_root=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 242098421760 > chunk_root_level=C2=A0=C2=A0=C2=A0 1 > log_root=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 0 > log_root_transid=C2=A0=C2=A0=C2=A0 0 > log_root_level=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 0 >=20 > Unfortunately when I try to do "btrfs rescue chunk-recover" I get > (beside others): >=20 > "... >=20 > Unrecoverable Chunks: > =C2=A0 Chunk: start =3D 0, len =3D 4194304, type =3D 2, num_stripes =3D= 1 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Stripes list: > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 [ 0] Stripe: devid =3D 1, offset =3D 0 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 No block group. > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 No device extent. >=20 > Total Chunks:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 184 > =C2=A0 Recoverable:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 183 > =C2=A0 Unrecoverable:=C2=A0=C2=A0=C2=A0 1 >=20 > Orphan Block Groups: >=20 > Orphan Device Extents: >=20 > Chunk tree recovery failed > " >=20 > And when I try "btrfs restore -m -S -v -i -D " I get only: > Could not open root, trying backup super > Could not open root, trying backup super > ERROR: superblock bytenr 274877906944 is larger than device size > 212000047104 > Could not open root, trying backup super >=20 > Is it possible to recover data (at least some of them)? And is it worth= > to upgrade to newest btrfs-progs? btrfs check --readonly output please. btrfs check --readonly is always the most reliable and detailed output for any possible recovery. Also kernel message for the mount failure could help. btrfs ins dump-tree/super is only useful when we have some ideas to verif= y. Thanks, Qu >=20 > uname -a: > Linux tisc5 4.15.0-43-generic #46-Ubuntu SMP Thu Dec 6 14:45:28 UTC 201= 8 > x86_64 x86_64 x86_64 GNU/Linux >=20 > btrfs-progs v4.15.1 >=20 > Thanks > Metaliza >=20 >=20 > On 24. 12. 18 13:02, Qu Wenruo wrote: >> >> >> On 2018/12/24 =E4=B8=8B=E5=8D=887:31, Peter Chant wrote: >>> On 12/24/18 12:58 AM, Chris Murphy wrote: >>>> On Sat, Dec 22, 2018 at 10:22 AM Peter Chant >>>> wrote: >>>> >>>>> btrfs rescue super -v /dev/sdb2 >>>> ... >>>>> All supers are valid, no need to recover >>>>> >>>>> >>>>> btrfs insp dump-s -f >>>> ... >>>>> generation=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 7937947 >>>> ... >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 backup 0: >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 backup_tree_root:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 1113909100544=C2=A0=C2=A0 gen: >>>>> 7937935=C2=A0=C2=A0=C2=A0 level: 1 >>>> ... >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 backup 1: >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 backup_tree_root:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 1113907347456=C2=A0=C2=A0 gen: >>>>> 7937936=C2=A0=C2=A0=C2=A0 level: 1 >>>> ... >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 backup 2: >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 backup_tree_root:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 1113911951360=C2=A0=C2=A0 gen: >>>>> 7937937=C2=A0=C2=A0=C2=A0 level: 1 >>>> ... >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 backup 3: >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 backup_tree_root:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 1113907494912=C2=A0=C2=A0 gen: >>>>> 7937934=C2=A0=C2=A0=C2=A0 level: 1 >>>> ... >>>> >>>> >>>> The kernel wrote out three valid checksummed supers, with what seems= >>>> to be a rather significant sanity violation. The super generation an= d >>>> tree root address do not match any of the backup tree roots. The >>>> *current* tree root is supposed to be in one of the backups as well.= >>>> >>> >>> I wonder if this is a result of my trying to fix things?=C2=A0 E.g. b= trfs >>> rescue super-recover or my attempts using the tools (and kernel) in M= int >>> 18.1 at one point? >> >> At least super-recover is not responsible for this. >> While btrfs check --repair could indeed cause problems. >> >> So it may be the case. >> >>> >>> I must admit, early on I had assumed that either this file system was= a >>> simple fix or was completely trashed, so I thought I'd have a quick g= o >>> at fixing it, or wipe it and start again.=C2=A0 But then I seemed to = get >>> close with only the one error, but unmountable. >>> >>> >>>> Qu, any idea how this is even theoretically possible? Bit flip right= >>>> before the super is computed and checksummed? Seems like some kind o= f >>>> corruption before checksum is computed. >>>> >>>> >>>>> I'm getting suspicious of the drive as when I was trying the variou= s >>>>> btrfs rescue * tools I saw a 'bad block', or similar, error display= ed. >>>>> I also have a separate basic install on ext4 on the same disk.=C2=A0= Though >>>>> e2fsck shows no errors and mounts fine I cannot log into that insta= ll. >>>>> Maybe a coincidence, but too many bad things thrown up make me >>>>> suspicious.=C2=A0 Whatever is happening this seems to be really fig= hting >>>>> me. >>>> >>>> I'm not sure how even a bad device accounts for the super generation= >>>> and backup mismatches. That's damn strange. >>> >>> I'm less suspicious of the drive now.=C2=A0 I've been using an ext4 p= artition >>> on the same drive for a few days now, having reinstalled on that and >>> everything _seems_ fine.=C2=A0 Mind you, apart from usb sticks, I've = not >>> experienced a ssd failure.=C2=A0 Perhaps my hdd failure experience is= not >>> relevent, i.e. they work until they start throwing errors and then >>> rapidly fail? >> >> I don't really believe a drive can be so easily corrupted to certain >> bits while all other bits are OK. >> >>> >>> >>>> >>>> If you get bored with the back and forth and just want to give up, >>>> that's fine. I suggest that if you have the time and space, to take = a >>>> btrfs-image in case Qu or some other developer wants to look at this= >>>> file system at some point. The btrfs-image is a read only process, c= an >>>> be set to scrub filenames, and only contains metadata. Size of the >>>> resulting file is around 1/2 of the size of metadata, when doing >>>> 'btrfs filesystem usage' or 'btrfs filesystem df'. So you'll need th= at >>>> much free space to direct the command to. >>>> >>>> btrfs-image -ss -c9 -t4 pathtofile >>> >>> Just done that: >>> bash-4.3# btrfs-image -ss -c9 -t4 /dev/sdd2 >>> /mnt/backup/btrfs_issue_dec_2018/btrfs_root_image_error_20181224.img >>> WARNING: cannot find a hash collision for '..', generating garbage, i= t >>> won't match indexes >>> >>> >>> >>>> >>>> It might fail, if so you can try adding -w and see if that helps. >>> >>> >>> OK, try with -w: >>> >>> OK, many many complaints about hash collisions: >>> ... >>> ARNING: cannot find a hash collision for 'ifup', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'catv', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'FDPC', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'LIBS', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'INTC', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'SPI', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'PDCA', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'EBI', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'SMC', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'WIFI', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'LWIP', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'HID', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'yun', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'avr4', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'avr6', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'WiFi', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'TFT', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'Knob', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'FP.h', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'SD.h', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'Beep', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'FORK', generating garbage,= it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'CHM', generating garbage, = it >>> won't match indexes >>> WARNING: cannot find a hash collision for 'HandS', generating garbage= , >>> it won't match indexes >>> WARNING: cannot find a hash collision for 'dm-0', generating garbage,= it >>> won't match indexes >>> >>> >>> Now seems to stopped producing output.=C2=A0 Can't see if it is doing= >>> something useful.=C2=A0 (note, started again, more such messages) >> >> I don't know about other developers, normally I don't like btrfs-image= >> -ss at all. >> >> Even plain btrfs-image isn't so helpful, especially considering its si= ze. >> >> Anyway, from all the data you collected, I suspect it's a corruption i= n >> tree blocks allocation, maybe a btrfs bug in older kernels, which buri= ed >> a dangerous seed into the fs, breaking the metadata CoW. >> >> And one day, an unexpected powerloss makes the seed grow and screw up >> the fs. >> >> Just a personal recommendation, for btrfs especially used with older >> kernels, after a powerloss, it's highly recommended to run btrfs check= >> --readonly before mounting it. >> >> Thanks, >> Qu >> >>> >>> >>>> >>>> There is no log listed in the super so zero-log isn't indicated, and= >>>> also tells me there were no fsync's still flushing at the time of th= e >>>> crash. The loss should be at most a minute of data, not an >>>> inconsistent file system that can't be mounted anymore. Pretty weird= =2E >>>> >>> >>> I think I ran zero-log to see if that helped.=C2=A0 Given that there = was no >>> important data and I'd assume I'd either easily fix it, or wipe it an= d >>> start over I may have taken the 'monkey radomly pounding the buttons'= >>> approach, short of 'btrfs check --repair'.=C2=A0 I only posted here a= s I >>> though I'd fixed it apart from the one error!=C2=A0 If it were a simp= le fix >>> then it was worth asking. >>> >>> >>>> What were your mount options? Defaults? Anything custom like discard= , >>>> commit=3D, notreelog? Any non-default mount options themselves would= not >>>> be the cause of the problem, but might suggest partial ideas for wha= t >>>> might have happened. >>>> >>> fstab states: >>> autodefrag,ssd,discard,noatime,defaults,subvol=3D_r_sl14. >>> 2,compress=3Dlzo >>> >>> However, I used an initrd, so I'm not sure if that is correct? >>> >>> Ok, digging into init within my initrd, the line where the root parti= on >>> is mounted: >>> =C2=A0=C2=A0 mount -o ro -t $ROOTFS $ROOTDEV /mnt >>> >>> Where $ROOTFS is: >>> btrfs -o subvol=3D_r_sl14.2 >>> >>> and $ROOTDEV is: >>> /dev/disk/by-uuid/6496aabd-d6aa-49e0-96ca-e49c316edd8e >>> >>> >>> >>> Pete >>> >> --p0LC1ianXcgTBD6xztXFcRCt4dEAtw1as-- --sVu9HiNKMOQqLHxyr5kIpnuo3bX9xoEDl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlwg2PIACgkQwj2R86El /qgB+Qf/dw0YcLolw3jh0icdgwz7CUNCy+AeBn09ZxR5Ea1b8LHoFE1bDRnnN6tB fuYQ00NFTUL0Iq53LImHcG0FDn44sN+WLopgA/5uHobTxVgYbLbdiCZvMEZWH5Rl InaYCRcfpXm7Ic76GgXSoCx4tSPbx6Bh/52MHThJWhXY/pCMxB1HWVuYl83pLjJA H1gDbNOBHvf90Kw901jgvht+lfUY0aOIye2iC3jisoErO6oz+XfY4U/PtkmM/kTa bsMhrc2AP46474u8JLn19rjj+ubi0ffiXIOv52Q3OxDHbnTPfHW4PevJHfFLXlRc KnO704i8tSy+rf24fedrUUZjGNCzcQ== =1+dD -----END PGP SIGNATURE----- --sVu9HiNKMOQqLHxyr5kIpnuo3bX9xoEDl--