* Damaged super block / fs root @ 2011-05-30 15:59 Dennis Bergmann 2011-05-30 16:12 ` Hugo Mills 0 siblings, 1 reply; 6+ messages in thread From: Dennis Bergmann @ 2011-05-30 15:59 UTC (permalink / raw) To: linux-btrfs I have accidently damaged the first block(s) of a btrfs partition and can't mount it anymore. I can see that my data is still intact by running a command like: cat /dev/sda5 | hexdump -C | more Do any (experimental) tools exist which would allow me to recover the files? Thank you ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Damaged super block / fs root 2011-05-30 15:59 Damaged super block / fs root Dennis Bergmann @ 2011-05-30 16:12 ` Hugo Mills 2011-05-30 16:47 ` Dennis Bergmann 2011-05-30 19:23 ` Peter Stuge 0 siblings, 2 replies; 6+ messages in thread From: Hugo Mills @ 2011-05-30 16:12 UTC (permalink / raw) To: Dennis Bergmann; +Cc: Btrfs mailing list [-- Attachment #1: Type: text/plain, Size: 1084 bytes --] On Mon, May 30, 2011 at 05:59:54PM +0200, Dennis Bergmann wrote: > I have accidently damaged the first block(s) of a btrfs partition > and can't mount it anymore. > > I can see that my data is still intact by running a command like: > > cat /dev/sda5 | hexdump -C | more > > Do any (experimental) tools exist which would allow me to recover the files? There's btrfs-select-super, which is in the git repo for btrfs tools, in the next or tmp branches. That should allow you to select an alternative superblock to use, which (I think) will help you. If it is just your superblock that's damaged, that should help. You can check whether it's likely to be of use by running "btrfsck -s 1" on your filesystem. If it passes OK, then btrfs-select-super should be useful. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Attempted murder, now honestly, what is that? Do they give a --- Nobel Prize for attempted chemistry? [-- Attachment #2: Digital signature --] [-- Type: application/pgp-signature, Size: 190 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Damaged super block / fs root 2011-05-30 16:12 ` Hugo Mills @ 2011-05-30 16:47 ` Dennis Bergmann 2011-05-30 19:03 ` Chris Mason 2011-05-30 19:23 ` Peter Stuge 1 sibling, 1 reply; 6+ messages in thread From: Dennis Bergmann @ 2011-05-30 16:47 UTC (permalink / raw) To: linux-btrfs On 30.05.2011 18:12, Hugo Mills wrote: > You can check whether it's likely to be of use by running "btrfsck > -s 1" on your filesystem. If it passes OK, then btrfs-select-super > should be useful. > > Hugo. Didn't work, unfortunately. My btrfsck version is v0.19-35-g1b444cd-dirty and running "btrfsck -s 1 /dev/sda5" quits with the following message: using SB copy 1, bytenr 67108864 No valid Btrfs found on /dev/sda5 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Damaged super block / fs root 2011-05-30 16:47 ` Dennis Bergmann @ 2011-05-30 19:03 ` Chris Mason 2011-05-31 8:50 ` Dennis Bergmann 0 siblings, 1 reply; 6+ messages in thread From: Chris Mason @ 2011-05-30 19:03 UTC (permalink / raw) To: Dennis Bergmann; +Cc: linux-btrfs Excerpts from Dennis Bergmann's message of 2011-05-30 12:47:01 -0400: > On 30.05.2011 18:12, Hugo Mills wrote: > > You can check whether it's likely to be of use by running "btrfsck > > -s 1" on your filesystem. If it passes OK, then btrfs-select-super > > should be useful. > > > > Hugo. > > Didn't work, unfortunately. > > My btrfsck version is v0.19-35-g1b444cd-dirty and running > "btrfsck -s 1 /dev/sda5" quits with the following message: > > using SB copy 1, bytenr 67108864 > No valid Btrfs found on /dev/sda5 > How big is the FS? What command did you use to overwrite the super block? Please try to tell us exactly which commands were run. There are other ways we can try to pull things off, but you should try btrfsck -s 2 as well. -chris ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Damaged super block / fs root 2011-05-30 19:03 ` Chris Mason @ 2011-05-31 8:50 ` Dennis Bergmann 0 siblings, 0 replies; 6+ messages in thread From: Dennis Bergmann @ 2011-05-31 8:50 UTC (permalink / raw) To: linux-btrfs; +Cc: Chris Mason Hello Chris On 30.05.2011 21:03, Chris Mason wrote: > How big is the FS? About 100 G on a 500 G partition. I would only like to recover some plain text files from it (source code), I don't need the partition to be mountable again. > What command did you use to overwrite the super > block? Please try to tell us exactly which commands were run. I had to install FreeBSD on that disk (with Linux, a btrfs partition, and several free partitions on it). When using the FreeBSD partition tool, I didn't create or delete any partitions. I only assigned a free partition to FreeBSD. When I booted later in Linux the Btrfs partition did not mount anymore. > There are other ways we can try to pull things off, but you should try > btrfsck -s 2 as well. btrfcsk -s 2 exits with: using SB copy 2, bytenr 274877906944 No valid Btrfs found on /dev/sda10 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Damaged super block / fs root 2011-05-30 16:12 ` Hugo Mills 2011-05-30 16:47 ` Dennis Bergmann @ 2011-05-30 19:23 ` Peter Stuge 1 sibling, 0 replies; 6+ messages in thread From: Peter Stuge @ 2011-05-30 19:23 UTC (permalink / raw) To: Btrfs mailing list; +Cc: Hugo Mills, Dennis Bergmann [-- Attachment #1: Type: text/plain, Size: 4964 bytes --] Hugo Mills wrote: > You can check whether it's likely to be of use by running "btrfsck > -s 1" on your filesystem. If it passes OK, then btrfs-select-super > should be useful. Inspired by this I cloned latest btrfs-progs-unstable and tried it on my broken 60-something GB btrfs, but no luck: $ btrfsck -s 0 /dev/sdb2 using SB copy 0, bytenr 65536 btrfsck: disk-io.c:739: open_ctree_fd: Assertion `!(!tree_root->node)' failed. Aborted $ btrfsck -s 1 /dev/sdb2 using SB copy 1, bytenr 67108864 btrfsck: disk-io.c:739: open_ctree_fd: Assertion `!(!tree_root->node)' failed. Aborted $ btrfsck -s 2 /dev/sdb2 using SB copy 2, bytenr 274877906944 No valid Btrfs found on /dev/sdb2 $ I created an empty 384 MB btrfs: $ dd if=/dev/zero of=/tmp/test_fs bs=1024k count=384 $ mkfs.btrfs /tmp/test_fs $ And then I compare output from btrfs-debug-tree between test_fs and my broken one: $ strace -e pread64 btrfs-debug-tree /tmp/test_fs 2>&1 | sed 's-,"\(.\{5\}\).*"-, "\1"-' pread64(3, "\351\"..., 2859, 65536) = 2859 pread64(3, "I\227"..., 2859, 67108864) = 2859 pread64(3, ""..., 2859, 274877906944) = 0 pread64(5, "\351\"..., 2859, 65536) = 2859 pread64(5, "I\227"..., 2859, 67108864) = 2859 pread64(5, ""..., 2859, 274877906944) = 0 pread64(5, "\37\2"..., 4096, 20971520) = 4096 pread64(5, "\311\"..., 4096, 37752832) = 4096 pread64(5, "\247C"..., 4096, 37756928) = 4096 pread64(5, "\225\"..., 4096, 37761024) = 4096 pread64(5, "\210z"..., 4096, 37765120) = 4096 pread64(5, "\3\34"..., 4096, 37748736) = 4096 root tree leaf 29364224 items 9 free space 2349 generation 7 owner 1 fs uuid d29c2f7a-0a4e-4a1d-8458-2d241f6f29de chunk uuid fb34ff75-1cb6-4974-af37-e0a464135216 item 0 key (EXTENT_TREE ROOT_ITEM 0) itemoff 3756 itemsize 239 root data bytenr 29368320 level 0 dirid 0 refs 1 item 1 key (DEV_TREE ROOT_ITEM 0) itemoff 3517 itemsize 239 root data bytenr 29372416 level 0 dirid 0 refs 1 ... $ strace -e pread64 btrfs-debug-tree /dev/sdb2 2>&1 | sed 's-, "\(.\{5\}\).*"-, "\1"-' pread64(3, "p\23{"..., 2859, 65536) = 2859 pread64(3, "\320r"..., 2859, 67108864) = 2859 pread64(3, ""..., 2859, 274877906944) = 0 pread64(5, "p\23{"..., 2859, 65536) = 2859 pread64(5, "\320r"..., 2859, 67108864) = 2859 pread64(5, ""..., 2859, 274877906944) = 0 pread64(5, "\353$"..., 4096, 20971520) = 4096 pread64(5, "\275\"..., 4096, 20987904) = 4096 pread64(5, "\253\"..., 4096, 20983808) = 4096 pread64(5, "\0\0\"..., 4096, 36675878912) = 4096 pread64(5, "\0\0\"..., 4096, 36675878912) = 4096 pread64(5, "\0\0\"..., 4096, 36944314368) = 4096 btrfs-debug-tree: disk-io.c:739: open_ctree_fd: Assertion `!(!tree_root->node)' failed. --- SIGABRT (Aborted) @ 0 (0) --- +++ killed by SIGABRT +++ I also tried the btrfsck again: $ strace -e pread64 btrfsck -s 0 /dev/sdb2 2>&1 | sed 's-, "\(.\?.\?.\?\).*"-, "\1"-' pread64(3, "p\2"..., 2859, 65536) = 2859 pread64(3, "\32"..., 2859, 67108864) = 2859 pread64(3, ""..., 2859, 274877906944) = 0 pread64(3, "p\2"..., 2859, 65536) = 2859 pread64(3, "\32"..., 2859, 67108864) = 2859 pread64(3, ""..., 2859, 274877906944) = 0 pread64(5, "p\2"..., 2859, 65536) = 2859 pread64(5, "\32"..., 2859, 67108864) = 2859 pread64(5, ""..., 2859, 274877906944) = 0 pread64(5, "\35"..., 4096, 20971520) = 4096 pread64(5, "\27"..., 4096, 20987904) = 4096 pread64(5, "\25"..., 4096, 20983808) = 4096 pread64(5, "\0\"..., 4096, 36675878912) = 4096 pread64(5, "\0\"..., 4096, 36675878912) = 4096 pread64(5, "\0\"..., 4096, 36944314368) = 4096 btrfsck: disk-io.c:739: open_ctree_fd: Assertion `!(!tree_root->node)' failed. using SB copy 0, bytenr 65536 --- SIGABRT (Aborted) @ 0 (0) --- +++ killed by SIGABRT +++ $ strace -e pread64 btrfsck -s 1 /dev/sdb2 2>&1 | sed 's-, "\(.\?.\?.\?\).*"-, "\1"-' pread64(3, "p\2"..., 2859, 65536) = 2859 pread64(3, "\32"..., 2859, 67108864) = 2859 pread64(3, ""..., 2859, 274877906944) = 0 pread64(3, "\32"..., 2859, 67108864) = 2859 pread64(5, "\32"..., 2859, 67108864) = 2859 pread64(5, "\35"..., 4096, 20971520) = 4096 pread64(5, "\27"..., 4096, 20987904) = 4096 pread64(5, "\25"..., 4096, 20983808) = 4096 pread64(5, "\0\"..., 4096, 36675878912) = 4096 pread64(5, "\0\"..., 4096, 36675878912) = 4096 pread64(5, "\0\"..., 4096, 36944314368) = 4096 btrfsck: disk-io.c:739: open_ctree_fd: Assertion `!(!tree_root->node)' failed. using SB copy 1, bytenr 67108864 --- SIGABRT (Aborted) @ 0 (0) --- +++ killed by SIGABRT +++ $ strace -e pread64 btrfsck -s 2 /dev/sdb2 2>&1 | sed 's-, "\(.\?.\?.\?\).*"-, "\1"-' pread64(3, "p\2"..., 2859, 65536) = 2859 pread64(3, "\32"..., 2859, 67108864) = 2859 pread64(3, ""..., 2859, 274877906944) = 0 pread64(3, ""..., 2859, 274877906944) = 0 No valid Btrfs found on /dev/sdb2 using SB copy 2, bytenr 274877906944 $ Does this give any hint about how the tree has been broken? //Peter [-- Attachment #2: Type: application/pgp-signature, Size: 190 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-05-31 8:50 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-05-30 15:59 Damaged super block / fs root Dennis Bergmann 2011-05-30 16:12 ` Hugo Mills 2011-05-30 16:47 ` Dennis Bergmann 2011-05-30 19:03 ` Chris Mason 2011-05-31 8:50 ` Dennis Bergmann 2011-05-30 19:23 ` Peter Stuge
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