Re: Btrfs check reports errors, filesystem seems fine

[Filippe LeMarchand <gasinvein@gmail.com>]

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> Maybe something wrong in grep happened which skip "(79177" ?
Yes, my bad. Now I used grep -E "\(79177| 79177" pattern, file on GDrive updated.

And btrfs check --mode=lowmem gives this:

checking extents
ERROR: extent[1609877700608, 94208] referencer count mismatch (root: 260, owner: 61720, offset: 6742016) wanted: 2, have: 5
ERROR: extent[1630301675520, 39583744] referencer count mismatch (root: 260, owner: 5847554, offset: 0) wanted: 36, have: 114
ERROR: extent[1658646986752, 10551296] referencer count mismatch (root: 274, owner: 283675, offset: 0) wanted: 2, have: 5
ERROR: extent[1672239132672, 84381696] referencer count mismatch (root: 274, owner: 2521382, offset: 0) wanted: 21, have: 25
ERROR: errors found in extent allocation tree or chunk allocation
checking free space cache
checking fs roots
ERROR: root 4546 DIR_ITEM[79177 54846528] relative INODE_REF missing namelen 14 filename deprecated.sxt filetype 1
ERROR: root 4546 INODE REF[4222342 79177] and DIR_ITEM[79177 54846528] mismatch namelen 14 filename deprecated.txt filetype 1
ERROR: root 5134 DIR_ITEM[79177 54846528] relative INODE_REF missing namelen 14 filename deprecated.sxt filetype 1
ERROR: errors found in fs roots
Checking filesystem on /dev/sda2
UUID: 12c84aa3-ce65-4390-807e-a72cc8a7445e
found 153429872640 bytes used, error(s) found
total csum bytes: 121991672
total tree bytes: 1940160512
total fs tree bytes: 1683767296
total extent tree bytes: 103841792
btree space waste bytes: 310722480
file data blocks allocated: 842455031808
 referenced 159286636544

In a letter from Wednesday, July 12, 2017 10:15:18 MSK user Qu Wenruo wrote:
> Sorry for the late reply.
> 
> After investigating the dumps, I found the output is quite strange.
> 
> 1) Mismatching output.
> In "btrfs-debug-tree-grep-79177.txt" I found only 79177 as offset for 
> INODE_REF is here, while 79177 as objectid for DIR_ITEM/DIR_INDEX is not 
> here at all.
> 
> While in "btrfs-debug-tree-grep-deprecated-txt.txt" there is epected 
> 79177 DIR_ITEM/DIR_INDEX.
> 
> Maybe something wrong in grep happened which skip "(79177" ?
> 
> 2) Mismatched hash
> The main problem I found is that, for key (79177 DIR_ITEM 54846528), the 
> number 54846528 is the hash(crc32c) of filename, and it contains 2 
> items, one for "deprecated.txt" and one for "deprecated.sxt".
> 
> But we found that 54846528 only matches the hash for "deprecated.txt", 
> not "deprecated.sxt".
> 
> I think that's the main problem.
> 
> BTW, would you please try "btrfs check --mode=lowmem" to see if lowmem 
> mode reports similar (well, output may differ) error?
> 
> If lowmem mode also reports error on such DIR_ITEM, I'm pretty sure 
> that's the problem.
> 
> However it may take some time before we can fix it in repair mode.
> 
> Thanks,
> Qu
> 
> 
> 
> 在 2017年07月04日 21:24, Filippe LeMarchand 写道:
> > Sure, here it is:
> > https://drive.google.com/drive/folders/0B1ax9Am81gx9YjJBVVA0LXRHeGc
> > 
> > In a letter dated Tuesday, July 4, 2017 16:16:36 MSK user Lu Fengqi wrote:
> >> On Mon, Jul 03, 2017 at 08:34:52AM +0800, Qu Wenruo wrote:
> >>>
> >>>
> >>> At 07/01/2017 07:59 PM, Filippe LeMarchand wrote:
> >>>> Hello everyone.
> >>>>
> >>>> I have an btrfs root partition on Intel 530 ssd, which mounts without errors and seem to work fine,
> >>>> but `btrfs check` gives me foloowing output (and --repair doesn't remove errors):
> >>>>
> >>>> enabling repair mode
> >>>> Checking filesystem on /dev/sda2
> >>>> UUID: 12c84aa3-ce65-4390-807e-a72cc8a7445e
> >>>> checking extents
> >>>> Fixed 0 roots.
> >>>> checking free space cache
> >>>> cache and super generation don't match, space cache will be invalidated
> >>>> checking fs roots
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>
> >>> This means that in dir whose inode number is 79177, it has a child inode
> >>> pointer pointing to depercated.sxt.
> >>>
> >>> But it doesn't have dir index and corresponding inode ref, which is breaking
> >>> the cross reference rule of btrfs.
> >>>
> >>> Would you please run the following command to dump needed info for us to
> >>> debug?
> >>>
> >>> # btrfs-debug-tree /dev/sda2 | grep 79177 -C 10
> >>>
> >>> and
> >>>
> >>> # btrfs-debug-tree /dev/sda2 | grep deprecated.sxt -C 10
> >>>
> >>> and
> >>>
> >>> # btrfs-debug-tree /dev/sda2 | grep deprecated.txt -C 10
> >>>
> >>>
> >>> Considering the output has both .txt and .sxt, I think that's the problem.
> >>> But such bit-flip should be detected by tree block csum.
> >>> I'm not sure what's wrong with it.
> >>>
> >>> Thanks,
> >>> Qu
> >>>
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> 	unresolved ref dir 79177 index 0 namelen 14 name deprecated.sxt filetype 1 errors 6, no dir index, no inode ref
> >>>> 	unresolved ref dir 79177 index 417 namelen 14 name deprecated.txt filetype 1 errors 1, no dir item
> >>>> checking csums
> >>>> checking root refs
> >>>> found 23421812736 bytes used err is 0
> >>>> total csum bytes: 21531608
> >>>> total tree bytes: 776650752
> >>>> total fs tree bytes: 711278592
> >>>> total extent tree bytes: 36798464
> >>>> btree space waste bytes: 116002036
> >>>> file data blocks allocated: 850546470912
> >>>>    referenced 27611987968
> >>>>
> >>>> Is it dangerous and what should I do about it?
> >>>>
> >>>> I also tried --clear-space-cache, but it just removes the line about space cache.
> >>>>
> >>>
> >>>
> >>> --
> >>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> >>> the body of a message to majordomo@vger.kernel.org
> >>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >>
> >> I'm afraid that your mail may be rejected because the attachment size
> >> exceeds the allowable limit(100kB) of btrfs mailing list. Could you
> >> share the attachment by google drive?
> >>
> >> Lastly, while Qu's timing is too tight, I will assist you on this issue.
> >>
> 

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