Re: Deleted files cause btrfs-send to fail

[Marc Joliet <marcec@gmx.de>]

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Am Thu, 13 Aug 2015 10:54:58 +0200
schrieb Marc Joliet <marcec@gmx.de>:

> Am Thu, 13 Aug 2015 08:29:19 +0000 (UTC)
> schrieb Duncan <1i5t5.duncan@cox.net>:
> 
> > Marc Joliet posted on Thu, 13 Aug 2015 09:05:41 +0200 as excerpted:
> > 
> > > Here's the actual output now, obtained via btrfs-progs 4.0.1 from an
> > > initramfs emergency shell:
> > > 
> > > checking extents checking free space cache checking fs roots root 5
> > > inode 8338813 errors 2000, link count wrong
> > >         unresolved ref dir 26699 index 50500 namelen 4 name root
> > >         filetype 0 errors 3, no dir item, no dir index
> > > root 5 inode 8338814 errors 2000, link count wrong
> > >         unresolved ref dir 26699 index 50502 namelen 6 name marcec
> > >         filetype 0 errors 3, no dir item, no dir index
> > > root 5 inode 8338815 errors 2000, link count wrong
> > >         unresolved ref dir 26699 index 50504 namelen 6 name systab
> > >         filetype 0 errors 3, no dir item, no dir index
> > > root 5 inode 8710030 errors 2000, link count wrong
> > >         unresolved ref dir 26699 index 59588 namelen 6 name marcec
> > >         filetype 0 errors 3, no dir item, no dir index
> > > root 5 inode 8710031 errors 2000, link count wrong
> > >         unresolved ref dir 26699 index 59590 namelen 4 name root
> > >         filetype 0 errors 3, no dir item, no dir index
> > > Checking filesystem on /dev/sda1 UUID:
> > > 0267d8b3-a074-460a-832d-5d5fd36bae64 found 63467610172 bytes used err is
> > > 1 total csum bytes: 59475016 total tree bytes: 1903411200 total fs tree
> > > bytes: 1691504640 total extent tree bytes: 130322432 btree space waste
> > > bytes: 442495212 file data blocks allocated: 555097092096
> > >  referenced 72887840768
> > > btrfs-progs v4.0.1
> > > 
> > > Again: is this fixable?
> > 
> > FWIW, root 5 (which you asked about upthread) is the main filesystem 
> > root.  So all these appear to be on the main filesystem, not on snapshots/
> > subvolumes.
> 
[...]
> > But if it's critical, you may wish to wait and have someone else confirm 
> > that before acting on it, just in case I have it wrong.
> 
> I can wait until tonight, at least.  The FS still mounts, and it's just the root
> subvolume that's affected; running btrfs-send on the /home subvolume still
> works.

Well, I got impatient, and just went ahead and did it (I have backups, after
all).  It looks like it worked: the affected files were moved to /lost+found/,
where I deleted them again, and btrfs-send works again.  The output of "btrfs
check" after --repair:

checking extents
checking free space cache
checking fs roots
checking csums
There are no extents for csum range 0-69632
Csum exists for 0-69632 but there is no extent record
Checking filesystem on /dev/sda1
UUID: 0267d8b3-a074-460a-832d-5d5fd36bae64
block group 274307481600 has wrong amount of free spacefailed to load free space cache for block group 274307481600
found 60980420666 bytes used err is 1
total csum bytes: 57521732
total tree bytes: 1996800000
total fs tree bytes: 1791721472
total extent tree bytes: 127942656
btree space waste bytes: 460072661
file data blocks allocated: 478650343424
 referenced 73326161920
btrfs-progs v4.1.2

If I notice anything amiss, I'll report back.

(One other thing I found interesting was that "btrfs scrub" didn't care about
the link count errors.)

Greetings.
-- 
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup

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