Re: Deleted files cause btrfs-send to fail

[Marc Joliet <marcec@gmx.de>]

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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.

OK

> As for the problem itself, noting that I'm not a dev, just a user/admin 
> following the list, I believe...
> 
> There was a recent bug (early 4.0 or 4.1, IDR which) that (as I recall 
> understanding it) would fail to decrement link count and would thus leave 
> unnamed inodes hanging around in directories with no way to delete them.  
> That looks very much like what you're seeing.

Now that you mention it, I think I remember seeing that patch (series?).

> The bug has indeed been 
> fixed in current, and a current btrfs check should fix it, but I don't 
> believe that v4.0.1 userspace from the initramfs is new enough to have 
> that fix.  The 4.1.2 userspace on your main system (from the first post) 
> is current and should fix it, I believe, however.

I have updated the initramfs in the meantime.  (Funny: I *just* started using
one, mainly to be able to use btrfstune on /, but now I have a genuine
necessity for it.)

> 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.

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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