On Tue, Jun 20, 2017 at 03:23:54PM +0000, Hugo Mills wrote:
> On Tue, Jun 20, 2017 at 07:39:16AM -0700, Marc MERLIN wrote:
> > My filesystem got remounted read only, and yet after a lengthy
> > btrfs check --repair, it ran clean.
> > 
> > Any idea what went wrong?
> > [846332.992285] WARNING: CPU: 4 PID: 4095 at fs/btrfs/free-space-cache.c:1476 tree_insert_offset+0x78/0xb1
> > [846333.744721] BTRFS critical (device dm-1): unable to add free space :-17
> > [847312.529660] BTRFS: Transaction aborted (error -17)
> > [847313.218391] BTRFS: error (device dm-1) in btrfs_run_delayed_refs:2961: errno=-17 Object already exists
> 
>    Error 17 is EEXIST, so I'd guess (and it is a guess) that it's
> trying to add a free space cache record for some space that already
> has such a record. This might also match with:
 
Thanks for having a look. Is it a bug, or is it a problem with my storage
subsystem?

> [...]
> > gargamel:~# btrfs check --repair /dev/mapper/dshelf2
> [...]
> > cache and super generation don't match, space cache will be invalidated
> [...]
> 
>    I'd try clearing the cache (mount with -o clear_cache, once), and
> then letting it rebuild.

"space cache will be invalidated " => doesn't that mean that my cache was
already cleared by check --repair, or are you saying I need to clear it
again?

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/