Btrfs Check - "type mismatch with chunk"

[Zach Fuller <conicawd@gmail.com>]

I am currently running btrfs on a 2TB GPT drive. The drive is working
fine, still mounts correctly, and I have experienced no data
corruption. Whenever I run "btrfs check" on the drive, it returns
100,000+ messages stating "bad extent [###, ###), type mismatch with
chunk". Whenever I try to run "btrfs check --repair" it says that it
has fixed the errors, but whenever I run "btrfs check" again, the
errors return. Should I be worried about data/filesystem corruption,
or are these errors meaningless?

Here are the links to the output of "btrfs check"
(https://app.box.com/s/z2c4ikp6lsn7siezafkth3amo27acs4o) and "btrfs
check --repair"
(https://app.box.com/s/tgg3c4dpfas1wulk30zpudw4mt4bvwoa)
Also, whenever I run btrfs scrub on the drive, it says there are no errors.

I see that there have been other posts on the mailing list with this
same error, such as this one
(https://www.mail-archive.com/linux-btrfs%40vger.kernel.org/msg48325.html).

I have my data backed up on 2 different drives, so I can afford to
lose the entire btrfs drive temporarily.

Here is some info about my system:

$ uname -a
Linux comp 4.2.5-1-ARCH #1 SMP PREEMPT Tue Oct 27 08:13:28 CET 2015
x86_64 GNU/Linux


$ btrfs --version
btrfs-progs v4.3.1


$ sudo btrfs fi show
Another drive...

Label: 'backup'  uuid: 1a160f37-7206-43f9-9285-6217ee97a665
Total devices 1 FS bytes used 1.53TiB
devid    1 size 1.82TiB used 1.54TiB path /dev/sdc1


$ sudo btrfs fi df /backup
Data, single: total=1.53TiB, used=1.53TiB
System, DUP: total=32.00MiB, used=224.00KiB
Metadata, DUP: total=3.50GiB, used=2.36GiB
GlobalReserve, single: total=512.00MiB, used=0.00B


Drive Mounting Options from /etc/fstab:
LABEL=backup    /backup  btrfs  noatime,compress=lzo,autodefrag  0 0