Documentation for BTRFS error (device dev): bdev /dev/xx errs: wr 22, rd 0, flush 0, corrupt 0, gen 0

[Marc MERLIN <marc@merlins.org>]

I have a freshly created md5 array, with drives that I specifically
scanned one by one block by block, and for good measure, I also scanned
the entire software raid with a check command which took 3 days to run.

Everything passed.

Then, I made a bcache of that device, an ssd that seems to work fine
otherwise (brand new), and dmcrypted the result

md5 - bache - dmcrypt - btrfs
ssd /

Now, I'm copying data over with btrfs send, and I'm seeing these slowly
show up and the write counter go up one by one.
BTRFS error (device dm-7): bdev /dev/mapper/oldds1 errs: wr 17, rd 0, flush 0, corrupt 0, gen 0

Where is the documentation for those counters?
Is the write error fatal, or a recovered error?
Should I consider that my filesystem is corrupted as soon as any of
those counters go up?
(I couldn't find an exact meaning of each of them)

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/                         | PGP 1024R/763BE901