On Mon, Jun 20, 2016 at 09:55:59PM -0400, Zygo Blaxell wrote:

In this current case, I'm getting things like this:

[12008.243867] BTRFS info (device vdc): csum failed ino 4420604 extent 26805825306624 csum 4105596028 wanted 787343232 mirror 0

[...]

The other other weird thing here is that I can't find an example in the
logs of an extent with an EIO that isn't compressed.  I've been looking
up a random sample of the extent numbers, matching them up to filefrag
output, and finding e.g. the one compressed extent in the middle of an
otherwise uncompressed git pack file.  That's...odd.  Maybe there's a
problem with compressed extents in particular?  I'll see if I can
script something to check all the logs at once...

No need for a script:  this message wording appears only in
fs/btrfs/compression.c so it can only ever be emitted by reading a
compressed extent.

Maybe there's a problem specific to raid5, degraded mode, and compressed
extents?