The encryption xlator is the last one before posix and it's here that the data 
is getting encrypted.  When the data is read back the encrypted data is 
returned. Decryption is supposed to happen in read callback which does not seem 
to be happening. The fact that encrypted data is getting returned indicates 
that data in turn is getting returned from the posix/underlying fs layer.  Is 
it possible that data be returned by reading from the underlying fs by any 
translator other than posix.

Thanks and Regards,
Ram
From: Ravishankar N [mailto:ravishan...@redhat.com]
Sent: Sunday, October 16, 2016 12:19 AM
To: Ankireddypalle Reddy; gluster-users@gluster.org
Subject: Re: [Gluster-users] rot-13 Translator query

On 10/15/2016 08:22 PM, Ankireddypalle Reddy wrote:
Hi,
      I am trying to follow the below document for developing a translator.
      
https://github.com/gluster/glusterfs/blob/master/doc/developer-guide/translator-development.md

      I've created a replica volume and modified the vol file to include rot-13 
translator. Below is the snippet from vol file.

volume myvol-posix
    type storage/posix
    option volume-id b492191e-77a5-4fc3-9394-49218e36dae2
    option directory /brick1/repli
end-volume

volume myvol-rot13
    type encryption/rot-13
    subvolumes myvol-posix
end-volume

volume myvol-trash
    type features/trash
    option trash-internal-op off
    option brick-path /brick1/repli
    option trash-dir .trashcan
    subvolumes myvol-rot13
end-volume
...

The writes are getting intercepted by the translator and the file is getting 
encrypted. But the reads don't seem to be getting intercepted by the 
translator.  I tried setting break point in the posix_readv function and attach 
the brick daemons to gdb. But posix_readv does not seem to be getting called on 
the brick daemon and the read completes on the application side.

Can someone please explain how the reads are getting serviced here without 
hitting the posix layer.
It could be due to client side caching. I usually disable all performance 
xlators (write-behind, read-head, io-cache, stat-prefetch, quick-read, 
open-behind) when I want to remove caching effects while debugging. drop-caches 
also helps.

HTH,
Ravi



Thanks and Regards,
Ram
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