LU-14306 sec: get rid of bad rss-counter state messages

LU-14306 sec: get rid of bad rss-counter state messages

When doing O_DIRECT IOs on encrypted files, messages about bad
rss-counter state can be seen in the console. The mm get confused
because we twist the Lustre pages used for RPCs so that they are
suitable for llcrypt API.
In order to do this properly, the original mapping on these pages
must be preserved outside of the encryption/decryption needs.

Fixes: 728036f256 ("LU-12275 sec: O_DIRECT for encrypted file")
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I80ebcd3f96c51a3d158d7ef66f23b8da13904c52
Reviewed-on: https://review.whamcloud.com/41199
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>