dm crypt: always disable discard_zeroes_data
authorMilan Broz <mbroz@redhat.com>
Sun, 25 Sep 2011 22:26:21 +0000 (23:26 +0100)
committerAlasdair G Kergon <agk@redhat.com>
Sun, 25 Sep 2011 22:26:21 +0000 (23:26 +0100)
commit983c7db347db8ce2d8453fd1d89b7a4bb6920d56
treef4302d7eb306b82db4227ba5defe6d178949831b
parent8232480944d173378082ebb2cac8a3207c08cf31
dm crypt: always disable discard_zeroes_data

If optional discard support in dm-crypt is enabled, discards requests
bypass the crypt queue and blocks of the underlying device are discarded.
For the read path, discarded blocks are handled the same as normal
ciphertext blocks, thus decrypted.

So if the underlying device announces discarded regions return zeroes,
dm-crypt must disable this flag because after decryption there is just
random noise instead of zeroes.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
drivers/md/dm-crypt.c
drivers/md/dm-table.c
include/linux/device-mapper.h