diff options
| author | Milan Broz <mbroz@redhat.com> | 2011-09-25 22:26:21 (GMT) |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2011-09-25 22:26:21 (GMT) |
| commit | 983c7db347db8ce2d8453fd1d89b7a4bb6920d56 (patch) | |
| tree | f4302d7eb306b82db4227ba5defe6d178949831b /drivers/md | |
| parent | 8232480944d173378082ebb2cac8a3207c08cf31 (diff) | |
| download | linux-983c7db347db8ce2d8453fd1d89b7a4bb6920d56.tar.xz | |
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>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-crypt.c | 2 | ||||
| -rw-r--r-- | drivers/md/dm-table.c | 19 |
2 files changed, 21 insertions, 0 deletions
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 49da55c..8c2a000 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1698,6 +1698,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv) } ti->num_flush_requests = 1; + ti->discard_zeroes_data_unsupported = 1; + return 0; bad: diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 3226698..bc04518 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1283,6 +1283,22 @@ static bool dm_table_supports_flush(struct dm_table *t, unsigned flush) return 0; } +static bool dm_table_discard_zeroes_data(struct dm_table *t) +{ + struct dm_target *ti; + unsigned i = 0; + + /* Ensure that all targets supports discard_zeroes_data. */ + while (i < dm_table_get_num_targets(t)) { + ti = dm_table_get_target(t, i++); + + if (ti->discard_zeroes_data_unsupported) + return 0; + } + + return 1; +} + void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, struct queue_limits *limits) { @@ -1305,6 +1321,9 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, } blk_queue_flush(q, flush); + if (!dm_table_discard_zeroes_data(t)) + q->limits.discard_zeroes_data = 0; + dm_table_set_integrity(t); /* |