summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorMilan Broz <mbroz@redhat.com>2011-09-25 23:26:21 +0100
committerAlasdair G Kergon <agk@redhat.com>2011-09-25 23:26:21 +0100
commit983c7db347db8ce2d8453fd1d89b7a4bb6920d56 (patch)
treef4302d7eb306b82db4227ba5defe6d178949831b
parent8232480944d173378082ebb2cac8a3207c08cf31 (diff)
downloadop-kernel-dev-983c7db347db8ce2d8453fd1d89b7a4bb6920d56.zip
op-kernel-dev-983c7db347db8ce2d8453fd1d89b7a4bb6920d56.tar.gz
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>
-rw-r--r--drivers/md/dm-crypt.c2
-rw-r--r--drivers/md/dm-table.c19
-rw-r--r--include/linux/device-mapper.h5
3 files changed, 26 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);
/*
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 3fa1f3d..99e3e50 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -197,6 +197,11 @@ struct dm_target {
* whether or not its underlying devices have support.
*/
unsigned discards_supported:1;
+
+ /*
+ * Set if this target does not return zeroes on discarded blocks.
+ */
+ unsigned discard_zeroes_data_unsupported:1;
};
/* Each target can link one of these into the table */
OpenPOWER on IntegriCloud