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authorMilan Broz <mbroz@redhat.com>2011-09-26 02:26:21 +0400
committerAlasdair G Kergon <agk@redhat.com>2011-09-26 02:26:21 +0400
commit983c7db347db8ce2d8453fd1d89b7a4bb6920d56 (patch)
treef4302d7eb306b82db4227ba5defe6d178949831b /drivers/md/dm-table.c
parent8232480944d173378082ebb2cac8a3207c08cf31 (diff)
downloadlinux-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/dm-table.c')
-rw-r--r--drivers/md/dm-table.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 322669807077..bc04518e9d8b 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);
/*