Otherwise #opt_params is the number of following arguments.
Example of optional parameters section:
- 2 allow_discards same_cpu_crypt
+ 3 allow_discards same_cpu_crypt submit_from_crypt_cpus
allow_discards
Block discard requests (a.k.a. TRIM) are passed through the crypt device.
The default is to use an unbound workqueue so that encryption work
is automatically balanced between available CPUs.
+submit_from_crypt_cpus
+ Disable offloading writes to a separate thread after encryption.
+ There are some situations where offloading write bios from the
+ encryption threads to a single thread degrades performance
+ significantly. The default is to offload write bios to the same
+ thread because it benefits CFQ to have writes submitted using the
+ same context.
+
Example scripts
===============
LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
* Crypt: maps a linear range of a block device
* and encrypts / decrypts at the same time.
*/
-enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID, DM_CRYPT_SAME_CPU };
+enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID,
+ DM_CRYPT_SAME_CPU, DM_CRYPT_NO_OFFLOAD };
/*
* The fields in here must be read only after initialization.
clone->bi_iter.bi_sector = cc->start + io->sector;
+ if (likely(!async) && test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags)) {
+ generic_make_request(clone);
+ return;
+ }
+
spin_lock_irqsave(&cc->write_thread_wait.lock, flags);
list_add_tail(&io->list, &cc->write_thread_list);
wake_up_locked(&cc->write_thread_wait);
char dummy;
static struct dm_arg _args[] = {
- {0, 2, "Invalid number of feature args"},
+ {0, 3, "Invalid number of feature args"},
};
if (argc < 5) {
else if (!strcasecmp(opt_string, "same_cpu_crypt"))
set_bit(DM_CRYPT_SAME_CPU, &cc->flags);
+ else if (!strcasecmp(opt_string, "submit_from_crypt_cpus"))
+ set_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags);
+
else {
ti->error = "Invalid feature arguments";
goto bad;
num_feature_args += !!ti->num_discard_bios;
num_feature_args += test_bit(DM_CRYPT_SAME_CPU, &cc->flags);
+ num_feature_args += test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags);
if (num_feature_args) {
DMEMIT(" %d", num_feature_args);
if (ti->num_discard_bios)
DMEMIT(" allow_discards");
if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags))
DMEMIT(" same_cpu_crypt");
+ if (test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags))
+ DMEMIT(" submit_from_crypt_cpus");
}
break;