Typically, dm-crypt instances each have their own set of kcrypt/kcrypt_io
work-queues. This patch adds an option which will create one set of
work-queues on init, and re-uses them for all dm-crypt target instances.

Cc: Milan Broz <mbroz@redhat.com>
Cc: Brian Swetland <swetland@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christophe Saout <christophe@saout.de>
Signed-off-by: San Mehat <san@google.com>
---
drivers/md/Kconfig | 10 ++++++++++
drivers/md/dm-crypt.c | 42 +++++++++++++++++++++++++++++++++++++++---
2 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 2158377..8d82dfc 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -244,6 +244,16 @@ config DM_CRYPT

If unsure, say N.

+config DM_CRYPT_GLOBAL_WORKQUEUES
+ boolean "Use global instead of per-device work-queues"
+ depends on DM_CRYPT
+ ---help---
+ Normally 2 kernel work-queue threads are created for every
+ dm-crypt target. This option creates only 1 set of work-queues
+ on init, and re-uses them.
+
+ If unsure, say N.
+
config DM_SNAPSHOT
tristate "Snapshot target"
depends on BLK_DEV_DM
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 959d6d1..875ad9a 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -104,8 +104,10 @@ struct crypt_config {
mempool_t *page_pool;
struct bio_set *bs;

+#ifndef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
struct workqueue_struct *io_queue;
struct workqueue_struct *crypt_queue;
+#endif

/*
* crypto related data
@@ -148,6 +150,10 @@ struct crypt_config {
#define MIN_BIO_PAGES 8

static struct kmem_cache *_crypt_io_pool;
+#ifdef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
+static struct workqueue_struct *_io_queue;
+static struct workqueue_struct *_crypt_queue;
+#endif

static void clone_init(struct dm_crypt_io *, struct bio *);
static void kcryptd_queue_crypt(struct dm_crypt_io *io);
@@ -730,7 +736,11 @@ static void kcryptd_queue_io(struct dm_crypt_io *io)
struct crypt_config *cc = io->target->private;

INIT_WORK(&io->work, kcryptd_io);
+#ifdef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
+ queue_work(_io_queue, &io->work);
+#else
queue_work(cc->io_queue, &io->work);
+#endif
}

static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
@@ -914,7 +924,11 @@ static void kcryptd_queue_crypt(struct dm_crypt_io *io)
struct crypt_config *cc = io->target->private;

INIT_WORK(&io->work, kcryptd_crypt);
+#ifdef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
+ queue_work(_crypt_queue, &io->work);
+#else
queue_work(cc->crypt_queue, &io->work);
+#endif
}

/*
@@ -1165,6 +1179,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
} else
cc->iv_mode = NULL;

+#ifndef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
cc->io_queue = create_singlethread_workqueue("kcryptd_io");
if (!cc->io_queue) {
ti->error = "Couldn't create kcryptd io queue";
@@ -1174,15 +1189,15 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
cc->crypt_queue = create_singlethread_workqueue("kcryptd");
if (!cc->crypt_queue) {
ti->error = "Couldn't create kcryptd queue";
- goto bad_crypt_queue;
+ destroy_workqueue(cc->io_queue);
+ goto bad_io_queue;
}
+#endif

ti->num_flush_requests = 1;
ti->private = cc;
return 0;

-bad_crypt_queue:
- destroy_workqueue(cc->io_queue);
bad_io_queue:
kfree(cc->iv_mode);
bad_ivmode_string:
@@ -1210,8 +1225,10 @@ static void crypt_dtr(struct dm_target *ti)
{
struct crypt_config *cc = (struct crypt_config *) ti->private;

+#ifndef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
destroy_workqueue(cc->io_queue);
destroy_workqueue(cc->crypt_queue);
+#endif

if (cc->req)
mempool_free(cc->req, cc->req_pool);
@@ -1399,6 +1416,21 @@ static int __init dm_crypt_init(void)
{
int r;

+#ifdef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
+ _io_queue = create_singlethread_workqueue("kcryptd_io");
+ if (!_io_queue) {
+ DMERR("couldn't create kcryptd io queue");
+ return -ENOMEM;
+ }
+
+ _crypt_queue = create_singlethread_workqueue("kcryptd");
+ if (!_crypt_queue) {
+ DMERR("couldn't create kcryptd queue");
+ destroy_workqueue(_io_queue);
+ return -ENOMEM;
+ }
+#endif
+
_crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
if (!_crypt_io_pool)
return -ENOMEM;
@@ -1416,6 +1448,10 @@ static void __exit dm_crypt_exit(void)
{
dm_unregister_target(&crypt_target);
kmem_cache_destroy(_crypt_io_pool);
+#ifdef CONFIG_DM_CRYPT_GLOBAL_WORKQUEUES
+ destroy_workqueue(_io_queue);
+ destroy_workqueue(_crypt_queue);
+#endif
}

module_init(dm_crypt_init);
--
1.7.0.1

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