On Thu, Nov 12, 2009 at 05:00:05PM -0500, Chris Mason wrote:
[ ...]
>
> The punch line is that the btrfs guy thinks we can solve all of this with
> just one more thread. If we change dm-crypt to have a thread dedicated
> to sync IO and a thread dedicated to async IO the system should smooth
> out.
This is pretty likely to set your dm data on fire. It's only for Mel
who starts his script w/mkfs.
It adds the second thread and more importantly makes sure the kcryptd
thread doesn't get stuck waiting for requests.
-chris
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index ed10381..295ffeb 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -94,6 +94,7 @@ struct crypt_config {
struct bio_set *bs;
struct workqueue_struct *io_queue;
+ struct workqueue_struct *async_io_queue;
struct workqueue_struct *crypt_queue;
/*
@@ -691,7 +692,10 @@ static void kcryptd_queue_io(struct dm_crypt_io *io)
struct crypt_config *cc = io->target->private;
INIT_WORK(&io->work, kcryptd_io);
- queue_work(cc->io_queue, &io->work);
+ if (io->base_bio->bi_rw & (1 << BIO_RW_SYNCIO))
+ queue_work(cc->io_queue, &io->work);
+ else
+ queue_work(cc->async_io_queue, &io->work);
}
static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
@@ -759,8 +763,7 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io
*io)
/* Encryption was already finished, submit io now */
if (crypt_finished) {
- kcryptd_crypt_write_io_submit(io, r, 0);
-
+ kcryptd_crypt_write_io_submit(io, r, 1);
/*
* If there was an error, do not try next fragments.
* For async, error is processed in async handler.
@@ -1120,6 +1123,12 @@ static int crypt_ctr(struct dm_target *ti, unsigned int
argc, char **argv)
} else
cc->iv_mode = NULL;
+ cc->async_io_queue = create_singlethread_workqueue("kcryptd_async_io");
+ if (!cc->async_io_queue) {
+ ti->error = "Couldn't create kcryptd io queue";
+ goto bad_async_io_queue;
+ }
+
cc->io_queue = create_singlethread_workqueue("kcryptd_io");
if (!cc->io_queue) {
ti->error = "Couldn't create kcryptd io queue";
@@ -1139,6 +1148,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int
argc, char **argv)
bad_crypt_queue:
destroy_workqueue(cc->io_queue);
bad_io_queue:
+ destroy_workqueue(cc->async_io_queue);
+bad_async_io_queue:
kfree(cc->iv_mode);
bad_ivmode_string:
dm_put_device(ti, cc->dev);
@@ -1166,6 +1177,7 @@ static void crypt_dtr(struct dm_target *ti)
struct crypt_config *cc = (struct crypt_config *) ti->private;
destroy_workqueue(cc->io_queue);
+ destroy_workqueue(cc->async_io_queue);
destroy_workqueue(cc->crypt_queue);
if (cc->req)
--
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