[dm-devel] [PATCH v3] dm-crypt: reexport sysfs of kcryptd workqueue

From: yangerkun <yangerkun@huaweicloud.com>
To: snitzer@kernel.org, mpatocka@redhat.com, agk@redhat.com, tj@kernel.org
Cc: yukuai3@huawei.com, dm-devel@redhat.com, yangerkun@huawei.com,
	yangerkun@huaweicloud.com
Subject: [dm-devel] [PATCH v3] dm-crypt: reexport sysfs of kcryptd workqueue
Date: Tue, 11 Jul 2023 14:11:29 +0800	[thread overview]
Message-ID: <20230711061129.2706759-1-yangerkun@huaweicloud.com> (raw)

From: yangerkun <yangerkun@huawei.com>

Once there is a heavy IO load, so many encrypt/decrypt work will occupy
all of the cpu, which may lead the poor performance for other service.
So the idea like 'a2b8b2d97567 ("dm crypt: export sysfs of kcryptd
workqueue")' said seems necessary. We can export "kcryptd" workqueue
sysfs, the entry like cpumask/max_active and so on can help us to limit
the usage for encrypt/decrypt work.

However, that commit does not consider the reload table will call .ctr
before .dtr, so the reload for dm-crypt will fail since the same sysfs
problem, and then we revert that commit('48b0777cd93d ("Revert "dm
crypt: export sysfs of kcryptd workqueue"")').

Actually, what we should do is give a unique name once we try reload
table, we can use ida to fix the problem.

Signed-off-by: yangerkun <yangerkun@huawei.com>
---
 drivers/md/dm-crypt.c | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

v1->v2:
rewrite the commit msg

v2->v3:
no logical change, just rebase to latest linux kernel

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 1dc6227d353e..f4678eb71322 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -47,6 +47,8 @@
 
 #define DM_MSG_PREFIX "crypt"
 
+static DEFINE_IDA(crypt_queue_ida);
+
 /*
  * context holding the current state of a multi-part conversion
  */
@@ -182,6 +184,7 @@ struct crypt_config {
 		struct crypto_aead **tfms_aead;
 	} cipher_tfm;
 	unsigned int tfms_count;
+	int crypt_queue_id;
 	unsigned long cipher_flags;
 
 	/*
@@ -2735,6 +2738,9 @@ static void crypt_dtr(struct dm_target *ti)
 	if (cc->crypt_queue)
 		destroy_workqueue(cc->crypt_queue);
 
+	if (cc->crypt_queue_id)
+		ida_free(&crypt_queue_ida, cc->crypt_queue_id);
+
 	crypt_free_tfms(cc);
 
 	bioset_exit(&cc->bs);
@@ -3371,12 +3377,24 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	}
 
 	if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags))
-		cc->crypt_queue = alloc_workqueue("kcryptd/%s", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM,
+		cc->crypt_queue = alloc_workqueue("kcryptd-%s", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM,
 						  1, devname);
-	else
-		cc->crypt_queue = alloc_workqueue("kcryptd/%s",
-						  WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND,
-						  num_online_cpus(), devname);
+	else {
+		int id = ida_alloc_min(&crypt_queue_ida, 1, GFP_KERNEL);
+
+		if (id < 0) {
+			ti->error = "Couldn't get kcryptd queue id";
+			ret = id;
+			goto bad;
+		}
+
+		cc->crypt_queue_id = id;
+		cc->crypt_queue = alloc_workqueue("kcryptd-%s-%d",
+						  WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM |
+						  WQ_UNBOUND | WQ_SYSFS,
+						  num_online_cpus(), devname, id);
+	}
+
 	if (!cc->crypt_queue) {
 		ti->error = "Couldn't create kcryptd queue";
 		goto bad;
-- 
2.39.2

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