dm-crypt: export sysfs of all workqueues

Once there is a heavy IO load, so many encrypt/decrypt work will occupy
all of the cpu, which may lead to the poor performance for other service.
So the improved visibility and controls over dm-crypt workqueues, as
was offered with commit a2b8b2d97567 ("dm crypt: export sysfs of
kcryptd workqueue"), seems necessary. By exporting dm-crypt's
workqueues in sysfs, the entry like cpumask/max_active and so on can
help us to limit the CPU usage for encrypt/decrypt work.

However, commit a2b8b2d97567 did not consider that DM table reload
will call .ctr before .dtr, so the reload for dm-crypt failed because
the same sysfs name was present. This was the original need for commit
48b0777cd93d ("Revert "dm crypt: export sysfs of kcryptd workqueue"").

Reintroduce the use of WQ_SYSFS, and use it for both the IO and crypt
workqueues, but make the workqueue names include a unique id (via ida)
to allow both old and new sysfs entries to coexist.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index eabc576d8d28f996abb7a9d235b8c4be5d4dd80e..5bfa3576016723b312d8d17fcb5af80220bbd019 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -47,6 +47,8 @@
 
 #define DM_MSG_PREFIX "crypt"
 
+static DEFINE_IDA(workqueue_ida);
+
 /*
  * context holding the current state of a multi-part conversion
  */
@@ -184,6 +186,7 @@ struct crypt_config {
                struct crypto_aead **tfms_aead;
        } cipher_tfm;
        unsigned int tfms_count;
+       int workqueue_id;
        unsigned long cipher_flags;
 
        /*
@@ -2771,6 +2774,9 @@ static void crypt_dtr(struct dm_target *ti)
        if (cc->crypt_queue)
                destroy_workqueue(cc->crypt_queue);
 
+       if (cc->workqueue_id)
+               ida_free(&workqueue_ida, cc->workqueue_id);
+
        crypt_free_tfms(cc);
 
        bioset_exit(&cc->bs);
@@ -3232,7 +3238,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
        struct crypt_config *cc;
        const char *devname = dm_table_device_name(ti->table);
-       int key_size;
+       int key_size, wq_id;
        unsigned int align_mask;
        unsigned int common_wq_flags;
        unsigned long long tmpll;
@@ -3401,25 +3407,33 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                cc->tag_pool_max_sectors <<= cc->sector_shift;
        }
 
+       wq_id = ida_alloc_min(&workqueue_ida, 1, GFP_KERNEL);
+       if (wq_id < 0) {
+               ti->error = "Couldn't get workqueue id";
+               ret = wq_id;
+               goto bad;
+       }
+       cc->workqueue_id = wq_id;
+
        ret = -ENOMEM;
-       common_wq_flags = WQ_MEM_RECLAIM;
+       common_wq_flags = WQ_MEM_RECLAIM | WQ_SYSFS;
        if (test_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags))
                common_wq_flags |= WQ_HIGHPRI;
 
-       cc->io_queue = alloc_workqueue("kcryptd_io/%s", common_wq_flags, 1, devname);
+       cc->io_queue = alloc_workqueue("kcryptd_io-%s-%d", common_wq_flags, 1, devname, wq_id);
        if (!cc->io_queue) {
                ti->error = "Couldn't create kcryptd io queue";
                goto bad;
        }
 
        if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags)) {
-               cc->crypt_queue = alloc_workqueue("kcryptd/%s",
+               cc->crypt_queue = alloc_workqueue("kcryptd-%s-%d",
                                                  common_wq_flags | WQ_CPU_INTENSIVE,
-                                                 1, devname);
+                                                 1, devname, wq_id);
        } else {
-               cc->crypt_queue = alloc_workqueue("kcryptd/%s",
+               cc->crypt_queue = alloc_workqueue("kcryptd-%s-%d",
                                                  common_wq_flags | WQ_CPU_INTENSIVE | WQ_UNBOUND,
-                                                 num_online_cpus(), devname);
+                                                 num_online_cpus(), devname, wq_id);
        }
        if (!cc->crypt_queue) {
                ti->error = "Couldn't create kcryptd queue";