dm kcopyd: private mempool

Change the global mempool in kcopyd into a per-device mempool to avoid
deadlock possibilities.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 19 insertions, 13 deletions

diff --git a/drivers/md/kcopyd.c b/drivers/md/kcopyd.c
index 3fb6c8334a82..0b2907d59a3f 100644
--- a/drivers/md/kcopyd.c
+++ b/drivers/md/kcopyd.c
@@ -43,6 +43,8 @@ struct dm_kcopyd_client {
         wait_queue_head_t destroyq;
         atomic_t nr_jobs;
 
+        mempool_t *job_pool;
+
         struct workqueue_struct *kcopyd_wq;
         struct work_struct kcopyd_work;
 
@@ -221,7 +223,6 @@ struct kcopyd_job {
 #define MIN_JOBS 512
 
 static struct kmem_cache *_job_cache;
-static mempool_t *_job_pool;
 
 static int jobs_init(void)
 {
@@ -229,20 +230,12 @@ static int jobs_init(void)
         if (!_job_cache)
                 return -ENOMEM;
 
-        _job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
-        if (!_job_pool) {
-                kmem_cache_destroy(_job_cache);
-                return -ENOMEM;
-        }
-
         return 0;
 }
 
 static void jobs_exit(void)
 {
-        mempool_destroy(_job_pool);
         kmem_cache_destroy(_job_cache);
-        _job_pool = NULL;
         _job_cache = NULL;
 }
 
@@ -295,7 +288,7 @@ static int run_complete_job(struct kcopyd_job *job)
         struct dm_kcopyd_client *kc = job->kc;
 
         kcopyd_put_pages(kc, job->pages);
-        mempool_free(job, _job_pool);
+        mempool_free(job, kc->job_pool);
         fn(read_err, write_err, context);
 
         if (atomic_dec_and_test(&kc->nr_jobs))
@@ -487,7 +480,8 @@ static void segment_complete(int read_err, unsigned long write_err,
 
         if (count) {
                 int i;
-                struct kcopyd_job *sub_job = mempool_alloc(_job_pool, GFP_NOIO);
+                struct kcopyd_job *sub_job = mempool_alloc(job->kc->job_pool,
+                                                           GFP_NOIO);
 
                 *sub_job = *job;
                 sub_job->source.sector += progress;
@@ -511,7 +505,7 @@ static void segment_complete(int read_err, unsigned long write_err,
                  * after we've completed.
                  */
                 job->fn(read_err, write_err, job->context);
-                mempool_free(job, _job_pool);
+                mempool_free(job, job->kc->job_pool);
         }
 }
 
@@ -538,7 +532,7 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
         /*
          * Allocate a new job.
          */
-        job = mempool_alloc(_job_pool, GFP_NOIO);
+        job = mempool_alloc(kc->job_pool, GFP_NOIO);
 
         /*
          * set up for the read.
@@ -666,10 +660,19 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
         INIT_LIST_HEAD(&kc->io_jobs);
         INIT_LIST_HEAD(&kc->pages_jobs);
 
+        kc->job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
+        if (!kc->job_pool) {
+                r = -ENOMEM;
+                kfree(kc);
+                kcopyd_exit();
+                return r;
+        }
+
         INIT_WORK(&kc->kcopyd_work, do_work);
         kc->kcopyd_wq = create_singlethread_workqueue("kcopyd");
         if (!kc->kcopyd_wq) {
                 r = -ENOMEM;
+                mempool_destroy(kc->job_pool);
                 kfree(kc);
                 kcopyd_exit();
                 return r;
@@ -680,6 +683,7 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
         r = client_alloc_pages(kc, nr_pages);
         if (r) {
                 destroy_workqueue(kc->kcopyd_wq);
+                mempool_destroy(kc->job_pool);
                 kfree(kc);
                 kcopyd_exit();
                 return r;
@@ -690,6 +694,7 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
                 r = PTR_ERR(kc->io_client);
                 client_free_pages(kc);
                 destroy_workqueue(kc->kcopyd_wq);
+                mempool_destroy(kc->job_pool);
                 kfree(kc);
                 kcopyd_exit();
                 return r;
@@ -716,6 +721,7 @@ void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc)
         dm_io_client_destroy(kc->io_client);
         client_free_pages(kc);
         client_del(kc);
+        mempool_destroy(kc->job_pool);
         kfree(kc);
         kcopyd_exit();
 }