btrfs: remove hipri_workers workqueue

Now that btrfs_wq_submit_bio is never called for synchronous I/O,
the hipri_workers workqueue is not used anymore and can be removed.
Reviewed-by: Chris Mason <clm@fb.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/bio.c

@@ -615,10 +615,7 @@ static bool btrfs_wq_submit_bio(struct btrfs_bio *bbio,
 
 	btrfs_init_work(&async->work, run_one_async_start, run_one_async_done,
 			run_one_async_free);
-	if (op_is_sync(bbio->bio.bi_opf))
-		btrfs_queue_work(fs_info->hipri_workers, &async->work);
-	else
-		btrfs_queue_work(fs_info->workers, &async->work);
+	btrfs_queue_work(fs_info->workers, &async->work);
 	return true;
 }
 

fs/btrfs/disk-io.c

@@ -1991,7 +1991,6 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
 {
 	btrfs_destroy_workqueue(fs_info->fixup_workers);
 	btrfs_destroy_workqueue(fs_info->delalloc_workers);
-	btrfs_destroy_workqueue(fs_info->hipri_workers);
 	btrfs_destroy_workqueue(fs_info->workers);
 	if (fs_info->endio_workers)
 		destroy_workqueue(fs_info->endio_workers);
@@ -2186,9 +2185,6 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info)
 
 	fs_info->workers =
 		btrfs_alloc_workqueue(fs_info, "worker", flags, max_active, 16);
-	fs_info->hipri_workers =
-		btrfs_alloc_workqueue(fs_info, "worker-high",
-				      flags | WQ_HIGHPRI, max_active, 16);
 
 	fs_info->delalloc_workers =
 		btrfs_alloc_workqueue(fs_info, "delalloc",
@@ -2225,7 +2221,7 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info)
 	fs_info->discard_ctl.discard_workers =
 		alloc_workqueue("btrfs_discard", WQ_UNBOUND | WQ_FREEZABLE, 1);
 
-	if (!(fs_info->workers && fs_info->hipri_workers &&
+	if (!(fs_info->workers &&
 	      fs_info->delalloc_workers && fs_info->flush_workers &&
 	      fs_info->endio_workers && fs_info->endio_meta_workers &&
 	      fs_info->compressed_write_workers &&

fs/btrfs/fs.h

@@ -543,7 +543,6 @@ struct btrfs_fs_info {
 	 * A third pool does submit_bio to avoid deadlocking with the other two.
 	 */
 	struct btrfs_workqueue *workers;
-	struct btrfs_workqueue *hipri_workers;
 	struct btrfs_workqueue *delalloc_workers;
 	struct btrfs_workqueue *flush_workers;
 	struct workqueue_struct *endio_workers;

fs/btrfs/super.c

@@ -1631,7 +1631,6 @@ static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
 	       old_pool_size, new_pool_size);
 
 	btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
-	btrfs_workqueue_set_max(fs_info->hipri_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
 	workqueue_set_max_active(fs_info->endio_workers, new_pool_size);