btrfs: add helper methods for workspace manager init and cleanup

Workspace manager init and cleanup code is open coded inside a for loop
over the compression types. This forces each compression type to rely on
the same workspace manager implementation. This patch creates helper
methods that will be the generic implementation for btrfs workspace
management.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NDennis Zhou <dennis@kernel.org>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -796,31 +796,42 @@ static const struct btrfs_compress_op * const btrfs_compress_op[] = {
 	&btrfs_zstd_compress,
 };
 
-void __init btrfs_init_compress(void)
+static void btrfs_init_workspace_manager(int type)
 {
+	struct workspace_manager *wsman = &wsm[type];
 	struct list_head *workspace;
-	int i;
 
-	for (i = 0; i < BTRFS_NR_WORKSPACE_MANAGERS; i++) {
-		wsm[i].ops = btrfs_compress_op[i];
+	wsman->ops = btrfs_compress_op[type];
 
-		INIT_LIST_HEAD(&wsm[i].idle_ws);
-		spin_lock_init(&wsm[i].ws_lock);
-		atomic_set(&wsm[i].total_ws, 0);
-		init_waitqueue_head(&wsm[i].ws_wait);
+	INIT_LIST_HEAD(&wsman->idle_ws);
+	spin_lock_init(&wsman->ws_lock);
+	atomic_set(&wsman->total_ws, 0);
+	init_waitqueue_head(&wsman->ws_wait);
 
-		/*
-		 * Preallocate one workspace for each compression type so
-		 * we can guarantee forward progress in the worst case
-		 */
-		workspace = wsm[i].ops->alloc_workspace();
-		if (IS_ERR(workspace)) {
-			pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
-		} else {
-			atomic_set(&wsm[i].total_ws, 1);
-			wsm[i].free_ws = 1;
-			list_add(workspace, &wsm[i].idle_ws);
-		}
+	/*
+	 * Preallocate one workspace for each compression type so we can
+	 * guarantee forward progress in the worst case
+	 */
+	workspace = wsman->ops->alloc_workspace();
+	if (IS_ERR(workspace)) {
+		pr_warn(
+	"BTRFS: cannot preallocate compression workspace, will try later\n");
+	} else {
+		atomic_set(&wsman->total_ws, 1);
+		wsman->free_ws = 1;
+		list_add(workspace, &wsman->idle_ws);
+	}
+}
+
+static void btrfs_cleanup_workspace_manager(struct workspace_manager *wsman)
+{
+	struct list_head *ws;
+
+	while (!list_empty(&wsman->idle_ws)) {
+		ws = wsman->idle_ws.next;
+		list_del(ws);
+		wsman->ops->free_workspace(ws);
+		atomic_dec(&wsman->total_ws);
 	}
 }
 
@@ -940,24 +951,6 @@ static void free_workspace(int type, struct list_head *workspace)
 	cond_wake_up(ws_wait);
 }
 
-/*
- * cleanup function for module exit
- */
-static void free_workspaces(void)
-{
-	struct list_head *workspace;
-	int i;
-
-	for (i = 0; i < BTRFS_NR_WORKSPACE_MANAGERS; i++) {
-		while (!list_empty(&wsm[i].idle_ws)) {
-			workspace = wsm[i].idle_ws.next;
-			list_del(workspace);
-			wsm[i].ops->free_workspace(workspace);
-			atomic_dec(&wsm[i].total_ws);
-		}
-	}
-}
-
 /*
  * Given an address space and start and length, compress the bytes into @pages
  * that are allocated on demand.
@@ -1050,9 +1043,20 @@ int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
 	return ret;
 }
 
+void __init btrfs_init_compress(void)
+{
+	int i;
+
+	for (i = 0; i < BTRFS_NR_WORKSPACE_MANAGERS; i++)
+		btrfs_init_workspace_manager(i);
+}
+
 void __cold btrfs_exit_compress(void)
 {
-	free_workspaces();
+	int i;
+
+	for (i = 0; i < BTRFS_NR_WORKSPACE_MANAGERS; i++)
+		btrfs_cleanup_workspace_manager(&wsm[i]);
 }
 
 /*