Btrfs: Throttle less often waiting for snapshots to delete

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/extent-tree.c

@@ -2535,6 +2535,10 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
 						root_gen, 0, 0, 1);
 			BUG_ON(ret);
 			mutex_unlock(&root->fs_info->alloc_mutex);
+
+			atomic_inc(&root->fs_info->throttle_gen);
+			wake_up(&root->fs_info->transaction_throttle);
+
 			continue;
 		}
 		/*
@@ -2603,7 +2607,6 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
 	root_owner = btrfs_header_owner(parent);
 	root_gen = btrfs_header_generation(parent);
 
-
 	mutex_lock(&root->fs_info->alloc_mutex);
 	ret = __btrfs_free_extent(trans, root, bytenr, blocksize,
 				  root_owner, root_gen, 0, 0, 1);
@@ -2726,7 +2729,6 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
 		}
 	}
 	while(1) {
-		atomic_inc(&root->fs_info->throttle_gen);
 		wret = walk_down_tree(trans, root, path, &level);
 		if (wret > 0)
 			break;
@@ -2742,6 +2744,7 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
 			ret = -EAGAIN;
 			break;
 		}
+		atomic_inc(&root->fs_info->throttle_gen);
 		wake_up(&root->fs_info->transaction_throttle);
 	}
 	for (i = 0; i <= orig_level; i++) {

fs/btrfs/transaction.c

@@ -211,11 +211,9 @@ static void throttle_on_drops(struct btrfs_root *root)
 {
 	struct btrfs_fs_info *info = root->fs_info;
 
-harder:
 	if (atomic_read(&info->throttles)) {
 		DEFINE_WAIT(wait);
 		int thr;
-		int harder_count = 0;
 		thr = atomic_read(&info->throttle_gen);
 
 		do {
@@ -228,18 +226,6 @@ static void throttle_on_drops(struct btrfs_root *root)
 			schedule();
 			finish_wait(&info->transaction_throttle, &wait);
 		} while (thr == atomic_read(&info->throttle_gen));
-
-		if (harder_count < 5 &&
-		    info->total_ref_cache_size > 1 * 1024 * 1024) {
-			harder_count++;
-			goto harder;
-		}
-
-		if (harder_count < 10 &&
-		    info->total_ref_cache_size > 5 * 1024 * 1024) {
-			harder_count++;
-			goto harder;
-		}
 	}
 }