+static struct fuse_sync_bucket *fuse_sync_bucket_alloc(void)
+{
+ struct fuse_sync_bucket *bucket;
+
+ bucket = kzalloc(sizeof(*bucket), GFP_KERNEL | __GFP_NOFAIL);
+ if (bucket) {
+ init_waitqueue_head(&bucket->waitq);
+ /* Initial active count */
+ atomic_set(&bucket->count, 1);
+ }
+ return bucket;
+}
+
+static void fuse_sync_fs_writes(struct fuse_conn *fc)
+{
+ struct fuse_sync_bucket *bucket, *new_bucket;
+ int count;
+
+ new_bucket = fuse_sync_bucket_alloc();
+ spin_lock(&fc->lock);
+ bucket = rcu_dereference_protected(fc->curr_bucket, 1);
+ count = atomic_read(&bucket->count);
+ WARN_ON(count < 1);
+ /* No outstanding writes? */
+ if (count == 1) {
+ spin_unlock(&fc->lock);
+ kfree(new_bucket);
+ return;
+ }
+
+ /*
+ * Completion of new bucket depends on completion of this bucket, so add
+ * one more count.
+ */
+ atomic_inc(&new_bucket->count);
+ rcu_assign_pointer(fc->curr_bucket, new_bucket);
+ spin_unlock(&fc->lock);
+ /*
+ * Drop initial active count. At this point if all writes in this and
+ * ancestor buckets complete, the count will go to zero and this task
+ * will be woken up.
+ */
+ atomic_dec(&bucket->count);
+
+ wait_event(bucket->waitq, atomic_read(&bucket->count) == 0);
+
+ /* Drop temp count on descendant bucket */
+ fuse_sync_bucket_dec(new_bucket);
+ kfree_rcu(bucket, rcu);
+}
+