[Virtio-fs] [PATCH 3/3] virtio-fs: Waiting for pending forget requests to finish

[Vivek Goyal]

Keep a track of pending forget requests and wait for these to finish
during ->kill_sb()

Signed-off-by: Vivek Goyal <vgoyal at redhat.com>
---
 fs/fuse/virtio_fs.c | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 737e92cdc5ed..abdb58285805 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -32,6 +32,7 @@ struct virtio_fs_vq {
 	struct delayed_work dispatch_work;
 	struct fuse_dev *fud;
 	bool connected;
+	long in_flight;
 	char name[24];
 } ____cacheline_aligned_in_smp;
 
@@ -183,8 +184,10 @@ static void virtio_fs_hiprio_done_work(struct work_struct *work)
 
 		virtqueue_disable_cb(vq);
 
-		while ((req = virtqueue_get_buf(vq, &len)) != NULL)
+		while ((req = virtqueue_get_buf(vq, &len)) != NULL) {
 			kfree(req);
+			fsvq->in_flight--;
+		}
 	} while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq)));
 	spin_unlock(&fsvq->lock);
 }
@@ -244,6 +247,7 @@ static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
 			return;
 		}
 
+		fsvq->in_flight++;
 		notify = virtqueue_kick_prepare(vq);
 		spin_unlock(&fsvq->lock);
 
@@ -753,6 +757,7 @@ __releases(fiq->waitq.lock)
 		goto out;
 	}
 
+	fsvq->in_flight++;
 	notify = virtqueue_kick_prepare(vq);
 
 	spin_unlock(&fsvq->lock);
@@ -982,6 +987,36 @@ __releases(fiq->waitq.lock)
 	}
 }
 
+static void virtio_fs_flush_hiprio_queue(struct virtio_fs_vq *fsvq)
+{
+	struct virtio_fs_forget *forget;
+
+	WARN_ON(fsvq->in_flight < 0);
+
+	/* Go through pending forget reuests and free them */
+	spin_lock(&fsvq->lock);
+	while(1) {
+		forget = list_first_entry_or_null(&fsvq->queued_reqs,
+					struct virtio_fs_forget, list);
+		if (!forget)
+			break;
+		kfree(forget);
+	}
+
+	spin_unlock(&fsvq->lock);
+
+	/* Wait for in flight requests to finish.*/
+	while (1) {
+		spin_lock(&fsvq->lock);
+		if (!fsvq->in_flight) {
+			spin_unlock(&fsvq->lock);
+			break;
+		}
+		spin_unlock(&fsvq->lock);
+		usleep_range(1000, 2000);
+	}
+}
+
 const static struct fuse_iqueue_ops virtio_fs_fiq_ops = {
 	.wake_forget_and_unlock		= virtio_fs_wake_forget_and_unlock,
 	.wake_interrupt_and_unlock	= virtio_fs_wake_interrupt_and_unlock,
@@ -1086,6 +1121,7 @@ static void virtio_kill_sb(struct super_block *sb)
 	spin_lock(&fsvq->lock);
 	fsvq->connected = false;
 	spin_unlock(&fsvq->lock);
+	virtio_fs_flush_hiprio_queue(fsvq);
 
 	fuse_kill_sb_anon(sb);
 	virtio_fs_free_devs(vfs);
-- 
2.20.1