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

Signed-off-by: Vivek Goyal <[email protected]>
---
 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

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