Subject: [PATCH 6/9] virtio_balloon: remove the balloon-kvm file system

From: Christoph Hellwig <[email-masked]>
Date: Tue, 9 Mar 2021 16:53:45 +0100

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <[email-masked]>
---
 drivers/virtio/virtio_balloon.c | 30 +++---------------------------
 1 file changed, 3 insertions(+), 27 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index cae76ee5bdd688..1efb890cd3ff09 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -6,6 +6,7 @@
  *  Copyright 2008 Rusty Russell IBM Corporation
  */
 
+#include <linux/anon_inodes.h>
 #include <linux/virtio.h>
 #include <linux/virtio_balloon.h>
 #include <linux/swap.h>
@@ -42,10 +43,6 @@
 	(1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT))
 #define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER)
 
-#ifdef CONFIG_BALLOON_COMPACTION
-static struct vfsmount *balloon_mnt;
-#endif
-
 enum virtio_balloon_vq {
 	VIRTIO_BALLOON_VQ_INFLATE,
 	VIRTIO_BALLOON_VQ_DEFLATE,
@@ -805,18 +802,6 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
 
 	return MIGRATEPAGE_SUCCESS;
 }
-
-static int balloon_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, BALLOON_KVM_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type balloon_fs = {
-	.name           = "balloon-kvm",
-	.init_fs_context = balloon_init_fs_context,
-	.kill_sb        = kill_anon_super,
-};
-
 #endif /* CONFIG_BALLOON_COMPACTION */
 
 static unsigned long shrink_free_pages(struct virtio_balloon *vb,
@@ -909,17 +894,11 @@ static int virtballoon_probe(struct virtio_device *vdev)
 		goto out_free_vb;
 
 #ifdef CONFIG_BALLOON_COMPACTION
-	balloon_mnt = kern_mount(&balloon_fs);
-	if (IS_ERR(balloon_mnt)) {
-		err = PTR_ERR(balloon_mnt);
-		goto out_del_vqs;
-	}
-
 	vb->vb_dev_info.migratepage = virtballoon_migratepage;
-	vb->vb_dev_info.inode = alloc_anon_inode_sb(balloon_mnt->mnt_sb);
+	vb->vb_dev_info.inode = alloc_anon_inode();
 	if (IS_ERR(vb->vb_dev_info.inode)) {
 		err = PTR_ERR(vb->vb_dev_info.inode);
-		goto out_kern_unmount;
+		goto out_del_vqs;
 	}
 	vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
 #endif
@@ -1016,8 +995,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 out_iput:
 #ifdef CONFIG_BALLOON_COMPACTION
 	iput(vb->vb_dev_info.inode);
-out_kern_unmount:
-	kern_unmount(balloon_mnt);
 out_del_vqs:
 #endif
 	vdev->config->del_vqs(vdev);
@@ -1070,7 +1047,6 @@ static void virtballoon_remove(struct virtio_device *vdev)
 	if (vb->vb_dev_info.inode)
 		iput(vb->vb_dev_info.inode);
 
-	kern_unmount(balloon_mnt);
 #endif
 	kfree(vb);
 }
-- 
2.30.1