Subject: [PATCH 4/9] drm: remove the drm file system

From: Christoph Hellwig <[email-masked]>
Date: Tue, 9 Mar 2021 16:53:43 +0100

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <[email-masked]>
---
 drivers/gpu/drm/drm_drv.c | 64 ++-------------------------------------
 1 file changed, 3 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 87e7214a8e3565..af293d76f979e5 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -26,6 +26,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/anon_inodes.h>
 #include <linux/debugfs.h>
 #include <linux/fs.h>
 #include <linux/module.h>
@@ -475,65 +476,6 @@ void drm_dev_unplug(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_dev_unplug);
 
-/*
- * DRM internal mount
- * We want to be able to allocate our own "struct address_space" to control
- * memory-mappings in VRAM (or stolen RAM, ...). However, core MM does not allow
- * stand-alone address_space objects, so we need an underlying inode. As there
- * is no way to allocate an independent inode easily, we need a fake internal
- * VFS mount-point.
- *
- * The drm_fs_inode_new() function allocates a new inode, drm_fs_inode_free()
- * frees it again. You are allowed to use iget() and iput() to get references to
- * the inode. But each drm_fs_inode_new() call must be paired with exactly one
- * drm_fs_inode_free() call (which does not have to be the last iput()).
- * We use drm_fs_inode_*() to manage our internal VFS mount-point and share it
- * between multiple inode-users. You could, technically, call
- * iget() + drm_fs_inode_free() directly after alloc and sometime later do an
- * iput(), but this way you'd end up with a new vfsmount for each inode.
- */
-
-static int drm_fs_cnt;
-static struct vfsmount *drm_fs_mnt;
-
-static int drm_fs_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, 0x010203ff) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type drm_fs_type = {
-	.name		= "drm",
-	.owner		= THIS_MODULE,
-	.init_fs_context = drm_fs_init_fs_context,
-	.kill_sb	= kill_anon_super,
-};
-
-static struct inode *drm_fs_inode_new(void)
-{
-	struct inode *inode;
-	int r;
-
-	r = simple_pin_fs(&drm_fs_type, &drm_fs_mnt, &drm_fs_cnt);
-	if (r < 0) {
-		DRM_ERROR("Cannot mount pseudo fs: %d\n", r);
-		return ERR_PTR(r);
-	}
-
-	inode = alloc_anon_inode_sb(drm_fs_mnt->mnt_sb);
-	if (IS_ERR(inode))
-		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
-
-	return inode;
-}
-
-static void drm_fs_inode_free(struct inode *inode)
-{
-	if (inode) {
-		iput(inode);
-		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
-	}
-}
-
 /**
  * DOC: component helper usage recommendations
  *
@@ -563,7 +505,7 @@ static void drm_dev_init_release(struct drm_device *dev, void *res)
 {
 	drm_legacy_ctxbitmap_cleanup(dev);
 	drm_legacy_remove_map_hash(dev);
-	drm_fs_inode_free(dev->anon_inode);
+	iput(dev->anon_inode);
 
 	put_device(dev->dev);
 	/* Prevent use-after-free in drm_managed_release when debugging is
@@ -616,7 +558,7 @@ static int drm_dev_init(struct drm_device *dev,
 	if (ret)
 		return ret;
 
-	dev->anon_inode = drm_fs_inode_new();
+	dev->anon_inode = alloc_anon_inode();
 	if (IS_ERR(dev->anon_inode)) {
 		ret = PTR_ERR(dev->anon_inode);
 		DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
-- 
2.30.1