Re: [PATCH] fs: export simple_dname for drm drivers.

From: Al Viro
Date: Sun Jan 19 2014 - 20:28:41 EST

On Mon, Jan 20, 2014 at 10:54:44AM +1000, Dave Airlie wrote:
> David Herrmann's changes to use a pseudo filesystem for drm's shared
> inodes requires this be exported for drm to build as a module.
> I'd like to merge this via the drm tree, so please ack.

Having looked through these patches... The problem is that you'll get
your module impossible to unload. Sane solution:

static struct vfsmount *drm_mnt;
static int count;
struct inode *drm_alloc_inode(void)
struct inode *res;
int err = simple_pin_fs(&drm_fs, &drm_mnt, &count);
if (err)
return ERR_PTR(err);
res = alloc_anon_inode(drm_mnt->mnt_sb);
if (IS_ERR(res))
simple_release_fs(&drm_mnt, &count);
return res;

/* call from drm_free_dev() */
void drm_put_anon_inode(struct drm_device *dev)
simple_release_fs(&drm_mnt, &count);

and lose those kern_mount/kern_umount.
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