AFS: Use d_automount() rather than abusing follow_link()

Make AFS use the new d_automount() dentry operation rather than abusing
follow_link() on directories.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/afs/dir.c

@@ -66,6 +66,7 @@ const struct dentry_operations afs_fs_dentry_operations = {
 	.d_revalidate	= afs_d_revalidate,
 	.d_delete	= afs_d_delete,
 	.d_release	= afs_d_release,
+	.d_automount	= afs_d_automount,
 };
 
 #define AFS_DIR_HASHTBL_SIZE	128

fs/afs/inode.c

@@ -184,7 +184,8 @@ struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
 	inode->i_generation	= 0;
 
 	set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
-	inode->i_flags |= S_NOATIME;
+	set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+	inode->i_flags |= S_AUTOMOUNT | S_NOATIME;
 	unlock_new_inode(inode);
 	_leave(" = %p", inode);
 	return inode;

fs/afs/internal.h

@@ -592,6 +592,7 @@ extern const struct inode_operations afs_mntpt_inode_operations;
 extern const struct inode_operations afs_autocell_inode_operations;
 extern const struct file_operations afs_mntpt_file_operations;
 
+extern struct vfsmount *afs_d_automount(struct path *);
 extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
 extern void afs_mntpt_kill_timer(void);
 

fs/afs/mntpt.c

@@ -24,7 +24,6 @@ static struct dentry *afs_mntpt_lookup(struct inode *dir,
 				       struct dentry *dentry,
 				       struct nameidata *nd);
 static int afs_mntpt_open(struct inode *inode, struct file *file);
-static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
 
 const struct file_operations afs_mntpt_file_operations = {
@@ -34,13 +33,11 @@ const struct file_operations afs_mntpt_file_operations = {
 
 const struct inode_operations afs_mntpt_inode_operations = {
 	.lookup		= afs_mntpt_lookup,
-	.follow_link	= afs_mntpt_follow_link,
 	.readlink	= page_readlink,
 	.getattr	= afs_getattr,
 };
 
 const struct inode_operations afs_autocell_inode_operations = {
-	.follow_link	= afs_mntpt_follow_link,
 	.getattr	= afs_getattr,
 };
 
@@ -88,6 +85,7 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
 		_debug("symlink is a mountpoint");
 		spin_lock(&vnode->lock);
 		set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+		vnode->vfs_inode.i_flags |= S_AUTOMOUNT;
 		spin_unlock(&vnode->lock);
 	}
 
@@ -238,49 +236,37 @@ static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
 }
 
 /*
- * follow a link from a mountpoint directory, thus causing it to be mounted
+ * handle an automount point
  */
-static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
+struct vfsmount *afs_d_automount(struct path *path)
 {
 	struct vfsmount *newmnt;
 	int err;
 
-	_enter("%p{%s},{%s:%p{%s},}",
-	       dentry,
-	       dentry->d_name.name,
-	       nd->path.mnt->mnt_devname,
-	       dentry,
-	       nd->path.dentry->d_name.name);
+	_enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name);
 
-	dput(nd->path.dentry);
-	nd->path.dentry = dget(dentry);
-
-	newmnt = afs_mntpt_do_automount(nd->path.dentry);
-	if (IS_ERR(newmnt)) {
-		path_put(&nd->path);
-		return (void *)newmnt;
-	}
+	newmnt = afs_mntpt_do_automount(path->dentry);
+	if (IS_ERR(newmnt))
+		return newmnt;
 
 	mntget(newmnt);
-	err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
+	err = do_add_mount(newmnt, path, MNT_SHRINKABLE, &afs_vfsmounts);
 	switch (err) {
 	case 0:
-		path_put(&nd->path);
-		nd->path.mnt = newmnt;
-		nd->path.dentry = dget(newmnt->mnt_root);
 		queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
 				   afs_mntpt_expiry_timeout * HZ);
-		break;
+		_leave(" = %p {%s}", newmnt, newmnt->mnt_devname);
+		return newmnt;
 	case -EBUSY:
 		/* someone else made a mount here whilst we were busy */
-		err = follow_down(&nd->path, false);
+		mntput(newmnt);
+		_leave(" = NULL [EBUSY]");
+		return NULL;
 	default:
 		mntput(newmnt);
-		break;
-	}
-
 		_leave(" = %d", err);
 		return ERR_PTR(err);
+	}
 }
 
 /*