Clean up refcounting on filesystems

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.55/fs/filesystems.c working-2.5.55-mountref/fs/filesystems.c
@@ -28,27 +28,6 @@
 static struct file_system_type *file_systems;
 static rwlock_t file_systems_lock = RW_LOCK_UNLOCKED;
 
-/* WARNING: This can be used only if we _already_ own a reference */
-void get_filesystem(struct file_system_type *fs)
-{
-	if (!try_module_get(fs->owner)) {
-#ifdef CONFIG_MODULE_UNLOAD
-		unsigned int cpu = get_cpu();
-		local_inc(&fs->owner->ref[cpu].count);
-		put_cpu();
-#else
-		/* Getting filesystem while it's starting up?  We're
-                   already supposed to have a reference. */
-		BUG();
-#endif
-	}
-}
-
-void put_filesystem(struct file_system_type *fs)
-{
-	module_put(fs->owner);
-}
-
 static struct file_system_type **find_filesystem(const char *name)
 {
 	struct file_system_type **p;

@@ -162,7 +141,7 @@ static int fs_name(unsigned int index, c
 	/* OK, we got the reference, so we can safely block */
 	len = strlen(tmp->name) + 1;
 	res = copy_to_user(buf, tmp->name, len) ? -EFAULT : 0;
-	put_filesystem(tmp);
+	put_fs_type(tmp);
 	return res;
 }
 

@@ -234,3 +213,8 @@ struct file_system_type *get_fs_type(con
 	}
 	return fs;
 }
+
+void put_fs_type(struct file_system_type *fs)
+{
+	module_put(fs->owner);
+}

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.55/fs/namespace.c working-2.5.55-mountref/fs/namespace.c
@@ -152,6 +152,7 @@ void __mntput(struct vfsmount *mnt)
 {
 	struct super_block *sb = mnt->mnt_sb;
 	dput(mnt->mnt_root);
+	put_fs_type(mnt->type);
 	free_vfsmnt(mnt);
 	deactivate_super(sb);
 }

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.55/fs/super.c working-2.5.55-mountref/fs/super.c
@@ -31,13 +31,9 @@
 #include <linux/mount.h>
 #include <linux/security.h>
 #include <linux/vfs.h>
+#include <linux/fs.h>
 #include <asm/uaccess.h>
 
-
-void get_filesystem(struct file_system_type *fs);
-void put_filesystem(struct file_system_type *fs);
-struct file_system_type *get_fs_type(const char *name);
-
 LIST_HEAD(super_blocks);
 spinlock_t sb_lock = SPIN_LOCK_UNLOCKED;
 

@@ -127,7 +123,6 @@ void deactivate_super(struct super_block
 		spin_unlock(&sb_lock);
 		down_write(&s->s_umount);
 		fs->kill_sb(s);
-		put_filesystem(fs);
 		put_super(s);
 	}
 }

@@ -253,7 +248,6 @@ retry:
 	list_add(&s->s_list, super_blocks.prev);
 	list_add(&s->s_instances, &type->fs_supers);
 	spin_unlock(&sb_lock);
-	get_filesystem(type);
 	return s;
 }
 

@@ -624,13 +618,13 @@ do_kern_mount(const char *fstype, int fl
 	mnt->mnt_root = dget(sb->s_root);
 	mnt->mnt_mountpoint = sb->s_root;
 	mnt->mnt_parent = mnt;
+	mnt->type = type;
 	up_write(&sb->s_umount);
-	put_filesystem(type);
 	return mnt;
 out_mnt:
 	free_vfsmnt(mnt);
 out:
-	put_filesystem(type);
+	put_fs_type(type);
 	return (struct vfsmount *)sb;
 }
 

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.55/include/linux/fs.h working-2.5.55-mountref/include/linux/fs.h
@@ -1289,6 +1289,7 @@ extern int vfs_lstat(char *, struct ksta
 extern int vfs_fstat(unsigned int, struct kstat *);
 
 extern struct file_system_type *get_fs_type(const char *name);
+extern void put_fs_type(struct file_system_type *fs);
 extern struct super_block *get_super(struct block_device *);
 extern struct super_block *user_get_super(dev_t);
 extern void drop_super(struct super_block *sb);

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.55/include/linux/mount.h working-2.5.55-mountref/include/linux/mount.h
@@ -30,6 +30,7 @@ struct vfsmount
 	atomic_t mnt_count;
 	int mnt_flags;
 	char *mnt_devname;		/* Name of device e.g. /dev/dsk/hda1 */
+	struct file_system_type *type;	/* Type (we hold a reference). */
 	struct list_head mnt_list;
 };