IMA: define readcount functions

Define i_readcount_inc/dec() functions to be called from the VFS layer.

Changelog:
- renamed iget/iput_readcount to i_readcount_inc/dec (Dave Chinner's suggestion)
- removed i_lock in iput_readcount() (based on comments:Dave Chinner,Eric Paris)
Signed-off-by: NMimi Zohar <zohar@us.ibm.com>
Acked-by: NEric Paris <eparis@redhat.com>

include/linux/fs.h

@@ -2186,6 +2186,26 @@ static inline void allow_write_access(struct file *file)
 	if (file)
 		atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
 }
+#ifdef CONFIG_IMA
+static inline void i_readcount_dec(struct inode *inode)
+{
+	BUG_ON(!atomic_read(&inode->i_readcount));
+	atomic_dec(&inode->i_readcount);
+}
+static inline void i_readcount_inc(struct inode *inode)
+{
+	atomic_inc(&inode->i_readcount);
+}
+#else
+static inline void i_readcount_dec(struct inode *inode)
+{
+	return;
+}
+static inline void i_readcount_inc(struct inode *inode)
+{
+	return;
+}
+#endif
 extern int do_pipe_flags(int *, int);
 extern struct file *create_read_pipe(struct file *f, int flags);
 extern struct file *create_write_pipe(int flags);