New method - evict_inode()

Hybrid of ->clear_inode() and ->delete_inode(); if present, does
all fs work to be done when in-core inode is about to be gone,
for whatever reason.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

@@ -1563,6 +1563,7 @@ struct super_operations {
    	void (*dirty_inode) (struct inode *);
 	int (*write_inode) (struct inode *, struct writeback_control *wbc);
 	void (*drop_inode) (struct inode *);
+	void (*evict_inode) (struct inode *);
 	void (*delete_inode) (struct inode *);
 	void (*put_super) (struct super_block *);
 	void (*write_super) (struct super_block *);