#ifndef __SHMEM_FS_H
  #define __SHMEM_FS_H
  
  #include <linux/swap.h>
  #include <linux/mempolicy.h>

  #include <linux/pagemap.h>

  #include <linux/percpu_counter.h>

  
  /* inode in-kernel data */

  struct shmem_inode_info {
  	spinlock_t		lock;
  	unsigned long		flags;
  	unsigned long		alloced;	/* data pages alloced to file */

  	union {

  		unsigned long	swapped;	/* subtotal assigned to swap */
  		char		*symlink;	/* unswappable short symlink */

  	};

  	struct shared_policy	policy;		/* NUMA memory alloc policy */

  	struct list_head	swaplist;	/* chain of maybes on swap */

  	struct list_head	xattr_list;	/* list of shmem_xattr */

  	struct inode		vfs_inode;
  };
  
  struct shmem_sb_info {
  	unsigned long max_blocks;   /* How many blocks are allowed */

  	struct percpu_counter used_blocks;  /* How many are allocated */

  	unsigned long max_inodes;   /* How many inodes are allowed */
  	unsigned long free_inodes;  /* How many are left for allocation */

  	spinlock_t stat_lock;	    /* Serialize shmem_sb_info changes */
  	uid_t uid;		    /* Mount uid for root directory */
  	gid_t gid;		    /* Mount gid for root directory */
  	mode_t mode;		    /* Mount mode for root directory */

  	struct mempolicy *mpol;     /* default memory policy for mappings */

  };
  
  static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
  {
  	return container_of(inode, struct shmem_inode_info, vfs_inode);
  }

  /*
   * Functions in mm/shmem.c called directly from elsewhere:
   */

  extern int shmem_init(void);

  extern int shmem_fill_super(struct super_block *sb, void *data, int silent);

  extern struct file *shmem_file_setup(const char *name,
  					loff_t size, unsigned long flags);
  extern int shmem_zero_setup(struct vm_area_struct *);
  extern int shmem_lock(struct file *file, int lock, struct user_struct *user);

  extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  					pgoff_t index, gfp_t gfp_mask);

  extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);

  extern int shmem_unuse(swp_entry_t entry, struct page *page);

  static inline struct page *shmem_read_mapping_page(
  				struct address_space *mapping, pgoff_t index)
  {
  	return shmem_read_mapping_page_gfp(mapping, index,
  					mapping_gfp_mask(mapping));
  }

  #endif