/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * reservations.h
   *
   * Allocation reservations function prototypes and structures.
   *
   * Copyright (C) 2010 Novell.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   */
  
  #ifndef	OCFS2_RESERVATIONS_H
  #define	OCFS2_RESERVATIONS_H
  
  #include <linux/rbtree.h>
  
  #define OCFS2_DEFAULT_RESV_LEVEL	2
  #define OCFS2_MAX_RESV_LEVEL	9
  #define OCFS2_MIN_RESV_LEVEL	0
  
  struct ocfs2_alloc_reservation {
  	struct rb_node	r_node;
  
  	unsigned int	r_start;	/* Beginning of current window */
  	unsigned int	r_len;		/* Length of the window */
  
  	unsigned int	r_last_len;	/* Length of most recent alloc */
  	unsigned int	r_last_start;	/* Start of most recent alloc */
  	struct list_head	r_lru;	/* LRU list head */
  
  	unsigned int	r_flags;
  };
  
  #define	OCFS2_RESV_FLAG_INUSE	0x01	/* Set when r_node is part of a btree */
  #define	OCFS2_RESV_FLAG_TMP	0x02	/* Temporary reservation, will be
  					 * destroyed immedately after use */
  #define	OCFS2_RESV_FLAG_DIR	0x04	/* Reservation is for an unindexed
  					 * directory btree */
  
  struct ocfs2_reservation_map {
  	struct rb_root		m_reservations;
  	char			*m_disk_bitmap;
  
  	struct ocfs2_super	*m_osb;
  
  	/* The following are not initialized to meaningful values until a disk
  	 * bitmap is provided. */
  	u32			m_bitmap_len;	/* Number of valid
  						 * bits available */
  
  	struct list_head	m_lru;		/* LRU of reservations
  						 * structures. */
  
  };
  
  void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv);
  
  #define OCFS2_RESV_TYPES	(OCFS2_RESV_FLAG_TMP|OCFS2_RESV_FLAG_DIR)
  void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
  			 unsigned int flags);
  
  int ocfs2_dir_resv_allowed(struct ocfs2_super *osb);
  
  /**
   * ocfs2_resv_discard() - truncate a reservation
   * @resmap:
   * @resv: the reservation to truncate.
   *
   * After this function is called, the reservation will be empty, and
   * unlinked from the rbtree.
   */
  void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
  			struct ocfs2_alloc_reservation *resv);
  
  
  /**
   * ocfs2_resmap_init() - Initialize fields of a reservations bitmap
   * @resmap: struct ocfs2_reservation_map to initialize
   * @obj: unused for now
   * @ops: unused for now
   * @max_bitmap_bytes: Maximum size of the bitmap (typically blocksize)
   *
   * Only possible return value other than '0' is -ENOMEM for failure to
   * allocation mirror bitmap.
   */
  int ocfs2_resmap_init(struct ocfs2_super *osb,
  		      struct ocfs2_reservation_map *resmap);
  
  /**
   * ocfs2_resmap_restart() - "restart" a reservation bitmap
   * @resmap: reservations bitmap
   * @clen: Number of valid bits in the bitmap
   * @disk_bitmap: the disk bitmap this resmap should refer to.
   *
   * Re-initialize the parameters of a reservation bitmap. This is
   * useful for local alloc window slides.
   *
   * This function will call ocfs2_trunc_resv against all existing
   * reservations. A future version will recalculate existing
   * reservations based on the new bitmap.
   */
  void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
  			  unsigned int clen, char *disk_bitmap);
  
  /**
   * ocfs2_resmap_uninit() - uninitialize a reservation bitmap structure
   * @resmap: the struct ocfs2_reservation_map to uninitialize
   */
  void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap);
  
  /**
   * ocfs2_resmap_resv_bits() - Return still-valid reservation bits
   * @resmap: reservations bitmap
   * @resv: reservation to base search from
   * @cstart: start of proposed allocation
   * @clen: length (in clusters) of proposed allocation
   *
   * Using the reservation data from resv, this function will compare
   * resmap and resmap->m_disk_bitmap to determine what part (if any) of
   * the reservation window is still clear to use. If resv is empty,
   * this function will try to allocate a window for it.
   *
   * On success, zero is returned and the valid allocation area is set in cstart
   * and clen.
   *
   * Returns -ENOSPC if reservations are disabled.
   */
  int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
  			   struct ocfs2_alloc_reservation *resv,
  			   int *cstart, int *clen);
  
  /**
   * ocfs2_resmap_claimed_bits() - Tell the reservation code that bits were used.
   * @resmap: reservations bitmap
   * @resv: optional reservation to recalulate based on new bitmap
   * @cstart: start of allocation in clusters
   * @clen: end of allocation in clusters.
   *
   * Tell the reservation code that bits were used to fulfill allocation in
   * resmap. The bits don't have to have been part of any existing
   * reservation. But we must always call this function when bits are claimed.
   * Internally, the reservations code will use this information to mark the
   * reservations bitmap. If resv is passed, it's next allocation window will be
   * calculated. It also expects that 'cstart' is the same as we passed back
   * from ocfs2_resmap_resv_bits().
   */
  void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
  			       struct ocfs2_alloc_reservation *resv,
  			       u32 cstart, u32 clen);
  
  #endif	/* OCFS2_RESERVATIONS_H */