reservations.h
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/* -*- 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 */