linux/fs/ocfs2/reservations.h
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   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * reservations.h
   5 *
   6 * Allocation reservations function prototypes and structures.
   7 *
   8 * Copyright (C) 2010 Novell.  All rights reserved.
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public
  12 * License version 2 as published by the Free Software Foundation.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17 * General Public License for more details.
  18 */
  19
  20#ifndef OCFS2_RESERVATIONS_H
  21#define OCFS2_RESERVATIONS_H
  22
  23#include <linux/rbtree.h>
  24
  25#define OCFS2_DEFAULT_RESV_LEVEL        2
  26#define OCFS2_MAX_RESV_LEVEL    9
  27#define OCFS2_MIN_RESV_LEVEL    0
  28
  29struct ocfs2_alloc_reservation {
  30        struct rb_node  r_node;
  31
  32        unsigned int    r_start;        /* Beginning of current window */
  33        unsigned int    r_len;          /* Length of the window */
  34
  35        unsigned int    r_last_len;     /* Length of most recent alloc */
  36        unsigned int    r_last_start;   /* Start of most recent alloc */
  37        struct list_head        r_lru;  /* LRU list head */
  38
  39        unsigned int    r_flags;
  40};
  41
  42#define OCFS2_RESV_FLAG_INUSE   0x01    /* Set when r_node is part of a btree */
  43#define OCFS2_RESV_FLAG_TMP     0x02    /* Temporary reservation, will be
  44                                         * destroyed immedately after use */
  45#define OCFS2_RESV_FLAG_DIR     0x04    /* Reservation is for an unindexed
  46                                         * directory btree */
  47
  48struct ocfs2_reservation_map {
  49        struct rb_root          m_reservations;
  50        char                    *m_disk_bitmap;
  51
  52        struct ocfs2_super      *m_osb;
  53
  54        /* The following are not initialized to meaningful values until a disk
  55         * bitmap is provided. */
  56        u32                     m_bitmap_len;   /* Number of valid
  57                                                 * bits available */
  58
  59        struct list_head        m_lru;          /* LRU of reservations
  60                                                 * structures. */
  61
  62};
  63
  64void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv);
  65
  66#define OCFS2_RESV_TYPES        (OCFS2_RESV_FLAG_TMP|OCFS2_RESV_FLAG_DIR)
  67void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
  68                         unsigned int flags);
  69
  70int ocfs2_dir_resv_allowed(struct ocfs2_super *osb);
  71
  72/**
  73 * ocfs2_resv_discard() - truncate a reservation
  74 * @resmap:
  75 * @resv: the reservation to truncate.
  76 *
  77 * After this function is called, the reservation will be empty, and
  78 * unlinked from the rbtree.
  79 */
  80void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
  81                        struct ocfs2_alloc_reservation *resv);
  82
  83
  84/**
  85 * ocfs2_resmap_init() - Initialize fields of a reservations bitmap
  86 * @resmap: struct ocfs2_reservation_map to initialize
  87 * @obj: unused for now
  88 * @ops: unused for now
  89 * @max_bitmap_bytes: Maximum size of the bitmap (typically blocksize)
  90 *
  91 * Only possible return value other than '0' is -ENOMEM for failure to
  92 * allocation mirror bitmap.
  93 */
  94int ocfs2_resmap_init(struct ocfs2_super *osb,
  95                      struct ocfs2_reservation_map *resmap);
  96
  97/**
  98 * ocfs2_resmap_restart() - "restart" a reservation bitmap
  99 * @resmap: reservations bitmap
 100 * @clen: Number of valid bits in the bitmap
 101 * @disk_bitmap: the disk bitmap this resmap should refer to.
 102 *
 103 * Re-initialize the parameters of a reservation bitmap. This is
 104 * useful for local alloc window slides.
 105 *
 106 * This function will call ocfs2_trunc_resv against all existing
 107 * reservations. A future version will recalculate existing
 108 * reservations based on the new bitmap.
 109 */
 110void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
 111                          unsigned int clen, char *disk_bitmap);
 112
 113/**
 114 * ocfs2_resmap_uninit() - uninitialize a reservation bitmap structure
 115 * @resmap: the struct ocfs2_reservation_map to uninitialize
 116 */
 117void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap);
 118
 119/**
 120 * ocfs2_resmap_resv_bits() - Return still-valid reservation bits
 121 * @resmap: reservations bitmap
 122 * @resv: reservation to base search from
 123 * @cstart: start of proposed allocation
 124 * @clen: length (in clusters) of proposed allocation
 125 *
 126 * Using the reservation data from resv, this function will compare
 127 * resmap and resmap->m_disk_bitmap to determine what part (if any) of
 128 * the reservation window is still clear to use. If resv is empty,
 129 * this function will try to allocate a window for it.
 130 *
 131 * On success, zero is returned and the valid allocation area is set in cstart
 132 * and clen.
 133 *
 134 * Returns -ENOSPC if reservations are disabled.
 135 */
 136int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
 137                           struct ocfs2_alloc_reservation *resv,
 138                           int *cstart, int *clen);
 139
 140/**
 141 * ocfs2_resmap_claimed_bits() - Tell the reservation code that bits were used.
 142 * @resmap: reservations bitmap
 143 * @resv: optional reservation to recalulate based on new bitmap
 144 * @cstart: start of allocation in clusters
 145 * @clen: end of allocation in clusters.
 146 *
 147 * Tell the reservation code that bits were used to fulfill allocation in
 148 * resmap. The bits don't have to have been part of any existing
 149 * reservation. But we must always call this function when bits are claimed.
 150 * Internally, the reservations code will use this information to mark the
 151 * reservations bitmap. If resv is passed, it's next allocation window will be
 152 * calculated. It also expects that 'cstart' is the same as we passed back
 153 * from ocfs2_resmap_resv_bits().
 154 */
 155void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
 156                               struct ocfs2_alloc_reservation *resv,
 157                               u32 cstart, u32 clen);
 158
 159#endif  /* OCFS2_RESERVATIONS_H */
 160
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