LXR linux/fs/ocfs2/reservations.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * reservations.h
   4 *
   5 * Allocation reservations function prototypes and structures.
   6 *
   7 * Copyright (C) 2010 Novell.  All rights reserved.
   8 */
   9
  10#ifndef OCFS2_RESERVATIONS_H
  11#define OCFS2_RESERVATIONS_H
  12
  13#include <linux/rbtree.h>
  14
  15#define OCFS2_DEFAULT_RESV_LEVEL        2
  16#define OCFS2_MAX_RESV_LEVEL    9
  17#define OCFS2_MIN_RESV_LEVEL    0
  18
  19struct ocfs2_alloc_reservation {
  20        struct rb_node  r_node;
  21
  22        unsigned int    r_start;        /* Beginning of current window */
  23        unsigned int    r_len;          /* Length of the window */
  24
  25        unsigned int    r_last_len;     /* Length of most recent alloc */
  26        unsigned int    r_last_start;   /* Start of most recent alloc */
  27        struct list_head        r_lru;  /* LRU list head */
  28
  29        unsigned int    r_flags;
  30};
  31
  32#define OCFS2_RESV_FLAG_INUSE   0x01    /* Set when r_node is part of a btree */
  33#define OCFS2_RESV_FLAG_TMP     0x02    /* Temporary reservation, will be
  34                                         * destroyed immedately after use */
  35#define OCFS2_RESV_FLAG_DIR     0x04    /* Reservation is for an unindexed
  36                                         * directory btree */
  37
  38struct ocfs2_reservation_map {
  39        struct rb_root          m_reservations;
  40        char                    *m_disk_bitmap;
  41
  42        struct ocfs2_super      *m_osb;
  43
  44        /* The following are not initialized to meaningful values until a disk
  45         * bitmap is provided. */
  46        u32                     m_bitmap_len;   /* Number of valid
  47                                                 * bits available */
  48
  49        struct list_head        m_lru;          /* LRU of reservations
  50                                                 * structures. */
  51
  52};
  53
  54void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv);
  55
  56#define OCFS2_RESV_TYPES        (OCFS2_RESV_FLAG_TMP|OCFS2_RESV_FLAG_DIR)
  57void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
  58                         unsigned int flags);
  59
  60int ocfs2_dir_resv_allowed(struct ocfs2_super *osb);
  61
  62/**
  63 * ocfs2_resv_discard() - truncate a reservation
  64 * @resmap:
  65 * @resv: the reservation to truncate.
  66 *
  67 * After this function is called, the reservation will be empty, and
  68 * unlinked from the rbtree.
  69 */
  70void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
  71                        struct ocfs2_alloc_reservation *resv);
  72
  73
  74/**
  75 * ocfs2_resmap_init() - Initialize fields of a reservations bitmap
  76 * @resmap: struct ocfs2_reservation_map to initialize
  77 * @obj: unused for now
  78 * @ops: unused for now
  79 * @max_bitmap_bytes: Maximum size of the bitmap (typically blocksize)
  80 *
  81 * Only possible return value other than '0' is -ENOMEM for failure to
  82 * allocation mirror bitmap.
  83 */
  84int ocfs2_resmap_init(struct ocfs2_super *osb,
  85                      struct ocfs2_reservation_map *resmap);
  86
  87/**
  88 * ocfs2_resmap_restart() - "restart" a reservation bitmap
  89 * @resmap: reservations bitmap
  90 * @clen: Number of valid bits in the bitmap
  91 * @disk_bitmap: the disk bitmap this resmap should refer to.
  92 *
  93 * Re-initialize the parameters of a reservation bitmap. This is
  94 * useful for local alloc window slides.
  95 *
  96 * This function will call ocfs2_trunc_resv against all existing
  97 * reservations. A future version will recalculate existing
  98 * reservations based on the new bitmap.
  99 */
 100void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
 101                          unsigned int clen, char *disk_bitmap);
 102
 103/**
 104 * ocfs2_resmap_uninit() - uninitialize a reservation bitmap structure
 105 * @resmap: the struct ocfs2_reservation_map to uninitialize
 106 */
 107void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap);
 108
 109/**
 110 * ocfs2_resmap_resv_bits() - Return still-valid reservation bits
 111 * @resmap: reservations bitmap
 112 * @resv: reservation to base search from
 113 * @cstart: start of proposed allocation
 114 * @clen: length (in clusters) of proposed allocation
 115 *
 116 * Using the reservation data from resv, this function will compare
 117 * resmap and resmap->m_disk_bitmap to determine what part (if any) of
 118 * the reservation window is still clear to use. If resv is empty,
 119 * this function will try to allocate a window for it.
 120 *
 121 * On success, zero is returned and the valid allocation area is set in cstart
 122 * and clen.
 123 *
 124 * Returns -ENOSPC if reservations are disabled.
 125 */
 126int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
 127                           struct ocfs2_alloc_reservation *resv,
 128                           int *cstart, int *clen);
 129
 130/**
 131 * ocfs2_resmap_claimed_bits() - Tell the reservation code that bits were used.
 132 * @resmap: reservations bitmap
 133 * @resv: optional reservation to recalulate based on new bitmap
 134 * @cstart: start of allocation in clusters
 135 * @clen: end of allocation in clusters.
 136 *
 137 * Tell the reservation code that bits were used to fulfill allocation in
 138 * resmap. The bits don't have to have been part of any existing
 139 * reservation. But we must always call this function when bits are claimed.
 140 * Internally, the reservations code will use this information to mark the
 141 * reservations bitmap. If resv is passed, it's next allocation window will be
 142 * calculated. It also expects that 'cstart' is the same as we passed back
 143 * from ocfs2_resmap_resv_bits().
 144 */
 145void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
 146                               struct ocfs2_alloc_reservation *resv,
 147                               u32 cstart, u32 clen);
 148
 149#endif  /* OCFS2_RESERVATIONS_H */
 150