fs/ocfs2/reservations.h

   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
  29 struct 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
  48 struct 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
  64 void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv);
  65
  66 #define OCFS2_RESV_TYPES        (OCFS2_RESV_FLAG_TMP|OCFS2_RESV_FLAG_DIR)
  67 void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
  68                          unsigned int flags);
  69
  70 int 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  */
  80 void 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  */
  94 int 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  */
 110 void 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  */
 117 void 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  */
 136 int 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  */
 155 void 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 */