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        4
  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;        /* Begining 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 /**
  71  * ocfs2_resv_discard() - truncate a reservation
  72  * @resmap:
  73  * @resv: the reservation to truncate.
  74  *
  75  * After this function is called, the reservation will be empty, and
  76  * unlinked from the rbtree.
  77  */
  78 void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
  79                         struct ocfs2_alloc_reservation *resv);
  80
  81
  82 /**
  83  * ocfs2_resmap_init() - Initialize fields of a reservations bitmap
  84  * @resmap: struct ocfs2_reservation_map to initialize
  85  * @obj: unused for now
  86  * @ops: unused for now
  87  * @max_bitmap_bytes: Maximum size of the bitmap (typically blocksize)
  88  *
  89  * Only possible return value other than '0' is -ENOMEM for failure to
  90  * allocation mirror bitmap.
  91  */
  92 int ocfs2_resmap_init(struct ocfs2_super *osb,
  93                       struct ocfs2_reservation_map *resmap);
  94
  95 /**
  96  * ocfs2_resmap_restart() - "restart" a reservation bitmap
  97  * @resmap: reservations bitmap
  98  * @clen: Number of valid bits in the bitmap
  99  * @disk_bitmap: the disk bitmap this resmap should refer to.
 100  *
 101  * Re-initialize the parameters of a reservation bitmap. This is
 102  * useful for local alloc window slides.
 103  *
 104  * This function will call ocfs2_trunc_resv against all existing
 105  * reservations. A future version will recalculate existing
 106  * reservations based on the new bitmap.
 107  */
 108 void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
 109                           unsigned int clen, char *disk_bitmap);
 110
 111 /**
 112  * ocfs2_resmap_uninit() - uninitialize a reservation bitmap structure
 113  * @resmap: the struct ocfs2_reservation_map to uninitialize
 114  */
 115 void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap);
 116
 117 /**
 118  * ocfs2_resmap_resv_bits() - Return still-valid reservation bits
 119  * @resmap: reservations bitmap
 120  * @resv: reservation to base search from
 121  * @cstart: start of proposed allocation
 122  * @clen: length (in clusters) of proposed allocation
 123  *
 124  * Using the reservation data from resv, this function will compare
 125  * resmap and resmap->m_disk_bitmap to determine what part (if any) of
 126  * the reservation window is still clear to use. If resv is empty,
 127  * this function will try to allocate a window for it.
 128  *
 129  * On success, zero is returned and the valid allocation area is set in cstart
 130  * and clen.
 131  *
 132  * Returns -ENOSPC if reservations are disabled.
 133  */
 134 int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
 135                            struct ocfs2_alloc_reservation *resv,
 136                            int *cstart, int *clen);
 137
 138 /**
 139  * ocfs2_resmap_claimed_bits() - Tell the reservation code that bits were used.
 140  * @resmap: reservations bitmap
 141  * @resv: optional reservation to recalulate based on new bitmap
 142  * @cstart: start of allocation in clusters
 143  * @clen: end of allocation in clusters.
 144  *
 145  * Tell the reservation code that bits were used to fulfill allocation in
 146  * resmap. The bits don't have to have been part of any existing
 147  * reservation. But we must always call this function when bits are claimed.
 148  * Internally, the reservations code will use this information to mark the
 149  * reservations bitmap. If resv is passed, it's next allocation window will be
 150  * calculated.
 151  */
 152 void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
 153                                struct ocfs2_alloc_reservation *resv,
 154                                u32 cstart, u32 clen);
 155
 156 #endif  /* OCFS2_RESERVATIONS_H */