fs/ocfs2/reservations.h

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