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TOMOYO Linux Cross Reference
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 
 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 '' 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 */
160 

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