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 */