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