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
21struct 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
40struct 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
56void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv);
57
58#define OCFS2_RESV_TYPES	(OCFS2_RESV_FLAG_TMP|OCFS2_RESV_FLAG_DIR)
59void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
60			 unsigned int flags);
61
62int 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 */
72void 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 */
86int 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 */
102void 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 */
109void 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 */
128int 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 */
147void 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 */
152