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