1 /*
2 * tmem.h
3 *
4 * Transcendent memory
5 *
6 * Copyright (c) 2009-2011, Dan Magenheimer, Oracle Corp.
7 */
8
9 #ifndef _TMEM_H_
10 #define _TMEM_H_
11
12 #include <linux/types.h>
13 #include <linux/highmem.h>
14 #include <linux/hash.h>
15 #include <linux/atomic.h>
16
17 /*
18 * These are pre-defined by the Xen<->Linux ABI
19 */
20 #define TMEM_PUT_PAGE 4
21 #define TMEM_GET_PAGE 5
22 #define TMEM_FLUSH_PAGE 6
23 #define TMEM_FLUSH_OBJECT 7
24 #define TMEM_POOL_PERSIST 1
25 #define TMEM_POOL_SHARED 2
26 #define TMEM_POOL_PRECOMPRESSED 4
27 #define TMEM_POOL_PAGESIZE_SHIFT 4
28 #define TMEM_POOL_PAGESIZE_MASK 0xf
29 #define TMEM_POOL_RESERVED_BITS 0x00ffff00
30
31 /*
32 * sentinels have proven very useful for debugging but can be removed
33 * or disabled before final merge.
34 */
35 #define SENTINELS
36 #ifdef SENTINELS
37 #define DECL_SENTINEL uint32_t sentinel;
38 #define SET_SENTINEL(_x, _y) (_x->sentinel = _y##_SENTINEL)
39 #define INVERT_SENTINEL(_x, _y) (_x->sentinel = ~_y##_SENTINEL)
40 #define ASSERT_SENTINEL(_x, _y) WARN_ON(_x->sentinel != _y##_SENTINEL)
41 #define ASSERT_INVERTED_SENTINEL(_x, _y) WARN_ON(_x->sentinel != ~_y##_SENTINEL)
42 #else
43 #define DECL_SENTINEL
44 #define SET_SENTINEL(_x, _y) do { } while (0)
45 #define INVERT_SENTINEL(_x, _y) do { } while (0)
46 #define ASSERT_SENTINEL(_x, _y) do { } while (0)
47 #define ASSERT_INVERTED_SENTINEL(_x, _y) do { } while (0)
48 #endif
49
50 #define ASSERT_SPINLOCK(_l) WARN_ON(!spin_is_locked(_l))
51
52 /*
53 * A pool is the highest-level data structure managed by tmem and
54 * usually corresponds to a large independent set of pages such as
55 * a filesystem. Each pool has an id, and certain attributes and counters.
56 * It also contains a set of hash buckets, each of which contains an rbtree
57 * of objects and a lock to manage concurrency within the pool.
58 */
59
60 #define TMEM_HASH_BUCKET_BITS 8
61 #define TMEM_HASH_BUCKETS (1<<TMEM_HASH_BUCKET_BITS)
62
63 struct tmem_hashbucket {
64 struct rb_root obj_rb_root;
65 spinlock_t lock;
66 };
67
68 struct tmem_pool {
69 void *client; /* "up" for some clients, avoids table lookup */
70 struct list_head pool_list;
71 uint32_t pool_id;
72 bool persistent;
73 bool shared;
74 atomic_t obj_count;
75 atomic_t refcount;
76 struct tmem_hashbucket hashbucket[TMEM_HASH_BUCKETS];
77 DECL_SENTINEL
78 };
79
80 #define is_persistent(_p) (_p->persistent)
81 #define is_ephemeral(_p) (!(_p->persistent))
82
83 /*
84 * An object id ("oid") is large: 192-bits (to ensure, for example, files
85 * in a modern filesystem can be uniquely identified).
86 */
87
88 struct tmem_oid {
89 uint64_t oid[3];
90 };
91
tmem_oid_set_invalid(struct tmem_oid * oidp)92 static inline void tmem_oid_set_invalid(struct tmem_oid *oidp)
93 {
94 oidp->oid[0] = oidp->oid[1] = oidp->oid[2] = -1UL;
95 }
96
tmem_oid_valid(struct tmem_oid * oidp)97 static inline bool tmem_oid_valid(struct tmem_oid *oidp)
98 {
99 return oidp->oid[0] != -1UL || oidp->oid[1] != -1UL ||
100 oidp->oid[2] != -1UL;
101 }
102
tmem_oid_compare(struct tmem_oid * left,struct tmem_oid * right)103 static inline int tmem_oid_compare(struct tmem_oid *left,
104 struct tmem_oid *right)
105 {
106 int ret;
107
108 if (left->oid[2] == right->oid[2]) {
109 if (left->oid[1] == right->oid[1]) {
110 if (left->oid[0] == right->oid[0])
111 ret = 0;
112 else if (left->oid[0] < right->oid[0])
113 ret = -1;
114 else
115 return 1;
116 } else if (left->oid[1] < right->oid[1])
117 ret = -1;
118 else
119 ret = 1;
120 } else if (left->oid[2] < right->oid[2])
121 ret = -1;
122 else
123 ret = 1;
124 return ret;
125 }
126
tmem_oid_hash(struct tmem_oid * oidp)127 static inline unsigned tmem_oid_hash(struct tmem_oid *oidp)
128 {
129 return hash_long(oidp->oid[0] ^ oidp->oid[1] ^ oidp->oid[2],
130 TMEM_HASH_BUCKET_BITS);
131 }
132
133 /*
134 * A tmem_obj contains an identifier (oid), pointers to the parent
135 * pool and the rb_tree to which it belongs, counters, and an ordered
136 * set of pampds, structured in a radix-tree-like tree. The intermediate
137 * nodes of the tree are called tmem_objnodes.
138 */
139
140 struct tmem_objnode;
141
142 struct tmem_obj {
143 struct tmem_oid oid;
144 struct tmem_pool *pool;
145 struct rb_node rb_tree_node;
146 struct tmem_objnode *objnode_tree_root;
147 unsigned int objnode_tree_height;
148 unsigned long objnode_count;
149 long pampd_count;
150 DECL_SENTINEL
151 };
152
153 #define OBJNODE_TREE_MAP_SHIFT 6
154 #define OBJNODE_TREE_MAP_SIZE (1UL << OBJNODE_TREE_MAP_SHIFT)
155 #define OBJNODE_TREE_MAP_MASK (OBJNODE_TREE_MAP_SIZE-1)
156 #define OBJNODE_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
157 #define OBJNODE_TREE_MAX_PATH \
158 (OBJNODE_TREE_INDEX_BITS/OBJNODE_TREE_MAP_SHIFT + 2)
159
160 struct tmem_objnode {
161 struct tmem_obj *obj;
162 DECL_SENTINEL
163 void *slots[OBJNODE_TREE_MAP_SIZE];
164 unsigned int slots_in_use;
165 };
166
167 /* pampd abstract datatype methods provided by the PAM implementation */
168 struct tmem_pamops {
169 void *(*create)(struct tmem_pool *, struct tmem_oid *, uint32_t,
170 struct page *);
171 int (*get_data)(struct page *, void *, struct tmem_pool *);
172 void (*free)(void *, struct tmem_pool *);
173 };
174 extern void tmem_register_pamops(struct tmem_pamops *m);
175
176 /* memory allocation methods provided by the host implementation */
177 struct tmem_hostops {
178 struct tmem_obj *(*obj_alloc)(struct tmem_pool *);
179 void (*obj_free)(struct tmem_obj *, struct tmem_pool *);
180 struct tmem_objnode *(*objnode_alloc)(struct tmem_pool *);
181 void (*objnode_free)(struct tmem_objnode *, struct tmem_pool *);
182 };
183 extern void tmem_register_hostops(struct tmem_hostops *m);
184
185 /* core tmem accessor functions */
186 extern int tmem_put(struct tmem_pool *, struct tmem_oid *, uint32_t index,
187 struct page *page);
188 extern int tmem_get(struct tmem_pool *, struct tmem_oid *, uint32_t index,
189 struct page *page);
190 extern int tmem_flush_page(struct tmem_pool *, struct tmem_oid *,
191 uint32_t index);
192 extern int tmem_flush_object(struct tmem_pool *, struct tmem_oid *);
193 extern int tmem_destroy_pool(struct tmem_pool *);
194 extern void tmem_new_pool(struct tmem_pool *, uint32_t);
195 #endif /* _TMEM_H */
196