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
 63struct tmem_hashbucket {
 64	struct rb_root obj_rb_root;
 65	spinlock_t lock;
 66};
 67
 68struct 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
 88struct tmem_oid {
 89	uint64_t oid[3];
 90};
 91
 92static inline void tmem_oid_set_invalid(struct tmem_oid *oidp)
 93{
 94	oidp->oid[0] = oidp->oid[1] = oidp->oid[2] = -1UL;
 95}
 96
 97static 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
103static 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
127static 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
140struct tmem_objnode;
141
142struct 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	void *extra; /* for private use by pampd implementation */
151	DECL_SENTINEL
152};
153
154#define OBJNODE_TREE_MAP_SHIFT 6
155#define OBJNODE_TREE_MAP_SIZE (1UL << OBJNODE_TREE_MAP_SHIFT)
156#define OBJNODE_TREE_MAP_MASK (OBJNODE_TREE_MAP_SIZE-1)
157#define OBJNODE_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
158#define OBJNODE_TREE_MAX_PATH \
159		(OBJNODE_TREE_INDEX_BITS/OBJNODE_TREE_MAP_SHIFT + 2)
160
161struct tmem_objnode {
162	struct tmem_obj *obj;
163	DECL_SENTINEL
164	void *slots[OBJNODE_TREE_MAP_SIZE];
165	unsigned int slots_in_use;
166};
167
168/* pampd abstract datatype methods provided by the PAM implementation */
169struct tmem_pamops {
170	void *(*create)(char *, size_t, bool, int,
171			struct tmem_pool *, struct tmem_oid *, uint32_t);
172	int (*get_data)(char *, size_t *, bool, void *, struct tmem_pool *,
173				struct tmem_oid *, uint32_t);
174	int (*get_data_and_free)(char *, size_t *, bool, void *,
175				struct tmem_pool *, struct tmem_oid *,
176				uint32_t);
177	void (*free)(void *, struct tmem_pool *, struct tmem_oid *, uint32_t);
178	void (*free_obj)(struct tmem_pool *, struct tmem_obj *);
179	bool (*is_remote)(void *);
180	void (*new_obj)(struct tmem_obj *);
181	int (*replace_in_obj)(void *, struct tmem_obj *);
182};
183extern void tmem_register_pamops(struct tmem_pamops *m);
184
185/* memory allocation methods provided by the host implementation */
186struct tmem_hostops {
187	struct tmem_obj *(*obj_alloc)(struct tmem_pool *);
188	void (*obj_free)(struct tmem_obj *, struct tmem_pool *);
189	struct tmem_objnode *(*objnode_alloc)(struct tmem_pool *);
190	void (*objnode_free)(struct tmem_objnode *, struct tmem_pool *);
191};
192extern void tmem_register_hostops(struct tmem_hostops *m);
193
194/* core tmem accessor functions */
195extern int tmem_put(struct tmem_pool *, struct tmem_oid *, uint32_t index,
196			char *, size_t, bool, bool);
197extern int tmem_get(struct tmem_pool *, struct tmem_oid *, uint32_t index,
198			char *, size_t *, bool, int);
199extern int tmem_replace(struct tmem_pool *, struct tmem_oid *, uint32_t index,
200			void *);
201extern int tmem_flush_page(struct tmem_pool *, struct tmem_oid *,
202			uint32_t index);
203extern int tmem_flush_object(struct tmem_pool *, struct tmem_oid *);
204extern int tmem_destroy_pool(struct tmem_pool *);
205extern void tmem_new_pool(struct tmem_pool *, uint32_t);
206#endif /* _TMEM_H */