1 typedef struct Source Source;
2 typedef struct VacFile VacFile;
3 typedef struct MetaBlock MetaBlock;
4 typedef struct MetaEntry MetaEntry;
5 typedef struct Lump Lump;
6 typedef struct Cache Cache;
7 typedef struct Super Super;
8 
9 enum {
10 	NilBlock	= (~0UL),
11 	MaxBlock	= (1UL<<31),
12 };
13 
14 
15 struct VacFS {
16 	int ref;
17 	
18 	/* need a read write lock? */
19 
20 	uchar score[VtScoreSize];
21 	VacFile *root;
22 	
23 	VtSession *z;
24 	int readOnly;
25 	int bsize;		/* maximum block size */
26 	uvlong qid;		/* next qid */
27 	Cache *cache;
28 };
29 
30 
31 struct Source {
32 	VtLock *lk;
33 
34 	Cache *cache;	/* immutable */
35 	int readOnly;	/* immutable */
36 
37 	Lump *lump;	/* lump containing venti dir entry */
38 	ulong block;	/* block number within parent: immutable */
39 	int entry;	/* which entry in the block: immutable */
40 
41 	/* most of a VtEntry, except the score */
42 	ulong gen;	/* generation: immutable */
43 	int dir;	/* dir flags: immutable */
44 	int depth;	/* number of levels of pointer blocks */
45 	int psize;	/* pointer block size: immutable */
46 	int dsize;	/* data block size: immutable */
47 	uvlong size;	/* size in bytes of file */
48 
49 	int epb;	/* dir entries per block = dize/VtEntrySize: immutable */
50 };
51 
52 struct MetaEntry {
53 	uchar *p;
54 	ushort size;
55 };
56 
57 struct MetaBlock {
58 	int maxsize;		/* size of block */
59 	int size;		/* size used */
60 	int free;		/* free space within used size */
61 	int maxindex;		/* entries allocated for table */
62 	int nindex;		/* amount of table used */
63 	int unbotch;
64 	uchar *buf;
65 };
66 
67 /*
68  * contains a one block buffer
69  * to avoid problems of the block changing underfoot
70  * and to enable an interface that supports unget.
71  */
72 struct VacDirEnum {
73 	VacFile *file;
74 	
75 	ulong block;	/* current block */
76 	MetaBlock mb;	/* parsed version of block */
77 	int index;	/* index in block */
78 };
79 
80 /* Lump states */
81 enum {
82 	LumpFree,
83 	LumpVenti,	/* on venti server: score > 2^32: just a cached copy */
84 	LumpActive,	/* active */
85 	LumpActiveRO,	/* active: read only block */
86 	LumpActiveA,	/* active: achrived */
87 	LumpSnap,	/* snapshot: */
88 	LumpSnapRO,	/* snapshot: read only */
89 	LumpSnapA,	/* snapshot: achived */
90 	LumpZombie,	/* block with no pointer to it: waiting to be freed */
91 	
92 	LumpMax
93 };
94 
95 /*
96  * Each lump has a state and generation
97  * The following invariants are maintained
98  * 	Each lump has no more than than one parent per generation
99  * 	For Active*, no child has a parent of a greater generation
100  *	For Snap*, there is a snap parent of given generation and there are
101  *		no parents of greater gen - implies no children of a greater gen
102  *	For *RO, the lump is fixed - no change ca be made - all pointers
103  *		are valid venti addresses
104  *	For *A, the lump is on the venti server
105  *	There are no pointers to Zombie lumps
106  *
107  * Transitions
108  *	Archiver at generation g
109  *	Mutator at generation h
110  *	
111  *	Want to modify a lump
112  *		Venti: create new Active(h)
113  *		Active(x): x == h: do nothing
114  *		Acitve(x): x < h: change to Snap(h-1) + add Active(h)
115  *		ActiveRO(x): change to SnapRO(h-1) + add Active(h)
116  *		ActiveA(x): add Active(h)
117  *		Snap*(x): should not occur
118  *		Zombie(x): should not occur
119  *	Want to archive
120  *		Active(x): x != g: should never happen
121  *		Active(x): x == g fix children and free them: move to ActoveRO(g);
122  *		ActiveRO(x): x != g: should never happen
123  *		ActiveRO(x): x == g: wait until it hits ActiveA or SnapA
124  *		ActiveA(x): done
125  *		Active(x): x < g: should never happen
126  *		Snap(x): x >= g: fix children, freeing all SnapA(y) x == y;
127  *		SnapRO(x): wait until it hits SnapA
128  *
129  */
130 
131 
132 struct Lump {
133 	int ref;
134 
135 	Cache *c;
136 
137 	VtLock *lk;
138 	
139 	int state;
140 	ulong gen;
141 
142 	uchar 	*data;
143 	uchar	score[VtScoreSize];	/* score of packet */
144 	uchar	vscore[VtScoreSize];	/* venti score - when archived */
145 	u8int	type;			/* type of packet */
146 	int	dir;			/* part of a directory - extension of type */
147 	u16int	asize;			/* allocated size of block */
148 	Lump	*next;			/* doubly linked hash chains */
149 	Lump	*prev;
150 	u32int	heap;			/* index in heap table */
151 	u32int	used;			/* last reference times */
152 	u32int	used2;
153 
154 	u32int	addr;			/* mutable block address */
155 };
156