1 /*
2  * Copyright (C) 2011 Red Hat, Inc.
3  *
4  * This file is released under the GPL.
5  */
6 
7 #ifndef DM_SPACE_MAP_COMMON_H
8 #define DM_SPACE_MAP_COMMON_H
9 
10 #include "dm-btree.h"
11 
12 /*----------------------------------------------------------------*/
13 
14 /*
15  * Low level disk format
16  *
17  * Bitmap btree
18  * ------------
19  *
20  * Each value stored in the btree is an index_entry.  This points to a
21  * block that is used as a bitmap.  Within the bitmap hold 2 bits per
22  * entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
23  * REF_COUNT = many.
24  *
25  * Refcount btree
26  * --------------
27  *
28  * Any entry that has a ref count higher than 2 gets entered in the ref
29  * count tree.  The leaf values for this tree is the 32-bit ref count.
30  */
31 
32 struct disk_index_entry {
33 	__le64 blocknr;
34 	__le32 nr_free;
35 	__le32 none_free_before;
36 } __attribute__ ((packed, aligned(8)));
37 
38 
39 #define MAX_METADATA_BITMAPS 255
40 struct disk_metadata_index {
41 	__le32 csum;
42 	__le32 padding;
43 	__le64 blocknr;
44 
45 	struct disk_index_entry index[MAX_METADATA_BITMAPS];
46 } __attribute__ ((packed, aligned(8)));
47 
48 struct ll_disk;
49 
50 typedef int (*load_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *result);
51 typedef int (*save_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *ie);
52 typedef int (*init_index_fn)(struct ll_disk *ll);
53 typedef int (*open_index_fn)(struct ll_disk *ll);
54 typedef dm_block_t (*max_index_entries_fn)(struct ll_disk *ll);
55 typedef int (*commit_fn)(struct ll_disk *ll);
56 
57 /*
58  * A lot of time can be wasted reading and writing the same
59  * index entry.  So we cache a few entries.
60  */
61 #define IE_CACHE_SIZE 64
62 #define IE_CACHE_MASK (IE_CACHE_SIZE - 1)
63 
64 struct ie_cache {
65 	bool valid;
66 	bool dirty;
67 	dm_block_t index;
68 	struct disk_index_entry ie;
69 };
70 
71 struct ll_disk {
72 	struct dm_transaction_manager *tm;
73 	struct dm_btree_info bitmap_info;
74 	struct dm_btree_info ref_count_info;
75 
76 	uint32_t block_size;
77 	uint32_t entries_per_block;
78 	dm_block_t nr_blocks;
79 	dm_block_t nr_allocated;
80 
81 	/*
82 	 * bitmap_root may be a btree root or a simple index.
83 	 */
84 	dm_block_t bitmap_root;
85 
86 	dm_block_t ref_count_root;
87 
88 	struct disk_metadata_index mi_le;
89 	load_ie_fn load_ie;
90 	save_ie_fn save_ie;
91 	init_index_fn init_index;
92 	open_index_fn open_index;
93 	max_index_entries_fn max_entries;
94 	commit_fn commit;
95 	bool bitmap_index_changed:1;
96 
97 	struct ie_cache ie_cache[IE_CACHE_SIZE];
98 };
99 
100 struct disk_sm_root {
101 	__le64 nr_blocks;
102 	__le64 nr_allocated;
103 	__le64 bitmap_root;
104 	__le64 ref_count_root;
105 } __attribute__ ((packed, aligned(8)));
106 
107 #define ENTRIES_PER_BYTE 4
108 
109 struct disk_bitmap_header {
110 	__le32 csum;
111 	__le32 not_used;
112 	__le64 blocknr;
113 } __attribute__ ((packed, aligned(8)));
114 
115 /*----------------------------------------------------------------*/
116 
117 int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks);
118 int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result);
119 int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result);
120 int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
121 			  dm_block_t end, dm_block_t *result);
122 int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
123 	                         dm_block_t begin, dm_block_t end, dm_block_t *result);
124 
125 /*
126  * The next three functions return (via nr_allocations) the net number of
127  * allocations that were made.  This number may be negative if there were
128  * more frees than allocs.
129  */
130 int sm_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count, int32_t *nr_allocations);
131 int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
132 int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
133 int sm_ll_commit(struct ll_disk *ll);
134 
135 int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm);
136 int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
137 			void *root_le, size_t len);
138 
139 int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm);
140 int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
141 		    void *root_le, size_t len);
142 
143 /*----------------------------------------------------------------*/
144 
145 #endif	/* DM_SPACE_MAP_COMMON_H */
146