1 /* SPDX-License-Identifier: GPL-2.0 */
2
3 #ifndef BTRFS_EXTENT_MAP_H
4 #define BTRFS_EXTENT_MAP_H
5
6 #include <linux/compiler_types.h>
7 #include <linux/spinlock_types.h>
8 #include <linux/rbtree.h>
9 #include <linux/list.h>
10 #include <linux/refcount.h>
11 #include "misc.h"
12 #include "compression.h"
13
14 struct btrfs_inode;
15 struct btrfs_fs_info;
16
17 #define EXTENT_MAP_LAST_BYTE ((u64)-4)
18 #define EXTENT_MAP_HOLE ((u64)-3)
19 #define EXTENT_MAP_INLINE ((u64)-2)
20
21 /* bits for the extent_map::flags field */
22 enum {
23 /* this entry not yet on disk, don't free it */
24 ENUM_BIT(EXTENT_FLAG_PINNED),
25 ENUM_BIT(EXTENT_FLAG_COMPRESS_ZLIB),
26 ENUM_BIT(EXTENT_FLAG_COMPRESS_LZO),
27 ENUM_BIT(EXTENT_FLAG_COMPRESS_ZSTD),
28 /* pre-allocated extent */
29 ENUM_BIT(EXTENT_FLAG_PREALLOC),
30 /* Logging this extent */
31 ENUM_BIT(EXTENT_FLAG_LOGGING),
32 /* This em is merged from two or more physically adjacent ems */
33 ENUM_BIT(EXTENT_FLAG_MERGED),
34 };
35
36 /*
37 * This structure represents file extents and holes.
38 *
39 * Unlike on-disk file extent items, extent maps can be merged to save memory.
40 * This means members only match file extent items before any merging.
41 *
42 * Keep this structure as compact as possible, as we can have really large
43 * amounts of allocated extent maps at any time.
44 */
45 struct extent_map {
46 struct rb_node rb_node;
47
48 /* All of these are in bytes. */
49
50 /* File offset matching the offset of a BTRFS_EXTENT_ITEM_KEY key. */
51 u64 start;
52
53 /*
54 * Length of the file extent.
55 *
56 * For non-inlined file extents it's btrfs_file_extent_item::num_bytes.
57 * For inline extents it's sectorsize, since inline data starts at
58 * offsetof(struct btrfs_file_extent_item, disk_bytenr) thus
59 * btrfs_file_extent_item::num_bytes is not valid.
60 */
61 u64 len;
62
63 /*
64 * The bytenr of the full on-disk extent.
65 *
66 * For regular extents it's btrfs_file_extent_item::disk_bytenr.
67 * For holes it's EXTENT_MAP_HOLE and for inline extents it's
68 * EXTENT_MAP_INLINE.
69 */
70 u64 disk_bytenr;
71
72 /*
73 * The full on-disk extent length, matching
74 * btrfs_file_extent_item::disk_num_bytes.
75 */
76 u64 disk_num_bytes;
77
78 /*
79 * Offset inside the decompressed extent.
80 *
81 * For regular extents it's btrfs_file_extent_item::offset.
82 * For holes and inline extents it's 0.
83 */
84 u64 offset;
85
86 /*
87 * The decompressed size of the whole on-disk extent, matching
88 * btrfs_file_extent_item::ram_bytes.
89 */
90 u64 ram_bytes;
91
92 /*
93 * Generation of the extent map, for merged em it's the highest
94 * generation of all merged ems.
95 * For non-merged extents, it's from btrfs_file_extent_item::generation.
96 */
97 u64 generation;
98 u32 flags;
99 refcount_t refs;
100 struct list_head list;
101 };
102
103 struct extent_map_tree {
104 struct rb_root root;
105 struct list_head modified_extents;
106 rwlock_t lock;
107 };
108
109 struct btrfs_inode;
110
111 static inline void extent_map_set_compression(struct extent_map *em,
112 enum btrfs_compression_type type)
113 {
114 if (type == BTRFS_COMPRESS_ZLIB)
115 em->flags |= EXTENT_FLAG_COMPRESS_ZLIB;
116 else if (type == BTRFS_COMPRESS_LZO)
117 em->flags |= EXTENT_FLAG_COMPRESS_LZO;
118 else if (type == BTRFS_COMPRESS_ZSTD)
119 em->flags |= EXTENT_FLAG_COMPRESS_ZSTD;
120 }
121
122 static inline enum btrfs_compression_type extent_map_compression(const struct extent_map *em)
123 {
124 if (em->flags & EXTENT_FLAG_COMPRESS_ZLIB)
125 return BTRFS_COMPRESS_ZLIB;
126
127 if (em->flags & EXTENT_FLAG_COMPRESS_LZO)
128 return BTRFS_COMPRESS_LZO;
129
130 if (em->flags & EXTENT_FLAG_COMPRESS_ZSTD)
131 return BTRFS_COMPRESS_ZSTD;
132
133 return BTRFS_COMPRESS_NONE;
134 }
135
136 /*
137 * More efficient way to determine if extent is compressed, instead of using
138 * 'extent_map_compression() != BTRFS_COMPRESS_NONE'.
139 */
140 static inline bool extent_map_is_compressed(const struct extent_map *em)
141 {
142 return (em->flags & (EXTENT_FLAG_COMPRESS_ZLIB |
143 EXTENT_FLAG_COMPRESS_LZO |
144 EXTENT_FLAG_COMPRESS_ZSTD)) != 0;
145 }
146
147 static inline int extent_map_in_tree(const struct extent_map *em)
148 {
149 return !RB_EMPTY_NODE(&em->rb_node);
150 }
151
152 static inline u64 extent_map_block_start(const struct extent_map *em)
153 {
154 if (em->disk_bytenr < EXTENT_MAP_LAST_BYTE) {
155 if (extent_map_is_compressed(em))
156 return em->disk_bytenr;
157 return em->disk_bytenr + em->offset;
158 }
159 return em->disk_bytenr;
160 }
161
162 static inline u64 extent_map_end(const struct extent_map *em)
163 {
164 if (em->start + em->len < em->start)
165 return (u64)-1;
166 return em->start + em->len;
167 }
168
169 void extent_map_tree_init(struct extent_map_tree *tree);
170 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
171 u64 start, u64 len);
172 void remove_extent_mapping(struct btrfs_inode *inode, struct extent_map *em);
173 int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
174 u64 new_logical);
175
176 struct extent_map *alloc_extent_map(void);
177 void free_extent_map(struct extent_map *em);
178 int __init extent_map_init(void);
179 void __cold extent_map_exit(void);
180 int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
181 void clear_em_logging(struct btrfs_inode *inode, struct extent_map *em);
182 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
183 u64 start, u64 len);
184 int btrfs_add_extent_mapping(struct btrfs_inode *inode,
185 struct extent_map **em_in, u64 start, u64 len);
186 void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
187 u64 start, u64 end,
188 bool skip_pinned);
189 int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
190 struct extent_map *new_em,
191 bool modified);
192 long btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan);
193
194 #endif
195
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