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 "fs.h"
12
13struct btrfs_inode;
14struct btrfs_fs_info;
15
16#define EXTENT_MAP_LAST_BYTE ((u64)-4)
17#define EXTENT_MAP_HOLE ((u64)-3)
18#define EXTENT_MAP_INLINE ((u64)-2)
19
20/* bits for the extent_map::flags field */
21enum {
22 /* this entry not yet on disk, don't free it */
23 ENUM_BIT(EXTENT_FLAG_PINNED),
24 ENUM_BIT(EXTENT_FLAG_COMPRESS_ZLIB),
25 ENUM_BIT(EXTENT_FLAG_COMPRESS_LZO),
26 ENUM_BIT(EXTENT_FLAG_COMPRESS_ZSTD),
27 /* pre-allocated extent */
28 ENUM_BIT(EXTENT_FLAG_PREALLOC),
29 /* Logging this extent */
30 ENUM_BIT(EXTENT_FLAG_LOGGING),
31 /* This em is merged from two or more physically adjacent ems */
32 ENUM_BIT(EXTENT_FLAG_MERGED),
33};
34
35/*
36 * This structure represents file extents and holes.
37 *
38 * Unlike on-disk file extent items, extent maps can be merged to save memory.
39 * This means members only match file extent items before any merging.
40 *
41 * Keep this structure as compact as possible, as we can have really large
42 * amounts of allocated extent maps at any time.
43 */
44struct extent_map {
45 struct rb_node rb_node;
46
47 /* All of these are in bytes. */
48
49 /* File offset matching the offset of a BTRFS_EXTENT_ITEM_KEY key. */
50 u64 start;
51
52 /*
53 * Length of the file extent.
54 *
55 * For non-inlined file extents it's btrfs_file_extent_item::num_bytes.
56 * For inline extents it's sectorsize, since inline data starts at
57 * offsetof(struct btrfs_file_extent_item, disk_bytenr) thus
58 * btrfs_file_extent_item::num_bytes is not valid.
59 */
60 u64 len;
61
62 /*
63 * The bytenr of the full on-disk extent.
64 *
65 * For regular extents it's btrfs_file_extent_item::disk_bytenr.
66 * For holes it's EXTENT_MAP_HOLE and for inline extents it's
67 * EXTENT_MAP_INLINE.
68 */
69 u64 disk_bytenr;
70
71 /*
72 * The full on-disk extent length, matching
73 * btrfs_file_extent_item::disk_num_bytes.
74 */
75 u64 disk_num_bytes;
76
77 /*
78 * Offset inside the decompressed extent.
79 *
80 * For regular extents it's btrfs_file_extent_item::offset.
81 * For holes and inline extents it's 0.
82 */
83 u64 offset;
84
85 /*
86 * The decompressed size of the whole on-disk extent, matching
87 * btrfs_file_extent_item::ram_bytes.
88 */
89 u64 ram_bytes;
90
91 /*
92 * Generation of the extent map, for merged em it's the highest
93 * generation of all merged ems.
94 * For non-merged extents, it's from btrfs_file_extent_item::generation.
95 */
96 u64 generation;
97 u32 flags;
98 refcount_t refs;
99 struct list_head list;
100};
101
102struct extent_map_tree {
103 struct rb_root root;
104 struct list_head modified_extents;
105 rwlock_t lock;
106};
107
108struct btrfs_inode;
109
110static inline void btrfs_extent_map_set_compression(struct extent_map *em,
111 enum btrfs_compression_type type)
112{
113 if (type == BTRFS_COMPRESS_ZLIB)
114 em->flags |= EXTENT_FLAG_COMPRESS_ZLIB;
115 else if (type == BTRFS_COMPRESS_LZO)
116 em->flags |= EXTENT_FLAG_COMPRESS_LZO;
117 else if (type == BTRFS_COMPRESS_ZSTD)
118 em->flags |= EXTENT_FLAG_COMPRESS_ZSTD;
119}
120
121static inline enum btrfs_compression_type btrfs_extent_map_compression(
122 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 */
140static inline bool btrfs_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
147static inline int btrfs_extent_map_in_tree(const struct extent_map *em)
148{
149 return !RB_EMPTY_NODE(&em->rb_node);
150}
151
152static inline u64 btrfs_extent_map_block_start(const struct extent_map *em)
153{
154 if (em->disk_bytenr < EXTENT_MAP_LAST_BYTE) {
155 if (btrfs_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
162static inline u64 btrfs_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
169void btrfs_extent_map_tree_init(struct extent_map_tree *tree);
170struct extent_map *btrfs_lookup_extent_mapping(struct extent_map_tree *tree,
171 u64 start, u64 len);
172void btrfs_remove_extent_mapping(struct btrfs_inode *inode, struct extent_map *em);
173int btrfs_split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
174 u64 new_logical);
175
176struct extent_map *btrfs_alloc_extent_map(void);
177void btrfs_free_extent_map(struct extent_map *em);
178int __init btrfs_extent_map_init(void);
179void __cold btrfs_extent_map_exit(void);
180int btrfs_unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
181void btrfs_clear_em_logging(struct btrfs_inode *inode, struct extent_map *em);
182struct extent_map *btrfs_search_extent_mapping(struct extent_map_tree *tree,
183 u64 start, u64 len);
184int btrfs_add_extent_mapping(struct btrfs_inode *inode,
185 struct extent_map **em_in, u64 start, u64 len);
186void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
187 u64 start, u64 end,
188 bool skip_pinned);
189int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
190 struct extent_map *new_em,
191 bool modified);
192void btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan);
193void btrfs_init_extent_map_shrinker_work(struct btrfs_fs_info *fs_info);
194
195#endif
196

source code of linux/fs/btrfs/extent_map.h