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  
extent_map_set_compression(struct extent_map * em,enum btrfs_compression_type type)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  
extent_map_compression(const struct extent_map * em)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   */
extent_map_is_compressed(const struct extent_map * em)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  
extent_map_in_tree(const struct extent_map * em)147  static inline int extent_map_in_tree(const struct extent_map *em)
148  {
149  	return !RB_EMPTY_NODE(&em->rb_node);
150  }
151  
extent_map_block_start(const struct extent_map * em)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  
extent_map_end(const struct extent_map * em)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