extent_map.h

  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