fs/btrfs/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 "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 void btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan);
 193 void btrfs_init_extent_map_shrinker_work(struct btrfs_fs_info *fs_info);
 194
 195 #endif