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-rw-r--r--fs/btrfs/extent_map.h67
1 files changed, 58 insertions, 9 deletions
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index c5a098c99c..6d587111f7 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -30,28 +30,77 @@ enum {
ENUM_BIT(EXTENT_FLAG_PREALLOC),
/* Logging this extent */
ENUM_BIT(EXTENT_FLAG_LOGGING),
- /* Filling in a preallocated extent */
- ENUM_BIT(EXTENT_FLAG_FILLING),
/* This em is merged from two or more physically adjacent ems */
ENUM_BIT(EXTENT_FLAG_MERGED),
};
/*
+ * This structure represents file extents and holes.
+ *
+ * Unlike on-disk file extent items, extent maps can be merged to save memory.
+ * This means members only match file extent items before any merging.
+ *
* Keep this structure as compact as possible, as we can have really large
* amounts of allocated extent maps at any time.
*/
struct extent_map {
struct rb_node rb_node;
- /* all of these are in bytes */
+ /* All of these are in bytes. */
+
+ /* File offset matching the offset of a BTRFS_EXTENT_ITEM_KEY key. */
u64 start;
+
+ /*
+ * Length of the file extent.
+ *
+ * For non-inlined file extents it's btrfs_file_extent_item::num_bytes.
+ * For inline extents it's sectorsize, since inline data starts at
+ * offsetof(struct btrfs_file_extent_item, disk_bytenr) thus
+ * btrfs_file_extent_item::num_bytes is not valid.
+ */
u64 len;
- u64 mod_start;
- u64 mod_len;
+
+ /*
+ * The file offset of the original file extent before splitting.
+ *
+ * This is an in-memory only member, matching
+ * extent_map::start - btrfs_file_extent_item::offset for
+ * regular/preallocated extents. EXTENT_MAP_HOLE otherwise.
+ */
u64 orig_start;
+
+ /*
+ * The full on-disk extent length, matching
+ * btrfs_file_extent_item::disk_num_bytes.
+ */
u64 orig_block_len;
+
+ /*
+ * The decompressed size of the whole on-disk extent, matching
+ * btrfs_file_extent_item::ram_bytes.
+ */
u64 ram_bytes;
+
+ /*
+ * The on-disk logical bytenr for the file extent.
+ *
+ * For compressed extents it matches btrfs_file_extent_item::disk_bytenr.
+ * For uncompressed extents it matches
+ * btrfs_file_extent_item::disk_bytenr + btrfs_file_extent_item::offset
+ *
+ * For holes it is EXTENT_MAP_HOLE and for inline extents it is
+ * EXTENT_MAP_INLINE.
+ */
u64 block_start;
+
+ /*
+ * The on-disk length for the file extent.
+ *
+ * For compressed extents it matches btrfs_file_extent_item::disk_num_bytes.
+ * For uncompressed extents it matches extent_map::len.
+ * For holes and inline extents it's -1 and shouldn't be used.
+ */
u64 block_len;
/*
@@ -124,7 +173,7 @@ static inline u64 extent_map_end(const struct extent_map *em)
void extent_map_tree_init(struct extent_map_tree *tree);
struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
u64 start, u64 len);
-void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
+void remove_extent_mapping(struct btrfs_inode *inode, struct extent_map *em);
int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
u64 new_logical);
@@ -133,11 +182,10 @@ void free_extent_map(struct extent_map *em);
int __init extent_map_init(void);
void __cold extent_map_exit(void);
int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
-void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em);
+void clear_em_logging(struct btrfs_inode *inode, struct extent_map *em);
struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
u64 start, u64 len);
-int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
- struct extent_map_tree *em_tree,
+int btrfs_add_extent_mapping(struct btrfs_inode *inode,
struct extent_map **em_in, u64 start, u64 len);
void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
u64 start, u64 end,
@@ -145,5 +193,6 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
struct extent_map *new_em,
bool modified);
+long btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan);
#endif