1 files changed, 82 insertions, 35 deletions

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index c5a098c99cc6..d4b81ee4d97b 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -4,12 +4,11 @@
 #define BTRFS_EXTENT_MAP_H
 
 #include <linux/compiler_types.h>
-#include <linux/rwlock_types.h>
+#include <linux/spinlock_types.h>
 #include <linux/rbtree.h>
 #include <linux/list.h>
 #include <linux/refcount.h>
 #include "misc.h"
-#include "extent_map.h"
 #include "compression.h"
 
 struct btrfs_inode;
@@ -30,29 +29,65 @@ 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;
-	u64 orig_start;
-	u64 orig_block_len;
+
+	/*
+	 * The bytenr of the full on-disk extent.
+	 *
+	 * For regular extents it's btrfs_file_extent_item::disk_bytenr.
+	 * For holes it's EXTENT_MAP_HOLE and for inline extents it's
+	 * EXTENT_MAP_INLINE.
+	 */
+	u64 disk_bytenr;
+
+	/*
+	 * The full on-disk extent length, matching
+	 * btrfs_file_extent_item::disk_num_bytes.
+	 */
+	u64 disk_num_bytes;
+
+	/*
+	 * Offset inside the decompressed extent.
+	 *
+	 * For regular extents it's btrfs_file_extent_item::offset.
+	 * For holes and inline extents it's 0.
+	 */
+	u64 offset;
+
+	/*
+	 * The decompressed size of the whole on-disk extent, matching
+	 * btrfs_file_extent_item::ram_bytes.
+	 */
 	u64 ram_bytes;
-	u64 block_start;
-	u64 block_len;
 
 	/*
 	 * Generation of the extent map, for merged em it's the highest
@@ -66,15 +101,15 @@ struct extent_map {
 };
 
 struct extent_map_tree {
-	struct rb_root_cached map;
+	struct rb_root root;
 	struct list_head modified_extents;
 	rwlock_t lock;
 };
 
 struct btrfs_inode;
 
-static inline void extent_map_set_compression(struct extent_map *em,
-					      enum btrfs_compression_type type)
+static inline void btrfs_extent_map_set_compression(struct extent_map *em,
+						    enum btrfs_compression_type type)
 {
 	if (type == BTRFS_COMPRESS_ZLIB)
 		em->flags |= EXTENT_FLAG_COMPRESS_ZLIB;
@@ -84,7 +119,8 @@ static inline void extent_map_set_compression(struct extent_map *em,
 		em->flags |= EXTENT_FLAG_COMPRESS_ZSTD;
 }
 
-static inline enum btrfs_compression_type extent_map_compression(const struct extent_map *em)
+static inline enum btrfs_compression_type btrfs_extent_map_compression(
+						       const struct extent_map *em)
 {
 	if (em->flags & EXTENT_FLAG_COMPRESS_ZLIB)
 		return BTRFS_COMPRESS_ZLIB;
@@ -102,42 +138,51 @@ static inline enum btrfs_compression_type extent_map_compression(const struct ex
  * More efficient way to determine if extent is compressed, instead of using
  * 'extent_map_compression() != BTRFS_COMPRESS_NONE'.
  */
-static inline bool extent_map_is_compressed(const struct extent_map *em)
+static inline bool btrfs_extent_map_is_compressed(const struct extent_map *em)
 {
 	return (em->flags & (EXTENT_FLAG_COMPRESS_ZLIB |
 			     EXTENT_FLAG_COMPRESS_LZO |
 			     EXTENT_FLAG_COMPRESS_ZSTD)) != 0;
 }
 
-static inline int extent_map_in_tree(const struct extent_map *em)
+static inline int btrfs_extent_map_in_tree(const struct extent_map *em)
 {
 	return !RB_EMPTY_NODE(&em->rb_node);
 }
 
-static inline u64 extent_map_end(const struct extent_map *em)
+static inline u64 btrfs_extent_map_block_start(const struct extent_map *em)
+{
+	if (em->disk_bytenr < EXTENT_MAP_LAST_BYTE) {
+		if (btrfs_extent_map_is_compressed(em))
+			return em->disk_bytenr;
+		return em->disk_bytenr + em->offset;
+	}
+	return em->disk_bytenr;
+}
+
+static inline u64 btrfs_extent_map_end(const struct extent_map *em)
 {
 	if (em->start + em->len < em->start)
 		return (u64)-1;
 	return em->start + em->len;
 }
 
-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);
-int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
-		     u64 new_logical);
-
-struct extent_map *alloc_extent_map(void);
-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);
-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,
+void btrfs_extent_map_tree_init(struct extent_map_tree *tree);
+struct extent_map *btrfs_lookup_extent_mapping(struct extent_map_tree *tree,
+					       u64 start, u64 len);
+void btrfs_remove_extent_mapping(struct btrfs_inode *inode, struct extent_map *em);
+int btrfs_split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
+			   u64 new_logical);
+
+struct extent_map *btrfs_alloc_extent_map(void);
+void btrfs_free_extent_map(struct extent_map *em);
+int __init btrfs_extent_map_init(void);
+void __cold btrfs_extent_map_exit(void);
+int btrfs_unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
+void btrfs_clear_em_logging(struct btrfs_inode *inode, struct extent_map *em);
+struct extent_map *btrfs_search_extent_mapping(struct extent_map_tree *tree,
+					       u64 start, u64 len);
+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 +190,7 @@ 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);
+void btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan);
+void btrfs_init_extent_map_shrinker_work(struct btrfs_fs_info *fs_info);
 
 #endif