1 files changed, 167 insertions, 48 deletions

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 61adc44b7805..6f685f3c9327 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -1,76 +1,195 @@
-#ifndef __EXTENTMAP__
-#define __EXTENTMAP__
+/* SPDX-License-Identifier: GPL-2.0 */
 
+#ifndef BTRFS_EXTENT_MAP_H
+#define BTRFS_EXTENT_MAP_H
+
+#include <linux/compiler_types.h>
+#include <linux/spinlock_types.h>
 #include <linux/rbtree.h>
+#include <linux/list.h>
+#include <linux/refcount.h>
+#include "fs.h"
+
+struct btrfs_inode;
+struct btrfs_fs_info;
 
-#define EXTENT_MAP_LAST_BYTE (u64)-4
-#define EXTENT_MAP_HOLE (u64)-3
-#define EXTENT_MAP_INLINE (u64)-2
-#define EXTENT_MAP_DELALLOC (u64)-1
+#define EXTENT_MAP_LAST_BYTE ((u64)-4)
+#define EXTENT_MAP_HOLE ((u64)-3)
+#define EXTENT_MAP_INLINE ((u64)-2)
 
-/* bits for the flags field */
-#define EXTENT_FLAG_PINNED 0 /* this entry not yet on disk, don't free it */
-#define EXTENT_FLAG_COMPRESSED 1
-#define EXTENT_FLAG_VACANCY 2 /* no file extent item found */
-#define EXTENT_FLAG_PREALLOC 3 /* pre-allocated extent */
-#define EXTENT_FLAG_LOGGING 4 /* Logging this extent */
-#define EXTENT_FLAG_FILLING 5 /* Filling in a preallocated extent */
+/* bits for the extent_map::flags field */
+enum {
+	/* this entry not yet on disk, don't free it */
+	ENUM_BIT(EXTENT_FLAG_PINNED),
+	ENUM_BIT(EXTENT_FLAG_COMPRESS_ZLIB),
+	ENUM_BIT(EXTENT_FLAG_COMPRESS_LZO),
+	ENUM_BIT(EXTENT_FLAG_COMPRESS_ZSTD),
+	/* pre-allocated extent */
+	ENUM_BIT(EXTENT_FLAG_PREALLOC),
+	/* Logging this extent */
+	ENUM_BIT(EXTENT_FLAG_LOGGING),
+	/* 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
+	 * generation of all merged ems.
+	 * For non-merged extents, it's from btrfs_file_extent_item::generation.
+	 */
 	u64 generation;
-	unsigned long flags;
-	struct block_device *bdev;
-	atomic_t refs;
-	unsigned int in_tree;
-	unsigned int compress_type;
+	u32 flags;
+	refcount_t refs;
 	struct list_head list;
 };
 
 struct extent_map_tree {
-	struct rb_root map;
+	struct rb_root root;
 	struct list_head modified_extents;
 	rwlock_t lock;
 };
 
-static inline u64 extent_map_end(struct extent_map *em)
+struct btrfs_inode;
+
+static inline void btrfs_extent_map_set_compression(struct extent_map *em,
+						    enum btrfs_compression_type type)
 {
-	if (em->start + em->len < em->start)
-		return (u64)-1;
-	return em->start + em->len;
+	if (type == BTRFS_COMPRESS_ZLIB)
+		em->flags |= EXTENT_FLAG_COMPRESS_ZLIB;
+	else if (type == BTRFS_COMPRESS_LZO)
+		em->flags |= EXTENT_FLAG_COMPRESS_LZO;
+	else if (type == BTRFS_COMPRESS_ZSTD)
+		em->flags |= EXTENT_FLAG_COMPRESS_ZSTD;
 }
 
-static inline u64 extent_map_block_end(struct extent_map *em)
+static inline enum btrfs_compression_type btrfs_extent_map_compression(
+						       const struct extent_map *em)
 {
-	if (em->block_start + em->block_len < em->block_start)
+	if (em->flags & EXTENT_FLAG_COMPRESS_ZLIB)
+		return BTRFS_COMPRESS_ZLIB;
+
+	if (em->flags & EXTENT_FLAG_COMPRESS_LZO)
+		return BTRFS_COMPRESS_LZO;
+
+	if (em->flags & EXTENT_FLAG_COMPRESS_ZSTD)
+		return BTRFS_COMPRESS_ZSTD;
+
+	return BTRFS_COMPRESS_NONE;
+}
+
+/*
+ * More efficient way to determine if extent is compressed, instead of using
+ * 'extent_map_compression() != BTRFS_COMPRESS_NONE'.
+ */
+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 btrfs_extent_map_in_tree(const struct extent_map *em)
+{
+	return !RB_EMPTY_NODE(&em->rb_node);
+}
+
+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->block_start + em->block_len;
+	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);
-int add_extent_mapping(struct extent_map_tree *tree,
-		       struct extent_map *em, int modified);
-int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
-
-struct extent_map *alloc_extent_map(void);
-void free_extent_map(struct extent_map *em);
-int __init extent_map_init(void);
-void extent_map_exit(void);
-int unpin_extent_cache(struct extent_map_tree *tree, 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);
+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,
+				 bool skip_pinned);
+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