Commit cbc0e928 authored by Filipe Manana's avatar Filipe Manana Committed by Josef Bacik
Browse files

Btrfs: remove unneeded field / smaller extent_map structure 



We don't need to have an unsigned int field in the extent_map struct
to tell us whether the extent map is in the inode's extent_map tree or
not. We can use the rb_node struct field and the RB_CLEAR_NODE and
RB_EMPTY_NODE macros to achieve the same task.

This reduces sizeof(struct extent_map) from 152 bytes to 144 bytes (on a
64 bits system).

Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
parent e84752d4

fs/btrfs/extent_io.c

+1 −1
Original line number Diff line number Diff line
@@ -2763,7 +2763,7 @@ __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset, 


	if (em_cached && *em_cached) {

		em = *em_cached;

		if (em->in_tree && start >= em->start &&

		if (extent_map_in_tree(em) && start >= em->start &&

		    start < extent_map_end(em)) {

			atomic_inc(&em->refs);

			return em;

fs/btrfs/extent_map.c

+6 −11
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ struct extent_map *alloc_extent_map(void) 
	em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);

	if (!em)

		return NULL;

	em->in_tree = 0;

	RB_CLEAR_NODE(&em->rb_node);

	em->flags = 0;

	em->compress_type = BTRFS_COMPRESS_NONE;

	em->generation = 0;
@@ -73,7 +73,7 @@ void free_extent_map(struct extent_map *em) 
		return;

	WARN_ON(atomic_read(&em->refs) == 0);

	if (atomic_dec_and_test(&em->refs)) {

		WARN_ON(em->in_tree);

		WARN_ON(extent_map_in_tree(em));

		WARN_ON(!list_empty(&em->list));

		kmem_cache_free(extent_map_cache, em);

	}
@@ -99,8 +99,6 @@ static int tree_insert(struct rb_root *root, struct extent_map *em) 
		parent = *p;

		entry = rb_entry(parent, struct extent_map, rb_node);



		WARN_ON(!entry->in_tree);



		if (em->start < entry->start)

			p = &(*p)->rb_left;

		else if (em->start >= extent_map_end(entry))
@@ -128,7 +126,6 @@ static int tree_insert(struct rb_root *root, struct extent_map *em) 
		if (end > entry->start && em->start < extent_map_end(entry))

			return -EEXIST;



	em->in_tree = 1;

	rb_link_node(&em->rb_node, orig_parent, p);

	rb_insert_color(&em->rb_node, root);

	return 0;
@@ -153,8 +150,6 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset, 
		prev = n;

		prev_entry = entry;



		WARN_ON(!entry->in_tree);



		if (offset < entry->start)

			n = n->rb_left;

		else if (offset >= extent_map_end(entry))
@@ -240,12 +235,12 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) 
			em->len += merge->len;

			em->block_len += merge->block_len;

			em->block_start = merge->block_start;

			merge->in_tree = 0;

			em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;

			em->mod_start = merge->mod_start;

			em->generation = max(em->generation, merge->generation);



			rb_erase(&merge->rb_node, &tree->map);

			RB_CLEAR_NODE(&merge->rb_node);

			free_extent_map(merge);

		}

	}
@@ -257,7 +252,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) 
		em->len += merge->len;

		em->block_len += merge->block_len;

		rb_erase(&merge->rb_node, &tree->map);

		merge->in_tree = 0;

		RB_CLEAR_NODE(&merge->rb_node);

		em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;

		em->generation = max(em->generation, merge->generation);

		free_extent_map(merge);
@@ -319,7 +314,7 @@ out: 
void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)

{

	clear_bit(EXTENT_FLAG_LOGGING, &em->flags);

	if (em->in_tree)

	if (extent_map_in_tree(em))

		try_merge_map(tree, em);

}
@@ -434,6 +429,6 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) 
	rb_erase(&em->rb_node, &tree->map);

	if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))

		list_del_init(&em->list);

	em->in_tree = 0;

	RB_CLEAR_NODE(&em->rb_node);

	return ret;

}

fs/btrfs/extent_map.h

+5 −1
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ struct extent_map { 
	unsigned long flags;

	struct block_device *bdev;

	atomic_t refs;

	unsigned int in_tree;

	unsigned int compress_type;

	struct list_head list;

};
@@ -44,6 +43,11 @@ struct extent_map_tree { 
	rwlock_t lock;

};



static inline int extent_map_in_tree(const struct extent_map *em)

{

	return !RB_EMPTY_NODE(&em->rb_node);

}



static inline u64 extent_map_end(struct extent_map *em)

{

	if (em->start + em->len < em->start)

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