From cbc0e9287d710ce7dce5f8daf667729e83316c45 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Tue, 25 Feb 2014 14:15:12 +0000 Subject: [PATCH] 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: Filipe David Borba Manana Reviewed-by: David Sterba Signed-off-by: Josef Bacik --- fs/btrfs/extent_io.c | 2 +- fs/btrfs/extent_map.c | 17 ++++++----------- fs/btrfs/extent_map.h | 6 +++++- 3 files changed, 12 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index fbe501d3bd01..2c9fbe3b6eec 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -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; diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index 996ad56b57db..64d08f94485d 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -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; } diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h index 93fba716d7f8..f0a645a14d6e 100644 --- a/fs/btrfs/extent_map.h +++ b/fs/btrfs/extent_map.h @@ -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) -- 2.11.0