Btrfs: record first logical byte in memory
This'd save us a rbtree search which may become expensive in large filesystem.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 22f012d..9ee099f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1250,6 +1250,7 @@
/* block group cache stuff */
spinlock_t block_group_cache_lock;
+ u64 first_logical_byte;
struct rb_root block_group_cache_tree;
/* keep track of unallocated space */
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1db8a99..04f98e3 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2130,6 +2130,7 @@
spin_lock_init(&fs_info->block_group_cache_lock);
fs_info->block_group_cache_tree = RB_ROOT;
+ fs_info->first_logical_byte = (u64)-1;
extent_io_tree_init(&fs_info->freed_extents[0],
fs_info->btree_inode->i_mapping);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 825f23b..82400b2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -161,6 +161,10 @@
rb_link_node(&block_group->cache_node, parent, p);
rb_insert_color(&block_group->cache_node,
&info->block_group_cache_tree);
+
+ if (info->first_logical_byte > block_group->key.objectid)
+ info->first_logical_byte = block_group->key.objectid;
+
spin_unlock(&info->block_group_cache_lock);
return 0;
@@ -202,8 +206,11 @@
break;
}
}
- if (ret)
+ if (ret) {
btrfs_get_block_group(ret);
+ if (bytenr == 0 && info->first_logical_byte > ret->key.objectid)
+ info->first_logical_byte = ret->key.objectid;
+ }
spin_unlock(&info->block_group_cache_lock);
return ret;
@@ -4848,6 +4855,13 @@
struct btrfs_block_group_cache *cache;
u64 bytenr;
+ spin_lock(&root->fs_info->block_group_cache_lock);
+ bytenr = root->fs_info->first_logical_byte;
+ spin_unlock(&root->fs_info->block_group_cache_lock);
+
+ if (bytenr < (u64)-1)
+ return bytenr;
+
cache = btrfs_lookup_first_block_group(root->fs_info, search_start);
if (!cache)
return 0;
@@ -8059,6 +8073,9 @@
spin_lock(&root->fs_info->block_group_cache_lock);
rb_erase(&block_group->cache_node,
&root->fs_info->block_group_cache_tree);
+
+ if (root->fs_info->first_logical_byte == block_group->key.objectid)
+ root->fs_info->first_logical_byte = (u64)-1;
spin_unlock(&root->fs_info->block_group_cache_lock);
down_write(&block_group->space_info->groups_sem);