btrfs: don't allocate file extent tree for non regular files

When not using the NO_HOLES feature we always allocate an io tree for an
inode's file_extent_tree. This is wasteful because that io tree is only
used for regular files, so we allocate more memory than needed for inodes
that represent directories or symlinks for example, or for inodes that
correspond to free space inodes.

So improve on this by allocating the io tree only for inodes of regular
files that are not free space inodes.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 35 insertions, 18 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 94dd338837bf..902ca1c64ff8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3781,6 +3781,30 @@ static noinline int acls_after_inode_item(struct extent_buffer *leaf,
 	return 1;
 }
 
+static int btrfs_init_file_extent_tree(struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	if (WARN_ON_ONCE(inode->file_extent_tree))
+		return 0;
+	if (btrfs_fs_incompat(fs_info, NO_HOLES))
+		return 0;
+	if (!S_ISREG(inode->vfs_inode.i_mode))
+		return 0;
+	if (btrfs_is_free_space_inode(inode))
+		return 0;
+
+	inode->file_extent_tree = kmalloc(sizeof(struct extent_io_tree), GFP_KERNEL);
+	if (!inode->file_extent_tree)
+		return -ENOMEM;
+
+	extent_io_tree_init(fs_info, inode->file_extent_tree, IO_TREE_INODE_FILE_EXTENT);
+	/* Lockdep class is set only for the file extent tree. */
+	lockdep_set_class(&inode->file_extent_tree->lock, &file_extent_tree_class);
+
+	return 0;
+}
+
 /*
  * read an inode from the btree into the in-memory inode
  */
@@ -3800,6 +3824,10 @@ static int btrfs_read_locked_inode(struct inode *inode,
 	bool filled = false;
 	int first_xattr_slot;
 
+	ret = btrfs_init_file_extent_tree(BTRFS_I(inode));
+	if (ret)
+		return ret;
+
 	ret = btrfs_fill_inode(inode, &rdev);
 	if (!ret)
 		filled = true;
@@ -6247,6 +6275,10 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
 		BTRFS_I(inode)->root = btrfs_grab_root(BTRFS_I(dir)->root);
 	root = BTRFS_I(inode)->root;
 
+	ret = btrfs_init_file_extent_tree(BTRFS_I(inode));
+	if (ret)
+		goto out;
+
 	ret = btrfs_get_free_objectid(root, &objectid);
 	if (ret)
 		goto out;
@@ -8413,20 +8445,10 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 	struct btrfs_inode *ei;
 	struct inode *inode;
-	struct extent_io_tree *file_extent_tree = NULL;
-
-	/* Self tests may pass a NULL fs_info. */
-	if (fs_info && !btrfs_fs_incompat(fs_info, NO_HOLES)) {
-		file_extent_tree = kmalloc(sizeof(struct extent_io_tree), GFP_KERNEL);
-		if (!file_extent_tree)
-			return NULL;
-	}
 
 	ei = alloc_inode_sb(sb, btrfs_inode_cachep, GFP_KERNEL);
-	if (!ei) {
-		kfree(file_extent_tree);
+	if (!ei)
 		return NULL;
-	}
 
 	ei->root = NULL;
 	ei->generation = 0;
@@ -8471,13 +8493,8 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 	extent_io_tree_init(fs_info, &ei->io_tree, IO_TREE_INODE_IO);
 	ei->io_tree.inode = ei;
 
-	ei->file_extent_tree = file_extent_tree;
-	if (file_extent_tree) {
-		extent_io_tree_init(fs_info, ei->file_extent_tree,
-				    IO_TREE_INODE_FILE_EXTENT);
-		/* Lockdep class is set only for the file extent tree. */
-		lockdep_set_class(&ei->file_extent_tree->lock, &file_extent_tree_class);
-	}
+	ei->file_extent_tree = NULL;
+
 	mutex_init(&ei->log_mutex);
 	spin_lock_init(&ei->ordered_tree_lock);
 	ei->ordered_tree = RB_ROOT;