Re: [PATCH] Btrfs: cleanup backref search commit root flag stuff

[Miao Xie <miaox@cn.fujitsu.com>]

On wed, 12 Jun 2013 16:22:26 -0400, Josef Bacik wrote:
> Looking into this backref problem I noticed we're using a macro to what turns
> out to essentially be a NULL check to see if we need to search the commit root.
> I'm killing this, let's just do what everybody else does and checks if trans ==
> NULL.  I've also made it so we pass in the path to __resolve_indirect_refs which
> will have the search_commit_root flag set properly already and that way we can
> avoid allocating another path when we have a perfectly good one to use.  Thanks,
> 
> Signed-off-by: Josef Bacik <jbacik@fusionio.com>

Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>

> ---
>  fs/btrfs/backref.c |   41 ++++++++++++++++-------------------------
>  fs/btrfs/backref.h |    2 --
>  2 files changed, 16 insertions(+), 27 deletions(-)
> 
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index 290e347..431ea92 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -255,13 +255,11 @@ static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
>   * to a logical address
>   */
>  static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
> -					int search_commit_root,
> -					u64 time_seq,
> -					struct __prelim_ref *ref,
> -					struct ulist *parents,
> -					const u64 *extent_item_pos)
> +				  struct btrfs_path *path, u64 time_seq,
> +				  struct __prelim_ref *ref,
> +				  struct ulist *parents,
> +				  const u64 *extent_item_pos)
>  {
> -	struct btrfs_path *path;
>  	struct btrfs_root *root;
>  	struct btrfs_key root_key;
>  	struct extent_buffer *eb;
> @@ -269,11 +267,6 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
>  	int root_level;
>  	int level = ref->level;
>  
> -	path = btrfs_alloc_path();
> -	if (!path)
> -		return -ENOMEM;
> -	path->search_commit_root = !!search_commit_root;
> -
>  	root_key.objectid = ref->root_id;
>  	root_key.type = BTRFS_ROOT_ITEM_KEY;
>  	root_key.offset = (u64)-1;
> @@ -314,7 +307,8 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
>  				time_seq, ref->wanted_disk_byte,
>  				extent_item_pos);
>  out:
> -	btrfs_free_path(path);
> +	path->lowest_level = 0;
> +	btrfs_release_path(path);
>  	return ret;
>  }
>  
> @@ -322,7 +316,7 @@ out:
>   * resolve all indirect backrefs from the list
>   */
>  static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
> -				   int search_commit_root, u64 time_seq,
> +				   struct btrfs_path *path, u64 time_seq,
>  				   struct list_head *head,
>  				   const u64 *extent_item_pos)
>  {
> @@ -349,9 +343,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
>  			continue;
>  		if (ref->count == 0)
>  			continue;
> -		err = __resolve_indirect_ref(fs_info, search_commit_root,
> -					     time_seq, ref, parents,
> -					     extent_item_pos);
> +		err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
> +					     parents, extent_item_pos);
>  		if (err == -ENOMEM)
>  			goto out;
>  		if (err)
> @@ -795,7 +788,6 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
>  	struct btrfs_delayed_ref_head *head;
>  	int info_level = 0;
>  	int ret;
> -	int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);
>  	struct list_head prefs_delayed;
>  	struct list_head prefs;
>  	struct __prelim_ref *ref;
> @@ -810,7 +802,8 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
>  	path = btrfs_alloc_path();
>  	if (!path)
>  		return -ENOMEM;
> -	path->search_commit_root = !!search_commit_root;
> +	if (!trans)
> +		path->search_commit_root = 1;
>  
>  	/*
>  	 * grab both a lock on the path and a lock on the delayed ref head.
> @@ -825,7 +818,7 @@ again:
>  		goto out;
>  	BUG_ON(ret == 0);
>  
> -	if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {
> +	if (trans) {
>  		/*
>  		 * look if there are updates for this ref queued and lock the
>  		 * head
> @@ -890,8 +883,8 @@ again:
>  
>  	__merge_refs(&prefs, 1);
>  
> -	ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq,
> -				      &prefs, extent_item_pos);
> +	ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
> +				      extent_item_pos);
>  	if (ret)
>  		goto out;
>  
> @@ -1459,7 +1452,7 @@ int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
>  				iterate_extent_inodes_t *iterate, void *ctx)
>  {
>  	int ret;
> -	struct btrfs_trans_handle *trans;
> +	struct btrfs_trans_handle *trans = NULL;
>  	struct ulist *refs = NULL;
>  	struct ulist *roots = NULL;
>  	struct ulist_node *ref_node = NULL;
> @@ -1471,9 +1464,7 @@ int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
>  	pr_debug("resolving all inodes for extent %llu\n",
>  			extent_item_objectid);
>  
> -	if (search_commit_root) {
> -		trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT;
> -	} else {
> +	if (!search_commit_root) {
>  		trans = btrfs_join_transaction(fs_info->extent_root);
>  		if (IS_ERR(trans))
>  			return PTR_ERR(trans);
> diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
> index 0f446d7..8f2e767 100644
> --- a/fs/btrfs/backref.h
> +++ b/fs/btrfs/backref.h
> @@ -23,8 +23,6 @@
>  #include "ulist.h"
>  #include "extent_io.h"
>  
> -#define BTRFS_BACKREF_SEARCH_COMMIT_ROOT ((struct btrfs_trans_handle *)0)
> -
>  struct inode_fs_paths {
>  	struct btrfs_path		*btrfs_path;
>  	struct btrfs_root		*fs_root;
>