Re: [PATCH 1/2] btrfs: tree-checker: Remove comprehensive root owner check

[Nikolay Borisov <nborisov@suse.com>]

On 4.04.19 г. 6:47 ч., Qu Wenruo wrote:
> Commit 1ba98d086fe3 ("Btrfs: detect corruption when non-root leaf has
> zero item") introduced comprehensive root owner checker.
> 
> However it's pretty expensive tree search to locate the owner root,
> especially when it get reused by mandatory read and write time
> tree-checker.
> 
> This patch will remove that check, and completely rely on owner based
> empty leaf check, which is much faster and still works fine for most
> case.
> 
> And since we skip the old root owner check, now write time tree check
> can be merged with btrfs_check_leaf_full().
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

This patch was sent yesterday, now it's sent again with no material
changes whatsoever? What's the point?

> ---
>  fs/btrfs/tree-checker.c | 24 ------------------------
>  1 file changed, 24 deletions(-)
> 
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index d2c3c1f8870d..e325d4df5c23 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -838,7 +838,6 @@ static int check_leaf(struct extent_buffer *leaf, bool check_item_data)
>  	 */
>  	if (nritems == 0 && !btrfs_header_flag(leaf, BTRFS_HEADER_FLAG_RELOC)) {
>  		u64 owner = btrfs_header_owner(leaf);
> -		struct btrfs_root *check_root;
>  
>  		/* These trees must never be empty */
>  		if (owner == BTRFS_ROOT_TREE_OBJECTID ||
> @@ -852,29 +851,6 @@ static int check_leaf(struct extent_buffer *leaf, bool check_item_data)
>  				    owner);
>  			return -EUCLEAN;
>  		}
> -		key.objectid = owner;
> -		key.type = BTRFS_ROOT_ITEM_KEY;
> -		key.offset = (u64)-1;
> -
> -		check_root = btrfs_get_fs_root(fs_info, &key, false);
> -		/*
> -		 * The only reason we also check NULL here is that during
> -		 * open_ctree() some roots has not yet been set up.
> -		 */
> -		if (!IS_ERR_OR_NULL(check_root)) {
> -			struct extent_buffer *eb;
> -
> -			eb = btrfs_root_node(check_root);
> -			/* if leaf is the root, then it's fine */
> -			if (leaf != eb) {
> -				generic_err(leaf, 0,
> -		"invalid nritems, have %u should not be 0 for non-root leaf",
> -					nritems);
> -				free_extent_buffer(eb);
> -				return -EUCLEAN;
> -			}
> -			free_extent_buffer(eb);
> -		}
>  		return 0;
>  	}
>  
>