Re: [PATCH v3 1/6] btrfs: btrfs_cleanup_fs_roots handle ret variable

[David Sterba <dsterba@suse.cz>]

On Thu, May 16, 2024 at 07:12:10PM +0800, Anand Jain wrote:
> Since err represents the function return value, rename it as ret,
> and rename the original ret, which serves as a helper return value,
> to found. Also, optimize the code to continue call btrfs_put_root()
> for the rest of the root if even after btrfs_orphan_cleanup() returns
> error.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
> v3: Add a code comment.
> v2: Rename to 'found' instead of 'ret2' (Josef).
>     Call btrfs_put_root() in the while-loop, avoids use of the variable
> 	'found' outside of the while loop (Qu).
>     Use 'unsigned int i' instead of 'int' (Goffredo).
> 
>  fs/btrfs/disk-io.c | 38 ++++++++++++++++++++------------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index a91a8056758a..d38cf973b02a 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2925,22 +2925,23 @@ static int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)
>  {
>  	u64 root_objectid = 0;
>  	struct btrfs_root *gang[8];
> -	int i = 0;
> -	int err = 0;
> -	unsigned int ret = 0;
> +	int ret = 0;
>  
>  	while (1) {
> +		unsigned int i;
> +		unsigned int found;
> +
>  		spin_lock(&fs_info->fs_roots_radix_lock);
> -		ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
> +		found = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
>  					     (void **)gang, root_objectid,
>  					     ARRAY_SIZE(gang));
> -		if (!ret) {
> +		if (!found) {
>  			spin_unlock(&fs_info->fs_roots_radix_lock);
>  			break;
>  		}
> -		root_objectid = btrfs_root_id(gang[ret - 1]) + 1;
> +		root_objectid = btrfs_root_id(gang[found - 1]) + 1;
>  
> -		for (i = 0; i < ret; i++) {
> +		for (i = 0; i < found; i++) {

You could also move the declaration of 'i' to the for loop as you move
the other definition anyway.

>  			/* Avoid to grab roots in dead_roots. */
>  			if (btrfs_root_refs(&gang[i]->root_item) == 0) {
>  				gang[i] = NULL;
> @@ -2951,24 +2952,25 @@ static int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)
>  		}
>  		spin_unlock(&fs_info->fs_roots_radix_lock);
>  
> -		for (i = 0; i < ret; i++) {
> +		for (i = 0; i < found; i++) {
>  			if (!gang[i])
>  				continue;
>  			root_objectid = btrfs_root_id(gang[i]);
> -			err = btrfs_orphan_cleanup(gang[i]);
> -			if (err)
> -				goto out;
> +			/*
> +			 * Continue to release the remaining roots after the first
> +			 * error without cleanup and preserve the first error
> +			 * for the return.
> +			 */
> +			if (!ret)
> +				ret = btrfs_orphan_cleanup(gang[i]);
>  			btrfs_put_root(gang[i]);
>  		}
> +		if (ret)
> +			break;
> +
>  		root_objectid++;
>  	}
> -out:
> -	/* Release the uncleaned roots due to error. */
> -	for (; i < ret; i++) {
> -		if (gang[i])
> -			btrfs_put_root(gang[i]);
> -	}
> -	return err;
> +	return ret;
>  }
>  
>  /*
> -- 
> 2.38.1
>