Re: [PATCH 08/20] init: refactor devt_from_partuuid

[Jan Kara <jack@suse.cz>]

On Wed 18-11-20 09:47:48, Christoph Hellwig wrote:
> The code in devt_from_partuuid is very convoluted.  Refactor a bit by
> sanitizing the goto and variable name usage.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  init/do_mounts.c | 68 ++++++++++++++++++++++--------------------------
>  1 file changed, 31 insertions(+), 37 deletions(-)
> 
> diff --git a/init/do_mounts.c b/init/do_mounts.c
> index aef2f24461c7f1..afa26a4028d25e 100644
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -105,13 +105,10 @@ static int match_dev_by_uuid(struct device *dev, const void *data)
>   */
>  static dev_t devt_from_partuuid(const char *uuid_str)
>  {
> -	dev_t res = 0;
>  	struct uuidcmp cmp;
>  	struct device *dev = NULL;
> -	struct gendisk *disk;
> -	struct hd_struct *part;
> +	dev_t devt = 0;
>  	int offset = 0;
> -	bool clear_root_wait = false;
>  	char *slash;
>  
>  	cmp.uuid = uuid_str;
> @@ -120,52 +117,49 @@ static dev_t devt_from_partuuid(const char *uuid_str)
>  	/* Check for optional partition number offset attributes. */
>  	if (slash) {
>  		char c = 0;
> +
>  		/* Explicitly fail on poor PARTUUID syntax. */
> -		if (sscanf(slash + 1,
> -			   "PARTNROFF=%d%c", &offset, &c) != 1) {
> -			clear_root_wait = true;
> -			goto done;
> -		}
> +		if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
> +			goto clear_root_wait;
>  		cmp.len = slash - uuid_str;
>  	} else {
>  		cmp.len = strlen(uuid_str);
>  	}
>  
> -	if (!cmp.len) {
> -		clear_root_wait = true;
> -		goto done;
> -	}
> +	if (!cmp.len)
> +		goto clear_root_wait;
>  
> -	dev = class_find_device(&block_class, NULL, &cmp,
> -				&match_dev_by_uuid);
> +	dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
>  	if (!dev)
> -		goto done;
> -
> -	res = dev->devt;
> +		return 0;
>  
> -	/* Attempt to find the partition by offset. */
> -	if (!offset)
> -		goto no_offset;
> +	if (offset) {
> +		/*
> +		 * Attempt to find the requested partition by adding an offset
> +		 * to the partition number found by UUID.
> +		 */
> +		struct hd_struct *part;
>  
> -	res = 0;
> -	disk = part_to_disk(dev_to_part(dev));
> -	part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
> -	if (part) {
> -		res = part_devt(part);
> -		put_device(part_to_dev(part));
> +		part = disk_get_part(dev_to_disk(dev),
> +				     dev_to_part(dev)->partno + offset);
> +		if (part) {
> +			devt = part_devt(part);
> +			put_device(part_to_dev(part));
> +		}
> +	} else {
> +		devt = dev->devt;
>  	}
>  
> -no_offset:
>  	put_device(dev);
> -done:
> -	if (clear_root_wait) {
> -		pr_err("VFS: PARTUUID= is invalid.\n"
> -		       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
> -		if (root_wait)
> -			pr_err("Disabling rootwait; root= is invalid.\n");
> -		root_wait = 0;
> -	}
> -	return res;
> +	return devt;
> +
> +clear_root_wait:
> +	pr_err("VFS: PARTUUID= is invalid.\n"
> +	       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
> +	if (root_wait)
> +		pr_err("Disabling rootwait; root= is invalid.\n");
> +	root_wait = 0;
> +	return 0;
>  }
>  
>  /**
> -- 
> 2.29.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR