Re: [PATCH v2] AOSP: erofs-utils: fix sub-directory prefix for canned fs_config

[Li GuiFu via Linux-erofs <linux-erofs@lists.ozlabs.org>]

Thank for your works, Yue Hu, Jianan, Gao Xiang

On 2020/12/28 18:51, Gao Xiang wrote:
> From: Gao Xiang <hsiangkao@aol.com>
> 
> "failed to find [%s] in canned fs_config" was observed by using
> "--fs-config-file" option as reported by Yue Hu [1].
> 
> The root cause was that the mountpoint prefix to subdirectories is
> also needed if "--mount-point" presents. However, such prefix cannot
> be added by just using erofs_fspath().
> 
> One exception is that the root directory itself needs to be handled
> specially for canned fs_config. For such case, the prefix of the root
> directory has to be dropped instead.
> 
> [1] https://lkml.kernel.org/r/20201222020430.12512-1-zbestahu@gmail.com
> 
> Link: https://lore.kernel.org/r/20201226062736.29920-1-hsiangkao@aol.com
> Fixes: 8a9e8046f170 ("AOSP: erofs-utils: add fs_config support")
> Reported-by: Yue Hu <huyue2@yulong.com>
> Signed-off-by: Gao Xiang <hsiangkao@aol.com>
> ---
> changes since v2:
>  - fix IS_ROOT misuse reported by Jianan, very sorry about this since
>    I know little about canned fs_config.
> 
> (please kindly test again...)
> 
>  lib/inode.c | 39 +++++++++++++++++++++++++--------------
>  1 file changed, 25 insertions(+), 14 deletions(-)
> 
> diff --git a/lib/inode.c b/lib/inode.c
> index 0c4839d..e6159c9 100644
> --- a/lib/inode.c
> +++ b/lib/inode.c
> @@ -696,32 +696,43 @@ int erofs_droid_inode_fsconfig(struct erofs_inode *inode,
>  	/* filesystem_config does not preserve file type bits */
>  	mode_t stat_file_type_mask = st->st_mode & S_IFMT;
>  	unsigned int uid = 0, gid = 0, mode = 0;
> -	char *fspath;
> +	const char *fspath;
> +	char *decorated = NULL;
>  
>  	inode->capabilities = 0;
> +	if (!cfg.fs_config_file && !cfg.mount_point)
> +		return 0;
> +
> +	if (!cfg.mount_point ||
> +	/* have to drop the mountpoint for rootdir of canned fsconfig */
> +	    (cfg.fs_config_file && erofs_fspath(path)[0] == '\0')) {
> +		fspath = erofs_fspath(path);
> +	} else {
> +		if (asprintf(&decorated, "%s/%s", cfg.mount_point,
> +			     erofs_fspath(path)) <= 0)
> +			return -ENOMEM;
> +		fspath = decorated;
> +	}
> +
erofs_fspath has been written for three times, and called always.
What do you think refact it ? Do it with
fspath = erofs_fspath(path);
if need decorated:
   fspath = decorated