Re: [PATCH] erofs-utils: lib: add support for symlink file in erofs_ilookup()

[Gao Xiang <hsiangkao@linux.alibaba.com>]

On 2024/8/11 16:09, Hongzhen Luo wrote:
> When the `path` contains symbolic links, erofs_ilookup() does not
> function properly. This adds support for symlink files.

Can you explain what's the use cases of this patch?

It seems both erofsfuse and fsck.erofs --extract don't need this.

> 
> Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
> ---
>   lib/namei.c | 25 ++++++++++++++++++++++++-
>   1 file changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/namei.c b/lib/namei.c
> index 6f35ee6..dce2991 100644
> --- a/lib/namei.c
> +++ b/lib/namei.c
> @@ -195,6 +195,22 @@ struct nameidata {
>   	unsigned int	ftype;
>   };
>   
> +static int link_path_walk(const char *name, struct nameidata *nd);
> +
> +static int step_into_link(struct nameidata *nd, struct erofs_inode *vi)
> +{
> +	char buf[EROFS_MAX_BLOCK_SIZE];
> +	int err;
> +
> +	if (vi->i_size > EROFS_MAX_BLOCK_SIZE)
> +		return -EINVAL;

No, symlink size is independent to EROFS_MAX_BLOCK_SIZE, currently
it's hard-code as 4096.

> +	memset(buf, 0, sizeof(buf));
> +	err = erofs_pread(vi, buf, vi->i_size, 0);
> +	if (err)
> +		return err;
> +	return link_path_walk(buf, nd);
> +}
> +
>   int erofs_namei(struct nameidata *nd, const char *name, unsigned int len)
>   {
>   	erofs_nid_t nid = nd->nid;
> @@ -233,6 +249,11 @@ int erofs_namei(struct nameidata *nd, const char *name, unsigned int len)
>   			return PTR_ERR(de);
>   
>   		if (de) {
> +			vi.nid = de->nid;
> +			ret = erofs_read_inode_from_disk(&vi);
> +			if (S_ISLNK(vi.i_mode)) {
> +				return step_into_link(nd, &vi);
> +			}

Why need brace here?

Thanks,
Gao Xiang