[OpenWrt-Devel] [PATCH] libfstools: Output error in case of loop blkdev failure

Jo-Philipp Wich jo at mein.io
Wed Mar 27 03:05:50 EDT 2019


Hi Petr,

I suggest to rephrase the subject to something like "print error in
case". I kept reading "output error" and wondered what went wrong with
the output.

> It took me quite some time today(while fixing squashfs+overlay on
> armvirt) to find out, that I was missing support for loop block device
> in kernel, so I'm adding error message which might be helpful for
> someone else in the future as well.
> 
> Signed-off-by: Petr Štetiar <ynezz at true.cz>
> ---
>  libfstools/rootdisk.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/libfstools/rootdisk.c b/libfstools/rootdisk.c
> index dd00c1b..68a6296 100644
> --- a/libfstools/rootdisk.c
> +++ b/libfstools/rootdisk.c
> @@ -258,8 +258,10 @@ static int rootdisk_volume_init(struct volume *v)
>  	char str[128];
>  	int ret = 0;
>  
> -	if (!p->loop_name[0] && rootdisk_create_loop(p) != 0)
> +	if (!p->loop_name[0] && rootdisk_create_loop(p) != 0) {
> +		ULOG_ERR("unable to create loop device\n");

Do we have a valid errno value here? Would be useful to append the
strerror(3) description as well to see whether its ENOSYS, EINVAL etc.

>  		return -1;
> +	}
>  
>  	v->type = BLOCKDEV;
>  	v->blk = p->loop_name;
> 

~ Jo

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