Re: [PATCH v7 3/8] file-posix: introduce get_sysfs_long_val for the long sysfs attribute

[Damien Le Moal]

On 2022/08/15 23:25, Sam Li wrote:
> Use sysfs attribute files to get the long value of zoned device
> information.
> 
> Signed-off-by: Sam Li <faithilikerun@gmail.com>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  block/file-posix.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/block/file-posix.c b/block/file-posix.c
> index c07ac4c697..727389488c 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -1258,6 +1258,33 @@ static int get_sysfs_zoned_model(struct stat *st, 
> BlockZoneModel *zoned) {
>      return 0;
>  }
>  
> +/*
> + * Get zoned device information (chunk_sectors, zoned_append_max_bytes,
> + * max_open_zones, max_active_zones) through sysfs attribute files.
> + */

The comment here needs to be more generic since this helper is used in patch 2
in hdev_get_max_segments(). So simply something like:

/*
 * Get a sysfs attribute value as a long integer.
 */

And since this helper is used in patch 2, this patch needs to go before patch 2
(reverse patch 2 and 3 order).

> +static long get_sysfs_long_val(struct stat *st, const char *attribute) {
> +#ifdef CONFIG_LINUX
> +    g_autofree char *str = NULL;
> +    const char *end;
> +    long val;
> +    int ret;
> +
> +    ret = get_sysfs_str_val(st, attribute, &str);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    /* The file is ended with '\n', pass 'end' to accept that. */
> +    ret = qemu_strtol(str, &end, 10, &val);
> +    if (ret == 0 && end && *end == '\n') {
> +        ret = val;
> +    }
> +    return ret;
> +#else
> +    return -ENOTSUP;
> +#endif
> +}
> +
>  static int hdev_get_max_segments(int fd, struct stat *st) {
>      int ret;
>      if (S_ISCHR(st->st_mode)) {


-- 
Damien Le Moal
Western Digital Research