On 04/07/2016 03:56 AM, Damien Le Moal wrote:
>
> Hannes,
>
>> Add a sysfs queue attribute 'zoned' to display the zone layout
>> for zoned devices.
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
>> ---
>> block/blk-sysfs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 47 insertions(+)
>>
>> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
>> index ff97091..748bb27 100644
>> --- a/block/blk-sysfs.c
>> +++ b/block/blk-sysfs.c
>> @@ -244,6 +244,43 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
>> return queue_var_show(max_hw_sectors_kb, (page));
>> }
>>
>> +#ifdef CONFIG_BLK_DEV_ZONED
>> +static ssize_t queue_zoned_show(struct request_queue *q, char *page)
>> +{
>> + struct rb_node *node;
>> + struct blk_zone *zone;
>> + ssize_t offset = 0, end = 0;
>> + size_t size = 0, num = 0;
>> + enum blk_zone_type type = BLK_ZONE_TYPE_UNKNOWN;
>> +
>> + for (node = rb_first(&q->zones); node; node = rb_next(node)) {
>> + zone = rb_entry(node, struct blk_zone, node);
>> + if (zone->type != type ||
>> + zone->len != size ||
>> + end != zone->start) {
>> + if (size != 0)
>> + offset += sprintf(page + offset, "%zu\n", num);
>> + /* We can only store one page ... */
>> + if (offset + 42 > PAGE_SIZE) {
>> + offset += sprintf(page + offset, "...\n");
>> + return offset;
>> + }
>> + size = zone->len;
>> + type = zone->type;
>> + offset += sprintf(page + offset, "%zu %zu %d ",
>> + zone->start, size, type);
>> + num = 0;
>> + end = zone->start + size;
>> + } else
>> + end += zone->len;
>> + num++;
>> + }
>> + if (num > 0)
>> + offset += sprintf(page + offset, "%zu\n", num);
>> + return offset > 0 ? offset : -EINVAL;
>> +}
>> +#endif
>
> With this, an application reading the “zoned” file for a non-SMR disk
> will get a -EINVAL error. Not really super nice. Could we just have the
> zoned files contain a single “0” for non-SMR disks ? Or at least have the
> file empty and read return 0 Bytes. That would allow applications to easily
> and cleanly detect if they are dealing with a SMR disk (or not) instead of
> assuming that “-EINVAL” means “not SMR”, which seems very ugly to me.
>
Sure.
Actually I was looking in blanking out this attribute entirely like
I did with the SCSI sysfs attributes, but as the 'queue' sysfs
directory is a blank kobj it's not easily done.
But yes, '0' seems like a reasonable value here.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
