Hannes,
>Add a sysfs queue attribute 'zoned' to display the zone layout
>for zoned devices.
>
>Signed-off-by: Hannes Reinecke <h...@suse.de>
>---
> 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.
Best.
--
Damien Le Moal, Ph.D.
Sr Manager, System Software Group, WW Research,
HGST, a Western Digital company
damien.lem...@hgst.com
Tel: (+81) 0466-98-3593 (Ext. 51-3593)
1 kirihara-cho, Fujisawa, Kanagawa, 252-0888 Japan
www.hgst.com <http://www.hgst.com>
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