Re: [PATCH v8 1/7] block: Add 'zoned' queue limit

[Hannes Reinecke]

On 10/18/2016 08:40 AM, Damien Le Moal wrote:
> From: Damien Le Moal 
> 
> Add the zoned queue limit to indicate the zoning model of a block device.
> Defined values are 0 (BLK_ZONED_NONE) for regular block devices,
> 1 (BLK_ZONED_HA) for host-aware zone block devices and 2 (BLK_ZONED_HM)
> for host-managed zone block devices. The standards defined drive managed
> model is not defined here since these block devices do not provide any
> command for accessing zone information. Drive managed model devices will
> be reported as BLK_ZONED_NONE.
> 
> The helper functions blk_queue_zoned_model and bdev_zoned_model return
> the zoned limit and the functions blk_queue_is_zoned and bdev_is_zoned
> return a boolean for callers to test if a block device is zoned.
> 
> The zoned attribute is also exported as a string to applications via
> sysfs. BLK_ZONED_NONE shows as "none", BLK_ZONED_HA as "host-aware" and
> BLK_ZONED_HM as "host-managed".
> 
> Signed-off-by: Damien Le Moal 
> Reviewed-by: Christoph Hellwig 
> Reviewed-by: Martin K. Petersen 
> Reviewed-by: Shaun Tancheff 
> Tested-by: Shaun Tancheff 
> ---
>  Documentation/ABI/testing/sysfs-block | 16 
>  block/blk-settings.c  |  1 +
>  block/blk-sysfs.c | 18 ++
>  include/linux/blkdev.h| 47 
> +++
>  4 files changed, 82 insertions(+)
> 
Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
-- 
Dr. Hannes ReineckeTeamlead Storage & Networking
h...@suse.de   +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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[PATCH v8 1/7] block: Add 'zoned' queue limit

[Damien Le Moal]

From: Damien Le Moal 

Add the zoned queue limit to indicate the zoning model of a block device.
Defined values are 0 (BLK_ZONED_NONE) for regular block devices,
1 (BLK_ZONED_HA) for host-aware zone block devices and 2 (BLK_ZONED_HM)
for host-managed zone block devices. The standards defined drive managed
model is not defined here since these block devices do not provide any
command for accessing zone information. Drive managed model devices will
be reported as BLK_ZONED_NONE.

The helper functions blk_queue_zoned_model and bdev_zoned_model return
the zoned limit and the functions blk_queue_is_zoned and bdev_is_zoned
return a boolean for callers to test if a block device is zoned.

The zoned attribute is also exported as a string to applications via
sysfs. BLK_ZONED_NONE shows as "none", BLK_ZONED_HA as "host-aware" and
BLK_ZONED_HM as "host-managed".

Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Shaun Tancheff 
Tested-by: Shaun Tancheff 
---
 Documentation/ABI/testing/sysfs-block | 16 
 block/blk-settings.c  |  1 +
 block/blk-sysfs.c | 18 ++
 include/linux/blkdev.h| 47 +++
 4 files changed, 82 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-block 
b/Documentation/ABI/testing/sysfs-block
index 71d184d..75a5055 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -235,3 +235,19 @@ Description:
write_same_max_bytes is 0, write same is not supported
by the device.
 
+What:  /sys/block//queue/zoned
+Date:  September 2016
+Contact:   Damien Le Moal 
+Description:
+   zoned indicates if the device is a zoned block device
+   and the zone model of the device if it is indeed zoned.
+   The possible values indicated by zoned are "none" for
+   regular block devices and "host-aware" or "host-managed"
+   for zoned block devices. The characteristics of
+   host-aware and host-managed zoned block devices are
+   described in the ZBC (Zoned Block Commands) and ZAC
+   (Zoned Device ATA Command Set) standards. These standards
+   also define the "drive-managed" zone model. However,
+   since drive-managed zoned block devices do not support
+   zone commands, they will be treated as regular block
+   devices and zoned will report "none".
diff --git a/block/blk-settings.c b/block/blk-settings.c
index f679ae1..b1d5b7f 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -107,6 +107,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->io_opt = 0;
lim->misaligned = 0;
lim->cluster = 1;
+   lim->zoned = BLK_ZONED_NONE;
 }
 EXPORT_SYMBOL(blk_set_default_limits);
 
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9cc8d7c..ff9cd9c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -257,6 +257,18 @@ QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
 QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
 #undef QUEUE_SYSFS_BIT_FNS
 
+static ssize_t queue_zoned_show(struct request_queue *q, char *page)
+{
+   switch (blk_queue_zoned_model(q)) {
+   case BLK_ZONED_HA:
+   return sprintf(page, "host-aware\n");
+   case BLK_ZONED_HM:
+   return sprintf(page, "host-managed\n");
+   default:
+   return sprintf(page, "none\n");
+   }
+}
+
 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 {
return queue_var_show((blk_queue_nomerges(q) << 1) |
@@ -485,6 +497,11 @@ static struct queue_sysfs_entry queue_nonrot_entry = {
.store = queue_store_nonrot,
 };
 
+static struct queue_sysfs_entry queue_zoned_entry = {
+   .attr = {.name = "zoned", .mode = S_IRUGO },
+   .show = queue_zoned_show,
+};
+
 static struct queue_sysfs_entry queue_nomerges_entry = {
.attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
.show = queue_nomerges_show,
@@ -546,6 +563,7 @@ static struct attribute *default_attrs[] = {
_discard_zeroes_data_entry.attr,
_write_same_max_entry.attr,
_nonrot_entry.attr,
+   _zoned_entry.attr,
_nomerges_entry.attr,
_rq_affinity_entry.attr,
_iostats_entry.attr,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c47c358..f19e16b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -261,6 +261,15 @@ struct blk_queue_tag {
 #define BLK_SCSI_MAX_CMDS  (256)
 #define BLK_SCSI_CMD_PER_LONG  (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))
 
+/*
+ * Zoned block device models (zoned limit).
+ */
+enum blk_zoned_model {