Re: [PATCH v4 1/4] ublk: change ublk IO command defines to enum

On 6/29/23 09:38, Ming Lei wrote:

On Thu, Jun 29, 2023 at 07:47:47AM +0900, Damien Le Moal wrote:

quoted

On 6/29/23 04:06, Andreas Hindborg wrote:

quoted

From: Andreas Hindborg <redacted>

This change is in preparation for zoned storage support.

Signed-off-by: Andreas Hindborg <redacted>
---
 include/uapi/linux/ublk_cmd.h | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 4b8558db90e1..471b3b983045 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h

@@ -229,12 +229,23 @@ struct ublksrv_ctrl_dev_info {
 	__u64   reserved2;
 };
 
-#define		UBLK_IO_OP_READ		0
-#define		UBLK_IO_OP_WRITE		1
-#define		UBLK_IO_OP_FLUSH		2
-#define		UBLK_IO_OP_DISCARD	3
-#define		UBLK_IO_OP_WRITE_SAME	4
-#define		UBLK_IO_OP_WRITE_ZEROES	5
+enum ublk_op {
+	UBLK_IO_OP_READ = 0,
+	UBLK_IO_OP_WRITE = 1,
+	UBLK_IO_OP_FLUSH = 2,
+	UBLK_IO_OP_DISCARD = 3,
+	UBLK_IO_OP_WRITE_SAME = 4,
+	UBLK_IO_OP_WRITE_ZEROES = 5,
+	UBLK_IO_OP_ZONE_OPEN = 10,
+	UBLK_IO_OP_ZONE_CLOSE = 11,
+	UBLK_IO_OP_ZONE_FINISH = 12,
+	UBLK_IO_OP_ZONE_APPEND = 13,
+	UBLK_IO_OP_ZONE_RESET = 15,
+	__UBLK_IO_OP_DRV_IN_START = 32,
+	__UBLK_IO_OP_DRV_IN_END = 96,
+	__UBLK_IO_OP_DRV_OUT_START = __UBLK_IO_OP_DRV_IN_END,
+	__UBLK_IO_OP_DRV_OUT_END = 160,
+};

This patch does not do what the title says. You are also introducing the zone
operations, and the very obscure __UBLK_IO_OP_DRV_XXX operations without an
explanation. Also, why the "__" prefix for these ? I do not see the point...

It should be to reserve space for ublk passthrough OP.

A comment about that would be nice.

quoted

Given that this is a uapi, a comment to explain the less obvious commands would
be nice.

So I think the change to an enum for the existing ops can be done either in
patch 2 or as a separate patch and the introduction of the zone operations done
in patch 3 or as a separate patch.

Also it might break userspace by changing to enum from macro for existed
definition, cause userspace may check something by '#ifdef UBLK_IO_OP_*',
so probably it is better to keep these OPs as enum, or at least keep
existed definition as macro.

Then let's keep defining things with #define instead of an enum.

Thanks,
Ming

-- 
Damien Le Moal
Western Digital Research