[PATCH v2] scsi: scsi_debug: fix zone transition to full condition

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

When a write command to a sequential write required or sequential write
preferred zone result in the zone write pointer reaching the end of the
zone, the zone condition must be set to full AND the number of
implicitly or explicitly open zones updated to have a correct accounting
for zone resources. However, the function zbc_inc_wp() only sets the
zone condition to full without updating the open zone counters,
resulting in a zone state machine breakage.

Introduce the helper function zbc_set_zone_full() and use it in
zbc_inc_wp() to correctly transition zones to the full condition.

Fixes: 0d1cf9378bd4 ("scsi: scsi_debug: Add ZBC zone commands")
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
Changes from v1:
* Simplify the patch to not modify the zbc_finish_zone() function and
  not use the CLOSED zone condition as an intermediate state in
  zbc_set_zone_full(). Cleanups to remove the use of the closed
  condition as an intermediate state will be sent later.

 drivers/scsi/scsi_debug.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 1f423f723d06..b8a76b89f85a 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -2826,6 +2826,24 @@ static void zbc_open_zone(struct sdebug_dev_info *devip,
 	}
 }
 
+static inline void zbc_set_zone_full(struct sdebug_dev_info *devip,
+				     struct sdeb_zone_state *zsp)
+{
+	switch (zsp->z_cond) {
+	case ZC2_IMPLICIT_OPEN:
+		devip->nr_imp_open--;
+		break;
+	case ZC3_EXPLICIT_OPEN:
+		devip->nr_exp_open--;
+		break;
+	default:
+		WARN_ONCE(true, "Invalid zone %llu condition %x\n",
+			  zsp->z_start, zsp->z_cond);
+		break;
+	}
+	zsp->z_cond = ZC5_FULL;
+}
+
 static void zbc_inc_wp(struct sdebug_dev_info *devip,
 		       unsigned long long lba, unsigned int num)
 {
@@ -2838,7 +2856,7 @@ static void zbc_inc_wp(struct sdebug_dev_info *devip,
 	if (zsp->z_type == ZBC_ZTYPE_SWR) {
 		zsp->z_wp += num;
 		if (zsp->z_wp >= zend)
-			zsp->z_cond = ZC5_FULL;
+			zbc_set_zone_full(devip, zsp);
 		return;
 	}
 
@@ -2857,7 +2875,7 @@ static void zbc_inc_wp(struct sdebug_dev_info *devip,
 			n = num;
 		}
 		if (zsp->z_wp >= zend)
-			zsp->z_cond = ZC5_FULL;
+			zbc_set_zone_full(devip, zsp);
 
 		num -= n;
 		lba += n;
-- 
2.36.1