[PATCH v9 20/29] scsi-multipath: provide callbacks for path state

[John Garry <john.garry@linux.dev>]

Provide callbacks for .is_disabled, .is_optimized, and .available_path.

These all use scsi_device.sdev_state and scsi_device.access_state.

Member scsi_device.access_state will be driven by ALUA. Currently
only device handlers support this, and in future we will have core
SCSI support for implicit ALUA (not relying on device handlers).

Signed-off-by: John Garry <john.garry@linux.dev>
---
 drivers/scsi/scsi_multipath.c | 49 +++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/scsi/scsi_multipath.c b/drivers/scsi/scsi_multipath.c
index 4c965650c2bd..2f47c39d8293 100644
--- a/drivers/scsi/scsi_multipath.c
+++ b/drivers/scsi/scsi_multipath.c
@@ -298,7 +298,56 @@ static struct bio *scsi_mpath_clone_bio(struct bio *bio)
 	return clone;
 }
 
+static bool scsi_mpath_is_disabled(struct mpath_device *mpath_device)
+{
+	struct scsi_mpath_device *scsi_mpath_dev =
+				to_scsi_mpath_device(mpath_device);
+	struct scsi_device *sdev = scsi_mpath_dev->sdev;
+	unsigned char access_state = READ_ONCE(sdev->access_state) &
+					SCSI_ACCESS_STATE_MASK;
+
+	if (READ_ONCE(sdev->sdev_state) != SDEV_RUNNING)
+		return true;
+
+	if (access_state == SCSI_ACCESS_STATE_OPTIMAL ||
+	    access_state == SCSI_ACCESS_STATE_ACTIVE)
+		return false;
+
+	return true;
+}
+
+static bool scsi_mpath_is_optimized(struct mpath_device *mpath_device)
+{
+	struct scsi_mpath_device *scsi_mpath_dev =
+				to_scsi_mpath_device(mpath_device);
+	struct scsi_device *sdev = scsi_mpath_dev->sdev;
+	unsigned char access_state = READ_ONCE(sdev->access_state) &
+					SCSI_ACCESS_STATE_MASK;
+
+	if (READ_ONCE(sdev->sdev_state) != SDEV_RUNNING)
+		return false;
+
+	return access_state == SCSI_ACCESS_STATE_OPTIMAL;
+}
+
+static bool scsi_mpath_available_path(struct mpath_device *mpath_device)
+{
+	struct scsi_mpath_device *scsi_mpath_dev =
+				to_scsi_mpath_device(mpath_device);
+	struct scsi_device *sdev = scsi_mpath_dev->sdev;
+	enum scsi_device_state sdev_state = READ_ONCE(sdev->sdev_state);
+
+	if (sdev_state == SDEV_RUNNING || sdev_state == SDEV_QUIESCE ||
+	    sdev_state == SDEV_BLOCK || sdev_state == SDEV_CREATED_BLOCK)
+		return true;
+
+	return false;
+}
+
 static struct mpath_head_template smpdt = {
+	.is_disabled = scsi_mpath_is_disabled,
+	.is_optimized = scsi_mpath_is_optimized,
+	.available_path = scsi_mpath_available_path,
 	.clone_bio = scsi_mpath_clone_bio,
 };
 
-- 
2.43.0