scst_vdisk: enable bind_alua_state for fileio devices

Wire the on_alua_state_change_{start,finish} callbacks into
vdisk_file_devtype and expose bind_alua_state as a sysfs attribute
and create-time parameter for fileio. The callback bodies were
already backing-agnostic; rename them from blockio_* to vdev_* to
match.

Default bind_alua_state=0 for fileio (vs. 1 for blockio) to preserve
existing behavior on upgrade. Adjust the sysfs show function to
compare against the per-backing default so scstadmin persists
explicit settings correctly.

scst/README

@@ -1273,24 +1273,29 @@ blocksize, nv_cache, read_only, removable, rotational, thin_provisioned,
 tst, dif_mode, dif_type, dif_static_app_tag, dif_filename. See
 vdisk_fileio above for description of those parameters.
 
-vdisk_blockio devices have the following two additional attributes:
+vdisk_fileio and vdisk_blockio devices have the following two additional
+attributes:
 
-- active - if this flag is set (the default), the backing block device
+- active - if this flag is set (the default), the backing device or file
   will be opened when the SCST device is added/opened. If a SCST device
-  is opened with active=0 then the backing block device will not be
+  is opened with active=0 then the backing device or file will not be
   opened, allowing for an active/passive SCST configuration. In addition,
   this attribute is writable via sysfs allowing the user to open/close the
-  backing block device on the fly, or via a script.
+  backing device or file on the fly, or via a script.
 
-- bind_alua_state - if this flag is set (the default), when the device is
-  associated with an ALUA device group, and a target group ALUA state
-  changes to the active/nonoptimized state, the active attribute will be
-  set to 1 which attempts to open the backing block device. If the target
-  group ALUA state changes to a value other than active/nonoptimized, the
-  backing device will be closed (active=0). If bind_alua_state=0 for a
+- bind_alua_state - if this flag is set, when the device is associated
+  with an ALUA device group, and a target group ALUA state changes to
+  the active/optimized or active/nonoptimized state, the active attribute
+  will be set to 1 which attempts to open the backing device or file. If
+  the target group ALUA state changes to any other value, the backing
+  device or file will be closed (active=0). If bind_alua_state=0 for a
   device the ALUA state changes have NO effect on the active attribute,
   it is left up to the user to use a script, or manually set the active
-  attribute to open/close the backing block device.
+  attribute to open/close the backing device or file.
+
+  The default differs by backing type: vdisk_blockio defaults to
+  bind_alua_state=1, vdisk_fileio defaults to bind_alua_state=0
+  (preserves the historical fileio behavior on upgrade).
 
 Handler vdisk_nullio provides NULLIO mode to create virtual devices. In
 this mode no real I/O is done, but success returned to initiators.
@@ -1768,14 +1773,14 @@ DEVICE_GROUP dgroup2 {
 	}
 }
 
-Note, if you are using "active" BLOCKIO device attribute to prevent open
-of the backend block device on the passive node, it is not recommended
-to set both active ("active", "nonoptimized") and passive ("standby",
-etc.) ALUA states for the same device if "bind_alua_state=1" is used, as
-shown above to keep internal "active" state of the BLOCKIO device consistent.
+Note, if you are using the "active" device attribute to prevent open of
+the backend device or file on the passive node, it is not recommended to
+set both active ("active", "nonoptimized") and passive ("standby", etc.)
+ALUA states for the same device if "bind_alua_state=1" is used, as shown
+above to keep the internal "active" state of the device consistent.
 
-If using the "active" BLOCKIO device attribute and multiple target groups
-exist per device on a SCST instance then "bind_alua_state=0" should be used
+If using the "active" device attribute and multiple target groups exist
+per device on a SCST instance then "bind_alua_state=0" should be used
 and it is left up to the user to modify the "active" attribute value.
 
 Explicit ALUA
@@ -1795,20 +1800,22 @@ DRBD as well as other replication/failover SW does not allow to open its
 device on the secondary as well as does not allow to perform primary to
 secondary transition, if this device is open.
 
-SCST BLOCKIO handler has necessary support for such behavior:
+SCST BLOCKIO and FILEIO handlers have necessary support for such behavior:
 
-1. If you need to prevent an SCST BLOCKIO device from opening its block
-device, you need to create it with parameter "active=0". In case of DRBD
+1. If you need to prevent an SCST device from opening its backing device
+or file, you need to create it with parameter "active=0". In case of DRBD
 it would be done automatically, you don't have to use the "active"
 attribute.
 
-2. By default, if you write new ALUA state in the "state" attribute and
-"bind_alua_state=1" for the device, SCST BLOCKIO handler before transition
+2. If you write new ALUA state in the "state" attribute and
+"bind_alua_state=1" for the device, the SCST handler before transition
 closes open handles on all affected SCST devices and after transition
 reopens them, if the new state is active or nonoptimized. Alternatively,
-set "bind_alua_state=0" for SCST BLOCKIO devices and ALUA state changes
-will not open/close the backing block device, the user will need to handle
-this manually or via a cluster RA in an HA setup.
+set "bind_alua_state=0" for SCST devices and ALUA state changes will not
+open/close the backing device or file; the user will need to handle this
+manually or via a cluster RA in an HA setup. Note that BLOCKIO defaults
+to "bind_alua_state=1" while FILEIO defaults to "bind_alua_state=0";
+enable it explicitly on FILEIO devices that should participate.
 
 Thus, the recommended implicit ALUA state change procedure for primary
 to secondary transition is:

scst/src/dev_handlers/scst_vdisk.c

@@ -6217,9 +6217,9 @@ static enum compl_status_e nullio_exec_verify(struct vdisk_cmd_params *p)
 	return CMD_SUCCEEDED;
 }
 
-static void blockio_on_alua_state_change_start(struct scst_device *dev,
-					       enum scst_tg_state old_state,
-					       enum scst_tg_state new_state)
+static void vdev_on_alua_state_change_start(struct scst_device *dev,
+					    enum scst_tg_state old_state,
+					    enum scst_tg_state new_state)
 {
 	struct scst_vdisk_dev *virt_dev = dev->dh_priv;
 	const bool close = virt_dev->dev_active &&
@@ -6246,9 +6246,9 @@ static void blockio_on_alua_state_change_start(struct scst_device *dev,
 	TRACE_EXIT();
 }
 
-static void blockio_on_alua_state_change_finish(struct scst_device *dev,
-						enum scst_tg_state old_state,
-						enum scst_tg_state new_state)
+static void vdev_on_alua_state_change_finish(struct scst_device *dev,
+					     enum scst_tg_state old_state,
+					     enum scst_tg_state new_state)
 {
 	struct scst_vdisk_dev *virt_dev = dev->dh_priv;
 	const bool open = !virt_dev->dev_active &&
@@ -7052,6 +7052,8 @@ static int vdev_fileio_add_device(const char *device_name, char *params)
 	virt_dev->wt_flag = DEF_WRITE_THROUGH;
 	virt_dev->nv_cache = DEF_NV_CACHE;
 	virt_dev->o_direct_flag = DEF_O_DIRECT;
+	/* Opt-in for fileio; preserves pre-existing behavior on upgrade. */
+	virt_dev->bind_alua_state = 0;
 
 	res = vdev_parse_add_dev_params(virt_dev, params, NULL);
 	if (res != 0)
@@ -9263,7 +9265,12 @@ static ssize_t vdev_sysfs_bind_alua_state_show(struct kobject *kobj,
 
 	ret = sysfs_emit(buf, "%d\n", bind_alua_state);
 
-	if (bind_alua_state != DEF_BIND_ALUA_STATE)
+	/*
+	 * Per-backing default: blockio defaults to 1 (close/reopen FD on ALUA
+	 * state change), fileio defaults to 0 (opt-in). Mark non-default so
+	 * scstadmin knows to persist explicit settings.
+	 */
+	if (bind_alua_state != (virt_dev->blockio ? 1 : 0))
 		ret += sysfs_emit_at(buf, ret, "%s\n", SCST_SYSFS_KEY_MARK);
 
 	TRACE_EXIT_RES(ret);
@@ -9502,6 +9509,7 @@ static struct scst_trace_log vdisk_local_trace_tbl[] = {
 
 static const struct attribute *vdisk_fileio_attrs[] = {
 	&vdev_active_attr.attr,
+	&vdev_bind_alua_state_attr.attr,
 	&vdev_size_ro_attr.attr,
 	&vdev_size_mb_ro_attr.attr,
 	&vdisk_blocksize_attr.attr,
@@ -9537,6 +9545,7 @@ static const struct attribute *vdisk_fileio_attrs[] = {
 static const char *const fileio_add_dev_params[] = {
 	"active",
 	"async",
+	"bind_alua_state",
 	"blocksize",
 	"cluster_mode",
 	"dif_filename",
@@ -9576,6 +9585,8 @@ static struct scst_dev_type vdisk_file_devtype = {
 	.parse =		fileio_parse,
 	.exec =			fileio_exec,
 	.on_free_cmd =		fileio_on_free_cmd,
+	.on_alua_state_change_start = vdev_on_alua_state_change_start,
+	.on_alua_state_change_finish = vdev_on_alua_state_change_finish,
 	.task_mgmt_fn_done =	vdisk_task_mgmt_fn_done,
 #ifdef CONFIG_DEBUG_EXT_COPY_REMAP
 	.ext_copy_remap =	vdev_ext_copy_remap,
@@ -9662,8 +9673,8 @@ static struct scst_dev_type vdisk_blk_devtype = {
 	.detach_tgt =		vdisk_detach_tgt,
 	.parse =		non_fileio_parse,
 	.exec =			blockio_exec,
-	.on_alua_state_change_start = blockio_on_alua_state_change_start,
-	.on_alua_state_change_finish = blockio_on_alua_state_change_finish,
+	.on_alua_state_change_start = vdev_on_alua_state_change_start,
+	.on_alua_state_change_finish = vdev_on_alua_state_change_finish,
 	.task_mgmt_fn_done =	vdisk_task_mgmt_fn_done,
 	.get_supported_opcodes = vdisk_get_supported_opcodes,
 	.devt_priv =		(void *)blockio_ops,

scstadmin/scstadmin.sysfs/scst-1.0.0/t/07-scstadmin-args.t

@@ -393,6 +393,7 @@ Collecting current configuration: done.
 	Device CREATE attributes available
 	----------------------------------
 	async
+	bind_alua_state
 	blocksize
 	cluster_mode
 	dif_filename