Black hole functionality added

Scst_mutex intentially used directly in the sysfs handler, because
comming sysfs improvements will allow that.



git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@5382 d57e44dd-8a1f-0410-8b47-8ef2f437770f

scst/README

@@ -580,7 +580,7 @@ Every target should have at least the following entries:
    mapping to the corresponding hardware port. It isn't anyhow used by
    SCST.
 
- - enabled - using this attribute you can enable or disable this target/
+ - enabled - using this attribute you can enable or disable this target.
    It allows to finish configuring it before it starts accepting new
    connections. 0 by default.
 
@@ -592,6 +592,28 @@ Every target should have at least the following entries:
    can assign the addressing method on per-initiator basis. See also the
    "Logical unit addressing (LUN)" section in SAM-5 for more information.
 
+ - black_hole - if set, all LUNs in the corresponding initiator group,
+   default target group in this case, start "swallowing" requests from
+   initiators. Possible values are:
+
+    * 0 - disable black hole mode
+
+    * 1 - immediately abort all coming commands
+
+    * 2 - immediately abort all coming commands and drop all coming TM
+      commands
+
+    * 3 - immediately abort all coming data transfer commands. This is
+      the most evil mode, because it is not too well handled by many
+      initiator OS'es, including Linux, so they may never recover from
+      it.
+
+    * 4 - immediately abort all coming data transfer commands and drop all
+      coming TM commands
+
+   CAUTION! With some target drivers modes 2 and 4 can cause internal
+   resources leaks, so don't abuse those options!
+
  - cpu_mask - defines CPU affinity mask for threads serving this target.
    For threads serving LUNs it is used only for devices with
    threads_pool_type "per_initiator".
@@ -750,7 +772,7 @@ commands by looking inside this file.
 
 Each security group's subdirectory contains 2 subdirectories: initiators
 and luns as well as the following attributes: addr_method, cpu_mask and
-io_grouping_type. See above description of them.
+io_grouping_type, black_hole. See above description of them.
 
 Each "initiators" subdirectory contains list of added to this groups
 initiator as well as as well as file "mgmt". This file has the following

scst/README_in-tree

@@ -442,7 +442,7 @@ Every target should have at least the following entries:
    mapping to the corresponding hardware port. It isn't anyhow used by
    SCST.
 
- - enabled - using this attribute you can enable or disable this target/
+ - enabled - using this attribute you can enable or disable this target.
    It allows to finish configuring it before it starts accepting new
    connections. 0 by default.
 
@@ -454,6 +454,28 @@ Every target should have at least the following entries:
    can assign the addressing method on per-initiator basis. See also the
    "Logical unit addressing (LUN)" section in SAM-5 for more information.
 
+ - black_hole - if set, all LUNs in the corresponding initiator group,
+   default target group in this case, start "swallowing" requests from
+   initiators. Possible values are:
+
+    * 0 - disable black hole mode
+
+    * 1 - immediately abort all coming commands
+
+    * 2 - immediately abort all coming commands and drop all coming TM
+      commands
+
+    * 3 - immediately abort all coming data transfer commands. This is
+      the most evil mode, because it is not too well handled by many
+      initiator OS'es, including Linux, so they may never recover from
+      it.
+
+    * 4 - immediately abort all coming data transfer commands and drop all
+      coming TM commands
+
+   CAUTION! With some target drivers modes 2 and 4 can cause internal
+   resources leaks, so don't abuse those options!
+
  - cpu_mask - defines CPU affinity mask for threads serving this target.
    For threads serving LUNs it is used only for devices with
    threads_pool_type "per_initiator".
@@ -612,7 +634,7 @@ commands by looking inside this file.
 
 Each security group's subdirectory contains 2 subdirectories: initiators
 and luns as well as the following attributes: addr_method, cpu_mask and
-io_grouping_type. See above description of them.
+io_grouping_type, black_hole. See above description of them.
 
 Each "initiators" subdirectory contains list of added to this groups
 initiator as well as as well as file "mgmt". This file has the following

scst/include/scst.h

@@ -592,6 +592,9 @@ enum scst_exec_context {
 /* Set if tgt_dev has Unit Attention sense */
 #define SCST_TGT_DEV_UA_PENDING		0
 
+/* Cache of acg->acg_black_hole_type */
+#define SCST_TGT_DEV_BLACK_HOLE	1
+
 /*************************************************************
  ** I/O grouping types. Changing them don't forget to change
  ** the corresponding *_STR values in scst_const.h!
@@ -2727,6 +2730,33 @@ struct scst_acg {
 
 	unsigned int tgt_acg:1;
 
+/* Not a black hole */
+#define SCST_ACG_BLACK_HOLE_NONE	0
+
+/* Immediately abort all coming commands */
+#define SCST_ACG_BLACK_HOLE_CMD		1
+
+/*
+ * Immediately abort all coming commands and drop all coming TM commands.
+ *
+ * CAUTION! With some target drivers it can cause internal resources
+ * leaks, so don't abuse this option!
+ */
+#define SCST_ACG_BLACK_HOLE_ALL		2
+
+/* Immediately abort all coming data transfer commands */
+#define SCST_ACG_BLACK_HOLE_DATA_CMD	3
+
+/*
+ * Immediately abort all coming data transfer commands and drop all
+ * coming TM commands.
+ *
+ * CAUTION! With some target drivers it can cause internal resources
+ * leaks, so don't abuse this option!
+ */
+#define SCST_ACG_BLACK_HOLE_DATA_MCMD	4
+	volatile int acg_black_hole_type;
+
 	/* sysfs release completion */
 	struct completion *acg_kobj_release_cmpl;
 

scst/src/scst_lib.c

@@ -4152,6 +4152,10 @@ static int scst_alloc_add_tgt_dev(struct scst_session *sess,
 	tgt_dev->tgt_dev_rd_only = acg_dev->acg_dev_rd_only || dev->dev_rd_only;
 	tgt_dev->sess = sess;
 	atomic_set(&tgt_dev->tgt_dev_cmd_count, 0);
+	if (sess->acg->acg_black_hole_type != SCST_ACG_BLACK_HOLE_NONE)
+		set_bit(SCST_TGT_DEV_BLACK_HOLE, &tgt_dev->tgt_dev_flags);
+	else
+		clear_bit(SCST_TGT_DEV_BLACK_HOLE, &tgt_dev->tgt_dev_flags);
 
 	scst_sgv_pool_use_norm(tgt_dev);
 

scst/src/scst_sysfs.c

@@ -1756,6 +1756,125 @@ static struct kobj_attribute scst_tgt_io_grouping_type =
 	       scst_tgt_io_grouping_type_show,
 	       scst_tgt_io_grouping_type_store);
 
+static ssize_t __scst_acg_black_hole_show(struct scst_acg *acg, char *buf)
+{
+	int res, t = acg->acg_black_hole_type;
+
+	res = sprintf(buf, "%d\n%s\n", t,
+		(t != SCST_ACG_BLACK_HOLE_NONE) ? SCST_SYSFS_KEY_MARK : "");
+
+	return res;
+}
+
+static ssize_t __scst_acg_black_hole_store(struct scst_acg *acg,
+	const char *buf, size_t count)
+{
+	int res = 0;
+	int prev, t;
+	struct scst_session *sess;
+
+	prev = acg->acg_black_hole_type;
+
+	if ((buf == NULL) || (count == 0)) {
+		res = 0;
+		goto out;
+	}
+
+	mutex_lock(&scst_mutex);
+
+	BUILD_BUG_ON((SCST_ACG_BLACK_HOLE_NONE != 0) ||
+		     (SCST_ACG_BLACK_HOLE_CMD != 1) ||
+		     (SCST_ACG_BLACK_HOLE_ALL != 2) ||
+		     (SCST_ACG_BLACK_HOLE_DATA_CMD != 3) ||
+		     (SCST_ACG_BLACK_HOLE_DATA_MCMD != 4));
+	switch (buf[0]) {
+	case '0':
+		acg->acg_black_hole_type = SCST_ACG_BLACK_HOLE_NONE;
+		break;
+	case '1':
+		acg->acg_black_hole_type = SCST_ACG_BLACK_HOLE_CMD;
+		break;
+	case '2':
+		acg->acg_black_hole_type = SCST_ACG_BLACK_HOLE_ALL;
+		break;
+	case '3':
+		acg->acg_black_hole_type = SCST_ACG_BLACK_HOLE_DATA_CMD;
+		break;
+	case '4':
+		acg->acg_black_hole_type = SCST_ACG_BLACK_HOLE_DATA_MCMD;
+		break;
+	default:
+		PRINT_ERROR("%s: Requested action not understood: %s",
+		       __func__, buf);
+		res = -EINVAL;
+		goto out_unlock;
+	}
+
+	t = acg->acg_black_hole_type;
+
+	if (prev == t)
+		goto out_unlock;
+
+	list_for_each_entry(sess, &acg->acg_sess_list, acg_sess_list_entry) {
+		int i;
+		for (i = 0; i < SESS_TGT_DEV_LIST_HASH_SIZE; i++) {
+			struct list_head *head = &sess->sess_tgt_dev_list[i];
+			struct scst_tgt_dev *tgt_dev;
+			list_for_each_entry(tgt_dev, head, sess_tgt_dev_list_entry) {
+				if (t != SCST_ACG_BLACK_HOLE_NONE)
+					set_bit(SCST_TGT_DEV_BLACK_HOLE, &tgt_dev->tgt_dev_flags);
+				else
+					clear_bit(SCST_TGT_DEV_BLACK_HOLE, &tgt_dev->tgt_dev_flags);
+			}
+		}
+	}
+
+	PRINT_INFO("Black hole set to %d for ACG %s", t, acg->acg_name);
+
+out_unlock:
+	mutex_unlock(&scst_mutex);
+
+out:
+	return res;
+}
+
+static ssize_t scst_tgt_black_hole_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	struct scst_acg *acg;
+	struct scst_tgt *tgt;
+
+	tgt = container_of(kobj, struct scst_tgt, tgt_kobj);
+	acg = tgt->default_acg;
+
+	return __scst_acg_black_hole_show(acg, buf);
+}
+
+static ssize_t scst_tgt_black_hole_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res;
+	struct scst_acg *acg;
+	struct scst_tgt *tgt;
+
+	tgt = container_of(kobj, struct scst_tgt, tgt_kobj);
+	acg = tgt->default_acg;
+
+	res = __scst_acg_black_hole_store(acg, buf, count);
+	if (res != 0)
+		goto out;
+
+	res = count;
+
+out:
+	TRACE_EXIT_RES(res);
+	return res;
+}
+
+static struct kobj_attribute scst_tgt_black_hole =
+	__ATTR(black_hole, S_IRUGO | S_IWUSR,
+	       scst_tgt_black_hole_show, scst_tgt_black_hole_store);
+
 static ssize_t __scst_acg_cpu_mask_show(struct scst_acg *acg, char *buf)
 {
 	int res;
@@ -2473,6 +2592,7 @@ static struct attribute *scst_tgt_attrs[] = {
 	&scst_tgt_comment.attr,
 	&scst_tgt_addr_method.attr,
 	&scst_tgt_io_grouping_type.attr,
+	&scst_tgt_black_hole.attr,
 	&scst_tgt_cpu_mask.attr,
 	&scst_tgt_unknown_cmd_count_attr.attr,
 	&scst_tgt_write_cmd_count_attr.attr,
@@ -4285,6 +4405,39 @@ static struct kobj_attribute scst_acg_io_grouping_type =
 	       scst_acg_io_grouping_type_show,
 	       scst_acg_io_grouping_type_store);
 
+static ssize_t scst_acg_black_hole_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	struct scst_acg *acg;
+
+	acg = container_of(kobj, struct scst_acg, acg_kobj);
+
+	return __scst_acg_black_hole_show(acg, buf);
+}
+
+static ssize_t scst_acg_black_hole_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res;
+	struct scst_acg *acg;
+
+	acg = container_of(kobj, struct scst_acg, acg_kobj);
+
+	res = __scst_acg_black_hole_store(acg, buf, count);
+	if (res != 0)
+		goto out;
+
+	res = count;
+
+out:
+	TRACE_EXIT_RES(res);
+	return res;
+}
+
+static struct kobj_attribute scst_acg_black_hole =
+	__ATTR(black_hole, S_IRUGO | S_IWUSR,
+	       scst_acg_black_hole_show, scst_acg_black_hole_store);
+
 static ssize_t scst_acg_cpu_mask_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf)
 {
@@ -4408,6 +4561,13 @@ int scst_acg_sysfs_create(struct scst_tgt *tgt,
 		goto out_del;
 	}
 
+	res = sysfs_create_file(&acg->acg_kobj, &scst_acg_black_hole.attr);
+	if (res != 0) {
+		PRINT_ERROR("Can't add tgt attr %s for tgt %s",
+			scst_acg_black_hole.attr.name, tgt->tgt_name);
+		goto out_del;
+	}
+
 	res = sysfs_create_file(&acg->acg_kobj, &scst_acg_cpu_mask.attr);
 	if (res != 0) {
 		PRINT_ERROR("Can't add tgt attr %s for tgt %s",

scst/src/scst_targ.c

@@ -972,6 +972,32 @@ out:
 	}
 #endif
 
+	if (unlikely(test_bit(SCST_TGT_DEV_BLACK_HOLE, &cmd->tgt_dev->tgt_dev_flags))) {
+		struct scst_session *sess = cmd->sess;
+		bool abort = false;
+		switch (sess->acg->acg_black_hole_type) {
+		case SCST_ACG_BLACK_HOLE_CMD:
+		case SCST_ACG_BLACK_HOLE_ALL:
+			abort = true;
+			break;
+		case SCST_ACG_BLACK_HOLE_DATA_CMD:
+		case SCST_ACG_BLACK_HOLE_DATA_MCMD:
+			if (cmd->data_direction != SCST_DATA_NONE)
+				abort = true;
+			break;
+		default:
+			break;
+		}
+		if (abort) {
+			TRACE_MGMT_DBG("Black hole: aborting cmd %p (op %x, "
+				"initiator %s)", cmd, cmd->cdb[0],
+				sess->initiator_name);
+			spin_lock_irq(&sess->sess_list_lock);
+			scst_abort_cmd(cmd, NULL, false, false);
+			spin_unlock_irq(&sess->sess_list_lock);
+		}
+	}
+
 	TRACE_EXIT_HRES(res);
 	return res;
 
@@ -5466,10 +5492,20 @@ static int scst_clear_task_set(struct scst_mgmt_cmd *mcmd)
  * >0, if it should be requeued, <0 otherwise */
 static int scst_mgmt_cmd_init(struct scst_mgmt_cmd *mcmd)
 {
-	int res = 0, rc;
+	int res = 0, rc, t;
 
 	TRACE_ENTRY();
 
+	t = mcmd->sess->acg->acg_black_hole_type;
+
+	if (unlikely((t == SCST_ACG_BLACK_HOLE_ALL) ||
+		     (t == SCST_ACG_BLACK_HOLE_DATA_MCMD))) {
+		TRACE_MGMT_DBG("Dropping mcmd %p (fn %d, initiator %s)", mcmd,
+			mcmd->fn, mcmd->sess->initiator_name);
+		mcmd->state = SCST_MCMD_STATE_FINISHED;
+		goto out;
+	}
+
 	switch (mcmd->fn) {
 	case SCST_ABORT_TASK:
 	{