target: Fix R_HOLDER bit usage for AllRegistrants

This patch fixes the usage of R_HOLDER bit for an All Registrants
reservation in READ_FULL_STATUS, where only the registration who
issued RESERVE was being reported as having an active reservation.

It changes core_scsi3_pri_read_full_status() to check ahead of the
list walk of active registrations to see if All Registrants is active,
and if so set R_HOLDER bit and scope/type fields for all active
registrations.

Reported-by: Ilias Tsitsimpis <i.tsitsimpis@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_pr.c

@@ -3834,7 +3834,8 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
 	unsigned char *buf;
 	u32 add_desc_len = 0, add_len = 0, desc_len, exp_desc_len;
 	u32 off = 8; /* off into first Full Status descriptor */
-	int format_code = 0;
+	int format_code = 0, pr_res_type = 0, pr_res_scope = 0;
+	bool all_reg = false;
 
 	if (cmd->data_length < 8) {
 		pr_err("PRIN SA READ_FULL_STATUS SCSI Data Length: %u"
@@ -3851,6 +3852,19 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
 	buf[2] = ((dev->t10_pr.pr_generation >> 8) & 0xff);
 	buf[3] = (dev->t10_pr.pr_generation & 0xff);
 
+	spin_lock(&dev->dev_reservation_lock);
+	if (dev->dev_pr_res_holder) {
+		struct t10_pr_registration *pr_holder = dev->dev_pr_res_holder;
+
+		if (pr_holder->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG ||
+		    pr_holder->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG) {
+			all_reg = true;
+			pr_res_type = pr_holder->pr_res_type;
+			pr_res_scope = pr_holder->pr_res_scope;
+		}
+	}
+	spin_unlock(&dev->dev_reservation_lock);
+
 	spin_lock(&pr_tmpl->registration_lock);
 	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
 			&pr_tmpl->registration_list, pr_reg_list) {
@@ -3898,14 +3912,20 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
 		 * reservation holder for PR_HOLDER bit.
 		 *
 		 * Also, if this registration is the reservation
-		 * holder, fill in SCOPE and TYPE in the next byte.
+		 * holder or there is an All Registrants reservation
+		 * active, fill in SCOPE and TYPE in the next byte.
 		 */
 		if (pr_reg->pr_res_holder) {
 			buf[off++] |= 0x01;
 			buf[off++] = (pr_reg->pr_res_scope & 0xf0) |
 				     (pr_reg->pr_res_type & 0x0f);
-		} else
+		} else if (all_reg) {
+			buf[off++] |= 0x01;
+			buf[off++] = (pr_res_scope & 0xf0) |
+				     (pr_res_type & 0x0f);
+		} else {
 			off += 2;
+		}
 
 		off += 4; /* Skip over reserved area */
 		/*