s390/dasd: add autoquiesce feature

Add the internal logic to check for autoquiesce triggers and handle
them.

Quiesce and resume are functions that tell Linux to stop/resume
issuing I/Os to a specific DASD.
The DASD driver allows a manual quiesce/resume via ioctl.

Autoquiesce will define an amount of triggers that will lead to
an automatic quiesce if a certain event occurs.
There is no automatic resume.

All events will be reported via DASD Extended Error Reporting (EER)
if configured.
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Link: https://lore.kernel.org/r/20230405142017.2446986-3-sth@linux.ibm.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

arch/s390/include/uapi/asm/dasd.h

@@ -78,6 +78,7 @@ typedef struct dasd_information2_t {
  * 0x040: give access to raw eckd data
  * 0x080: enable discard support
  * 0x100: enable autodisable for IFCC errors (default)
+ * 0x200: enable requeue of all requests on autoquiesce
  */
 #define DASD_FEATURE_READONLY	      0x001
 #define DASD_FEATURE_USEDIAG	      0x002
@@ -88,6 +89,7 @@ typedef struct dasd_information2_t {
 #define DASD_FEATURE_USERAW	      0x040
 #define DASD_FEATURE_DISCARD	      0x080
 #define DASD_FEATURE_PATH_AUTODISABLE 0x100
+#define DASD_FEATURE_REQUEUEQUIESCE   0x200
 #define DASD_FEATURE_DEFAULT	      DASD_FEATURE_PATH_AUTODISABLE
 
 #define DASD_PARTN_BITS 2

drivers/s390/block/dasd.c

@@ -73,7 +73,8 @@ static void dasd_profile_init(struct dasd_profile *, struct dentry *);
 static void dasd_profile_exit(struct dasd_profile *);
 static void dasd_hosts_init(struct dentry *, struct dasd_device *);
 static void dasd_hosts_exit(struct dasd_device *);
-
+static int dasd_handle_autoquiesce(struct dasd_device *, struct dasd_ccw_req *,
+				   unsigned int);
 /*
  * SECTION: Operations on the device structure.
  */
@@ -2325,7 +2326,7 @@ static int _dasd_sleep_on(struct dasd_ccw_req *maincqr, int interruptible)
 		/* Non-temporary stop condition will trigger fail fast */
 		if (device->stopped & ~DASD_STOPPED_PENDING &&
 		    test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
-		    (!dasd_eer_enabled(device))) {
+		    !dasd_eer_enabled(device) && device->aq_mask == 0) {
 			cqr->status = DASD_CQR_FAILED;
 			cqr->intrc = -ENOLINK;
 			continue;
@@ -2801,20 +2802,18 @@ static void __dasd_process_block_ccw_queue(struct dasd_block *block,
 			dasd_log_sense(cqr, &cqr->irb);
 		}
 
-		/* First of all call extended error reporting. */
-		if (dasd_eer_enabled(base) &&
-		    cqr->status == DASD_CQR_FAILED) {
-			dasd_eer_write(base, cqr, DASD_EER_FATALERROR);
-
-			/* restart request  */
+		/*
+		 * First call extended error reporting and check for autoquiesce
+		 */
+		spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
+		if (cqr->status == DASD_CQR_FAILED &&
+		    dasd_handle_autoquiesce(base, cqr, DASD_EER_FATALERROR)) {
 			cqr->status = DASD_CQR_FILLED;
 			cqr->retries = 255;
-			spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
-			dasd_device_set_stop_bits(base, DASD_STOPPED_QUIESCE);
-			spin_unlock_irqrestore(get_ccwdev_lock(base->cdev),
-					       flags);
+			spin_unlock_irqrestore(get_ccwdev_lock(base->cdev), flags);
 			goto restart;
 		}
+		spin_unlock_irqrestore(get_ccwdev_lock(base->cdev), flags);
 
 		/* Process finished ERP request. */
 		if (cqr->refers) {
@@ -2856,7 +2855,7 @@ static void __dasd_block_start_head(struct dasd_block *block)
 		/* Non-temporary stop condition will trigger fail fast */
 		if (block->base->stopped & ~DASD_STOPPED_PENDING &&
 		    test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
-		    (!dasd_eer_enabled(block->base))) {
+		    !dasd_eer_enabled(block->base) && block->base->aq_mask == 0) {
 			cqr->status = DASD_CQR_FAILED;
 			cqr->intrc = -ENOLINK;
 			dasd_schedule_block_bh(block);
@@ -3670,8 +3669,8 @@ int dasd_generic_last_path_gone(struct dasd_device *device)
 	dev_warn(&device->cdev->dev, "No operational channel path is left "
 		 "for the device\n");
 	DBF_DEV_EVENT(DBF_WARNING, device, "%s", "last path gone");
-	/* First of all call extended error reporting. */
-	dasd_eer_write(device, NULL, DASD_EER_NOPATH);
+	/* First call extended error reporting and check for autoquiesce. */
+	dasd_handle_autoquiesce(device, NULL, DASD_EER_NOPATH);
 
 	if (device->state < DASD_STATE_BASIC)
 		return 0;
@@ -3803,7 +3802,8 @@ void dasd_generic_path_event(struct ccw_device *cdev, int *path_event)
 			 "No verified channel paths remain for the device\n");
 		DBF_DEV_EVENT(DBF_WARNING, device,
 			      "%s", "last verified path gone");
-		dasd_eer_write(device, NULL, DASD_EER_NOPATH);
+		/* First call extended error reporting and check for autoquiesce. */
+		dasd_handle_autoquiesce(device, NULL, DASD_EER_NOPATH);
 		dasd_device_set_stop_bits(device,
 					  DASD_STOPPED_DC_WAIT);
 	}
@@ -3825,7 +3825,8 @@ EXPORT_SYMBOL_GPL(dasd_generic_verify_path);
 void dasd_generic_space_exhaust(struct dasd_device *device,
 				struct dasd_ccw_req *cqr)
 {
-	dasd_eer_write(device, NULL, DASD_EER_NOSPC);
+	/* First call extended error reporting and check for autoquiesce. */
+	dasd_handle_autoquiesce(device, NULL, DASD_EER_NOSPC);
 
 	if (device->state < DASD_STATE_BASIC)
 		return;
@@ -3958,6 +3959,31 @@ void dasd_schedule_requeue(struct dasd_device *device)
 }
 EXPORT_SYMBOL(dasd_schedule_requeue);
 
+static int dasd_handle_autoquiesce(struct dasd_device *device,
+				   struct dasd_ccw_req *cqr,
+				   unsigned int reason)
+{
+	/* in any case write eer message with reason */
+	if (dasd_eer_enabled(device))
+		dasd_eer_write(device, cqr, reason);
+
+	if (!test_bit(reason, &device->aq_mask))
+		return 0;
+
+	/* notify eer about autoquiesce */
+	if (dasd_eer_enabled(device))
+		dasd_eer_write(device, NULL, DASD_EER_AUTOQUIESCE);
+
+	pr_info("%s: The DASD has been put in the quiesce state\n",
+		dev_name(&device->cdev->dev));
+	dasd_device_set_stop_bits(device, DASD_STOPPED_QUIESCE);
+
+	if (device->features & DASD_FEATURE_REQUEUEQUIESCE)
+		dasd_schedule_requeue(device);
+
+	return 1;
+}
+
 static struct dasd_ccw_req *dasd_generic_build_rdc(struct dasd_device *device,
 						   int rdc_buffer_size,
 						   int magic)

drivers/s390/block/dasd_eer.c

@@ -387,6 +387,7 @@ void dasd_eer_write(struct dasd_device *device, struct dasd_ccw_req *cqr,
 		break;
 	case DASD_EER_NOPATH:
 	case DASD_EER_NOSPC:
+	case DASD_EER_AUTOQUIESCE:
 		dasd_eer_write_standard_trigger(device, NULL, id);
 		break;
 	case DASD_EER_STATECHANGE:

drivers/s390/block/dasd_int.h

@@ -450,6 +450,7 @@ extern struct dasd_discipline *dasd_diag_discipline_pointer;
 #define DASD_EER_STATECHANGE 3
 #define DASD_EER_PPRCSUSPEND 4
 #define DASD_EER_NOSPC	     5
+#define DASD_EER_AUTOQUIESCE 31
 
 /* DASD path handling */
 
@@ -627,6 +628,7 @@ struct dasd_device {
 	struct dasd_format_entry format_entry;
 	struct kset *paths_info;
 	struct dasd_copy_relation *copy;
+	unsigned long aq_mask;
 };
 
 struct dasd_block {