Commit d07dc5d8 authored by Stefan Haberland's avatar Stefan Haberland Committed by Martin Schwidefsky
Browse files

s390/dasd: add safe offline interface 



The regular behavior of the DASD device driver when setting a device
offline is to return all outstanding I/O as failed. This behavior is
different from that of other System z operating systems and may lead
to unexpected data loss. Adding an explicit 'safe' offline function
will allow customers to use DASDs in the way they expect them to work.

Signed-off-by: default avatarStefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 55d3a85c

drivers/s390/block/dasd.c

+80 −17
Original line number Diff line number Diff line
@@ -349,6 +349,16 @@ static int dasd_state_basic_to_ready(struct dasd_device *device) 
	return rc;

}



static inline

int _wait_for_empty_queues(struct dasd_device *device)

{

	if (device->block)

		return list_empty(&device->ccw_queue) &&

			list_empty(&device->block->ccw_queue);

	else

		return list_empty(&device->ccw_queue);

}



/*

 * Remove device from block device layer. Destroy dirty buffers.

 * Forget format information. Check if the target level is basic
@@ -1841,6 +1851,13 @@ static void __dasd_device_check_expire(struct dasd_device *device) 
	cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, devlist);

	if ((cqr->status == DASD_CQR_IN_IO && cqr->expires != 0) &&

	    (time_after_eq(jiffies, cqr->expires + cqr->starttime))) {

		if (test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {

			/*

			 * IO in safe offline processing should not

			 * run out of retries

			 */

			cqr->retries++;

		}

		if (device->discipline->term_IO(cqr) != 0) {

			/* Hmpf, try again in 5 sec */

			dev_err(&device->cdev->dev,
@@ -3024,11 +3041,11 @@ void dasd_generic_remove(struct ccw_device *cdev) 


	cdev->handler = NULL;



	dasd_remove_sysfs_files(cdev);

	device = dasd_device_from_cdev(cdev);

	if (IS_ERR(device))

		return;

	if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {

	if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags) &&

	    !test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {

		/* Already doing offline processing */

		dasd_put_device(device);

		return;
@@ -3048,6 +3065,8 @@ void dasd_generic_remove(struct ccw_device *cdev) 
	 */

	if (block)

		dasd_free_block(block);



	dasd_remove_sysfs_files(cdev);

}



/*
@@ -3126,16 +3145,13 @@ int dasd_generic_set_offline(struct ccw_device *cdev) 
{

	struct dasd_device *device;

	struct dasd_block *block;

	int max_count, open_count;

	int max_count, open_count, rc;



	rc = 0;

	device = dasd_device_from_cdev(cdev);

	if (IS_ERR(device))

		return PTR_ERR(device);

	if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {

		/* Already doing offline processing */

		dasd_put_device(device);

		return 0;

	}



	/*

	 * We must make sure that this device is currently not in use.

	 * The open_count is increased for every opener, that includes
@@ -3159,6 +3175,54 @@ int dasd_generic_set_offline(struct ccw_device *cdev) 
			return -EBUSY;

		}

	}



	if (test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {

		/*

		 * safe offline allready running

		 * could only be called by normal offline so safe_offline flag

		 * needs to be removed to run normal offline and kill all I/O

		 */

		if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {

			/* Already doing normal offline processing */

			dasd_put_device(device);

			return -EBUSY;

		} else

			clear_bit(DASD_FLAG_SAFE_OFFLINE, &device->flags);



	} else

		if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {

			/* Already doing offline processing */

			dasd_put_device(device);

			return -EBUSY;

		}



	/*

	 * if safe_offline called set safe_offline_running flag and

	 * clear safe_offline so that a call to normal offline

	 * can overrun safe_offline processing

	 */

	if (test_and_clear_bit(DASD_FLAG_SAFE_OFFLINE, &device->flags) &&

	    !test_and_set_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {

		/*

		 * If we want to set the device safe offline all IO operations

		 * should be finished before continuing the offline process

		 * so sync bdev first and then wait for our queues to become

		 * empty

		 */

		/* sync blockdev and partitions */

		rc = fsync_bdev(device->block->bdev);

		if (rc != 0)

			goto interrupted;



		/* schedule device tasklet and wait for completion */

		dasd_schedule_device_bh(device);

		rc = wait_event_interruptible(shutdown_waitq,

					      _wait_for_empty_queues(device));

		if (rc != 0)

			goto interrupted;

	}



	set_bit(DASD_FLAG_OFFLINE, &device->flags);

	dasd_set_target_state(device, DASD_STATE_NEW);

	/* dasd_delete_device destroys the device reference. */

	block = device->block;
@@ -3170,6 +3234,14 @@ int dasd_generic_set_offline(struct ccw_device *cdev) 
	if (block)

		dasd_free_block(block);

	return 0;



interrupted:

	/* interrupted by signal */

	clear_bit(DASD_FLAG_SAFE_OFFLINE, &device->flags);

	clear_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags);

	clear_bit(DASD_FLAG_OFFLINE, &device->flags);

	dasd_put_device(device);

	return rc;

}



int dasd_generic_last_path_gone(struct dasd_device *device)
@@ -3489,15 +3561,6 @@ char *dasd_get_sense(struct irb *irb) 
}

EXPORT_SYMBOL_GPL(dasd_get_sense);



static inline int _wait_for_empty_queues(struct dasd_device *device)

{

	if (device->block)

		return list_empty(&device->ccw_queue) &&

			list_empty(&device->block->ccw_queue);

	else

		return list_empty(&device->ccw_queue);

}



void dasd_generic_shutdown(struct ccw_device *cdev)

{

	struct dasd_device *device;

drivers/s390/block/dasd_devmap.c

+34 −0
Original line number Diff line number Diff line
@@ -951,6 +951,39 @@ dasd_use_raw_store(struct device *dev, struct device_attribute *attr, 
static DEVICE_ATTR(raw_track_access, 0644, dasd_use_raw_show,

		   dasd_use_raw_store);



static ssize_t

dasd_safe_offline_store(struct device *dev, struct device_attribute *attr,

			const char *buf, size_t count)

{

	struct ccw_device *cdev = to_ccwdev(dev);

	struct dasd_device *device;

	int rc;



	device = dasd_device_from_cdev(cdev);

	if (IS_ERR(device)) {

		rc = PTR_ERR(device);

		goto out;

	}



	if (test_bit(DASD_FLAG_OFFLINE, &device->flags) ||

	    test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {

		/* Already doing offline processing */

		dasd_put_device(device);

		rc = -EBUSY;

		goto out;

	}



	set_bit(DASD_FLAG_SAFE_OFFLINE, &device->flags);

	dasd_put_device(device);



	rc = ccw_device_set_offline(cdev);



out:

	return rc ? rc : count;

}



static DEVICE_ATTR(safe_offline, 0200, NULL, dasd_safe_offline_store);



static ssize_t

dasd_discipline_show(struct device *dev, struct device_attribute *attr,

		     char *buf)
@@ -1320,6 +1353,7 @@ static struct attribute * dasd_attrs[] = { 
	&dev_attr_expires.attr,

	&dev_attr_reservation_policy.attr,

	&dev_attr_last_known_reservation_state.attr,

	&dev_attr_safe_offline.attr,

	NULL,

};

drivers/s390/block/dasd_int.h

+2 −0
Original line number Diff line number Diff line
@@ -516,6 +516,8 @@ struct dasd_block { 
#define DASD_FLAG_IS_RESERVED	7	/* The device is reserved */

#define DASD_FLAG_LOCK_STOLEN	8	/* The device lock was stolen */

#define DASD_FLAG_SUSPENDED	9	/* The device was suspended */

#define DASD_FLAG_SAFE_OFFLINE	10	/* safe offline processing requested*/

#define DASD_FLAG_SAFE_OFFLINE_RUNNING	11	/* safe offline running */





void dasd_put_device_wake(struct dasd_device *);

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