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Commit 13de227b authored by Holger Smolinski's avatar Holger Smolinski Committed by Martin Schwidefsky
Browse files

[S390] dasd: add device attribute to disable blocking on lost paths 



When the connection between host and storage server is lost, the
dasd device driver usually blocks all I/O on affected devices and
waits for them to reappear. In some setups however it would be
better if the I/O is returned as error so that device can be
recovered by some other means, eg. in a raid or multipath setup.

Signed-off-by: default avatarHolger Smolinski <Holger.Smolinski@de.ibm.com>
Signed-off-by: default avatarStefan Weinhuber <wein@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 1301809b

arch/s390/include/asm/dasd.h

+1 −0
Original line number Diff line number Diff line
@@ -78,6 +78,7 @@ typedef struct dasd_information2_t { 
#define DASD_FEATURE_USEDIAG	     0x02

#define DASD_FEATURE_INITIAL_ONLINE  0x04

#define DASD_FEATURE_ERPLOG	     0x08

#define DASD_FEATURE_FAILFAST	     0x10



#define DASD_PARTN_BITS 2

drivers/s390/block/dasd_devmap.c

+48 −0
Original line number Diff line number Diff line
@@ -206,6 +206,8 @@ dasd_feature_list(char *str, char **endp) 
			features |= DASD_FEATURE_USEDIAG;

		else if (len == 6 && !strncmp(str, "erplog", 6))

			features |= DASD_FEATURE_ERPLOG;

		else if (len == 8 && !strncmp(str, "failfast", 8))

			features |= DASD_FEATURE_FAILFAST;

		else {

			MESSAGE(KERN_WARNING,

				"unsupported feature: %*s, "
@@ -666,6 +668,51 @@ dasd_device_from_cdev(struct ccw_device *cdev) 
 * SECTION: files in sysfs

 */



/*

 * failfast controls the behaviour, if no path is available

 */

static ssize_t dasd_ff_show(struct device *dev, struct device_attribute *attr,

			    char *buf)

{

	struct dasd_devmap *devmap;

	int ff_flag;



	devmap = dasd_find_busid(dev->bus_id);

	if (!IS_ERR(devmap))

		ff_flag = (devmap->features & DASD_FEATURE_FAILFAST) != 0;

	else

		ff_flag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_FAILFAST) != 0;

	return snprintf(buf, PAGE_SIZE, ff_flag ? "1\n" : "0\n");

}



static ssize_t dasd_ff_store(struct device *dev, struct device_attribute *attr,

	      const char *buf, size_t count)

{

	struct dasd_devmap *devmap;

	int val;

	char *endp;



	devmap = dasd_devmap_from_cdev(to_ccwdev(dev));

	if (IS_ERR(devmap))

		return PTR_ERR(devmap);



	val = simple_strtoul(buf, &endp, 0);

	if (((endp + 1) < (buf + count)) || (val > 1))

		return -EINVAL;



	spin_lock(&dasd_devmap_lock);

	if (val)

		devmap->features |= DASD_FEATURE_FAILFAST;

	else

		devmap->features &= ~DASD_FEATURE_FAILFAST;

	if (devmap->device)

		devmap->device->features = devmap->features;

	spin_unlock(&dasd_devmap_lock);

	return count;

}



static DEVICE_ATTR(failfast, 0644, dasd_ff_show, dasd_ff_store);



/*

 * readonly controls the readonly status of a dasd

 */
@@ -1020,6 +1067,7 @@ static struct attribute * dasd_attrs[] = { 
	&dev_attr_use_diag.attr,

	&dev_attr_eer_enabled.attr,

	&dev_attr_erplog.attr,

	&dev_attr_failfast.attr,

	NULL,

};

drivers/s390/block/dasd_diag.c

+2 −1
Original line number Diff line number Diff line
@@ -544,7 +544,8 @@ static struct dasd_ccw_req *dasd_diag_build_cp(struct dasd_device *memdev, 
	}

	cqr->retries = DIAG_MAX_RETRIES;

	cqr->buildclk = get_clock();

	if (blk_noretry_request(req))

	if (blk_noretry_request(req) ||

	    block->base->features & DASD_FEATURE_FAILFAST)

		set_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags);

	cqr->startdev = memdev;

	cqr->memdev = memdev;

drivers/s390/block/dasd_eckd.c

+2 −1
Original line number Diff line number Diff line
@@ -1700,7 +1700,8 @@ static struct dasd_ccw_req *dasd_eckd_build_cp(struct dasd_device *startdev, 
			recid++;

		}

	}

	if (blk_noretry_request(req))

	if (blk_noretry_request(req) ||

	    block->base->features & DASD_FEATURE_FAILFAST)

		set_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags);

	cqr->startdev = startdev;

	cqr->memdev = startdev;

drivers/s390/block/dasd_fba.c

+2 −1
Original line number Diff line number Diff line
@@ -355,7 +355,8 @@ static struct dasd_ccw_req *dasd_fba_build_cp(struct dasd_device * memdev, 
			recid++;

		}

	}

	if (blk_noretry_request(req))

	if (blk_noretry_request(req) ||

	    block->base->features & DASD_FEATURE_FAILFAST)

		set_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags);

	cqr->startdev = memdev;

	cqr->memdev = memdev;