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linux/drivers/s390/block/dasd_erp.c
Stefan Weinhuber 8e09f21574 [S390] dasd: add hyper PAV support to DASD device driver, part 1 
Parallel access volumes (PAV) is a storage server feature, that allows
to start multiple channel programs on the same DASD in parallel. It
defines alias devices which can be used as alternative paths to the
same disk. With the old base PAV support we only needed rudimentary
functionality in the DASD device driver. As the mapping between base
and alias devices was static, we just had to export an identifier
(uid) and could leave the combining of devices to external layers
like a device mapper multipath.
Now hyper PAV removes the requirement to dedicate alias devices to
specific base devices. Instead each alias devices can be combined with
multiple base device on a per request basis. This requires full
support by the DASD device driver as now each channel program itself
has to identify the target base device.
The changes to the dasd device driver and the ECKD discipline are:
- Separate subchannel device representation (dasd_device) from block
  device representation (dasd_block). Only base devices are block
  devices.
- Gather information about base and alias devices and possible
  combinations.
- For each request decide which dasd_device should be used (base or
  alias) and build specific channel program.
- Support summary unit checks, which allow the storage server to
  upgrade / downgrade between base and hyper PAV at runtime (support
  is mandatory).

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-01-26 14:11:28 +01:00

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/*
* File...........: linux/drivers/s390/block/dasd.c
* Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
* Horst Hummel <Horst.Hummel@de.ibm.com>
* Carsten Otte <Cotte@de.ibm.com>
* Martin Schwidefsky <schwidefsky@de.ibm.com>
* Bugreports.to..: <Linux390@de.ibm.com>
* (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
*
*/
#include <linux/ctype.h>
#include <linux/init.h>
#include <asm/debug.h>
#include <asm/ebcdic.h>
#include <asm/uaccess.h>
/* This is ugly... */
#define PRINTK_HEADER "dasd_erp:"
#include "dasd_int.h"
struct dasd_ccw_req *
dasd_alloc_erp_request(char *magic, int cplength, int datasize,
struct dasd_device * device)
{
unsigned long flags;
struct dasd_ccw_req *cqr;
char *data;
int size;
/* Sanity checks */
BUG_ON( magic == NULL || datasize > PAGE_SIZE ||
(cplength*sizeof(struct ccw1)) > PAGE_SIZE);
size = (sizeof(struct dasd_ccw_req) + 7L) & -8L;
if (cplength > 0)
size += cplength * sizeof(struct ccw1);
if (datasize > 0)
size += datasize;
spin_lock_irqsave(&device->mem_lock, flags);
cqr = (struct dasd_ccw_req *)
dasd_alloc_chunk(&device->erp_chunks, size);
spin_unlock_irqrestore(&device->mem_lock, flags);
if (cqr == NULL)
return ERR_PTR(-ENOMEM);
memset(cqr, 0, sizeof(struct dasd_ccw_req));
INIT_LIST_HEAD(&cqr->devlist);
INIT_LIST_HEAD(&cqr->blocklist);
data = (char *) cqr + ((sizeof(struct dasd_ccw_req) + 7L) & -8L);
cqr->cpaddr = NULL;
if (cplength > 0) {
cqr->cpaddr = (struct ccw1 *) data;
data += cplength*sizeof(struct ccw1);
memset(cqr->cpaddr, 0, cplength*sizeof(struct ccw1));
}
cqr->data = NULL;
if (datasize > 0) {
cqr->data = data;
memset(cqr->data, 0, datasize);
}
strncpy((char *) &cqr->magic, magic, 4);
ASCEBC((char *) &cqr->magic, 4);
set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
dasd_get_device(device);
return cqr;
}
void
dasd_free_erp_request(struct dasd_ccw_req *cqr, struct dasd_device * device)
{
unsigned long flags;
spin_lock_irqsave(&device->mem_lock, flags);
dasd_free_chunk(&device->erp_chunks, cqr);
spin_unlock_irqrestore(&device->mem_lock, flags);
atomic_dec(&device->ref_count);
}
/*
* dasd_default_erp_action just retries the current cqr
*/
struct dasd_ccw_req *
dasd_default_erp_action(struct dasd_ccw_req *cqr)
{
struct dasd_device *device;
device = cqr->startdev;
/* just retry - there is nothing to save ... I got no sense data.... */
if (cqr->retries > 0) {
DEV_MESSAGE (KERN_DEBUG, device,
"default ERP called (%i retries left)",
cqr->retries);
cqr->lpm = LPM_ANYPATH;
cqr->status = DASD_CQR_FILLED;
} else {
DEV_MESSAGE (KERN_WARNING, device, "%s",
"default ERP called (NO retry left)");
cqr->status = DASD_CQR_FAILED;
cqr->stopclk = get_clock();
}
return cqr;
} /* end dasd_default_erp_action */
/*
* DESCRIPTION
* Frees all ERPs of the current ERP Chain and set the status
* of the original CQR either to DASD_CQR_DONE if ERP was successful
* or to DASD_CQR_FAILED if ERP was NOT successful.
* NOTE: This function is only called if no discipline postaction
* is available
*
* PARAMETER
* erp current erp_head
*
* RETURN VALUES
* cqr pointer to the original CQR
*/
struct dasd_ccw_req *dasd_default_erp_postaction(struct dasd_ccw_req *cqr)
{
int success;
BUG_ON(cqr->refers == NULL || cqr->function == NULL);
success = cqr->status == DASD_CQR_DONE;
/* free all ERPs - but NOT the original cqr */
while (cqr->refers != NULL) {
struct dasd_ccw_req *refers;
refers = cqr->refers;
/* remove the request from the block queue */
list_del(&cqr->blocklist);
/* free the finished erp request */
dasd_free_erp_request(cqr, cqr->memdev);
cqr = refers;
}
/* set corresponding status to original cqr */
if (success)
cqr->status = DASD_CQR_DONE;
else {
cqr->status = DASD_CQR_FAILED;
cqr->stopclk = get_clock();
}
return cqr;
} /* end default_erp_postaction */
void
dasd_log_sense(struct dasd_ccw_req *cqr, struct irb *irb)
{
struct dasd_device *device;
device = cqr->startdev;
/* dump sense data */
if (device->discipline && device->discipline->dump_sense)
device->discipline->dump_sense(device, cqr, irb);
}
EXPORT_SYMBOL(dasd_default_erp_action);
EXPORT_SYMBOL(dasd_default_erp_postaction);
EXPORT_SYMBOL(dasd_alloc_erp_request);
EXPORT_SYMBOL(dasd_free_erp_request);
EXPORT_SYMBOL(dasd_log_sense);
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