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/*
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*
* Multipath hardware handler registration.
*/
#include "dm.h"
#include "dm-hw-handler.h"
#include <linux/slab.h>
struct hwh_internal {
struct hw_handler_type hwht;
struct list_head list;
long use;
};
#define hwht_to_hwhi(__hwht) container_of((__hwht), struct hwh_internal, hwht)
static LIST_HEAD(_hw_handlers);
static DECLARE_RWSEM(_hwh_lock);
struct hwh_internal *__find_hw_handler_type(const char *name)
{
struct hwh_internal *hwhi;
list_for_each_entry(hwhi, &_hw_handlers, list) {
if (!strcmp(name, hwhi->hwht.name))
return hwhi;
}
return NULL;
}
static struct hwh_internal *get_hw_handler(const char *name)
{
struct hwh_internal *hwhi;
down_read(&_hwh_lock);
hwhi = __find_hw_handler_type(name);
if (hwhi) {
if ((hwhi->use == 0) && !try_module_get(hwhi->hwht.module))
hwhi = NULL;
else
hwhi->use++;
}
up_read(&_hwh_lock);
return hwhi;
}
struct hw_handler_type *dm_get_hw_handler(const char *name)
{
struct hwh_internal *hwhi;
if (!name)
return NULL;
hwhi = get_hw_handler(name);
if (!hwhi) {
request_module("dm-%s", name);
hwhi = get_hw_handler(name);
}
return hwhi ? &hwhi->hwht : NULL;
}
void dm_put_hw_handler(struct hw_handler_type *hwht)
{
struct hwh_internal *hwhi;
if (!hwht)
return;
down_read(&_hwh_lock);
hwhi = __find_hw_handler_type(hwht->name);
if (!hwhi)
goto out;
if (--hwhi->use == 0)
module_put(hwhi->hwht.module);
if (hwhi->use < 0)
BUG();
out:
up_read(&_hwh_lock);
}
static struct hwh_internal *_alloc_hw_handler(struct hw_handler_type *hwht)
{
struct hwh_internal *hwhi = kmalloc(sizeof(*hwhi), GFP_KERNEL);
if (hwhi) {
memset(hwhi, 0, sizeof(*hwhi));
hwhi->hwht = *hwht;
}
return hwhi;
}
int dm_register_hw_handler(struct hw_handler_type *hwht)
{
int r = 0;
struct hwh_internal *hwhi = _alloc_hw_handler(hwht);
if (!hwhi)
return -ENOMEM;
down_write(&_hwh_lock);
if (__find_hw_handler_type(hwht->name)) {
kfree(hwhi);
r = -EEXIST;
} else
list_add(&hwhi->list, &_hw_handlers);
up_write(&_hwh_lock);
return r;
}
int dm_unregister_hw_handler(struct hw_handler_type *hwht)
{
struct hwh_internal *hwhi;
down_write(&_hwh_lock);
hwhi = __find_hw_handler_type(hwht->name);
if (!hwhi) {
up_write(&_hwh_lock);
return -EINVAL;
}
if (hwhi->use) {
up_write(&_hwh_lock);
return -ETXTBSY;
}
list_del(&hwhi->list);
up_write(&_hwh_lock);
kfree(hwhi);
return 0;
}
unsigned dm_scsi_err_handler(struct hw_handler *hwh, struct bio *bio)
{
#if 0
int sense_key, asc, ascq;
if (bio->bi_error & BIO_SENSE) {
/* FIXME: This is just an initial guess. */
/* key / asc / ascq */
sense_key = (bio->bi_error >> 16) & 0xff;
asc = (bio->bi_error >> 8) & 0xff;
ascq = bio->bi_error & 0xff;
switch (sense_key) {
/* This block as a whole comes from the device.
* So no point retrying on another path. */
case 0x03: /* Medium error */
case 0x05: /* Illegal request */
case 0x07: /* Data protect */
case 0x08: /* Blank check */
case 0x0a: /* copy aborted */
case 0x0c: /* obsolete - no clue ;-) */
case 0x0d: /* volume overflow */
case 0x0e: /* data miscompare */
case 0x0f: /* reserved - no idea either. */
return MP_ERROR_IO;
/* For these errors it's unclear whether they
* come from the device or the controller.
* So just lets try a different path, and if
* it eventually succeeds, user-space will clear
* the paths again... */
case 0x02: /* Not ready */
case 0x04: /* Hardware error */
case 0x09: /* vendor specific */
case 0x0b: /* Aborted command */
return MP_FAIL_PATH;
case 0x06: /* Unit attention - might want to decode */
if (asc == 0x04 && ascq == 0x01)
/* "Unit in the process of
* becoming ready" */
return 0;
return MP_FAIL_PATH;
/* FIXME: For Unit Not Ready we may want
* to have a generic pg activation
* feature (START_UNIT). */
/* Should these two ever end up in the
* error path? I don't think so. */
case 0x00: /* No sense */
case 0x01: /* Recovered error */
return 0;
}
}
#endif
/* We got no idea how to decode the other kinds of errors ->
* assume generic error condition. */
return MP_FAIL_PATH;
}
EXPORT_SYMBOL_GPL(dm_register_hw_handler);
EXPORT_SYMBOL_GPL(dm_unregister_hw_handler);
EXPORT_SYMBOL_GPL(dm_scsi_err_handler);
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