diff options
Diffstat (limited to 'drivers/md/dm-hw-handler.c')
| -rw-r--r-- | drivers/md/dm-hw-handler.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/md/dm-hw-handler.c b/drivers/md/dm-hw-handler.c new file mode 100644 index 0000000..ae63772 --- /dev/null +++ b/drivers/md/dm-hw-handler.c @@ -0,0 +1,216 @@ +/* + * 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); |