/* * Generic SCSI-3 ALUA SCSI Device Handler * * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH. * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * */ #include #include #include #include #include #define ALUA_DH_NAME "alua" #define ALUA_DH_VER "1.3" #define TPGS_STATE_OPTIMIZED 0x0 #define TPGS_STATE_NONOPTIMIZED 0x1 #define TPGS_STATE_STANDBY 0x2 #define TPGS_STATE_UNAVAILABLE 0x3 #define TPGS_STATE_LBA_DEPENDENT 0x4 #define TPGS_STATE_OFFLINE 0xe #define TPGS_STATE_TRANSITIONING 0xf #define TPGS_SUPPORT_NONE 0x00 #define TPGS_SUPPORT_OPTIMIZED 0x01 #define TPGS_SUPPORT_NONOPTIMIZED 0x02 #define TPGS_SUPPORT_STANDBY 0x04 #define TPGS_SUPPORT_UNAVAILABLE 0x08 #define TPGS_SUPPORT_LBA_DEPENDENT 0x10 #define TPGS_SUPPORT_OFFLINE 0x40 #define TPGS_SUPPORT_TRANSITION 0x80 #define TPGS_MODE_UNINITIALIZED -1 #define TPGS_MODE_NONE 0x0 #define TPGS_MODE_IMPLICIT 0x1 #define TPGS_MODE_EXPLICIT 0x2 #define ALUA_INQUIRY_SIZE 36 #define ALUA_FAILOVER_TIMEOUT (60 * HZ) #define ALUA_FAILOVER_RETRIES 5 struct alua_dh_data { int group_id; int rel_port; int tpgs; int state; unsigned char inq[ALUA_INQUIRY_SIZE]; unsigned char *buff; int bufflen; unsigned char sense[SCSI_SENSE_BUFFERSIZE]; int senselen; struct scsi_device *sdev; activate_complete callback_fn; void *callback_data; }; #define ALUA_POLICY_SWITCH_CURRENT 0 #define ALUA_POLICY_SWITCH_ALL 1 static char print_alua_state(int); static int alua_check_sense(struct scsi_device *, struct scsi_sense_hdr *); static inline struct alua_dh_data *get_alua_data(struct scsi_device *sdev) { struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data; BUG_ON(scsi_dh_data == NULL); return ((struct alua_dh_data *) scsi_dh_data->buf); } static int realloc_buffer(struct alua_dh_data *h, unsigned len) { if (h->buff && h->buff != h->inq) kfree(h->buff); h->buff = kmalloc(len, GFP_NOIO); if (!h->buff) { h->buff = h->inq; h->bufflen = ALUA_INQUIRY_SIZE; return 1; } h->bufflen = len; return 0; } static struct request *get_alua_req(struct scsi_device *sdev, void *buffer, unsigned buflen, int rw) { struct request *rq; struct request_queue *q = sdev->request_queue; rq = blk_get_request(q, rw, GFP_NOIO); if (!rq) { sdev_printk(KERN_INFO, sdev, "%s: blk_get_request failed\n", __func__); return NULL; } if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) { blk_put_request(rq); sdev_printk(KERN_INFO, sdev, "%s: blk_rq_map_kern failed\n", __func__); return NULL; } rq->cmd_type = REQ_TYPE_BLOCK_PC; rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER; rq->retries = ALUA_FAILOVER_RETRIES; rq->timeout = ALUA_FAILOVER_TIMEOUT; return rq; } /* * submit_std_inquiry - Issue a standard INQUIRY command * @sdev: sdev the command should be send to */ static int submit_std_inquiry(struct scsi_device *sdev, struct alua_dh_data *h) { struct request *rq; int err = SCSI_DH_RES_TEMP_UNAVAIL; rq = get_alua_req(sdev, h->inq, ALUA_INQUIRY_SIZE, READ); if (!rq) goto done; /* Prepare the command. */ rq->cmd[0] = INQUIRY; rq->cmd[1] = 0; rq->cmd[2] = 0; rq->cmd[4] = ALUA_INQUIRY_SIZE; rq->cmd_len = COMMAND_SIZE(INQUIRY); rq->sense = h->sense; memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE); rq->sense_len = h->senselen = 0; err = blk_execute_rq(rq->q, NULL, rq, 1); if (err == -EIO) { sdev_printk(KERN_INFO, sdev, "%s: std inquiry failed with %x\n", ALUA_DH_NAME, rq->errors); h->senselen = rq->sense_len; err = SCSI_DH_IO; } blk_put_request(rq); done: return err; } /* * submit_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command * @sdev: sdev the command should be sent to */ static int submit_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h) { struct request *rq; int err = SCSI_DH_RES_TEMP_UNAVAIL; rq = get_alua_req(sdev, h->buff, h->bufflen, READ); if (!rq) goto done; /* Prepare the command. */ rq->cmd[0] = INQUIRY; rq->cmd[1] = 1; rq->cmd[2] = 0x83; rq->cmd[4] = h->bufflen; rq->cmd_len = COMMAND_SIZE(INQUIRY); rq->sense = h->sense; memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE); rq->sense_len = h->senselen = 0; err = blk_execute_rq(rq->q, NULL, rq, 1); if (err == -EIO) { sdev_printk(KERN_INFO, sdev, "%s: evpd inquiry failed with %x\n", ALUA_DH_NAME, rq->errors); h->senselen = rq->sense_len; err = SCSI_DH_IO; } blk_put_request(rq); done: return err; } /* * submit_rtpg - Issue a REPORT TARGET GROUP STATES command * @sdev: sdev the command should be sent to */ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h) { struct request *rq; int err = SCSI_DH_RES_TEMP_UNAVAIL; rq = get_alua_req(sdev, h->buff, h->bufflen, READ); if (!rq) goto done; /* Prepare the command. */ rq->cmd[0] = MAINTENANCE_IN; rq->cmd[1] = MI_REPORT_TARGET_PGS; rq->cmd[6] = (h->bufflen >> 24) & 0xff; rq->cmd[7] = (h->bufflen >> 16) & 0xff; rq->cmd[8] = (h->bufflen >> 8) & 0xff; rq->cmd[9] = h->bufflen & 0xff; rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN); rq->sense = h->sense; memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE); rq->sense_len = h->senselen = 0; err = blk_execute_rq(rq->q, NULL, rq, 1); if (err == -EIO) { sdev_printk(KERN_INFO, sdev, "%s: rtpg failed with %x\n", ALUA_DH_NAME, rq->errors); h->senselen = rq->sense_len; err = SCSI_DH_IO; } blk_put_request(rq); done: return err; } /* * alua_stpg - Evaluate SET TARGET GROUP STATES * @sdev: the device to be evaluated * @state: the new target group state * * Send a SET TARGET GROUP STATES command to the device. * We only have to test here if we should resubmit the command; * any other error is assumed as a failure. */ static void stpg_endio(struct request *req, int error) { struct alua_dh_data *h = req->end_io_data; struct scsi_sense_hdr sense_hdr; unsigned err = SCSI_DH_OK; if (error || host_byte(req->errors) != DID_OK || msg_byte(req->errors) != COMMAND_COMPLETE) { err = SCSI_DH_IO; goto done; } if (h->senselen > 0) { err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE, &sense_hdr); if (!err) { err = SCSI_DH_IO; goto done; } err = alua_check_sense(h->sdev, &sense_hdr); if (err == ADD_TO_MLQUEUE) { err = SCSI_DH_RETRY; goto done; } sdev_printk(KERN_INFO, h->sdev, "%s: stpg sense code: %02x/%02x/%02x\n", ALUA_DH_NAME, sense_hdr.sense_key, sense_hdr.asc, sense_hdr.ascq); err = SCSI_DH_IO; } if (err == SCSI_DH_OK) { h->state = TPGS_STATE_OPTIMIZED; sdev_printk(KERN_INFO, h->sdev, "%s: port group %02x switched to state %c\n", ALUA_DH_NAME, h->group_id, print_alua_state(h->state)); } done: req->end_io_data = NULL; __blk_put_request(req->q, req); if (h->callback_fn) { h->callback_fn(h->callback_data, err); h->callback_fn = h->callback_data = NULL; } return; } /* * submit_stpg - Issue a SET TARGET GROUP STATES command * * Currently we're only setting the current target port group state * to 'active/optimized' and let the array firmware figure out * the states of the remaining groups. */ static unsigned submit_stpg(struct alua_dh_data *h) { struct request *rq; int stpg_len = 8; struct scsi_device *sdev = h->sdev; /* Prepare the data buffer */ memset(h->buff, 0, stpg_len); h->buff[4] = TPGS_STATE_OPTIMIZED & 0x0f; h->buff[6] = (h->group_id >> 8) & 0xff; h->buff[7] = h->group_id & 0xff; rq = get_alua_req(sdev, h->buff, stpg_len, WRITE); if (!rq) return SCSI_DH_RES_TEMP_UNAVAIL; /* Prepare the command. */ rq->cmd[0] = MAINTENANCE_OUT; rq->cmd[1] = MO_SET_TARGET_PGS; rq->cmd[6] = (stpg_len >> 24) & 0xff; rq->cmd[7] = (stpg_len >> 16) & 0xff; rq->cmd[8] = (stpg_len >> 8) & 0xff; rq->cmd[9] = stpg_len & 0xff; rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT); rq->sense = h->sense; memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE); rq->sense_len = h->senselen = 0; rq->end_io_data = h; blk_execute_rq_nowait(rq->q, NULL, rq, 1, stpg_endio); return SCSI_DH_OK; } /* * alua_std_inquiry - Evaluate standard INQUIRY command * @sdev: device to be checked * * Just extract the TPGS setting to find out if ALUA * is supported. */ static int alua_std_inquiry(struct scsi_device *sdev, struct alua_dh_data *h) { int err; err = submit_std_inquiry(sdev, h); if (err != SCSI_DH_OK) return err; /* Check TPGS setting */ h->tpgs = (h->inq[5] >> 4) & 0x3; switch (h->tpgs) { case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT: sdev_printk(KERN_INFO, sdev, "%s: supports implicit and explicit TPGS\n", ALUA_DH_NAME); break; case TPGS_MODE_EXPLICIT: sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n", ALUA_DH_NAME); break; case TPGS_MODE_IMPLICIT: sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n", ALUA_DH_NAME); break; default: h->tpgs = TPGS_MODE_NONE; sdev_printk(KERN_INFO, sdev, "%s: not supported\n", ALUA_DH_NAME); err = SCSI_DH_DEV_UNSUPP; break; } return err; } /* * alua_vpd_inquiry - Evaluate INQUIRY vpd page 0x83 * @sdev: device to be checked * * Extract the relative target port and the target port group * descriptor from the list of identificators. */ static int alua_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h) { int len; unsigned err; unsigned char *d; retry: err = submit_vpd_inquiry(sdev, h); if (err != SCSI_DH_OK) return err; /* Check if vpd page exceeds initial buffer */ len = (h->buff[2] << 8) + h->buff[3] + 4; if (len > h->bufflen) { /* Resubmit with the correct length */ if (realloc_buffer(h, len)) { sdev_printk(KERN_WARNING, sdev, "%s: kmalloc buffer failed\n", ALUA_DH_NAME); /* Temporary failure, bypass */ return SCSI_DH_DEV_TEMP_BUSY; } goto retry; } /* * Now look for the correct descriptor. */ d = h->buff + 4; while (d < h->buff + len) { switch (d[1] & 0xf) { case 0x4: /* Relative target port */ h->rel_port = (d[6] << 8) + d[7]; break; case 0x5: /* Target port group */ h->group_id = (d[6] << 8) + d[7]; break; default: break; } d += d[3] + 4; } if (h->group_id == -1) { /* * Internal error; TPGS supported but required * VPD identification descriptors not present. * Disable ALUA support */ sdev_printk(KERN_INFO, sdev, "%s: No target port descriptors found\n", ALUA_DH_NAME); h->state = TPGS_STATE_OPTIMIZED; h->tpgs = TPGS_MODE_NONE; err = SCSI_DH_DEV_UNSUPP; } else { sdev_printk(KERN_INFO, sdev, "%s: port group %02x rel port %02x\n", ALUA_DH_NAME, h->group_id, h->rel_port); } return err; } static char print_alua_state(int state) { switch (state) { case TPGS_STATE_OPTIMIZED: return 'A'; case TPGS_STATE_NONOPTIMIZED: return 'N'; case TPGS_STATE_STANDBY: return 'S'; case TPGS_STATE_UNAVAILABLE: return 'U'; case TPGS_STATE_LBA_DEPENDENT: return 'L'; case TPGS_STATE_OFFLINE: return 'O'; case TPGS_STATE_TRANSITIONING: return 'T'; default: return 'X'; } } static int alua_check_sense(struct scsi_device *sdev, struct scsi_sense_hdr *sense_hdr) { switch (sense_hdr->sense_key) { case NOT_READY: if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) /* * LUN Not Accessible - ALUA state transition */ return ADD_TO_MLQUEUE; if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0b) /* * LUN Not Accessible -- Target port in standby state */ return SUCCESS; if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0c) /* * LUN Not Accessible -- Target port in unavailable state */ return SUCCESS; if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x12) /* * LUN Not Ready -- Offline */ return SUCCESS; break; case UNIT_ATTENTION: if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) /* * Power On, Reset, or Bus Device Reset, just retry. */ return ADD_TO_MLQUEUE; if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) { /* * ALUA state changed */ return ADD_TO_MLQUEUE; } if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) { /* * Implicit ALUA state transition failed */ return ADD_TO_MLQUEUE; } if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e) { /* * REPORTED_LUNS_DATA_HAS_CHANGED is reported * when switching controllers on targets like * Intel Multi-Flex. We can just retry. */ return ADD_TO_MLQUEUE; } break; } return SCSI_RETURN_NOT_HANDLED; } /* * alua_rtpg - Evaluate REPORT TARGET GROUP STATES * @sdev: the device to be evaluated. * * Evaluate the Target Port Group State. * Returns SCSI_DH_DEV_OFFLINED if the path is * found to be unuseable. */ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h) { struct scsi_sense_hdr sense_hdr; int len, k, off, valid_states = 0; char *ucp; unsigned err; unsigned long expiry, interval = 10; expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT); retry: err = submit_rtpg(sdev, h); if (err == SCSI_DH_IO && h->senselen > 0) { err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE, &sense_hdr); if (!err) return SCSI_DH_IO; err = alua_check_sense(sdev, &sense_hdr); if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry)) goto retry; sdev_printk(KERN_INFO, sdev, "%s: rtpg sense code %02x/%02x/%02x\n", ALUA_DH_NAME, sense_hdr.sense_key, sense_hdr.asc, sense_hdr.ascq); err = SCSI_DH_IO; } if (err != SCSI_DH_OK) return err; len = (h->buff[0] << 24) + (h->buff[1] << 16) + (h->buff[2] << 8) + h->buff[3] + 4; if (len > h->bufflen) { /* Resubmit with the correct length */ if (realloc_buffer(h, len)) { sdev_printk(KERN_WARNING, sdev, "%s: kmalloc buffer failed\n",__func__); /* Temporary failure, bypass */ return SCSI_DH_DEV_TEMP_BUSY; } goto retry; } for (k = 4, ucp = h->buff + 4; k < len; k += off, ucp += off) { if (h->group_id == (ucp[2] << 8) + ucp[3]) { h->state = ucp[0] & 0x0f; valid_states = ucp[1]; } off = 8 + (ucp[7] * 4); } sdev_printk(KERN_INFO, sdev, "%s: port group %02x state %c supports %c%c%c%c%c%c%c\n", ALUA_DH_NAME, h->group_id, print_alua_state(h->state), valid_states&TPGS_SUPPORT_TRANSITION?'T':'t', valid_states&TPGS_SUPPORT_OFFLINE?'O':'o', valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l', valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u', valid_states&TPGS_SUPPORT_STANDBY?'S':'s', valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n', valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a'); switch (h->state) { case TPGS_STATE_TRANSITIONING: if (time_before(jiffies, expiry)) { /* State transition, retry */ interval *= 10; msleep(interval); goto retry; } /* Transitioning time exceeded, set port to standby */ err = SCSI_DH_RETRY; h->state = TPGS_STATE_STANDBY; break; case TPGS_STATE_OFFLINE: case TPGS_STATE_UNAVAILABLE: /* Path unuseable for unavailable/offline */ err = SCSI_DH_DEV_OFFLINED; break; default: /* Useable path if active */ err = SCSI_DH_OK; break; } return err; } /* * alua_initialize - Initialize ALUA state * @sdev: the device to be initialized * * For the prep_fn to work correctly we have * to initialize the ALUA state for the device. */ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h) { int err; err = alua_std_inquiry(sdev, h); if (err != SCSI_DH_OK) goto out; err = alua_vpd_inquiry(sdev, h); if (err != SCSI_DH_OK) goto out; err = alua_rtpg(sdev, h); if (err != SCSI_DH_OK) goto out; out: return err; } /* * alua_activate - activate a path * @sdev: device on the path to be activated * * We're currently switching the port group to be activated only and * let the array figure out the rest. * There may be other arrays which require us to switch all port groups * based on a certain policy. But until we actually encounter them it * should be okay. */ static int alua_activate(struct scsi_device *sdev, activate_complete fn, void *data) { struct alua_dh_data *h = get_alua_data(sdev); int err = SCSI_DH_OK; if (h->group_id != -1) { err = alua_rtpg(sdev, h); if (err != SCSI_DH_OK) goto out; } if (h->tpgs & TPGS_MODE_EXPLICIT && h->state != TPGS_STATE_OPTIMIZED && h->state != TPGS_STATE_LBA_DEPENDENT) { h->callback_fn = fn; h->callback_data = data; err = submit_stpg(h); if (err == SCSI_DH_OK) return 0; h->callback_fn = h->callback_data = NULL; } out: if (fn) fn(data, err); return 0; } /* * alua_prep_fn - request callback * * Fail I/O to all paths not in state * active/optimized or active/non-optimized. */ static int alua_prep_fn(struct scsi_device *sdev, struct request *req) { struct alua_dh_data *h = get_alua_data(sdev); int ret = BLKPREP_OK; if (h->state == TPGS_STATE_TRANSITIONING) ret = BLKPREP_DEFER; else if (h->state != TPGS_STATE_OPTIMIZED && h->state != TPGS_STATE_NONOPTIMIZED && h->state != TPGS_STATE_LBA_DEPENDENT) { ret = BLKPREP_KILL; req->cmd_flags |= REQ_QUIET; } return ret; } static const struct scsi_dh_devlist alua_dev_list[] = { {"HP", "MSA VOLUME" }, {"HP", "HSV101" }, {"HP", "HSV111" }, {"HP", "HSV200" }, {"HP", "HSV210" }, {"HP", "HSV300" }, {"IBM", "2107900" }, {"IBM", "2145" }, {"Pillar", "Axiom" }, {"Intel", "Multi-Flex"}, {"NETAPP", "LUN"}, {"AIX", "NVDISK"}, {"Promise", "VTrak"}, {NULL, NULL} }; static int alua_bus_attach(struct scsi_device *sdev); static void alua_bus_detach(struct scsi_device *sdev); static struct scsi_device_handler alua_dh = { .name = ALUA_DH_NAME, .module = THIS_MODULE, .devlist = alua_dev_list, .attach = alua_bus_attach, .detach = alua_bus_detach, .prep_fn = alua_prep_fn, .check_sense = alua_check_sense, .activate = alua_activate, }; /* * alua_bus_attach - Attach device handler * @sdev: device to be attached to */ static int alua_bus_attach(struct scsi_device *sdev) { struct scsi_dh_data *scsi_dh_data; struct alua_dh_data *h; unsigned long flags; int err = SCSI_DH_OK; scsi_dh_data = kzalloc(sizeof(struct scsi_device_handler *) + sizeof(*h) , GFP_KERNEL); if (!scsi_dh_data) { sdev_printk(KERN_ERR, sdev, "%s: Attach failed\n", ALUA_DH_NAME); return -ENOMEM; } scsi_dh_data->scsi_dh = &alua_dh; h = (struct alua_dh_data *) scsi_dh_data->buf; h->tpgs = TPGS_MODE_UNINITIALIZED; h->state = TPGS_STATE_OPTIMIZED; h->group_id = -1; h->rel_port = -1; h->buff = h->inq; h->bufflen = ALUA_INQUIRY_SIZE; h->sdev = sdev; err = alua_initialize(sdev, h); if (err != SCSI_DH_OK) goto failed; if (!try_module_get(THIS_MODULE)) goto failed; spin_lock_irqsave(sdev->request_queue->queue_lock, flags); sdev->scsi_dh_data = scsi_dh_data; spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); return 0; failed: kfree(scsi_dh_data); sdev_printk(KERN_ERR, sdev, "%s: not attached\n", ALUA_DH_NAME); return -EINVAL; } /* * alua_bus_detach - Detach device handler * @sdev: device to be detached from */ static void alua_bus_detach(struct scsi_device *sdev) { struct scsi_dh_data *scsi_dh_data; struct alua_dh_data *h; unsigned long flags; spin_lock_irqsave(sdev->request_queue->queue_lock, flags); scsi_dh_data = sdev->scsi_dh_data; sdev->scsi_dh_data = NULL; spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); h = (struct alua_dh_data *) scsi_dh_data->buf; if (h->buff && h->inq != h->buff) kfree(h->buff); kfree(scsi_dh_data); module_put(THIS_MODULE); sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", ALUA_DH_NAME); } static int __init alua_init(void) { int r; r = scsi_register_device_handler(&alua_dh); if (r != 0) printk(KERN_ERR "%s: Failed to register scsi device handler", ALUA_DH_NAME); return r; } static void __exit alua_exit(void) { scsi_unregister_device_handler(&alua_dh); } module_init(alua_init); module_exit(alua_exit); MODULE_DESCRIPTION("DM Multipath ALUA support"); MODULE_AUTHOR("Hannes Reinecke "); MODULE_LICENSE("GPL"); MODULE_VERSION(ALUA_DH_VER);