2 * Generic SCSI-3 ALUA SCSI Device Handler
4 * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22 #include <linux/slab.h>
23 #include <linux/delay.h>
24 #include <linux/module.h>
25 #include <scsi/scsi.h>
26 #include <scsi/scsi_eh.h>
27 #include <scsi/scsi_dh.h>
29 #define ALUA_DH_NAME "alua"
30 #define ALUA_DH_VER "1.3"
32 #define TPGS_STATE_OPTIMIZED 0x0
33 #define TPGS_STATE_NONOPTIMIZED 0x1
34 #define TPGS_STATE_STANDBY 0x2
35 #define TPGS_STATE_UNAVAILABLE 0x3
36 #define TPGS_STATE_LBA_DEPENDENT 0x4
37 #define TPGS_STATE_OFFLINE 0xe
38 #define TPGS_STATE_TRANSITIONING 0xf
40 #define TPGS_SUPPORT_NONE 0x00
41 #define TPGS_SUPPORT_OPTIMIZED 0x01
42 #define TPGS_SUPPORT_NONOPTIMIZED 0x02
43 #define TPGS_SUPPORT_STANDBY 0x04
44 #define TPGS_SUPPORT_UNAVAILABLE 0x08
45 #define TPGS_SUPPORT_LBA_DEPENDENT 0x10
46 #define TPGS_SUPPORT_OFFLINE 0x40
47 #define TPGS_SUPPORT_TRANSITION 0x80
49 #define RTPG_FMT_MASK 0x70
50 #define RTPG_FMT_EXT_HDR 0x10
52 #define TPGS_MODE_UNINITIALIZED -1
53 #define TPGS_MODE_NONE 0x0
54 #define TPGS_MODE_IMPLICIT 0x1
55 #define TPGS_MODE_EXPLICIT 0x2
57 #define ALUA_INQUIRY_SIZE 36
58 #define ALUA_FAILOVER_TIMEOUT 60
59 #define ALUA_FAILOVER_RETRIES 5
61 /* flags passed from user level */
62 #define ALUA_OPTIMIZE_STPG 1
70 unsigned flags; /* used for optimizing STPG */
71 unsigned char inq[ALUA_INQUIRY_SIZE];
74 unsigned char transition_tmo;
75 unsigned char sense[SCSI_SENSE_BUFFERSIZE];
77 struct scsi_device *sdev;
78 activate_complete callback_fn;
82 #define ALUA_POLICY_SWITCH_CURRENT 0
83 #define ALUA_POLICY_SWITCH_ALL 1
85 static char print_alua_state(int);
86 static int alua_check_sense(struct scsi_device *, struct scsi_sense_hdr *);
88 static int realloc_buffer(struct alua_dh_data *h, unsigned len)
90 if (h->buff && h->buff != h->inq)
93 h->buff = kmalloc(len, GFP_NOIO);
96 h->bufflen = ALUA_INQUIRY_SIZE;
103 static struct request *get_alua_req(struct scsi_device *sdev,
104 void *buffer, unsigned buflen, int rw)
107 struct request_queue *q = sdev->request_queue;
109 rq = blk_get_request(q, rw, GFP_NOIO);
112 sdev_printk(KERN_INFO, sdev,
113 "%s: blk_get_request failed\n", __func__);
116 blk_rq_set_block_pc(rq);
118 if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
120 sdev_printk(KERN_INFO, sdev,
121 "%s: blk_rq_map_kern failed\n", __func__);
125 rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
127 rq->retries = ALUA_FAILOVER_RETRIES;
128 rq->timeout = ALUA_FAILOVER_TIMEOUT * HZ;
134 * submit_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command
135 * @sdev: sdev the command should be sent to
137 static int submit_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
140 int err = SCSI_DH_RES_TEMP_UNAVAIL;
142 rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
146 /* Prepare the command. */
147 rq->cmd[0] = INQUIRY;
150 rq->cmd[4] = h->bufflen;
151 rq->cmd_len = COMMAND_SIZE(INQUIRY);
153 rq->sense = h->sense;
154 memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
155 rq->sense_len = h->senselen = 0;
157 err = blk_execute_rq(rq->q, NULL, rq, 1);
159 sdev_printk(KERN_INFO, sdev,
160 "%s: evpd inquiry failed with %x\n",
161 ALUA_DH_NAME, rq->errors);
162 h->senselen = rq->sense_len;
171 * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
172 * @sdev: sdev the command should be sent to
174 static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
175 bool rtpg_ext_hdr_req)
178 int err = SCSI_DH_RES_TEMP_UNAVAIL;
180 rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
184 /* Prepare the command. */
185 rq->cmd[0] = MAINTENANCE_IN;
186 if (rtpg_ext_hdr_req)
187 rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
189 rq->cmd[1] = MI_REPORT_TARGET_PGS;
190 rq->cmd[6] = (h->bufflen >> 24) & 0xff;
191 rq->cmd[7] = (h->bufflen >> 16) & 0xff;
192 rq->cmd[8] = (h->bufflen >> 8) & 0xff;
193 rq->cmd[9] = h->bufflen & 0xff;
194 rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN);
196 rq->sense = h->sense;
197 memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
198 rq->sense_len = h->senselen = 0;
200 err = blk_execute_rq(rq->q, NULL, rq, 1);
202 sdev_printk(KERN_INFO, sdev,
203 "%s: rtpg failed with %x\n",
204 ALUA_DH_NAME, rq->errors);
205 h->senselen = rq->sense_len;
214 * alua_stpg - Evaluate SET TARGET GROUP STATES
215 * @sdev: the device to be evaluated
216 * @state: the new target group state
218 * Send a SET TARGET GROUP STATES command to the device.
219 * We only have to test here if we should resubmit the command;
220 * any other error is assumed as a failure.
222 static void stpg_endio(struct request *req, int error)
224 struct alua_dh_data *h = req->end_io_data;
225 struct scsi_sense_hdr sense_hdr;
226 unsigned err = SCSI_DH_OK;
228 if (host_byte(req->errors) != DID_OK ||
229 msg_byte(req->errors) != COMMAND_COMPLETE) {
234 if (req->sense_len > 0) {
235 err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
241 err = alua_check_sense(h->sdev, &sense_hdr);
242 if (err == ADD_TO_MLQUEUE) {
246 sdev_printk(KERN_INFO, h->sdev,
247 "%s: stpg sense code: %02x/%02x/%02x\n",
248 ALUA_DH_NAME, sense_hdr.sense_key,
249 sense_hdr.asc, sense_hdr.ascq);
254 if (err == SCSI_DH_OK) {
255 h->state = TPGS_STATE_OPTIMIZED;
256 sdev_printk(KERN_INFO, h->sdev,
257 "%s: port group %02x switched to state %c\n",
258 ALUA_DH_NAME, h->group_id,
259 print_alua_state(h->state));
262 req->end_io_data = NULL;
263 __blk_put_request(req->q, req);
264 if (h->callback_fn) {
265 h->callback_fn(h->callback_data, err);
266 h->callback_fn = h->callback_data = NULL;
272 * submit_stpg - Issue a SET TARGET GROUP STATES command
274 * Currently we're only setting the current target port group state
275 * to 'active/optimized' and let the array firmware figure out
276 * the states of the remaining groups.
278 static unsigned submit_stpg(struct alua_dh_data *h)
282 struct scsi_device *sdev = h->sdev;
284 /* Prepare the data buffer */
285 memset(h->buff, 0, stpg_len);
286 h->buff[4] = TPGS_STATE_OPTIMIZED & 0x0f;
287 h->buff[6] = (h->group_id >> 8) & 0xff;
288 h->buff[7] = h->group_id & 0xff;
290 rq = get_alua_req(sdev, h->buff, stpg_len, WRITE);
292 return SCSI_DH_RES_TEMP_UNAVAIL;
294 /* Prepare the command. */
295 rq->cmd[0] = MAINTENANCE_OUT;
296 rq->cmd[1] = MO_SET_TARGET_PGS;
297 rq->cmd[6] = (stpg_len >> 24) & 0xff;
298 rq->cmd[7] = (stpg_len >> 16) & 0xff;
299 rq->cmd[8] = (stpg_len >> 8) & 0xff;
300 rq->cmd[9] = stpg_len & 0xff;
301 rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT);
303 rq->sense = h->sense;
304 memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
305 rq->sense_len = h->senselen = 0;
308 blk_execute_rq_nowait(rq->q, NULL, rq, 1, stpg_endio);
313 * alua_check_tpgs - Evaluate TPGS setting
314 * @sdev: device to be checked
316 * Examine the TPGS setting of the sdev to find out if ALUA
319 static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
321 int err = SCSI_DH_OK;
323 h->tpgs = scsi_device_tpgs(sdev);
325 case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
326 sdev_printk(KERN_INFO, sdev,
327 "%s: supports implicit and explicit TPGS\n",
330 case TPGS_MODE_EXPLICIT:
331 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
334 case TPGS_MODE_IMPLICIT:
335 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
339 h->tpgs = TPGS_MODE_NONE;
340 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
342 err = SCSI_DH_DEV_UNSUPP;
350 * alua_vpd_inquiry - Evaluate INQUIRY vpd page 0x83
351 * @sdev: device to be checked
353 * Extract the relative target port and the target port group
354 * descriptor from the list of identificators.
356 static int alua_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
363 err = submit_vpd_inquiry(sdev, h);
365 if (err != SCSI_DH_OK)
368 /* Check if vpd page exceeds initial buffer */
369 len = (h->buff[2] << 8) + h->buff[3] + 4;
370 if (len > h->bufflen) {
371 /* Resubmit with the correct length */
372 if (realloc_buffer(h, len)) {
373 sdev_printk(KERN_WARNING, sdev,
374 "%s: kmalloc buffer failed\n",
376 /* Temporary failure, bypass */
377 return SCSI_DH_DEV_TEMP_BUSY;
383 * Now look for the correct descriptor.
386 while (d < h->buff + len) {
387 switch (d[1] & 0xf) {
389 /* Relative target port */
390 h->rel_port = (d[6] << 8) + d[7];
393 /* Target port group */
394 h->group_id = (d[6] << 8) + d[7];
402 if (h->group_id == -1) {
404 * Internal error; TPGS supported but required
405 * VPD identification descriptors not present.
406 * Disable ALUA support
408 sdev_printk(KERN_INFO, sdev,
409 "%s: No target port descriptors found\n",
411 h->state = TPGS_STATE_OPTIMIZED;
412 h->tpgs = TPGS_MODE_NONE;
413 err = SCSI_DH_DEV_UNSUPP;
415 sdev_printk(KERN_INFO, sdev,
416 "%s: port group %02x rel port %02x\n",
417 ALUA_DH_NAME, h->group_id, h->rel_port);
423 static char print_alua_state(int state)
426 case TPGS_STATE_OPTIMIZED:
428 case TPGS_STATE_NONOPTIMIZED:
430 case TPGS_STATE_STANDBY:
432 case TPGS_STATE_UNAVAILABLE:
434 case TPGS_STATE_LBA_DEPENDENT:
436 case TPGS_STATE_OFFLINE:
438 case TPGS_STATE_TRANSITIONING:
445 static int alua_check_sense(struct scsi_device *sdev,
446 struct scsi_sense_hdr *sense_hdr)
448 switch (sense_hdr->sense_key) {
450 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a)
452 * LUN Not Accessible - ALUA state transition
454 return ADD_TO_MLQUEUE;
455 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0b)
457 * LUN Not Accessible -- Target port in standby state
460 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0c)
462 * LUN Not Accessible -- Target port in unavailable state
465 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x12)
467 * LUN Not Ready -- Offline
470 if (sdev->allow_restart &&
471 sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x02)
473 * if the device is not started, we need to wake
474 * the error handler to start the motor
479 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
481 * Power On, Reset, or Bus Device Reset, just retry.
483 return ADD_TO_MLQUEUE;
484 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
486 * Device internal reset
488 return ADD_TO_MLQUEUE;
489 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
491 * Mode Parameters Changed
493 return ADD_TO_MLQUEUE;
494 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
498 return ADD_TO_MLQUEUE;
499 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)
501 * Implicit ALUA state transition failed
503 return ADD_TO_MLQUEUE;
504 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
506 * Inquiry data has changed
508 return ADD_TO_MLQUEUE;
509 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
511 * REPORTED_LUNS_DATA_HAS_CHANGED is reported
512 * when switching controllers on targets like
513 * Intel Multi-Flex. We can just retry.
515 return ADD_TO_MLQUEUE;
519 return SCSI_RETURN_NOT_HANDLED;
523 * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
524 * @sdev: the device to be evaluated.
525 * @wait_for_transition: if nonzero, wait ALUA_FAILOVER_TIMEOUT seconds for device to exit transitioning state
527 * Evaluate the Target Port Group State.
528 * Returns SCSI_DH_DEV_OFFLINED if the path is
529 * found to be unusable.
531 static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_for_transition)
533 struct scsi_sense_hdr sense_hdr;
534 int len, k, off, valid_states = 0;
537 bool rtpg_ext_hdr_req = 1;
538 unsigned long expiry, interval = 0;
539 unsigned int tpg_desc_tbl_off;
540 unsigned char orig_transition_tmo;
542 if (!h->transition_tmo)
543 expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT * HZ);
545 expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
548 err = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
550 if (err == SCSI_DH_IO && h->senselen > 0) {
551 err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
557 * submit_rtpg() has failed on existing arrays
558 * when requesting extended header info, and
559 * the array doesn't support extended headers,
560 * even though it shouldn't according to T10.
561 * The retry without rtpg_ext_hdr_req set
564 if (rtpg_ext_hdr_req == 1 &&
565 sense_hdr.sense_key == ILLEGAL_REQUEST &&
566 sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
567 rtpg_ext_hdr_req = 0;
571 err = alua_check_sense(sdev, &sense_hdr);
572 if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
574 sdev_printk(KERN_INFO, sdev,
575 "%s: rtpg sense code %02x/%02x/%02x\n",
576 ALUA_DH_NAME, sense_hdr.sense_key,
577 sense_hdr.asc, sense_hdr.ascq);
580 if (err != SCSI_DH_OK)
583 len = (h->buff[0] << 24) + (h->buff[1] << 16) +
584 (h->buff[2] << 8) + h->buff[3] + 4;
586 if (len > h->bufflen) {
587 /* Resubmit with the correct length */
588 if (realloc_buffer(h, len)) {
589 sdev_printk(KERN_WARNING, sdev,
590 "%s: kmalloc buffer failed\n",__func__);
591 /* Temporary failure, bypass */
592 return SCSI_DH_DEV_TEMP_BUSY;
597 orig_transition_tmo = h->transition_tmo;
598 if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && h->buff[5] != 0)
599 h->transition_tmo = h->buff[5];
601 h->transition_tmo = ALUA_FAILOVER_TIMEOUT;
603 if (wait_for_transition && (orig_transition_tmo != h->transition_tmo)) {
604 sdev_printk(KERN_INFO, sdev,
605 "%s: transition timeout set to %d seconds\n",
606 ALUA_DH_NAME, h->transition_tmo);
607 expiry = jiffies + h->transition_tmo * HZ;
610 if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
611 tpg_desc_tbl_off = 8;
613 tpg_desc_tbl_off = 4;
615 for (k = tpg_desc_tbl_off, ucp = h->buff + tpg_desc_tbl_off;
617 k += off, ucp += off) {
619 if (h->group_id == (ucp[2] << 8) + ucp[3]) {
620 h->state = ucp[0] & 0x0f;
621 h->pref = ucp[0] >> 7;
622 valid_states = ucp[1];
624 off = 8 + (ucp[7] * 4);
627 sdev_printk(KERN_INFO, sdev,
628 "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
629 ALUA_DH_NAME, h->group_id, print_alua_state(h->state),
630 h->pref ? "preferred" : "non-preferred",
631 valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
632 valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
633 valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
634 valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
635 valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
636 valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
637 valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
640 case TPGS_STATE_TRANSITIONING:
641 if (wait_for_transition) {
642 if (time_before(jiffies, expiry)) {
643 /* State transition, retry */
653 /* Transitioning time exceeded, set port to standby */
654 h->state = TPGS_STATE_STANDBY;
656 case TPGS_STATE_OFFLINE:
658 err = SCSI_DH_DEV_OFFLINED;
661 /* Useable path if active */
669 * alua_initialize - Initialize ALUA state
670 * @sdev: the device to be initialized
672 * For the prep_fn to work correctly we have
673 * to initialize the ALUA state for the device.
675 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
679 err = alua_check_tpgs(sdev, h);
680 if (err != SCSI_DH_OK)
683 err = alua_vpd_inquiry(sdev, h);
684 if (err != SCSI_DH_OK)
687 err = alua_rtpg(sdev, h, 0);
688 if (err != SCSI_DH_OK)
695 * alua_set_params - set/unset the optimize flag
696 * @sdev: device on the path to be activated
697 * params - parameters in the following format
698 * "no_of_params\0param1\0param2\0param3\0...\0"
699 * For example, to set the flag pass the following parameters
700 * from multipath.conf
701 * hardware_handler "2 alua 1"
703 static int alua_set_params(struct scsi_device *sdev, const char *params)
705 struct alua_dh_data *h = sdev->handler_data;
706 unsigned int optimize = 0, argc;
707 const char *p = params;
708 int result = SCSI_DH_OK;
710 if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
715 if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
719 h->flags |= ALUA_OPTIMIZE_STPG;
721 h->flags &= ~ALUA_OPTIMIZE_STPG;
726 static uint optimize_stpg;
727 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
728 MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0.");
731 * alua_activate - activate a path
732 * @sdev: device on the path to be activated
734 * We're currently switching the port group to be activated only and
735 * let the array figure out the rest.
736 * There may be other arrays which require us to switch all port groups
737 * based on a certain policy. But until we actually encounter them it
740 static int alua_activate(struct scsi_device *sdev,
741 activate_complete fn, void *data)
743 struct alua_dh_data *h = sdev->handler_data;
744 int err = SCSI_DH_OK;
747 err = alua_rtpg(sdev, h, 1);
748 if (err != SCSI_DH_OK)
752 h->flags |= ALUA_OPTIMIZE_STPG;
754 if (h->tpgs & TPGS_MODE_EXPLICIT) {
756 case TPGS_STATE_NONOPTIMIZED:
758 if ((h->flags & ALUA_OPTIMIZE_STPG) &&
760 (h->tpgs & TPGS_MODE_IMPLICIT))
763 case TPGS_STATE_STANDBY:
764 case TPGS_STATE_UNAVAILABLE:
767 case TPGS_STATE_OFFLINE:
770 case TPGS_STATE_TRANSITIONING:
780 h->callback_data = data;
781 err = submit_stpg(h);
782 if (err == SCSI_DH_OK)
784 h->callback_fn = h->callback_data = NULL;
794 * alua_prep_fn - request callback
796 * Fail I/O to all paths not in state
797 * active/optimized or active/non-optimized.
799 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
801 struct alua_dh_data *h = sdev->handler_data;
802 int ret = BLKPREP_OK;
804 if (h->state == TPGS_STATE_TRANSITIONING)
806 else if (h->state != TPGS_STATE_OPTIMIZED &&
807 h->state != TPGS_STATE_NONOPTIMIZED &&
808 h->state != TPGS_STATE_LBA_DEPENDENT) {
810 req->cmd_flags |= REQ_QUIET;
817 * alua_bus_attach - Attach device handler
818 * @sdev: device to be attached to
820 static int alua_bus_attach(struct scsi_device *sdev)
822 struct alua_dh_data *h;
825 h = kzalloc(sizeof(*h) , GFP_KERNEL);
828 h->tpgs = TPGS_MODE_UNINITIALIZED;
829 h->state = TPGS_STATE_OPTIMIZED;
833 h->bufflen = ALUA_INQUIRY_SIZE;
836 err = alua_initialize(sdev, h);
837 if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
840 sdev->handler_data = h;
848 * alua_bus_detach - Detach device handler
849 * @sdev: device to be detached from
851 static void alua_bus_detach(struct scsi_device *sdev)
853 struct alua_dh_data *h = sdev->handler_data;
855 if (h->buff && h->inq != h->buff)
857 sdev->handler_data = NULL;
861 static struct scsi_device_handler alua_dh = {
862 .name = ALUA_DH_NAME,
863 .module = THIS_MODULE,
864 .attach = alua_bus_attach,
865 .detach = alua_bus_detach,
866 .prep_fn = alua_prep_fn,
867 .check_sense = alua_check_sense,
868 .activate = alua_activate,
869 .set_params = alua_set_params,
872 static int __init alua_init(void)
876 r = scsi_register_device_handler(&alua_dh);
878 printk(KERN_ERR "%s: Failed to register scsi device handler",
883 static void __exit alua_exit(void)
885 scsi_unregister_device_handler(&alua_dh);
888 module_init(alua_init);
889 module_exit(alua_exit);
891 MODULE_DESCRIPTION("DM Multipath ALUA support");
892 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
893 MODULE_LICENSE("GPL");
894 MODULE_VERSION(ALUA_DH_VER);