1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Generic SCSI-3 ALUA SCSI Device Handler
4 *
5 * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
6 * All rights reserved.
7 */
8 #include <linux/slab.h>
9 #include <linux/delay.h>
10 #include <linux/module.h>
11 #include <asm/unaligned.h>
12 #include <scsi/scsi.h>
13 #include <scsi/scsi_proto.h>
14 #include <scsi/scsi_dbg.h>
15 #include <scsi/scsi_eh.h>
16 #include <scsi/scsi_dh.h>
17
18 #define ALUA_DH_NAME "alua"
19 #define ALUA_DH_VER "2.0"
20
21 #define TPGS_SUPPORT_NONE 0x00
22 #define TPGS_SUPPORT_OPTIMIZED 0x01
23 #define TPGS_SUPPORT_NONOPTIMIZED 0x02
24 #define TPGS_SUPPORT_STANDBY 0x04
25 #define TPGS_SUPPORT_UNAVAILABLE 0x08
26 #define TPGS_SUPPORT_LBA_DEPENDENT 0x10
27 #define TPGS_SUPPORT_OFFLINE 0x40
28 #define TPGS_SUPPORT_TRANSITION 0x80
29 #define TPGS_SUPPORT_ALL 0xdf
30
31 #define RTPG_FMT_MASK 0x70
32 #define RTPG_FMT_EXT_HDR 0x10
33
34 #define TPGS_MODE_UNINITIALIZED -1
35 #define TPGS_MODE_NONE 0x0
36 #define TPGS_MODE_IMPLICIT 0x1
37 #define TPGS_MODE_EXPLICIT 0x2
38
39 #define ALUA_RTPG_SIZE 128
40 #define ALUA_FAILOVER_TIMEOUT 60
41 #define ALUA_FAILOVER_RETRIES 5
42 #define ALUA_RTPG_DELAY_MSECS 5
43 #define ALUA_RTPG_RETRY_DELAY 2
44
45 /* device handler flags */
46 #define ALUA_OPTIMIZE_STPG 0x01
47 #define ALUA_RTPG_EXT_HDR_UNSUPP 0x02
48 /* State machine flags */
49 #define ALUA_PG_RUN_RTPG 0x10
50 #define ALUA_PG_RUN_STPG 0x20
51 #define ALUA_PG_RUNNING 0x40
52
53 static uint optimize_stpg;
54 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
55 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.");
56
57 static LIST_HEAD(port_group_list);
58 static DEFINE_SPINLOCK(port_group_lock);
59 static struct workqueue_struct *kaluad_wq;
60
61 struct alua_port_group {
62 struct kref kref;
63 struct rcu_head rcu;
64 struct list_head node;
65 struct list_head dh_list;
66 unsigned char device_id_str[256];
67 int device_id_len;
68 int group_id;
69 int tpgs;
70 int state;
71 int pref;
72 int valid_states;
73 unsigned flags; /* used for optimizing STPG */
74 unsigned char transition_tmo;
75 unsigned long expiry;
76 unsigned long interval;
77 struct delayed_work rtpg_work;
78 spinlock_t lock;
79 struct list_head rtpg_list;
80 struct scsi_device *rtpg_sdev;
81 };
82
83 struct alua_dh_data {
84 struct list_head node;
85 struct alua_port_group __rcu *pg;
86 int group_id;
87 spinlock_t pg_lock;
88 struct scsi_device *sdev;
89 int init_error;
90 struct mutex init_mutex;
91 bool disabled;
92 };
93
94 struct alua_queue_data {
95 struct list_head entry;
96 activate_complete callback_fn;
97 void *callback_data;
98 };
99
100 #define ALUA_POLICY_SWITCH_CURRENT 0
101 #define ALUA_POLICY_SWITCH_ALL 1
102
103 static void alua_rtpg_work(struct work_struct *work);
104 static bool alua_rtpg_queue(struct alua_port_group *pg,
105 struct scsi_device *sdev,
106 struct alua_queue_data *qdata, bool force);
107 static void alua_check(struct scsi_device *sdev, bool force);
108
release_port_group(struct kref * kref)109 static void release_port_group(struct kref *kref)
110 {
111 struct alua_port_group *pg;
112
113 pg = container_of(kref, struct alua_port_group, kref);
114 if (pg->rtpg_sdev)
115 flush_delayed_work(&pg->rtpg_work);
116 spin_lock(&port_group_lock);
117 list_del(&pg->node);
118 spin_unlock(&port_group_lock);
119 kfree_rcu(pg, rcu);
120 }
121
122 /*
123 * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
124 * @sdev: sdev the command should be sent to
125 */
submit_rtpg(struct scsi_device * sdev,unsigned char * buff,int bufflen,struct scsi_sense_hdr * sshdr,int flags)126 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
127 int bufflen, struct scsi_sense_hdr *sshdr, int flags)
128 {
129 u8 cdb[MAX_COMMAND_SIZE];
130 blk_opf_t opf = REQ_OP_DRV_IN | REQ_FAILFAST_DEV |
131 REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER;
132 const struct scsi_exec_args exec_args = {
133 .sshdr = sshdr,
134 };
135
136 /* Prepare the command. */
137 memset(cdb, 0x0, MAX_COMMAND_SIZE);
138 cdb[0] = MAINTENANCE_IN;
139 if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
140 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
141 else
142 cdb[1] = MI_REPORT_TARGET_PGS;
143 put_unaligned_be32(bufflen, &cdb[6]);
144
145 return scsi_execute_cmd(sdev, cdb, opf, buff, bufflen,
146 ALUA_FAILOVER_TIMEOUT * HZ,
147 ALUA_FAILOVER_RETRIES, &exec_args);
148 }
149
150 /*
151 * submit_stpg - Issue a SET TARGET PORT GROUP command
152 *
153 * Currently we're only setting the current target port group state
154 * to 'active/optimized' and let the array firmware figure out
155 * the states of the remaining groups.
156 */
submit_stpg(struct scsi_device * sdev,int group_id,struct scsi_sense_hdr * sshdr)157 static int submit_stpg(struct scsi_device *sdev, int group_id,
158 struct scsi_sense_hdr *sshdr)
159 {
160 u8 cdb[MAX_COMMAND_SIZE];
161 unsigned char stpg_data[8];
162 int stpg_len = 8;
163 blk_opf_t opf = REQ_OP_DRV_OUT | REQ_FAILFAST_DEV |
164 REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER;
165 const struct scsi_exec_args exec_args = {
166 .sshdr = sshdr,
167 };
168
169 /* Prepare the data buffer */
170 memset(stpg_data, 0, stpg_len);
171 stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
172 put_unaligned_be16(group_id, &stpg_data[6]);
173
174 /* Prepare the command. */
175 memset(cdb, 0x0, MAX_COMMAND_SIZE);
176 cdb[0] = MAINTENANCE_OUT;
177 cdb[1] = MO_SET_TARGET_PGS;
178 put_unaligned_be32(stpg_len, &cdb[6]);
179
180 return scsi_execute_cmd(sdev, cdb, opf, stpg_data,
181 stpg_len, ALUA_FAILOVER_TIMEOUT * HZ,
182 ALUA_FAILOVER_RETRIES, &exec_args);
183 }
184
alua_find_get_pg(char * id_str,size_t id_size,int group_id)185 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
186 int group_id)
187 {
188 struct alua_port_group *pg;
189
190 if (!id_str || !id_size || !strlen(id_str))
191 return NULL;
192
193 list_for_each_entry(pg, &port_group_list, node) {
194 if (pg->group_id != group_id)
195 continue;
196 if (!pg->device_id_len || pg->device_id_len != id_size)
197 continue;
198 if (strncmp(pg->device_id_str, id_str, id_size))
199 continue;
200 if (!kref_get_unless_zero(&pg->kref))
201 continue;
202 return pg;
203 }
204
205 return NULL;
206 }
207
208 /*
209 * alua_alloc_pg - Allocate a new port_group structure
210 * @sdev: scsi device
211 * @group_id: port group id
212 * @tpgs: target port group settings
213 *
214 * Allocate a new port_group structure for a given
215 * device.
216 */
alua_alloc_pg(struct scsi_device * sdev,int group_id,int tpgs)217 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
218 int group_id, int tpgs)
219 {
220 struct alua_port_group *pg, *tmp_pg;
221
222 pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
223 if (!pg)
224 return ERR_PTR(-ENOMEM);
225
226 pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
227 sizeof(pg->device_id_str));
228 if (pg->device_id_len <= 0) {
229 /*
230 * TPGS supported but no device identification found.
231 * Generate private device identification.
232 */
233 sdev_printk(KERN_INFO, sdev,
234 "%s: No device descriptors found\n",
235 ALUA_DH_NAME);
236 pg->device_id_str[0] = '\0';
237 pg->device_id_len = 0;
238 }
239 pg->group_id = group_id;
240 pg->tpgs = tpgs;
241 pg->state = SCSI_ACCESS_STATE_OPTIMAL;
242 pg->valid_states = TPGS_SUPPORT_ALL;
243 if (optimize_stpg)
244 pg->flags |= ALUA_OPTIMIZE_STPG;
245 kref_init(&pg->kref);
246 INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
247 INIT_LIST_HEAD(&pg->rtpg_list);
248 INIT_LIST_HEAD(&pg->node);
249 INIT_LIST_HEAD(&pg->dh_list);
250 spin_lock_init(&pg->lock);
251
252 spin_lock(&port_group_lock);
253 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
254 group_id);
255 if (tmp_pg) {
256 spin_unlock(&port_group_lock);
257 kfree(pg);
258 return tmp_pg;
259 }
260
261 list_add(&pg->node, &port_group_list);
262 spin_unlock(&port_group_lock);
263
264 return pg;
265 }
266
267 /*
268 * alua_check_tpgs - Evaluate TPGS setting
269 * @sdev: device to be checked
270 *
271 * Examine the TPGS setting of the sdev to find out if ALUA
272 * is supported.
273 */
alua_check_tpgs(struct scsi_device * sdev)274 static int alua_check_tpgs(struct scsi_device *sdev)
275 {
276 int tpgs = TPGS_MODE_NONE;
277
278 /*
279 * ALUA support for non-disk devices is fraught with
280 * difficulties, so disable it for now.
281 */
282 if (sdev->type != TYPE_DISK) {
283 sdev_printk(KERN_INFO, sdev,
284 "%s: disable for non-disk devices\n",
285 ALUA_DH_NAME);
286 return tpgs;
287 }
288
289 tpgs = scsi_device_tpgs(sdev);
290 switch (tpgs) {
291 case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
292 sdev_printk(KERN_INFO, sdev,
293 "%s: supports implicit and explicit TPGS\n",
294 ALUA_DH_NAME);
295 break;
296 case TPGS_MODE_EXPLICIT:
297 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
298 ALUA_DH_NAME);
299 break;
300 case TPGS_MODE_IMPLICIT:
301 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
302 ALUA_DH_NAME);
303 break;
304 case TPGS_MODE_NONE:
305 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
306 ALUA_DH_NAME);
307 break;
308 default:
309 sdev_printk(KERN_INFO, sdev,
310 "%s: unsupported TPGS setting %d\n",
311 ALUA_DH_NAME, tpgs);
312 tpgs = TPGS_MODE_NONE;
313 break;
314 }
315
316 return tpgs;
317 }
318
319 /*
320 * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
321 * @sdev: device to be checked
322 *
323 * Extract the relative target port and the target port group
324 * descriptor from the list of identificators.
325 */
alua_check_vpd(struct scsi_device * sdev,struct alua_dh_data * h,int tpgs)326 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
327 int tpgs)
328 {
329 int rel_port = -1, group_id;
330 struct alua_port_group *pg, *old_pg = NULL;
331 bool pg_updated = false;
332 unsigned long flags;
333
334 group_id = scsi_vpd_tpg_id(sdev, &rel_port);
335 if (group_id < 0) {
336 /*
337 * Internal error; TPGS supported but required
338 * VPD identification descriptors not present.
339 * Disable ALUA support
340 */
341 sdev_printk(KERN_INFO, sdev,
342 "%s: No target port descriptors found\n",
343 ALUA_DH_NAME);
344 return SCSI_DH_DEV_UNSUPP;
345 }
346
347 pg = alua_alloc_pg(sdev, group_id, tpgs);
348 if (IS_ERR(pg)) {
349 if (PTR_ERR(pg) == -ENOMEM)
350 return SCSI_DH_NOMEM;
351 return SCSI_DH_DEV_UNSUPP;
352 }
353 if (pg->device_id_len)
354 sdev_printk(KERN_INFO, sdev,
355 "%s: device %s port group %x rel port %x\n",
356 ALUA_DH_NAME, pg->device_id_str,
357 group_id, rel_port);
358 else
359 sdev_printk(KERN_INFO, sdev,
360 "%s: port group %x rel port %x\n",
361 ALUA_DH_NAME, group_id, rel_port);
362
363 kref_get(&pg->kref);
364
365 /* Check for existing port group references */
366 spin_lock(&h->pg_lock);
367 old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
368 if (old_pg != pg) {
369 /* port group has changed. Update to new port group */
370 if (h->pg) {
371 spin_lock_irqsave(&old_pg->lock, flags);
372 list_del_rcu(&h->node);
373 spin_unlock_irqrestore(&old_pg->lock, flags);
374 }
375 rcu_assign_pointer(h->pg, pg);
376 pg_updated = true;
377 }
378
379 spin_lock_irqsave(&pg->lock, flags);
380 if (pg_updated)
381 list_add_rcu(&h->node, &pg->dh_list);
382 spin_unlock_irqrestore(&pg->lock, flags);
383
384 spin_unlock(&h->pg_lock);
385
386 alua_rtpg_queue(pg, sdev, NULL, true);
387 kref_put(&pg->kref, release_port_group);
388
389 if (old_pg)
390 kref_put(&old_pg->kref, release_port_group);
391
392 return SCSI_DH_OK;
393 }
394
print_alua_state(unsigned char state)395 static char print_alua_state(unsigned char state)
396 {
397 switch (state) {
398 case SCSI_ACCESS_STATE_OPTIMAL:
399 return 'A';
400 case SCSI_ACCESS_STATE_ACTIVE:
401 return 'N';
402 case SCSI_ACCESS_STATE_STANDBY:
403 return 'S';
404 case SCSI_ACCESS_STATE_UNAVAILABLE:
405 return 'U';
406 case SCSI_ACCESS_STATE_LBA:
407 return 'L';
408 case SCSI_ACCESS_STATE_OFFLINE:
409 return 'O';
410 case SCSI_ACCESS_STATE_TRANSITIONING:
411 return 'T';
412 default:
413 return 'X';
414 }
415 }
416
alua_check_sense(struct scsi_device * sdev,struct scsi_sense_hdr * sense_hdr)417 static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
418 struct scsi_sense_hdr *sense_hdr)
419 {
420 struct alua_dh_data *h = sdev->handler_data;
421 struct alua_port_group *pg;
422
423 switch (sense_hdr->sense_key) {
424 case NOT_READY:
425 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
426 /*
427 * LUN Not Accessible - ALUA state transition
428 */
429 rcu_read_lock();
430 pg = rcu_dereference(h->pg);
431 if (pg)
432 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
433 rcu_read_unlock();
434 alua_check(sdev, false);
435 return NEEDS_RETRY;
436 }
437 break;
438 case UNIT_ATTENTION:
439 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
440 /*
441 * Power On, Reset, or Bus Device Reset.
442 * Might have obscured a state transition,
443 * so schedule a recheck.
444 */
445 alua_check(sdev, true);
446 return ADD_TO_MLQUEUE;
447 }
448 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
449 /*
450 * Device internal reset
451 */
452 return ADD_TO_MLQUEUE;
453 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
454 /*
455 * Mode Parameters Changed
456 */
457 return ADD_TO_MLQUEUE;
458 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
459 /*
460 * ALUA state changed
461 */
462 alua_check(sdev, true);
463 return ADD_TO_MLQUEUE;
464 }
465 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
466 /*
467 * Implicit ALUA state transition failed
468 */
469 alua_check(sdev, true);
470 return ADD_TO_MLQUEUE;
471 }
472 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
473 /*
474 * Inquiry data has changed
475 */
476 return ADD_TO_MLQUEUE;
477 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
478 /*
479 * REPORTED_LUNS_DATA_HAS_CHANGED is reported
480 * when switching controllers on targets like
481 * Intel Multi-Flex. We can just retry.
482 */
483 return ADD_TO_MLQUEUE;
484 break;
485 }
486
487 return SCSI_RETURN_NOT_HANDLED;
488 }
489
490 /*
491 * alua_tur - Send a TEST UNIT READY
492 * @sdev: device to which the TEST UNIT READY command should be send
493 *
494 * Send a TEST UNIT READY to @sdev to figure out the device state
495 * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
496 * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
497 */
alua_tur(struct scsi_device * sdev)498 static int alua_tur(struct scsi_device *sdev)
499 {
500 struct scsi_sense_hdr sense_hdr;
501 int retval;
502
503 retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
504 ALUA_FAILOVER_RETRIES, &sense_hdr);
505 if (sense_hdr.sense_key == NOT_READY &&
506 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
507 return SCSI_DH_RETRY;
508 else if (retval)
509 return SCSI_DH_IO;
510 else
511 return SCSI_DH_OK;
512 }
513
514 /*
515 * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
516 * @sdev: the device to be evaluated.
517 *
518 * Evaluate the Target Port Group State.
519 * Returns SCSI_DH_DEV_OFFLINED if the path is
520 * found to be unusable.
521 */
alua_rtpg(struct scsi_device * sdev,struct alua_port_group * pg)522 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
523 {
524 struct scsi_sense_hdr sense_hdr;
525 struct alua_port_group *tmp_pg;
526 int len, k, off, bufflen = ALUA_RTPG_SIZE;
527 int group_id_old, state_old, pref_old, valid_states_old;
528 unsigned char *desc, *buff;
529 unsigned err;
530 int retval;
531 unsigned int tpg_desc_tbl_off;
532 unsigned char orig_transition_tmo;
533 unsigned long flags;
534 bool transitioning_sense = false;
535
536 group_id_old = pg->group_id;
537 state_old = pg->state;
538 pref_old = pg->pref;
539 valid_states_old = pg->valid_states;
540
541 if (!pg->expiry) {
542 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
543
544 if (pg->transition_tmo)
545 transition_tmo = pg->transition_tmo * HZ;
546
547 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
548 }
549
550 buff = kzalloc(bufflen, GFP_KERNEL);
551 if (!buff)
552 return SCSI_DH_DEV_TEMP_BUSY;
553
554 retry:
555 err = 0;
556 retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
557
558 if (retval) {
559 /*
560 * Some (broken) implementations have a habit of returning
561 * an error during things like firmware update etc.
562 * But if the target only supports active/optimized there's
563 * not much we can do; it's not that we can switch paths
564 * or anything.
565 * So ignore any errors to avoid spurious failures during
566 * path failover.
567 */
568 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) {
569 sdev_printk(KERN_INFO, sdev,
570 "%s: ignoring rtpg result %d\n",
571 ALUA_DH_NAME, retval);
572 kfree(buff);
573 return SCSI_DH_OK;
574 }
575 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
576 sdev_printk(KERN_INFO, sdev,
577 "%s: rtpg failed, result %d\n",
578 ALUA_DH_NAME, retval);
579 kfree(buff);
580 if (retval < 0)
581 return SCSI_DH_DEV_TEMP_BUSY;
582 if (host_byte(retval) == DID_NO_CONNECT)
583 return SCSI_DH_RES_TEMP_UNAVAIL;
584 return SCSI_DH_IO;
585 }
586
587 /*
588 * submit_rtpg() has failed on existing arrays
589 * when requesting extended header info, and
590 * the array doesn't support extended headers,
591 * even though it shouldn't according to T10.
592 * The retry without rtpg_ext_hdr_req set
593 * handles this.
594 * Note: some arrays return a sense key of ILLEGAL_REQUEST
595 * with ASC 00h if they don't support the extended header.
596 */
597 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
598 sense_hdr.sense_key == ILLEGAL_REQUEST) {
599 pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
600 goto retry;
601 }
602 /*
603 * If the array returns with 'ALUA state transition'
604 * sense code here it cannot return RTPG data during
605 * transition. So set the state to 'transitioning' directly.
606 */
607 if (sense_hdr.sense_key == NOT_READY &&
608 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
609 transitioning_sense = true;
610 goto skip_rtpg;
611 }
612 /*
613 * Retry on any other UNIT ATTENTION occurred.
614 */
615 if (sense_hdr.sense_key == UNIT_ATTENTION)
616 err = SCSI_DH_RETRY;
617 if (err == SCSI_DH_RETRY &&
618 pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
619 sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
620 ALUA_DH_NAME);
621 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
622 kfree(buff);
623 return err;
624 }
625 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
626 ALUA_DH_NAME);
627 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
628 kfree(buff);
629 pg->expiry = 0;
630 return SCSI_DH_IO;
631 }
632
633 len = get_unaligned_be32(&buff[0]) + 4;
634
635 if (len > bufflen) {
636 /* Resubmit with the correct length */
637 kfree(buff);
638 bufflen = len;
639 buff = kmalloc(bufflen, GFP_KERNEL);
640 if (!buff) {
641 sdev_printk(KERN_WARNING, sdev,
642 "%s: kmalloc buffer failed\n",__func__);
643 /* Temporary failure, bypass */
644 pg->expiry = 0;
645 return SCSI_DH_DEV_TEMP_BUSY;
646 }
647 goto retry;
648 }
649
650 orig_transition_tmo = pg->transition_tmo;
651 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
652 pg->transition_tmo = buff[5];
653 else
654 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
655
656 if (orig_transition_tmo != pg->transition_tmo) {
657 sdev_printk(KERN_INFO, sdev,
658 "%s: transition timeout set to %d seconds\n",
659 ALUA_DH_NAME, pg->transition_tmo);
660 pg->expiry = jiffies + pg->transition_tmo * HZ;
661 }
662
663 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
664 tpg_desc_tbl_off = 8;
665 else
666 tpg_desc_tbl_off = 4;
667
668 for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
669 k < len;
670 k += off, desc += off) {
671 u16 group_id = get_unaligned_be16(&desc[2]);
672
673 spin_lock_irqsave(&port_group_lock, flags);
674 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
675 group_id);
676 spin_unlock_irqrestore(&port_group_lock, flags);
677 if (tmp_pg) {
678 if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
679 if ((tmp_pg == pg) ||
680 !(tmp_pg->flags & ALUA_PG_RUNNING)) {
681 struct alua_dh_data *h;
682
683 tmp_pg->state = desc[0] & 0x0f;
684 tmp_pg->pref = desc[0] >> 7;
685 rcu_read_lock();
686 list_for_each_entry_rcu(h,
687 &tmp_pg->dh_list, node) {
688 if (!h->sdev)
689 continue;
690 h->sdev->access_state = desc[0];
691 }
692 rcu_read_unlock();
693 }
694 if (tmp_pg == pg)
695 tmp_pg->valid_states = desc[1];
696 spin_unlock_irqrestore(&tmp_pg->lock, flags);
697 }
698 kref_put(&tmp_pg->kref, release_port_group);
699 }
700 off = 8 + (desc[7] * 4);
701 }
702
703 skip_rtpg:
704 spin_lock_irqsave(&pg->lock, flags);
705 if (transitioning_sense)
706 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
707
708 if (group_id_old != pg->group_id || state_old != pg->state ||
709 pref_old != pg->pref || valid_states_old != pg->valid_states)
710 sdev_printk(KERN_INFO, sdev,
711 "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
712 ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
713 pg->pref ? "preferred" : "non-preferred",
714 pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
715 pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
716 pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
717 pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
718 pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
719 pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
720 pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
721
722 switch (pg->state) {
723 case SCSI_ACCESS_STATE_TRANSITIONING:
724 if (time_before(jiffies, pg->expiry)) {
725 /* State transition, retry */
726 pg->interval = ALUA_RTPG_RETRY_DELAY;
727 err = SCSI_DH_RETRY;
728 } else {
729 struct alua_dh_data *h;
730
731 /* Transitioning time exceeded, set port to standby */
732 err = SCSI_DH_IO;
733 pg->state = SCSI_ACCESS_STATE_STANDBY;
734 pg->expiry = 0;
735 rcu_read_lock();
736 list_for_each_entry_rcu(h, &pg->dh_list, node) {
737 if (!h->sdev)
738 continue;
739 h->sdev->access_state =
740 (pg->state & SCSI_ACCESS_STATE_MASK);
741 if (pg->pref)
742 h->sdev->access_state |=
743 SCSI_ACCESS_STATE_PREFERRED;
744 }
745 rcu_read_unlock();
746 }
747 break;
748 case SCSI_ACCESS_STATE_OFFLINE:
749 /* Path unusable */
750 err = SCSI_DH_DEV_OFFLINED;
751 pg->expiry = 0;
752 break;
753 default:
754 /* Useable path if active */
755 err = SCSI_DH_OK;
756 pg->expiry = 0;
757 break;
758 }
759 spin_unlock_irqrestore(&pg->lock, flags);
760 kfree(buff);
761 return err;
762 }
763
764 /*
765 * alua_stpg - Issue a SET TARGET PORT GROUP command
766 *
767 * Issue a SET TARGET PORT GROUP command and evaluate the
768 * response. Returns SCSI_DH_RETRY per default to trigger
769 * a re-evaluation of the target group state or SCSI_DH_OK
770 * if no further action needs to be taken.
771 */
alua_stpg(struct scsi_device * sdev,struct alua_port_group * pg)772 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
773 {
774 int retval;
775 struct scsi_sense_hdr sense_hdr;
776
777 if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
778 /* Only implicit ALUA supported, retry */
779 return SCSI_DH_RETRY;
780 }
781 switch (pg->state) {
782 case SCSI_ACCESS_STATE_OPTIMAL:
783 return SCSI_DH_OK;
784 case SCSI_ACCESS_STATE_ACTIVE:
785 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
786 !pg->pref &&
787 (pg->tpgs & TPGS_MODE_IMPLICIT))
788 return SCSI_DH_OK;
789 break;
790 case SCSI_ACCESS_STATE_STANDBY:
791 case SCSI_ACCESS_STATE_UNAVAILABLE:
792 break;
793 case SCSI_ACCESS_STATE_OFFLINE:
794 return SCSI_DH_IO;
795 case SCSI_ACCESS_STATE_TRANSITIONING:
796 break;
797 default:
798 sdev_printk(KERN_INFO, sdev,
799 "%s: stpg failed, unhandled TPGS state %d",
800 ALUA_DH_NAME, pg->state);
801 return SCSI_DH_NOSYS;
802 }
803 retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
804
805 if (retval) {
806 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
807 sdev_printk(KERN_INFO, sdev,
808 "%s: stpg failed, result %d",
809 ALUA_DH_NAME, retval);
810 if (retval < 0)
811 return SCSI_DH_DEV_TEMP_BUSY;
812 } else {
813 sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
814 ALUA_DH_NAME);
815 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
816 }
817 }
818 /* Retry RTPG */
819 return SCSI_DH_RETRY;
820 }
821
822 /*
823 * The caller must call scsi_device_put() on the returned pointer if it is not
824 * NULL.
825 */
826 static struct scsi_device * __must_check
alua_rtpg_select_sdev(struct alua_port_group * pg)827 alua_rtpg_select_sdev(struct alua_port_group *pg)
828 {
829 struct alua_dh_data *h;
830 struct scsi_device *sdev = NULL, *prev_sdev;
831
832 lockdep_assert_held(&pg->lock);
833 if (WARN_ON(!pg->rtpg_sdev))
834 return NULL;
835
836 /*
837 * RCU protection isn't necessary for dh_list here
838 * as we hold pg->lock, but for access to h->pg.
839 */
840 rcu_read_lock();
841 list_for_each_entry_rcu(h, &pg->dh_list, node) {
842 if (!h->sdev)
843 continue;
844 if (h->sdev == pg->rtpg_sdev) {
845 h->disabled = true;
846 continue;
847 }
848 if (rcu_dereference(h->pg) == pg &&
849 !h->disabled &&
850 !scsi_device_get(h->sdev)) {
851 sdev = h->sdev;
852 break;
853 }
854 }
855 rcu_read_unlock();
856
857 if (!sdev) {
858 pr_warn("%s: no device found for rtpg\n",
859 (pg->device_id_len ?
860 (char *)pg->device_id_str : "(nameless PG)"));
861 return NULL;
862 }
863
864 sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n");
865
866 prev_sdev = pg->rtpg_sdev;
867 pg->rtpg_sdev = sdev;
868
869 return prev_sdev;
870 }
871
alua_rtpg_work(struct work_struct * work)872 static void alua_rtpg_work(struct work_struct *work)
873 {
874 struct alua_port_group *pg =
875 container_of(work, struct alua_port_group, rtpg_work.work);
876 struct scsi_device *sdev, *prev_sdev = NULL;
877 LIST_HEAD(qdata_list);
878 int err = SCSI_DH_OK;
879 struct alua_queue_data *qdata, *tmp;
880 struct alua_dh_data *h;
881 unsigned long flags;
882
883 spin_lock_irqsave(&pg->lock, flags);
884 sdev = pg->rtpg_sdev;
885 if (!sdev) {
886 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
887 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
888 spin_unlock_irqrestore(&pg->lock, flags);
889 kref_put(&pg->kref, release_port_group);
890 return;
891 }
892 pg->flags |= ALUA_PG_RUNNING;
893 if (pg->flags & ALUA_PG_RUN_RTPG) {
894 int state = pg->state;
895
896 pg->flags &= ~ALUA_PG_RUN_RTPG;
897 spin_unlock_irqrestore(&pg->lock, flags);
898 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
899 if (alua_tur(sdev) == SCSI_DH_RETRY) {
900 spin_lock_irqsave(&pg->lock, flags);
901 pg->flags &= ~ALUA_PG_RUNNING;
902 pg->flags |= ALUA_PG_RUN_RTPG;
903 if (!pg->interval)
904 pg->interval = ALUA_RTPG_RETRY_DELAY;
905 spin_unlock_irqrestore(&pg->lock, flags);
906 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
907 pg->interval * HZ);
908 return;
909 }
910 /* Send RTPG on failure or if TUR indicates SUCCESS */
911 }
912 err = alua_rtpg(sdev, pg);
913 spin_lock_irqsave(&pg->lock, flags);
914
915 /* If RTPG failed on the current device, try using another */
916 if (err == SCSI_DH_RES_TEMP_UNAVAIL &&
917 (prev_sdev = alua_rtpg_select_sdev(pg)))
918 err = SCSI_DH_IMM_RETRY;
919
920 if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY ||
921 pg->flags & ALUA_PG_RUN_RTPG) {
922 pg->flags &= ~ALUA_PG_RUNNING;
923 if (err == SCSI_DH_IMM_RETRY)
924 pg->interval = 0;
925 else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
926 pg->interval = ALUA_RTPG_RETRY_DELAY;
927 pg->flags |= ALUA_PG_RUN_RTPG;
928 spin_unlock_irqrestore(&pg->lock, flags);
929 goto queue_rtpg;
930 }
931 if (err != SCSI_DH_OK)
932 pg->flags &= ~ALUA_PG_RUN_STPG;
933 }
934 if (pg->flags & ALUA_PG_RUN_STPG) {
935 pg->flags &= ~ALUA_PG_RUN_STPG;
936 spin_unlock_irqrestore(&pg->lock, flags);
937 err = alua_stpg(sdev, pg);
938 spin_lock_irqsave(&pg->lock, flags);
939 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
940 pg->flags |= ALUA_PG_RUN_RTPG;
941 pg->interval = 0;
942 pg->flags &= ~ALUA_PG_RUNNING;
943 spin_unlock_irqrestore(&pg->lock, flags);
944 goto queue_rtpg;
945 }
946 }
947
948 list_splice_init(&pg->rtpg_list, &qdata_list);
949 /*
950 * We went through an RTPG, for good or bad.
951 * Re-enable all devices for the next attempt.
952 */
953 list_for_each_entry(h, &pg->dh_list, node)
954 h->disabled = false;
955 pg->rtpg_sdev = NULL;
956 spin_unlock_irqrestore(&pg->lock, flags);
957
958 if (prev_sdev)
959 scsi_device_put(prev_sdev);
960
961 list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
962 list_del(&qdata->entry);
963 if (qdata->callback_fn)
964 qdata->callback_fn(qdata->callback_data, err);
965 kfree(qdata);
966 }
967 spin_lock_irqsave(&pg->lock, flags);
968 pg->flags &= ~ALUA_PG_RUNNING;
969 spin_unlock_irqrestore(&pg->lock, flags);
970 scsi_device_put(sdev);
971 kref_put(&pg->kref, release_port_group);
972 return;
973
974 queue_rtpg:
975 if (prev_sdev)
976 scsi_device_put(prev_sdev);
977 queue_delayed_work(kaluad_wq, &pg->rtpg_work, pg->interval * HZ);
978 }
979
980 /**
981 * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
982 * @pg: ALUA port group associated with @sdev.
983 * @sdev: SCSI device for which to submit an RTPG.
984 * @qdata: Information about the callback to invoke after the RTPG.
985 * @force: Whether or not to submit an RTPG if a work item that will submit an
986 * RTPG already has been scheduled.
987 *
988 * Returns true if and only if alua_rtpg_work() will be called asynchronously.
989 * That function is responsible for calling @qdata->fn().
990 *
991 * Context: may be called from atomic context (alua_check()) only if the caller
992 * holds an sdev reference.
993 */
alua_rtpg_queue(struct alua_port_group * pg,struct scsi_device * sdev,struct alua_queue_data * qdata,bool force)994 static bool alua_rtpg_queue(struct alua_port_group *pg,
995 struct scsi_device *sdev,
996 struct alua_queue_data *qdata, bool force)
997 {
998 int start_queue = 0;
999 unsigned long flags;
1000
1001 if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
1002 return false;
1003
1004 spin_lock_irqsave(&pg->lock, flags);
1005 if (qdata) {
1006 list_add_tail(&qdata->entry, &pg->rtpg_list);
1007 pg->flags |= ALUA_PG_RUN_STPG;
1008 force = true;
1009 }
1010 if (pg->rtpg_sdev == NULL) {
1011 struct alua_dh_data *h = sdev->handler_data;
1012
1013 rcu_read_lock();
1014 if (h && rcu_dereference(h->pg) == pg) {
1015 pg->interval = 0;
1016 pg->flags |= ALUA_PG_RUN_RTPG;
1017 kref_get(&pg->kref);
1018 pg->rtpg_sdev = sdev;
1019 start_queue = 1;
1020 }
1021 rcu_read_unlock();
1022 } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
1023 pg->flags |= ALUA_PG_RUN_RTPG;
1024 /* Do not queue if the worker is already running */
1025 if (!(pg->flags & ALUA_PG_RUNNING)) {
1026 kref_get(&pg->kref);
1027 start_queue = 1;
1028 }
1029 }
1030
1031 spin_unlock_irqrestore(&pg->lock, flags);
1032
1033 if (start_queue) {
1034 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
1035 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
1036 sdev = NULL;
1037 else
1038 kref_put(&pg->kref, release_port_group);
1039 }
1040 if (sdev)
1041 scsi_device_put(sdev);
1042
1043 return true;
1044 }
1045
1046 /*
1047 * alua_initialize - Initialize ALUA state
1048 * @sdev: the device to be initialized
1049 *
1050 * For the prep_fn to work correctly we have
1051 * to initialize the ALUA state for the device.
1052 */
alua_initialize(struct scsi_device * sdev,struct alua_dh_data * h)1053 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
1054 {
1055 int err = SCSI_DH_DEV_UNSUPP, tpgs;
1056
1057 mutex_lock(&h->init_mutex);
1058 h->disabled = false;
1059 tpgs = alua_check_tpgs(sdev);
1060 if (tpgs != TPGS_MODE_NONE)
1061 err = alua_check_vpd(sdev, h, tpgs);
1062 h->init_error = err;
1063 mutex_unlock(&h->init_mutex);
1064 return err;
1065 }
1066 /*
1067 * alua_set_params - set/unset the optimize flag
1068 * @sdev: device on the path to be activated
1069 * params - parameters in the following format
1070 * "no_of_params\0param1\0param2\0param3\0...\0"
1071 * For example, to set the flag pass the following parameters
1072 * from multipath.conf
1073 * hardware_handler "2 alua 1"
1074 */
alua_set_params(struct scsi_device * sdev,const char * params)1075 static int alua_set_params(struct scsi_device *sdev, const char *params)
1076 {
1077 struct alua_dh_data *h = sdev->handler_data;
1078 struct alua_port_group *pg = NULL;
1079 unsigned int optimize = 0, argc;
1080 const char *p = params;
1081 int result = SCSI_DH_OK;
1082 unsigned long flags;
1083
1084 if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
1085 return -EINVAL;
1086
1087 while (*p++)
1088 ;
1089 if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
1090 return -EINVAL;
1091
1092 rcu_read_lock();
1093 pg = rcu_dereference(h->pg);
1094 if (!pg) {
1095 rcu_read_unlock();
1096 return -ENXIO;
1097 }
1098 spin_lock_irqsave(&pg->lock, flags);
1099 if (optimize)
1100 pg->flags |= ALUA_OPTIMIZE_STPG;
1101 else
1102 pg->flags &= ~ALUA_OPTIMIZE_STPG;
1103 spin_unlock_irqrestore(&pg->lock, flags);
1104 rcu_read_unlock();
1105
1106 return result;
1107 }
1108
1109 /*
1110 * alua_activate - activate a path
1111 * @sdev: device on the path to be activated
1112 *
1113 * We're currently switching the port group to be activated only and
1114 * let the array figure out the rest.
1115 * There may be other arrays which require us to switch all port groups
1116 * based on a certain policy. But until we actually encounter them it
1117 * should be okay.
1118 */
alua_activate(struct scsi_device * sdev,activate_complete fn,void * data)1119 static int alua_activate(struct scsi_device *sdev,
1120 activate_complete fn, void *data)
1121 {
1122 struct alua_dh_data *h = sdev->handler_data;
1123 int err = SCSI_DH_OK;
1124 struct alua_queue_data *qdata;
1125 struct alua_port_group *pg;
1126
1127 qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1128 if (!qdata) {
1129 err = SCSI_DH_RES_TEMP_UNAVAIL;
1130 goto out;
1131 }
1132 qdata->callback_fn = fn;
1133 qdata->callback_data = data;
1134
1135 mutex_lock(&h->init_mutex);
1136 rcu_read_lock();
1137 pg = rcu_dereference(h->pg);
1138 if (!pg || !kref_get_unless_zero(&pg->kref)) {
1139 rcu_read_unlock();
1140 kfree(qdata);
1141 err = h->init_error;
1142 mutex_unlock(&h->init_mutex);
1143 goto out;
1144 }
1145 rcu_read_unlock();
1146 mutex_unlock(&h->init_mutex);
1147
1148 if (alua_rtpg_queue(pg, sdev, qdata, true)) {
1149 fn = NULL;
1150 } else {
1151 kfree(qdata);
1152 err = SCSI_DH_DEV_OFFLINED;
1153 }
1154 kref_put(&pg->kref, release_port_group);
1155 out:
1156 if (fn)
1157 fn(data, err);
1158 return 0;
1159 }
1160
1161 /*
1162 * alua_check - check path status
1163 * @sdev: device on the path to be checked
1164 *
1165 * Check the device status
1166 */
alua_check(struct scsi_device * sdev,bool force)1167 static void alua_check(struct scsi_device *sdev, bool force)
1168 {
1169 struct alua_dh_data *h = sdev->handler_data;
1170 struct alua_port_group *pg;
1171
1172 rcu_read_lock();
1173 pg = rcu_dereference(h->pg);
1174 if (!pg || !kref_get_unless_zero(&pg->kref)) {
1175 rcu_read_unlock();
1176 return;
1177 }
1178 rcu_read_unlock();
1179 alua_rtpg_queue(pg, sdev, NULL, force);
1180 kref_put(&pg->kref, release_port_group);
1181 }
1182
1183 /*
1184 * alua_prep_fn - request callback
1185 *
1186 * Fail I/O to all paths not in state
1187 * active/optimized or active/non-optimized.
1188 */
alua_prep_fn(struct scsi_device * sdev,struct request * req)1189 static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
1190 {
1191 struct alua_dh_data *h = sdev->handler_data;
1192 struct alua_port_group *pg;
1193 unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1194
1195 rcu_read_lock();
1196 pg = rcu_dereference(h->pg);
1197 if (pg)
1198 state = pg->state;
1199 rcu_read_unlock();
1200
1201 switch (state) {
1202 case SCSI_ACCESS_STATE_OPTIMAL:
1203 case SCSI_ACCESS_STATE_ACTIVE:
1204 case SCSI_ACCESS_STATE_LBA:
1205 case SCSI_ACCESS_STATE_TRANSITIONING:
1206 return BLK_STS_OK;
1207 default:
1208 req->rq_flags |= RQF_QUIET;
1209 return BLK_STS_IOERR;
1210 }
1211 }
1212
alua_rescan(struct scsi_device * sdev)1213 static void alua_rescan(struct scsi_device *sdev)
1214 {
1215 struct alua_dh_data *h = sdev->handler_data;
1216
1217 alua_initialize(sdev, h);
1218 }
1219
1220 /*
1221 * alua_bus_attach - Attach device handler
1222 * @sdev: device to be attached to
1223 */
alua_bus_attach(struct scsi_device * sdev)1224 static int alua_bus_attach(struct scsi_device *sdev)
1225 {
1226 struct alua_dh_data *h;
1227 int err;
1228
1229 h = kzalloc(sizeof(*h) , GFP_KERNEL);
1230 if (!h)
1231 return SCSI_DH_NOMEM;
1232 spin_lock_init(&h->pg_lock);
1233 rcu_assign_pointer(h->pg, NULL);
1234 h->init_error = SCSI_DH_OK;
1235 h->sdev = sdev;
1236 INIT_LIST_HEAD(&h->node);
1237
1238 mutex_init(&h->init_mutex);
1239 err = alua_initialize(sdev, h);
1240 if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1241 goto failed;
1242
1243 sdev->handler_data = h;
1244 return SCSI_DH_OK;
1245 failed:
1246 kfree(h);
1247 return err;
1248 }
1249
1250 /*
1251 * alua_bus_detach - Detach device handler
1252 * @sdev: device to be detached from
1253 */
alua_bus_detach(struct scsi_device * sdev)1254 static void alua_bus_detach(struct scsi_device *sdev)
1255 {
1256 struct alua_dh_data *h = sdev->handler_data;
1257 struct alua_port_group *pg;
1258
1259 spin_lock(&h->pg_lock);
1260 pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1261 rcu_assign_pointer(h->pg, NULL);
1262 spin_unlock(&h->pg_lock);
1263 if (pg) {
1264 spin_lock_irq(&pg->lock);
1265 list_del_rcu(&h->node);
1266 spin_unlock_irq(&pg->lock);
1267 kref_put(&pg->kref, release_port_group);
1268 }
1269 sdev->handler_data = NULL;
1270 synchronize_rcu();
1271 kfree(h);
1272 }
1273
1274 static struct scsi_device_handler alua_dh = {
1275 .name = ALUA_DH_NAME,
1276 .module = THIS_MODULE,
1277 .attach = alua_bus_attach,
1278 .detach = alua_bus_detach,
1279 .prep_fn = alua_prep_fn,
1280 .check_sense = alua_check_sense,
1281 .activate = alua_activate,
1282 .rescan = alua_rescan,
1283 .set_params = alua_set_params,
1284 };
1285
alua_init(void)1286 static int __init alua_init(void)
1287 {
1288 int r;
1289
1290 kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1291 if (!kaluad_wq)
1292 return -ENOMEM;
1293
1294 r = scsi_register_device_handler(&alua_dh);
1295 if (r != 0) {
1296 printk(KERN_ERR "%s: Failed to register scsi device handler",
1297 ALUA_DH_NAME);
1298 destroy_workqueue(kaluad_wq);
1299 }
1300 return r;
1301 }
1302
alua_exit(void)1303 static void __exit alua_exit(void)
1304 {
1305 scsi_unregister_device_handler(&alua_dh);
1306 destroy_workqueue(kaluad_wq);
1307 }
1308
1309 module_init(alua_init);
1310 module_exit(alua_exit);
1311
1312 MODULE_DESCRIPTION("DM Multipath ALUA support");
1313 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1314 MODULE_LICENSE("GPL");
1315 MODULE_VERSION(ALUA_DH_VER);
1316
