aboutsummaryrefslogtreecommitdiff
path: root/drivers/md/dm-emc.c
blob: a2191a4fcf77120d6d9033b0cedb58ab3adc1c3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
/*
 * Copyright (C) 2004 SUSE LINUX Products GmbH. All rights reserved.
 * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 *
 * Multipath support for EMC CLARiiON AX/CX-series hardware.
 */

#include "dm.h"
#include "dm-hw-handler.h"
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>

#define DM_MSG_PREFIX "multipath emc"

struct emc_handler {
	spinlock_t lock;

	/* Whether we should send the short trespass command (FC-series)
	 * or the long version (default for AX/CX CLARiiON arrays). */
	unsigned short_trespass;
	/* Whether or not to honor SCSI reservations when initiating a
	 * switch-over. Default: Don't. */
	unsigned hr;

	unsigned char sense[SCSI_SENSE_BUFFERSIZE];
};

#define TRESPASS_PAGE 0x22
#define EMC_FAILOVER_TIMEOUT (60 * HZ)

/* Code borrowed from dm-lsi-rdac by Mike Christie */

static inline void free_bio(struct bio *bio)
{
	__free_page(bio->bi_io_vec[0].bv_page);
	bio_put(bio);
}

static void emc_endio(struct bio *bio, int error)
{
	struct dm_path *path = bio->bi_private;

	/* We also need to look at the sense keys here whether or not to
	 * switch to the next PG etc.
	 *
	 * For now simple logic: either it works or it doesn't.
	 */
	if (error)
		dm_pg_init_complete(path, MP_FAIL_PATH);
	else
		dm_pg_init_complete(path, 0);

	/* request is freed in block layer */
	free_bio(bio);

	return 0;
}

static struct bio *get_failover_bio(struct dm_path *path, unsigned data_size)
{
	struct bio *bio;
	struct page *page;

	bio = bio_alloc(GFP_ATOMIC, 1);
	if (!bio) {
		DMERR("get_failover_bio: bio_alloc() failed.");
		return NULL;
	}

	bio->bi_rw |= (1 << BIO_RW);
	bio->bi_bdev = path->dev->bdev;
	bio->bi_sector = 0;
	bio->bi_private = path;
	bio->bi_end_io = emc_endio;

	page = alloc_page(GFP_ATOMIC);
	if (!page) {
		DMERR("get_failover_bio: alloc_page() failed.");
		bio_put(bio);
		return NULL;
	}

	if (bio_add_page(bio, page, data_size, 0) != data_size) {
		DMERR("get_failover_bio: alloc_page() failed.");
		__free_page(page);
		bio_put(bio);
		return NULL;
	}

	return bio;
}

static struct request *get_failover_req(struct emc_handler *h,
					struct bio *bio, struct dm_path *path)
{
	struct request *rq;
	struct block_device *bdev = bio->bi_bdev;
	struct request_queue *q = bdev_get_queue(bdev);

	/* FIXME: Figure out why it fails with GFP_ATOMIC. */
	rq = blk_get_request(q, WRITE, __GFP_WAIT);
	if (!rq) {
		DMERR("get_failover_req: blk_get_request failed");
		return NULL;
	}

	blk_rq_append_bio(q, rq, bio);

	rq->sense = h->sense;
	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
	rq->sense_len = 0;

	memset(&rq->cmd, 0, BLK_MAX_CDB);

	rq->timeout = EMC_FAILOVER_TIMEOUT;
	rq->cmd_type = REQ_TYPE_BLOCK_PC;
	rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;

	return rq;
}

static struct request *emc_trespass_get(struct emc_handler *h,
					struct dm_path *path)
{
	struct bio *bio;
	struct request *rq;
	unsigned char *page22;
	unsigned char long_trespass_pg[] = {
		0, 0, 0, 0,
		TRESPASS_PAGE,        /* Page code */
		0x09,                 /* Page length - 2 */
		h->hr ? 0x01 : 0x81,  /* Trespass code + Honor reservation bit */
		0xff, 0xff,           /* Trespass target */
		0, 0, 0, 0, 0, 0      /* Reserved bytes / unknown */
		};
	unsigned char short_trespass_pg[] = {
		0, 0, 0, 0,
		TRESPASS_PAGE,        /* Page code */
		0x02,                 /* Page length - 2 */
		h->hr ? 0x01 : 0x81,  /* Trespass code + Honor reservation bit */
		0xff,                 /* Trespass target */
		};
	unsigned data_size = h->short_trespass ? sizeof(short_trespass_pg) :
				sizeof(long_trespass_pg);

	/* get bio backing */
	if (data_size > PAGE_SIZE)
		/* this should never happen */
		return NULL;

	bio = get_failover_bio(path, data_size);
	if (!bio) {
		DMERR("emc_trespass_get: no bio");
		return NULL;
	}

	page22 = (unsigned char *)bio_data(bio);
	memset(page22, 0, data_size);

	memcpy(page22, h->short_trespass ?
		short_trespass_pg : long_trespass_pg, data_size);

	/* get request for block layer packet command */
	rq = get_failover_req(h, bio, path);
	if (!rq) {
		DMERR("emc_trespass_get: no rq");
		free_bio(bio);
		return NULL;
	}

	/* Prepare the command. */
	rq->cmd[0] = MODE_SELECT;
	rq->cmd[1] = 0x10;
	rq->cmd[4] = data_size;
	rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);

	return rq;
}

static void emc_pg_init(struct hw_handler *hwh, unsigned bypassed,
			struct dm_path *path)
{
	struct request *rq;
	struct request_queue *q = bdev_get_queue(path->dev->bdev);

	/*
	 * We can either blindly init the pg (then look at the sense),
	 * or we can send some commands to get the state here (then
	 * possibly send the fo cmnd), or we can also have the
	 * initial state passed into us and then get an update here.
	 */
	if (!q) {
		DMINFO("emc_pg_init: no queue");
		goto fail_path;
	}

	/* FIXME: The request should be pre-allocated. */
	rq = emc_trespass_get(hwh->context, path);
	if (!rq) {
		DMERR("emc_pg_init: no rq");
		goto fail_path;
	}

	DMINFO("emc_pg_init: sending switch-over command");
	elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
	return;

fail_path:
	dm_pg_init_complete(path, MP_FAIL_PATH);
}

static struct emc_handler *alloc_emc_handler(void)
{
	struct emc_handler *h = kmalloc(sizeof(*h), GFP_KERNEL);

	if (h) {
		memset(h, 0, sizeof(*h));
		spin_lock_init(&h->lock);
	}

	return h;
}

static int emc_create(struct hw_handler *hwh, unsigned argc, char **argv)
{
	struct emc_handler *h;
	unsigned hr, short_trespass;

	if (argc == 0) {
		/* No arguments: use defaults */
		hr = 0;
		short_trespass = 0;
	} else if (argc != 2) {
		DMWARN("incorrect number of arguments");
		return -EINVAL;
	} else {
		if ((sscanf(argv[0], "%u", &short_trespass) != 1)
			|| (short_trespass > 1)) {
			DMWARN("invalid trespass mode selected");
			return -EINVAL;
		}

		if ((sscanf(argv[1], "%u", &hr) != 1)
			|| (hr > 1)) {
			DMWARN("invalid honor reservation flag selected");
			return -EINVAL;
		}
	}

	h = alloc_emc_handler();
	if (!h)
		return -ENOMEM;

	hwh->context = h;

	if ((h->short_trespass = short_trespass))
		DMWARN("short trespass command will be send");
	else
		DMWARN("long trespass command will be send");

	if ((h->hr = hr))
		DMWARN("honor reservation bit will be set");
	else
		DMWARN("honor reservation bit will not be set (default)");

	return 0;
}

static void emc_destroy(struct hw_handler *hwh)
{
	struct emc_handler *h = (struct emc_handler *) hwh->context;

	kfree(h);
	hwh->context = NULL;
}

static unsigned emc_error(struct hw_handler *hwh, struct bio *bio)
{
	/* FIXME: Patch from axboe still missing */
#if 0
	int sense;

	if (bio->bi_error & BIO_SENSE) {
		sense = bio->bi_error & 0xffffff; /* sense key / asc / ascq */

		if (sense == 0x020403) {
			/* LUN Not Ready - Manual Intervention Required
			 * indicates this is a passive path.
			 *
			 * FIXME: However, if this is seen and EVPD C0
			 * indicates that this is due to a NDU in
			 * progress, we should set FAIL_PATH too.
			 * This indicates we might have to do a SCSI
			 * inquiry in the end_io path. Ugh. */
			return MP_BYPASS_PG | MP_RETRY_IO;
		} else if (sense == 0x052501) {
			/* An array based copy is in progress. Do not
			 * fail the path, do not bypass to another PG,
			 * do not retry. Fail the IO immediately.
			 * (Actually this is the same conclusion as in
			 * the default handler, but lets make sure.) */
			return 0;
		} else if (sense == 0x062900) {
			/* Unit Attention Code. This is the first IO
			 * to the new path, so just retry. */
			return MP_RETRY_IO;
		}
	}
#endif

	/* Try default handler */
	return dm_scsi_err_handler(hwh, bio);
}

static struct hw_handler_type emc_hwh = {
	.name = "emc",
	.module = THIS_MODULE,
	.create = emc_create,
	.destroy = emc_destroy,
	.pg_init = emc_pg_init,
	.error = emc_error,
};

static int __init dm_emc_init(void)
{
	int r = dm_register_hw_handler(&emc_hwh);

	if (r < 0)
		DMERR("register failed %d", r);

	DMINFO("version 0.0.3 loaded");

	return r;
}

static void __exit dm_emc_exit(void)
{
	int r = dm_unregister_hw_handler(&emc_hwh);

	if (r < 0)
		DMERR("unregister failed %d", r);
}

module_init(dm_emc_init);
module_exit(dm_emc_exit);

MODULE_DESCRIPTION(DM_NAME " EMC CX/AX/FC-family multipath");
MODULE_AUTHOR("Lars Marowsky-Bree <lmb@suse.de>");
MODULE_LICENSE("GPL");