drivers/md/dm-emc.c

   1 /*
   2  * Copyright (C) 2004 SUSE LINUX Products GmbH. All rights reserved.
   3  * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  *
   7  * Multipath support for EMC CLARiiON AX/CX-series hardware.
   8  */
   9
  10 #include "dm.h"
  11 #include "dm-hw-handler.h"
  12 #include <scsi/scsi.h>
  13 #include <scsi/scsi_cmnd.h>
  14
  15 #define DM_MSG_PREFIX "multipath emc"
  16
  17 struct emc_handler {
  18         spinlock_t lock;
  19
  20         /* Whether we should send the short trespass command (FC-series)
  21          * or the long version (default for AX/CX CLARiiON arrays). */
  22         unsigned short_trespass;
  23         /* Whether or not to honor SCSI reservations when initiating a
  24          * switch-over. Default: Don't. */
  25         unsigned hr;
  26
  27         unsigned char sense[SCSI_SENSE_BUFFERSIZE];
  28 };
  29
  30 #define TRESPASS_PAGE 0x22
  31 #define EMC_FAILOVER_TIMEOUT (60 * HZ)
  32
  33 /* Code borrowed from dm-lsi-rdac by Mike Christie */
  34
  35 static inline void free_bio(struct bio *bio)
  36 {
  37         __free_page(bio->bi_io_vec[0].bv_page);
  38         bio_put(bio);
  39 }
  40
  41 static void emc_endio(struct bio *bio, int error)
  42 {
  43         struct dm_path *path = bio->bi_private;
  44
  45         /* We also need to look at the sense keys here whether or not to
  46          * switch to the next PG etc.
  47          *
  48          * For now simple logic: either it works or it doesn't.
  49          */
  50         if (error)
  51                 dm_pg_init_complete(path, MP_FAIL_PATH);
  52         else
  53                 dm_pg_init_complete(path, 0);
  54
  55         /* request is freed in block layer */
  56         free_bio(bio);
  57
  58         return 0;
  59 }
  60
  61 static struct bio *get_failover_bio(struct dm_path *path, unsigned data_size)
  62 {
  63         struct bio *bio;
  64         struct page *page;
  65
  66         bio = bio_alloc(GFP_ATOMIC, 1);
  67         if (!bio) {
  68                 DMERR("get_failover_bio: bio_alloc() failed.");
  69                 return NULL;
  70         }
  71
  72         bio->bi_rw |= (1 << BIO_RW);
  73         bio->bi_bdev = path->dev->bdev;
  74         bio->bi_sector = 0;
  75         bio->bi_private = path;
  76         bio->bi_end_io = emc_endio;
  77
  78         page = alloc_page(GFP_ATOMIC);
  79         if (!page) {
  80                 DMERR("get_failover_bio: alloc_page() failed.");
  81                 bio_put(bio);
  82                 return NULL;
  83         }
  84
  85         if (bio_add_page(bio, page, data_size, 0) != data_size) {
  86                 DMERR("get_failover_bio: alloc_page() failed.");
  87                 __free_page(page);
  88                 bio_put(bio);
  89                 return NULL;
  90         }
  91
  92         return bio;
  93 }
  94
  95 static struct request *get_failover_req(struct emc_handler *h,
  96                                         struct bio *bio, struct dm_path *path)
  97 {
  98         struct request *rq;
  99         struct block_device *bdev = bio->bi_bdev;
 100         struct request_queue *q = bdev_get_queue(bdev);
 101
 102         /* FIXME: Figure out why it fails with GFP_ATOMIC. */
 103         rq = blk_get_request(q, WRITE, __GFP_WAIT);
 104         if (!rq) {
 105                 DMERR("get_failover_req: blk_get_request failed");
 106                 return NULL;
 107         }
 108
 109         blk_rq_append_bio(q, rq, bio);
 110
 111         rq->sense = h->sense;
 112         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 113         rq->sense_len = 0;
 114
 115         memset(&rq->cmd, 0, BLK_MAX_CDB);
 116
 117         rq->timeout = EMC_FAILOVER_TIMEOUT;
 118         rq->cmd_type = REQ_TYPE_BLOCK_PC;
 119         rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
 120
 121         return rq;
 122 }
 123
 124 static struct request *emc_trespass_get(struct emc_handler *h,
 125                                         struct dm_path *path)
 126 {
 127         struct bio *bio;
 128         struct request *rq;
 129         unsigned char *page22;
 130         unsigned char long_trespass_pg[] = {
 131                 0, 0, 0, 0,
 132                 TRESPASS_PAGE,        /* Page code */
 133                 0x09,                 /* Page length - 2 */
 134                 h->hr ? 0x01 : 0x81,  /* Trespass code + Honor reservation bit */
 135                 0xff, 0xff,           /* Trespass target */
 136                 0, 0, 0, 0, 0, 0      /* Reserved bytes / unknown */
 137                 };
 138         unsigned char short_trespass_pg[] = {
 139                 0, 0, 0, 0,
 140                 TRESPASS_PAGE,        /* Page code */
 141                 0x02,                 /* Page length - 2 */
 142                 h->hr ? 0x01 : 0x81,  /* Trespass code + Honor reservation bit */
 143                 0xff,                 /* Trespass target */
 144                 };
 145         unsigned data_size = h->short_trespass ? sizeof(short_trespass_pg) :
 146                                 sizeof(long_trespass_pg);
 147
 148         /* get bio backing */
 149         if (data_size > PAGE_SIZE)
 150                 /* this should never happen */
 151                 return NULL;
 152
 153         bio = get_failover_bio(path, data_size);
 154         if (!bio) {
 155                 DMERR("emc_trespass_get: no bio");
 156                 return NULL;
 157         }
 158
 159         page22 = (unsigned char *)bio_data(bio);
 160         memset(page22, 0, data_size);
 161
 162         memcpy(page22, h->short_trespass ?
 163                 short_trespass_pg : long_trespass_pg, data_size);
 164
 165         /* get request for block layer packet command */
 166         rq = get_failover_req(h, bio, path);
 167         if (!rq) {
 168                 DMERR("emc_trespass_get: no rq");
 169                 free_bio(bio);
 170                 return NULL;
 171         }
 172
 173         /* Prepare the command. */
 174         rq->cmd[0] = MODE_SELECT;
 175         rq->cmd[1] = 0x10;
 176         rq->cmd[4] = data_size;
 177         rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
 178
 179         return rq;
 180 }
 181
 182 static void emc_pg_init(struct hw_handler *hwh, unsigned bypassed,
 183                         struct dm_path *path)
 184 {
 185         struct request *rq;
 186         struct request_queue *q = bdev_get_queue(path->dev->bdev);
 187
 188         /*
 189          * We can either blindly init the pg (then look at the sense),
 190          * or we can send some commands to get the state here (then
 191          * possibly send the fo cmnd), or we can also have the
 192          * initial state passed into us and then get an update here.
 193          */
 194         if (!q) {
 195                 DMINFO("emc_pg_init: no queue");
 196                 goto fail_path;
 197         }
 198
 199         /* FIXME: The request should be pre-allocated. */
 200         rq = emc_trespass_get(hwh->context, path);
 201         if (!rq) {
 202                 DMERR("emc_pg_init: no rq");
 203                 goto fail_path;
 204         }
 205
 206         DMINFO("emc_pg_init: sending switch-over command");
 207         elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
 208         return;
 209
 210 fail_path:
 211         dm_pg_init_complete(path, MP_FAIL_PATH);
 212 }
 213
 214 static struct emc_handler *alloc_emc_handler(void)
 215 {
 216         struct emc_handler *h = kmalloc(sizeof(*h), GFP_KERNEL);
 217
 218         if (h) {
 219                 memset(h, 0, sizeof(*h));
 220                 spin_lock_init(&h->lock);
 221         }
 222
 223         return h;
 224 }
 225
 226 static int emc_create(struct hw_handler *hwh, unsigned argc, char **argv)
 227 {
 228         struct emc_handler *h;
 229         unsigned hr, short_trespass;
 230
 231         if (argc == 0) {
 232                 /* No arguments: use defaults */
 233                 hr = 0;
 234                 short_trespass = 0;
 235         } else if (argc != 2) {
 236                 DMWARN("incorrect number of arguments");
 237                 return -EINVAL;
 238         } else {
 239                 if ((sscanf(argv[0], "%u", &short_trespass) != 1)
 240                         || (short_trespass > 1)) {
 241                         DMWARN("invalid trespass mode selected");
 242                         return -EINVAL;
 243                 }
 244
 245                 if ((sscanf(argv[1], "%u", &hr) != 1)
 246                         || (hr > 1)) {
 247                         DMWARN("invalid honor reservation flag selected");
 248                         return -EINVAL;
 249                 }
 250         }
 251
 252         h = alloc_emc_handler();
 253         if (!h)
 254                 return -ENOMEM;
 255
 256         hwh->context = h;
 257
 258         if ((h->short_trespass = short_trespass))
 259                 DMWARN("short trespass command will be send");
 260         else
 261                 DMWARN("long trespass command will be send");
 262
 263         if ((h->hr = hr))
 264                 DMWARN("honor reservation bit will be set");
 265         else
 266                 DMWARN("honor reservation bit will not be set (default)");
 267
 268         return 0;
 269 }
 270
 271 static void emc_destroy(struct hw_handler *hwh)
 272 {
 273         struct emc_handler *h = (struct emc_handler *) hwh->context;
 274
 275         kfree(h);
 276         hwh->context = NULL;
 277 }
 278
 279 static unsigned emc_error(struct hw_handler *hwh, struct bio *bio)
 280 {
 281         /* FIXME: Patch from axboe still missing */
 282 #if 0
 283         int sense;
 284
 285         if (bio->bi_error & BIO_SENSE) {
 286                 sense = bio->bi_error & 0xffffff; /* sense key / asc / ascq */
 287
 288                 if (sense == 0x020403) {
 289                         /* LUN Not Ready - Manual Intervention Required
 290                          * indicates this is a passive path.
 291                          *
 292                          * FIXME: However, if this is seen and EVPD C0
 293                          * indicates that this is due to a NDU in
 294                          * progress, we should set FAIL_PATH too.
 295                          * This indicates we might have to do a SCSI
 296                          * inquiry in the end_io path. Ugh. */
 297                         return MP_BYPASS_PG | MP_RETRY_IO;
 298                 } else if (sense == 0x052501) {
 299                         /* An array based copy is in progress. Do not
 300                          * fail the path, do not bypass to another PG,
 301                          * do not retry. Fail the IO immediately.
 302                          * (Actually this is the same conclusion as in
 303                          * the default handler, but lets make sure.) */
 304                         return 0;
 305                 } else if (sense == 0x062900) {
 306                         /* Unit Attention Code. This is the first IO
 307                          * to the new path, so just retry. */
 308                         return MP_RETRY_IO;
 309                 }
 310         }
 311 #endif
 312
 313         /* Try default handler */
 314         return dm_scsi_err_handler(hwh, bio);
 315 }
 316
 317 static struct hw_handler_type emc_hwh = {
 318         .name = "emc",
 319         .module = THIS_MODULE,
 320         .create = emc_create,
 321         .destroy = emc_destroy,
 322         .pg_init = emc_pg_init,
 323         .error = emc_error,
 324 };
 325
 326 static int __init dm_emc_init(void)
 327 {
 328         int r = dm_register_hw_handler(&emc_hwh);
 329
 330         if (r < 0)
 331                 DMERR("register failed %d", r);
 332
 333         DMINFO("version 0.0.3 loaded");
 334
 335         return r;
 336 }
 337
 338 static void __exit dm_emc_exit(void)
 339 {
 340         int r = dm_unregister_hw_handler(&emc_hwh);
 341
 342         if (r < 0)
 343                 DMERR("unregister failed %d", r);
 344 }
 345
 346 module_init(dm_emc_init);
 347 module_exit(dm_emc_exit);
 348
 349 MODULE_DESCRIPTION(DM_NAME " EMC CX/AX/FC-family multipath");
 350 MODULE_AUTHOR("Lars Marowsky-Bree <lmb@suse.de>");
 351 MODULE_LICENSE("GPL");