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 int emc_endio(struct bio *bio, unsigned int bytes_done, int error)
  42 {
  43         struct path *path = bio->bi_private;
  44
  45         if (bio->bi_size)
  46                 return 1;
  47
  48         /* We also need to look at the sense keys here whether or not to
  49          * switch to the next PG etc.
  50          *
  51          * For now simple logic: either it works or it doesn't.
  52          */
  53         if (error)
  54                 dm_pg_init_complete(path, MP_FAIL_PATH);
  55         else
  56                 dm_pg_init_complete(path, 0);
  57
  58         /* request is freed in block layer */
  59         free_bio(bio);
  60
  61         return 0;
  62 }
  63
  64 static struct bio *get_failover_bio(struct path *path, unsigned data_size)
  65 {
  66         struct bio *bio;
  67         struct page *page;
  68
  69         bio = bio_alloc(GFP_ATOMIC, 1);
  70         if (!bio) {
  71                 DMERR("get_failover_bio: bio_alloc() failed.");
  72                 return NULL;
  73         }
  74
  75         bio->bi_rw |= (1 << BIO_RW);
  76         bio->bi_bdev = path->dev->bdev;
  77         bio->bi_sector = 0;
  78         bio->bi_private = path;
  79         bio->bi_end_io = emc_endio;
  80
  81         page = alloc_page(GFP_ATOMIC);
  82         if (!page) {
  83                 DMERR("get_failover_bio: alloc_page() failed.");
  84                 bio_put(bio);
  85                 return NULL;
  86         }
  87
  88         if (bio_add_page(bio, page, data_size, 0) != data_size) {
  89                 DMERR("get_failover_bio: alloc_page() failed.");
  90                 __free_page(page);
  91                 bio_put(bio);
  92                 return NULL;
  93         }
  94
  95         return bio;
  96 }
  97
  98 static struct request *get_failover_req(struct emc_handler *h,
  99                                         struct bio *bio, struct path *path)
 100 {
 101         struct request *rq;
 102         struct block_device *bdev = bio->bi_bdev;
 103         struct request_queue *q = bdev_get_queue(bdev);
 104
 105         /* FIXME: Figure out why it fails with GFP_ATOMIC. */
 106         rq = blk_get_request(q, WRITE, __GFP_WAIT);
 107         if (!rq) {
 108                 DMERR("get_failover_req: blk_get_request failed");
 109                 return NULL;
 110         }
 111
 112         rq->bio = rq->biotail = bio;
 113         blk_rq_bio_prep(q, rq, bio);
 114
 115         rq->rq_disk = bdev->bd_contains->bd_disk;
 116
 117         /* bio backed don't set data */
 118         rq->buffer = rq->data = NULL;
 119         /* rq data_len used for pc cmd's request_bufflen */
 120         rq->data_len = bio->bi_size;
 121
 122         rq->sense = h->sense;
 123         memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 124         rq->sense_len = 0;
 125
 126         memset(&rq->cmd, 0, BLK_MAX_CDB);
 127
 128         rq->timeout = EMC_FAILOVER_TIMEOUT;
 129         rq->cmd_type = REQ_TYPE_BLOCK_PC;
 130         rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
 131
 132         return rq;
 133 }
 134
 135 static struct request *emc_trespass_get(struct emc_handler *h,
 136                                         struct path *path)
 137 {
 138         struct bio *bio;
 139         struct request *rq;
 140         unsigned char *page22;
 141         unsigned char long_trespass_pg[] = {
 142                 0, 0, 0, 0,
 143                 TRESPASS_PAGE,        /* Page code */
 144                 0x09,                 /* Page length - 2 */
 145                 h->hr ? 0x01 : 0x81,  /* Trespass code + Honor reservation bit */
 146                 0xff, 0xff,           /* Trespass target */
 147                 0, 0, 0, 0, 0, 0      /* Reserved bytes / unknown */
 148                 };
 149         unsigned char short_trespass_pg[] = {
 150                 0, 0, 0, 0,
 151                 TRESPASS_PAGE,        /* Page code */
 152                 0x02,                 /* Page length - 2 */
 153                 h->hr ? 0x01 : 0x81,  /* Trespass code + Honor reservation bit */
 154                 0xff,                 /* Trespass target */
 155                 };
 156         unsigned data_size = h->short_trespass ? sizeof(short_trespass_pg) :
 157                                 sizeof(long_trespass_pg);
 158
 159         /* get bio backing */
 160         if (data_size > PAGE_SIZE)
 161                 /* this should never happen */
 162                 return NULL;
 163
 164         bio = get_failover_bio(path, data_size);
 165         if (!bio) {
 166                 DMERR("emc_trespass_get: no bio");
 167                 return NULL;
 168         }
 169
 170         page22 = (unsigned char *)bio_data(bio);
 171         memset(page22, 0, data_size);
 172
 173         memcpy(page22, h->short_trespass ?
 174                 short_trespass_pg : long_trespass_pg, data_size);
 175
 176         /* get request for block layer packet command */
 177         rq = get_failover_req(h, bio, path);
 178         if (!rq) {
 179                 DMERR("emc_trespass_get: no rq");
 180                 free_bio(bio);
 181                 return NULL;
 182         }
 183
 184         /* Prepare the command. */
 185         rq->cmd[0] = MODE_SELECT;
 186         rq->cmd[1] = 0x10;
 187         rq->cmd[4] = data_size;
 188         rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
 189
 190         return rq;
 191 }
 192
 193 static void emc_pg_init(struct hw_handler *hwh, unsigned bypassed,
 194                         struct path *path)
 195 {
 196         struct request *rq;
 197         struct request_queue *q = bdev_get_queue(path->dev->bdev);
 198
 199         /*
 200          * We can either blindly init the pg (then look at the sense),
 201          * or we can send some commands to get the state here (then
 202          * possibly send the fo cmnd), or we can also have the
 203          * initial state passed into us and then get an update here.
 204          */
 205         if (!q) {
 206                 DMINFO("emc_pg_init: no queue");
 207                 goto fail_path;
 208         }
 209
 210         /* FIXME: The request should be pre-allocated. */
 211         rq = emc_trespass_get(hwh->context, path);
 212         if (!rq) {
 213                 DMERR("emc_pg_init: no rq");
 214                 goto fail_path;
 215         }
 216
 217         DMINFO("emc_pg_init: sending switch-over command");
 218         elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
 219         return;
 220
 221 fail_path:
 222         dm_pg_init_complete(path, MP_FAIL_PATH);
 223 }
 224
 225 static struct emc_handler *alloc_emc_handler(void)
 226 {
 227         struct emc_handler *h = kmalloc(sizeof(*h), GFP_KERNEL);
 228
 229         if (h) {
 230                 memset(h, 0, sizeof(*h));
 231                 spin_lock_init(&h->lock);
 232         }
 233
 234         return h;
 235 }
 236
 237 static int emc_create(struct hw_handler *hwh, unsigned argc, char **argv)
 238 {
 239         struct emc_handler *h;
 240         unsigned hr, short_trespass;
 241
 242         if (argc == 0) {
 243                 /* No arguments: use defaults */
 244                 hr = 0;
 245                 short_trespass = 0;
 246         } else if (argc != 2) {
 247                 DMWARN("incorrect number of arguments");
 248                 return -EINVAL;
 249         } else {
 250                 if ((sscanf(argv[0], "%u", &short_trespass) != 1)
 251                         || (short_trespass > 1)) {
 252                         DMWARN("invalid trespass mode selected");
 253                         return -EINVAL;
 254                 }
 255
 256                 if ((sscanf(argv[1], "%u", &hr) != 1)
 257                         || (hr > 1)) {
 258                         DMWARN("invalid honor reservation flag selected");
 259                         return -EINVAL;
 260                 }
 261         }
 262
 263         h = alloc_emc_handler();
 264         if (!h)
 265                 return -ENOMEM;
 266
 267         hwh->context = h;
 268
 269         if ((h->short_trespass = short_trespass))
 270                 DMWARN("short trespass command will be send");
 271         else
 272                 DMWARN("long trespass command will be send");
 273
 274         if ((h->hr = hr))
 275                 DMWARN("honor reservation bit will be set");
 276         else
 277                 DMWARN("honor reservation bit will not be set (default)");
 278
 279         return 0;
 280 }
 281
 282 static void emc_destroy(struct hw_handler *hwh)
 283 {
 284         struct emc_handler *h = (struct emc_handler *) hwh->context;
 285
 286         kfree(h);
 287         hwh->context = NULL;
 288 }
 289
 290 static unsigned emc_error(struct hw_handler *hwh, struct bio *bio)
 291 {
 292         /* FIXME: Patch from axboe still missing */
 293 #if 0
 294         int sense;
 295
 296         if (bio->bi_error & BIO_SENSE) {
 297                 sense = bio->bi_error & 0xffffff; /* sense key / asc / ascq */
 298
 299                 if (sense == 0x020403) {
 300                         /* LUN Not Ready - Manual Intervention Required
 301                          * indicates this is a passive path.
 302                          *
 303                          * FIXME: However, if this is seen and EVPD C0
 304                          * indicates that this is due to a NDU in
 305                          * progress, we should set FAIL_PATH too.
 306                          * This indicates we might have to do a SCSI
 307                          * inquiry in the end_io path. Ugh. */
 308                         return MP_BYPASS_PG | MP_RETRY_IO;
 309                 } else if (sense == 0x052501) {
 310                         /* An array based copy is in progress. Do not
 311                          * fail the path, do not bypass to another PG,
 312                          * do not retry. Fail the IO immediately.
 313                          * (Actually this is the same conclusion as in
 314                          * the default handler, but lets make sure.) */
 315                         return 0;
 316                 } else if (sense == 0x062900) {
 317                         /* Unit Attention Code. This is the first IO
 318                          * to the new path, so just retry. */
 319                         return MP_RETRY_IO;
 320                 }
 321         }
 322 #endif
 323
 324         /* Try default handler */
 325         return dm_scsi_err_handler(hwh, bio);
 326 }
 327
 328 static struct hw_handler_type emc_hwh = {
 329         .name = "emc",
 330         .module = THIS_MODULE,
 331         .create = emc_create,
 332         .destroy = emc_destroy,
 333         .pg_init = emc_pg_init,
 334         .error = emc_error,
 335 };
 336
 337 static int __init dm_emc_init(void)
 338 {
 339         int r = dm_register_hw_handler(&emc_hwh);
 340
 341         if (r < 0)
 342                 DMERR("register failed %d", r);
 343
 344         DMINFO("version 0.0.3 loaded");
 345
 346         return r;
 347 }
 348
 349 static void __exit dm_emc_exit(void)
 350 {
 351         int r = dm_unregister_hw_handler(&emc_hwh);
 352
 353         if (r < 0)
 354                 DMERR("unregister failed %d", r);
 355 }
 356
 357 module_init(dm_emc_init);
 358 module_exit(dm_emc_exit);
 359
 360 MODULE_DESCRIPTION(DM_NAME " EMC CX/AX/FC-family multipath");
 361 MODULE_AUTHOR("Lars Marowsky-Bree <lmb@suse.de>");
 362 MODULE_LICENSE("GPL");