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