drivers/s390/block/scm_blk.c

   1 /*
   2  * Block driver for s390 storage class memory.
   3  *
   4  * Copyright IBM Corp. 2012
   5  * Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
   6  */
   7
   8 #define KMSG_COMPONENT "scm_block"
   9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11 #include <linux/interrupt.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/module.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/genhd.h>
  16 #include <linux/slab.h>
  17 #include <linux/list.h>
  18 #include <asm/eadm.h>
  19 #include "scm_blk.h"
  20
  21 debug_info_t *scm_debug;
  22 static int scm_major;
  23 static DEFINE_SPINLOCK(list_lock);
  24 static LIST_HEAD(inactive_requests);
  25 static unsigned int nr_requests = 64;
  26 static atomic_t nr_devices = ATOMIC_INIT(0);
  27 module_param(nr_requests, uint, S_IRUGO);
  28 MODULE_PARM_DESC(nr_requests, "Number of parallel requests.");
  29
  30 MODULE_DESCRIPTION("Block driver for s390 storage class memory.");
  31 MODULE_LICENSE("GPL");
  32 MODULE_ALIAS("scm:scmdev*");
  33
  34 static void __scm_free_rq(struct scm_request *scmrq)
  35 {
  36         struct aob_rq_header *aobrq = to_aobrq(scmrq);
  37
  38         free_page((unsigned long) scmrq->aob);
  39         free_page((unsigned long) scmrq->aidaw);
  40         __scm_free_rq_cluster(scmrq);
  41         kfree(aobrq);
  42 }
  43
  44 static void scm_free_rqs(void)
  45 {
  46         struct list_head *iter, *safe;
  47         struct scm_request *scmrq;
  48
  49         spin_lock_irq(&list_lock);
  50         list_for_each_safe(iter, safe, &inactive_requests) {
  51                 scmrq = list_entry(iter, struct scm_request, list);
  52                 list_del(&scmrq->list);
  53                 __scm_free_rq(scmrq);
  54         }
  55         spin_unlock_irq(&list_lock);
  56 }
  57
  58 static int __scm_alloc_rq(void)
  59 {
  60         struct aob_rq_header *aobrq;
  61         struct scm_request *scmrq;
  62
  63         aobrq = kzalloc(sizeof(*aobrq) + sizeof(*scmrq), GFP_KERNEL);
  64         if (!aobrq)
  65                 return -ENOMEM;
  66
  67         scmrq = (void *) aobrq->data;
  68         scmrq->aidaw = (void *) get_zeroed_page(GFP_DMA);
  69         scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
  70         if (!scmrq->aob || !scmrq->aidaw) {
  71                 __scm_free_rq(scmrq);
  72                 return -ENOMEM;
  73         }
  74
  75         if (__scm_alloc_rq_cluster(scmrq)) {
  76                 __scm_free_rq(scmrq);
  77                 return -ENOMEM;
  78         }
  79
  80         INIT_LIST_HEAD(&scmrq->list);
  81         spin_lock_irq(&list_lock);
  82         list_add(&scmrq->list, &inactive_requests);
  83         spin_unlock_irq(&list_lock);
  84
  85         return 0;
  86 }
  87
  88 static int scm_alloc_rqs(unsigned int nrqs)
  89 {
  90         int ret = 0;
  91
  92         while (nrqs-- && !ret)
  93                 ret = __scm_alloc_rq();
  94
  95         return ret;
  96 }
  97
  98 static struct scm_request *scm_request_fetch(void)
  99 {
 100         struct scm_request *scmrq = NULL;
 101
 102         spin_lock(&list_lock);
 103         if (list_empty(&inactive_requests))
 104                 goto out;
 105         scmrq = list_first_entry(&inactive_requests, struct scm_request, list);
 106         list_del(&scmrq->list);
 107 out:
 108         spin_unlock(&list_lock);
 109         return scmrq;
 110 }
 111
 112 static void scm_request_done(struct scm_request *scmrq)
 113 {
 114         unsigned long flags;
 115
 116         spin_lock_irqsave(&list_lock, flags);
 117         list_add(&scmrq->list, &inactive_requests);
 118         spin_unlock_irqrestore(&list_lock, flags);
 119 }
 120
 121 static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
 122 {
 123         return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
 124 }
 125
 126 static void scm_request_prepare(struct scm_request *scmrq)
 127 {
 128         struct scm_blk_dev *bdev = scmrq->bdev;
 129         struct scm_device *scmdev = bdev->gendisk->private_data;
 130         struct aidaw *aidaw = scmrq->aidaw;
 131         struct msb *msb = &scmrq->aob->msb[0];
 132         struct req_iterator iter;
 133         struct bio_vec bv;
 134
 135         msb->bs = MSB_BS_4K;
 136         scmrq->aob->request.msb_count = 1;
 137         msb->scm_addr = scmdev->address +
 138                 ((u64) blk_rq_pos(scmrq->request) << 9);
 139         msb->oc = (rq_data_dir(scmrq->request) == READ) ?
 140                 MSB_OC_READ : MSB_OC_WRITE;
 141         msb->flags |= MSB_FLAG_IDA;
 142         msb->data_addr = (u64) aidaw;
 143
 144         rq_for_each_segment(bv, scmrq->request, iter) {
 145                 WARN_ON(bv.bv_offset);
 146                 msb->blk_count += bv.bv_len >> 12;
 147                 aidaw->data_addr = (u64) page_address(bv.bv_page);
 148                 aidaw++;
 149         }
 150 }
 151
 152 static inline void scm_request_init(struct scm_blk_dev *bdev,
 153                                     struct scm_request *scmrq,
 154                                     struct request *req)
 155 {
 156         struct aob_rq_header *aobrq = to_aobrq(scmrq);
 157         struct aob *aob = scmrq->aob;
 158
 159         memset(aob, 0, sizeof(*aob));
 160         memset(scmrq->aidaw, 0, PAGE_SIZE);
 161         aobrq->scmdev = bdev->scmdev;
 162         aob->request.cmd_code = ARQB_CMD_MOVE;
 163         aob->request.data = (u64) aobrq;
 164         scmrq->request = req;
 165         scmrq->bdev = bdev;
 166         scmrq->retries = 4;
 167         scmrq->error = 0;
 168         scm_request_cluster_init(scmrq);
 169 }
 170
 171 static void scm_ensure_queue_restart(struct scm_blk_dev *bdev)
 172 {
 173         if (atomic_read(&bdev->queued_reqs)) {
 174                 /* Queue restart is triggered by the next interrupt. */
 175                 return;
 176         }
 177         blk_delay_queue(bdev->rq, SCM_QUEUE_DELAY);
 178 }
 179
 180 void scm_request_requeue(struct scm_request *scmrq)
 181 {
 182         struct scm_blk_dev *bdev = scmrq->bdev;
 183
 184         scm_release_cluster(scmrq);
 185         blk_requeue_request(bdev->rq, scmrq->request);
 186         atomic_dec(&bdev->queued_reqs);
 187         scm_request_done(scmrq);
 188         scm_ensure_queue_restart(bdev);
 189 }
 190
 191 void scm_request_finish(struct scm_request *scmrq)
 192 {
 193         struct scm_blk_dev *bdev = scmrq->bdev;
 194
 195         scm_release_cluster(scmrq);
 196         blk_end_request_all(scmrq->request, scmrq->error);
 197         atomic_dec(&bdev->queued_reqs);
 198         scm_request_done(scmrq);
 199 }
 200
 201 static void scm_blk_request(struct request_queue *rq)
 202 {
 203         struct scm_device *scmdev = rq->queuedata;
 204         struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
 205         struct scm_request *scmrq;
 206         struct request *req;
 207         int ret;
 208
 209         while ((req = blk_peek_request(rq))) {
 210                 if (req->cmd_type != REQ_TYPE_FS) {
 211                         blk_start_request(req);
 212                         blk_dump_rq_flags(req, KMSG_COMPONENT " bad request");
 213                         blk_end_request_all(req, -EIO);
 214                         continue;
 215                 }
 216
 217                 if (!scm_permit_request(bdev, req)) {
 218                         scm_ensure_queue_restart(bdev);
 219                         return;
 220                 }
 221                 scmrq = scm_request_fetch();
 222                 if (!scmrq) {
 223                         SCM_LOG(5, "no request");
 224                         scm_ensure_queue_restart(bdev);
 225                         return;
 226                 }
 227                 scm_request_init(bdev, scmrq, req);
 228                 if (!scm_reserve_cluster(scmrq)) {
 229                         SCM_LOG(5, "cluster busy");
 230                         scm_request_done(scmrq);
 231                         return;
 232                 }
 233                 if (scm_need_cluster_request(scmrq)) {
 234                         atomic_inc(&bdev->queued_reqs);
 235                         blk_start_request(req);
 236                         scm_initiate_cluster_request(scmrq);
 237                         return;
 238                 }
 239                 scm_request_prepare(scmrq);
 240                 atomic_inc(&bdev->queued_reqs);
 241                 blk_start_request(req);
 242
 243                 ret = eadm_start_aob(scmrq->aob);
 244                 if (ret) {
 245                         SCM_LOG(5, "no subchannel");
 246                         scm_request_requeue(scmrq);
 247                         return;
 248                 }
 249         }
 250 }
 251
 252 static void __scmrq_log_error(struct scm_request *scmrq)
 253 {
 254         struct aob *aob = scmrq->aob;
 255
 256         if (scmrq->error == -ETIMEDOUT)
 257                 SCM_LOG(1, "Request timeout");
 258         else {
 259                 SCM_LOG(1, "Request error");
 260                 SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
 261         }
 262         if (scmrq->retries)
 263                 SCM_LOG(1, "Retry request");
 264         else
 265                 pr_err("An I/O operation to SCM failed with rc=%d\n",
 266                        scmrq->error);
 267 }
 268
 269 void scm_blk_irq(struct scm_device *scmdev, void *data, int error)
 270 {
 271         struct scm_request *scmrq = data;
 272         struct scm_blk_dev *bdev = scmrq->bdev;
 273
 274         scmrq->error = error;
 275         if (error)
 276                 __scmrq_log_error(scmrq);
 277
 278         spin_lock(&bdev->lock);
 279         list_add_tail(&scmrq->list, &bdev->finished_requests);
 280         spin_unlock(&bdev->lock);
 281         tasklet_hi_schedule(&bdev->tasklet);
 282 }
 283
 284 static void scm_blk_handle_error(struct scm_request *scmrq)
 285 {
 286         struct scm_blk_dev *bdev = scmrq->bdev;
 287         unsigned long flags;
 288
 289         if (scmrq->error != -EIO)
 290                 goto restart;
 291
 292         /* For -EIO the response block is valid. */
 293         switch (scmrq->aob->response.eqc) {
 294         case EQC_WR_PROHIBIT:
 295                 spin_lock_irqsave(&bdev->lock, flags);
 296                 if (bdev->state != SCM_WR_PROHIBIT)
 297                         pr_info("%lx: Write access to the SCM increment is suspended\n",
 298                                 (unsigned long) bdev->scmdev->address);
 299                 bdev->state = SCM_WR_PROHIBIT;
 300                 spin_unlock_irqrestore(&bdev->lock, flags);
 301                 goto requeue;
 302         default:
 303                 break;
 304         }
 305
 306 restart:
 307         if (!eadm_start_aob(scmrq->aob))
 308                 return;
 309
 310 requeue:
 311         spin_lock_irqsave(&bdev->rq_lock, flags);
 312         scm_request_requeue(scmrq);
 313         spin_unlock_irqrestore(&bdev->rq_lock, flags);
 314 }
 315
 316 static void scm_blk_tasklet(struct scm_blk_dev *bdev)
 317 {
 318         struct scm_request *scmrq;
 319         unsigned long flags;
 320
 321         spin_lock_irqsave(&bdev->lock, flags);
 322         while (!list_empty(&bdev->finished_requests)) {
 323                 scmrq = list_first_entry(&bdev->finished_requests,
 324                                          struct scm_request, list);
 325                 list_del(&scmrq->list);
 326                 spin_unlock_irqrestore(&bdev->lock, flags);
 327
 328                 if (scmrq->error && scmrq->retries-- > 0) {
 329                         scm_blk_handle_error(scmrq);
 330
 331                         /* Request restarted or requeued, handle next. */
 332                         spin_lock_irqsave(&bdev->lock, flags);
 333                         continue;
 334                 }
 335
 336                 if (scm_test_cluster_request(scmrq)) {
 337                         scm_cluster_request_irq(scmrq);
 338                         spin_lock_irqsave(&bdev->lock, flags);
 339                         continue;
 340                 }
 341
 342                 scm_request_finish(scmrq);
 343                 spin_lock_irqsave(&bdev->lock, flags);
 344         }
 345         spin_unlock_irqrestore(&bdev->lock, flags);
 346         /* Look out for more requests. */
 347         blk_run_queue(bdev->rq);
 348 }
 349
 350 static const struct block_device_operations scm_blk_devops = {
 351         .owner = THIS_MODULE,
 352 };
 353
 354 int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
 355 {
 356         struct request_queue *rq;
 357         int len, ret = -ENOMEM;
 358         unsigned int devindex, nr_max_blk;
 359
 360         devindex = atomic_inc_return(&nr_devices) - 1;
 361         /* scma..scmz + scmaa..scmzz */
 362         if (devindex > 701) {
 363                 ret = -ENODEV;
 364                 goto out;
 365         }
 366
 367         bdev->scmdev = scmdev;
 368         bdev->state = SCM_OPER;
 369         spin_lock_init(&bdev->rq_lock);
 370         spin_lock_init(&bdev->lock);
 371         INIT_LIST_HEAD(&bdev->finished_requests);
 372         atomic_set(&bdev->queued_reqs, 0);
 373         tasklet_init(&bdev->tasklet,
 374                      (void (*)(unsigned long)) scm_blk_tasklet,
 375                      (unsigned long) bdev);
 376
 377         rq = blk_init_queue(scm_blk_request, &bdev->rq_lock);
 378         if (!rq)
 379                 goto out;
 380
 381         bdev->rq = rq;
 382         nr_max_blk = min(scmdev->nr_max_block,
 383                          (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
 384
 385         blk_queue_logical_block_size(rq, 1 << 12);
 386         blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
 387         blk_queue_max_segments(rq, nr_max_blk);
 388         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
 389         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, rq);
 390         scm_blk_dev_cluster_setup(bdev);
 391
 392         bdev->gendisk = alloc_disk(SCM_NR_PARTS);
 393         if (!bdev->gendisk)
 394                 goto out_queue;
 395
 396         rq->queuedata = scmdev;
 397         bdev->gendisk->driverfs_dev = &scmdev->dev;
 398         bdev->gendisk->private_data = scmdev;
 399         bdev->gendisk->fops = &scm_blk_devops;
 400         bdev->gendisk->queue = rq;
 401         bdev->gendisk->major = scm_major;
 402         bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
 403
 404         len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
 405         if (devindex > 25) {
 406                 len += snprintf(bdev->gendisk->disk_name + len,
 407                                 DISK_NAME_LEN - len, "%c",
 408                                 'a' + (devindex / 26) - 1);
 409                 devindex = devindex % 26;
 410         }
 411         snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
 412                  'a' + devindex);
 413
 414         /* 512 byte sectors */
 415         set_capacity(bdev->gendisk, scmdev->size >> 9);
 416         add_disk(bdev->gendisk);
 417         return 0;
 418
 419 out_queue:
 420         blk_cleanup_queue(rq);
 421 out:
 422         atomic_dec(&nr_devices);
 423         return ret;
 424 }
 425
 426 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
 427 {
 428         tasklet_kill(&bdev->tasklet);
 429         del_gendisk(bdev->gendisk);
 430         blk_cleanup_queue(bdev->gendisk->queue);
 431         put_disk(bdev->gendisk);
 432 }
 433
 434 void scm_blk_set_available(struct scm_blk_dev *bdev)
 435 {
 436         unsigned long flags;
 437
 438         spin_lock_irqsave(&bdev->lock, flags);
 439         if (bdev->state == SCM_WR_PROHIBIT)
 440                 pr_info("%lx: Write access to the SCM increment is restored\n",
 441                         (unsigned long) bdev->scmdev->address);
 442         bdev->state = SCM_OPER;
 443         spin_unlock_irqrestore(&bdev->lock, flags);
 444 }
 445
 446 static int __init scm_blk_init(void)
 447 {
 448         int ret = -EINVAL;
 449
 450         if (!scm_cluster_size_valid())
 451                 goto out;
 452
 453         ret = register_blkdev(0, "scm");
 454         if (ret < 0)
 455                 goto out;
 456
 457         scm_major = ret;
 458         ret = scm_alloc_rqs(nr_requests);
 459         if (ret)
 460                 goto out_free;
 461
 462         scm_debug = debug_register("scm_log", 16, 1, 16);
 463         if (!scm_debug) {
 464                 ret = -ENOMEM;
 465                 goto out_free;
 466         }
 467
 468         debug_register_view(scm_debug, &debug_hex_ascii_view);
 469         debug_set_level(scm_debug, 2);
 470
 471         ret = scm_drv_init();
 472         if (ret)
 473                 goto out_dbf;
 474
 475         return ret;
 476
 477 out_dbf:
 478         debug_unregister(scm_debug);
 479 out_free:
 480         scm_free_rqs();
 481         unregister_blkdev(scm_major, "scm");
 482 out:
 483         return ret;
 484 }
 485 module_init(scm_blk_init);
 486
 487 static void __exit scm_blk_cleanup(void)
 488 {
 489         scm_drv_cleanup();
 490         debug_unregister(scm_debug);
 491         scm_free_rqs();
 492         unregister_blkdev(scm_major, "scm");
 493 }
 494 module_exit(scm_blk_cleanup);