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 int scm_open(struct block_device *blkdev, fmode_t mode)
 122 {
 123         return scm_get_ref();
 124 }
 125
 126 static int scm_release(struct gendisk *gendisk, fmode_t mode)
 127 {
 128         scm_put_ref();
 129         return 0;
 130 }
 131
 132 static const struct block_device_operations scm_blk_devops = {
 133         .owner = THIS_MODULE,
 134         .open = scm_open,
 135         .release = scm_release,
 136 };
 137
 138 static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
 139 {
 140         return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
 141 }
 142
 143 static void scm_request_prepare(struct scm_request *scmrq)
 144 {
 145         struct scm_blk_dev *bdev = scmrq->bdev;
 146         struct scm_device *scmdev = bdev->gendisk->private_data;
 147         struct aidaw *aidaw = scmrq->aidaw;
 148         struct msb *msb = &scmrq->aob->msb[0];
 149         struct req_iterator iter;
 150         struct bio_vec *bv;
 151
 152         msb->bs = MSB_BS_4K;
 153         scmrq->aob->request.msb_count = 1;
 154         msb->scm_addr = scmdev->address +
 155                 ((u64) blk_rq_pos(scmrq->request) << 9);
 156         msb->oc = (rq_data_dir(scmrq->request) == READ) ?
 157                 MSB_OC_READ : MSB_OC_WRITE;
 158         msb->flags |= MSB_FLAG_IDA;
 159         msb->data_addr = (u64) aidaw;
 160
 161         rq_for_each_segment(bv, scmrq->request, iter) {
 162                 WARN_ON(bv->bv_offset);
 163                 msb->blk_count += bv->bv_len >> 12;
 164                 aidaw->data_addr = (u64) page_address(bv->bv_page);
 165                 aidaw++;
 166         }
 167 }
 168
 169 static inline void scm_request_init(struct scm_blk_dev *bdev,
 170                                     struct scm_request *scmrq,
 171                                     struct request *req)
 172 {
 173         struct aob_rq_header *aobrq = to_aobrq(scmrq);
 174         struct aob *aob = scmrq->aob;
 175
 176         memset(aob, 0, sizeof(*aob));
 177         memset(scmrq->aidaw, 0, PAGE_SIZE);
 178         aobrq->scmdev = bdev->scmdev;
 179         aob->request.cmd_code = ARQB_CMD_MOVE;
 180         aob->request.data = (u64) aobrq;
 181         scmrq->request = req;
 182         scmrq->bdev = bdev;
 183         scmrq->retries = 4;
 184         scmrq->error = 0;
 185         scm_request_cluster_init(scmrq);
 186 }
 187
 188 static void scm_ensure_queue_restart(struct scm_blk_dev *bdev)
 189 {
 190         if (atomic_read(&bdev->queued_reqs)) {
 191                 /* Queue restart is triggered by the next interrupt. */
 192                 return;
 193         }
 194         blk_delay_queue(bdev->rq, SCM_QUEUE_DELAY);
 195 }
 196
 197 void scm_request_requeue(struct scm_request *scmrq)
 198 {
 199         struct scm_blk_dev *bdev = scmrq->bdev;
 200
 201         scm_release_cluster(scmrq);
 202         blk_requeue_request(bdev->rq, scmrq->request);
 203         atomic_dec(&bdev->queued_reqs);
 204         scm_request_done(scmrq);
 205         scm_ensure_queue_restart(bdev);
 206 }
 207
 208 void scm_request_finish(struct scm_request *scmrq)
 209 {
 210         struct scm_blk_dev *bdev = scmrq->bdev;
 211
 212         scm_release_cluster(scmrq);
 213         blk_end_request_all(scmrq->request, scmrq->error);
 214         atomic_dec(&bdev->queued_reqs);
 215         scm_request_done(scmrq);
 216 }
 217
 218 static void scm_blk_request(struct request_queue *rq)
 219 {
 220         struct scm_device *scmdev = rq->queuedata;
 221         struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
 222         struct scm_request *scmrq;
 223         struct request *req;
 224         int ret;
 225
 226         while ((req = blk_peek_request(rq))) {
 227                 if (req->cmd_type != REQ_TYPE_FS)
 228                         continue;
 229
 230                 if (!scm_permit_request(bdev, req)) {
 231                         scm_ensure_queue_restart(bdev);
 232                         return;
 233                 }
 234                 scmrq = scm_request_fetch();
 235                 if (!scmrq) {
 236                         SCM_LOG(5, "no request");
 237                         scm_ensure_queue_restart(bdev);
 238                         return;
 239                 }
 240                 scm_request_init(bdev, scmrq, req);
 241                 if (!scm_reserve_cluster(scmrq)) {
 242                         SCM_LOG(5, "cluster busy");
 243                         scm_request_done(scmrq);
 244                         return;
 245                 }
 246                 if (scm_need_cluster_request(scmrq)) {
 247                         atomic_inc(&bdev->queued_reqs);
 248                         blk_start_request(req);
 249                         scm_initiate_cluster_request(scmrq);
 250                         return;
 251                 }
 252                 scm_request_prepare(scmrq);
 253                 atomic_inc(&bdev->queued_reqs);
 254                 blk_start_request(req);
 255
 256                 ret = scm_start_aob(scmrq->aob);
 257                 if (ret) {
 258                         SCM_LOG(5, "no subchannel");
 259                         scm_request_requeue(scmrq);
 260                         return;
 261                 }
 262         }
 263 }
 264
 265 static void __scmrq_log_error(struct scm_request *scmrq)
 266 {
 267         struct aob *aob = scmrq->aob;
 268
 269         if (scmrq->error == -ETIMEDOUT)
 270                 SCM_LOG(1, "Request timeout");
 271         else {
 272                 SCM_LOG(1, "Request error");
 273                 SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
 274         }
 275         if (scmrq->retries)
 276                 SCM_LOG(1, "Retry request");
 277         else
 278                 pr_err("An I/O operation to SCM failed with rc=%d\n",
 279                        scmrq->error);
 280 }
 281
 282 void scm_blk_irq(struct scm_device *scmdev, void *data, int error)
 283 {
 284         struct scm_request *scmrq = data;
 285         struct scm_blk_dev *bdev = scmrq->bdev;
 286
 287         scmrq->error = error;
 288         if (error)
 289                 __scmrq_log_error(scmrq);
 290
 291         spin_lock(&bdev->lock);
 292         list_add_tail(&scmrq->list, &bdev->finished_requests);
 293         spin_unlock(&bdev->lock);
 294         tasklet_hi_schedule(&bdev->tasklet);
 295 }
 296
 297 static void scm_blk_handle_error(struct scm_request *scmrq)
 298 {
 299         struct scm_blk_dev *bdev = scmrq->bdev;
 300         unsigned long flags;
 301
 302         if (scmrq->error != -EIO)
 303                 goto restart;
 304
 305         /* For -EIO the response block is valid. */
 306         switch (scmrq->aob->response.eqc) {
 307         case EQC_WR_PROHIBIT:
 308                 spin_lock_irqsave(&bdev->lock, flags);
 309                 if (bdev->state != SCM_WR_PROHIBIT)
 310                         pr_info("%lx: Write access to the SCM increment is suspended\n",
 311                                 (unsigned long) bdev->scmdev->address);
 312                 bdev->state = SCM_WR_PROHIBIT;
 313                 spin_unlock_irqrestore(&bdev->lock, flags);
 314                 goto requeue;
 315         default:
 316                 break;
 317         }
 318
 319 restart:
 320         if (!scm_start_aob(scmrq->aob))
 321                 return;
 322
 323 requeue:
 324         spin_lock_irqsave(&bdev->rq_lock, flags);
 325         scm_request_requeue(scmrq);
 326         spin_unlock_irqrestore(&bdev->rq_lock, flags);
 327 }
 328
 329 static void scm_blk_tasklet(struct scm_blk_dev *bdev)
 330 {
 331         struct scm_request *scmrq;
 332         unsigned long flags;
 333
 334         spin_lock_irqsave(&bdev->lock, flags);
 335         while (!list_empty(&bdev->finished_requests)) {
 336                 scmrq = list_first_entry(&bdev->finished_requests,
 337                                          struct scm_request, list);
 338                 list_del(&scmrq->list);
 339                 spin_unlock_irqrestore(&bdev->lock, flags);
 340
 341                 if (scmrq->error && scmrq->retries-- > 0) {
 342                         scm_blk_handle_error(scmrq);
 343
 344                         /* Request restarted or requeued, handle next. */
 345                         spin_lock_irqsave(&bdev->lock, flags);
 346                         continue;
 347                 }
 348
 349                 if (scm_test_cluster_request(scmrq)) {
 350                         scm_cluster_request_irq(scmrq);
 351                         spin_lock_irqsave(&bdev->lock, flags);
 352                         continue;
 353                 }
 354
 355                 scm_request_finish(scmrq);
 356                 spin_lock_irqsave(&bdev->lock, flags);
 357         }
 358         spin_unlock_irqrestore(&bdev->lock, flags);
 359         /* Look out for more requests. */
 360         blk_run_queue(bdev->rq);
 361 }
 362
 363 int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
 364 {
 365         struct request_queue *rq;
 366         int len, ret = -ENOMEM;
 367         unsigned int devindex, nr_max_blk;
 368
 369         devindex = atomic_inc_return(&nr_devices) - 1;
 370         /* scma..scmz + scmaa..scmzz */
 371         if (devindex > 701) {
 372                 ret = -ENODEV;
 373                 goto out;
 374         }
 375
 376         bdev->scmdev = scmdev;
 377         bdev->state = SCM_OPER;
 378         spin_lock_init(&bdev->rq_lock);
 379         spin_lock_init(&bdev->lock);
 380         INIT_LIST_HEAD(&bdev->finished_requests);
 381         atomic_set(&bdev->queued_reqs, 0);
 382         tasklet_init(&bdev->tasklet,
 383                      (void (*)(unsigned long)) scm_blk_tasklet,
 384                      (unsigned long) bdev);
 385
 386         rq = blk_init_queue(scm_blk_request, &bdev->rq_lock);
 387         if (!rq)
 388                 goto out;
 389
 390         bdev->rq = rq;
 391         nr_max_blk = min(scmdev->nr_max_block,
 392                          (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
 393
 394         blk_queue_logical_block_size(rq, 1 << 12);
 395         blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
 396         blk_queue_max_segments(rq, nr_max_blk);
 397         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rq);
 398         scm_blk_dev_cluster_setup(bdev);
 399
 400         bdev->gendisk = alloc_disk(SCM_NR_PARTS);
 401         if (!bdev->gendisk)
 402                 goto out_queue;
 403
 404         rq->queuedata = scmdev;
 405         bdev->gendisk->driverfs_dev = &scmdev->dev;
 406         bdev->gendisk->private_data = scmdev;
 407         bdev->gendisk->fops = &scm_blk_devops;
 408         bdev->gendisk->queue = rq;
 409         bdev->gendisk->major = scm_major;
 410         bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
 411
 412         len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
 413         if (devindex > 25) {
 414                 len += snprintf(bdev->gendisk->disk_name + len,
 415                                 DISK_NAME_LEN - len, "%c",
 416                                 'a' + (devindex / 26) - 1);
 417                 devindex = devindex % 26;
 418         }
 419         snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
 420                  'a' + devindex);
 421
 422         /* 512 byte sectors */
 423         set_capacity(bdev->gendisk, scmdev->size >> 9);
 424         add_disk(bdev->gendisk);
 425         return 0;
 426
 427 out_queue:
 428         blk_cleanup_queue(rq);
 429 out:
 430         atomic_dec(&nr_devices);
 431         return ret;
 432 }
 433
 434 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
 435 {
 436         tasklet_kill(&bdev->tasklet);
 437         del_gendisk(bdev->gendisk);
 438         blk_cleanup_queue(bdev->gendisk->queue);
 439         put_disk(bdev->gendisk);
 440 }
 441
 442 void scm_blk_set_available(struct scm_blk_dev *bdev)
 443 {
 444         unsigned long flags;
 445
 446         spin_lock_irqsave(&bdev->lock, flags);
 447         if (bdev->state == SCM_WR_PROHIBIT)
 448                 pr_info("%lx: Write access to the SCM increment is restored\n",
 449                         (unsigned long) bdev->scmdev->address);
 450         bdev->state = SCM_OPER;
 451         spin_unlock_irqrestore(&bdev->lock, flags);
 452 }
 453
 454 static int __init scm_blk_init(void)
 455 {
 456         int ret = -EINVAL;
 457
 458         if (!scm_cluster_size_valid())
 459                 goto out;
 460
 461         ret = register_blkdev(0, "scm");
 462         if (ret < 0)
 463                 goto out;
 464
 465         scm_major = ret;
 466         ret = scm_alloc_rqs(nr_requests);
 467         if (ret)
 468                 goto out_unreg;
 469
 470         scm_debug = debug_register("scm_log", 16, 1, 16);
 471         if (!scm_debug) {
 472                 ret = -ENOMEM;
 473                 goto out_free;
 474         }
 475
 476         debug_register_view(scm_debug, &debug_hex_ascii_view);
 477         debug_set_level(scm_debug, 2);
 478
 479         ret = scm_drv_init();
 480         if (ret)
 481                 goto out_dbf;
 482
 483         return ret;
 484
 485 out_dbf:
 486         debug_unregister(scm_debug);
 487 out_free:
 488         scm_free_rqs();
 489 out_unreg:
 490         unregister_blkdev(scm_major, "scm");
 491 out:
 492         return ret;
 493 }
 494 module_init(scm_blk_init);
 495
 496 static void __exit scm_blk_cleanup(void)
 497 {
 498         scm_drv_cleanup();
 499         debug_unregister(scm_debug);
 500         scm_free_rqs();
 501         unregister_blkdev(scm_major, "scm");
 502 }
 503 module_exit(scm_blk_cleanup);