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