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