drivers/s390/char/tape_block.c

   1 /*
   2  *  drivers/s390/char/tape_block.c
   3  *    block device frontend for tape device driver
   4  *
   5  *  S390 and zSeries version
   6  *    Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *    Author(s): Carsten Otte <cotte@de.ibm.com>
   8  *               Tuan Ngo-Anh <ngoanh@de.ibm.com>
   9  *               Martin Schwidefsky <schwidefsky@de.ibm.com>
  10  *               Stefan Bader <shbader@de.ibm.com>
  11  */
  12
  13 #define KMSG_COMPONENT "tape"
  14 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  15
  16 #include <linux/fs.h>
  17 #include <linux/module.h>
  18 #include <linux/blkdev.h>
  19 #include <linux/mutex.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/kernel.h>
  23
  24 #include <asm/debug.h>
  25
  26 #define TAPE_DBF_AREA   tape_core_dbf
  27
  28 #include "tape.h"
  29
  30 #define TAPEBLOCK_MAX_SEC       100
  31 #define TAPEBLOCK_MIN_REQUEUE   3
  32
  33 /*
  34  * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
  35  *
  36  * In 2.5/2.6 the block device request function is very likely to be called
  37  * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
  38  * just call any function that tries to allocate CCW requests from that con-
  39  * text since it might sleep. There are two choices to work around this:
  40  *      a) do not allocate with kmalloc but use its own memory pool
  41  *      b) take requests from the queue outside that context, knowing that
  42  *         allocation might sleep
  43  */
  44
  45 /*
  46  * file operation structure for tape block frontend
  47  */
  48 static DEFINE_MUTEX(tape_block_mutex);
  49 static int tapeblock_open(struct block_device *, fmode_t);
  50 static int tapeblock_release(struct gendisk *, fmode_t);
  51 static unsigned int tapeblock_check_events(struct gendisk *, unsigned int);
  52 static int tapeblock_revalidate_disk(struct gendisk *);
  53
  54 static const struct block_device_operations tapeblock_fops = {
  55         .owner           = THIS_MODULE,
  56         .open            = tapeblock_open,
  57         .release         = tapeblock_release,
  58         .check_events    = tapeblock_check_events,
  59         .revalidate_disk = tapeblock_revalidate_disk,
  60 };
  61
  62 static int tapeblock_major = 0;
  63
  64 static void
  65 tapeblock_trigger_requeue(struct tape_device *device)
  66 {
  67         /* Protect against rescheduling. */
  68         if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
  69                 return;
  70         schedule_work(&device->blk_data.requeue_task);
  71 }
  72
  73 /*
  74  * Post finished request.
  75  */
  76 static void
  77 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  78 {
  79         struct tape_device *device;
  80         struct request *req;
  81
  82         DBF_LH(6, "__tapeblock_end_request()\n");
  83
  84         device = ccw_req->device;
  85         req = (struct request *) data;
  86         blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
  87         if (ccw_req->rc == 0)
  88                 /* Update position. */
  89                 device->blk_data.block_position =
  90                   (blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
  91         else
  92                 /* We lost the position information due to an error. */
  93                 device->blk_data.block_position = -1;
  94         device->discipline->free_bread(ccw_req);
  95         if (!list_empty(&device->req_queue) ||
  96             blk_peek_request(device->blk_data.request_queue))
  97                 tapeblock_trigger_requeue(device);
  98 }
  99
 100 /*
 101  * Feed the tape device CCW queue with requests supplied in a list.
 102  */
 103 static int
 104 tapeblock_start_request(struct tape_device *device, struct request *req)
 105 {
 106         struct tape_request *   ccw_req;
 107         int                     rc;
 108
 109         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 110
 111         ccw_req = device->discipline->bread(device, req);
 112         if (IS_ERR(ccw_req)) {
 113                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 114                 blk_end_request_all(req, -EIO);
 115                 return PTR_ERR(ccw_req);
 116         }
 117         ccw_req->callback = __tapeblock_end_request;
 118         ccw_req->callback_data = (void *) req;
 119         ccw_req->retries = TAPEBLOCK_RETRIES;
 120
 121         rc = tape_do_io_async(device, ccw_req);
 122         if (rc) {
 123                 /*
 124                  * Start/enqueueing failed. No retries in
 125                  * this case.
 126                  */
 127                 blk_end_request_all(req, -EIO);
 128                 device->discipline->free_bread(ccw_req);
 129         }
 130
 131         return rc;
 132 }
 133
 134 /*
 135  * Move requests from the block device request queue to the tape device ccw
 136  * queue.
 137  */
 138 static void
 139 tapeblock_requeue(struct work_struct *work) {
 140         struct tape_blk_data *  blkdat;
 141         struct tape_device *    device;
 142         struct request_queue *  queue;
 143         int                     nr_queued;
 144         struct request *        req;
 145         struct list_head *      l;
 146         int                     rc;
 147
 148         blkdat = container_of(work, struct tape_blk_data, requeue_task);
 149         device = blkdat->device;
 150         if (!device)
 151                 return;
 152
 153         spin_lock_irq(get_ccwdev_lock(device->cdev));
 154         queue  = device->blk_data.request_queue;
 155
 156         /* Count number of requests on ccw queue. */
 157         nr_queued = 0;
 158         list_for_each(l, &device->req_queue)
 159                 nr_queued++;
 160         spin_unlock(get_ccwdev_lock(device->cdev));
 161
 162         spin_lock_irq(&device->blk_data.request_queue_lock);
 163         while (
 164                 blk_peek_request(queue) &&
 165                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 166         ) {
 167                 req = blk_fetch_request(queue);
 168                 if (rq_data_dir(req) == WRITE) {
 169                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 170                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 171                         blk_end_request_all(req, -EIO);
 172                         spin_lock_irq(&device->blk_data.request_queue_lock);
 173                         continue;
 174                 }
 175                 nr_queued++;
 176                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 177                 rc = tapeblock_start_request(device, req);
 178                 spin_lock_irq(&device->blk_data.request_queue_lock);
 179         }
 180         spin_unlock_irq(&device->blk_data.request_queue_lock);
 181         atomic_set(&device->blk_data.requeue_scheduled, 0);
 182 }
 183
 184 /*
 185  * Tape request queue function. Called from ll_rw_blk.c
 186  */
 187 static void
 188 tapeblock_request_fn(struct request_queue *queue)
 189 {
 190         struct tape_device *device;
 191
 192         device = (struct tape_device *) queue->queuedata;
 193         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 194         BUG_ON(device == NULL);
 195         tapeblock_trigger_requeue(device);
 196 }
 197
 198 /*
 199  * This function is called for every new tapedevice
 200  */
 201 int
 202 tapeblock_setup_device(struct tape_device * device)
 203 {
 204         struct tape_blk_data *  blkdat;
 205         struct gendisk *        disk;
 206         int                     rc;
 207
 208         blkdat = &device->blk_data;
 209         blkdat->device = device;
 210         spin_lock_init(&blkdat->request_queue_lock);
 211         atomic_set(&blkdat->requeue_scheduled, 0);
 212
 213         blkdat->request_queue = blk_init_queue(
 214                 tapeblock_request_fn,
 215                 &blkdat->request_queue_lock
 216         );
 217         if (!blkdat->request_queue)
 218                 return -ENOMEM;
 219
 220         rc = elevator_change(blkdat->request_queue, "noop");
 221         if (rc)
 222                 goto cleanup_queue;
 223
 224         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 225         blk_queue_max_hw_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 226         blk_queue_max_segments(blkdat->request_queue, -1L);
 227         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 228         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 229
 230         disk = alloc_disk(1);
 231         if (!disk) {
 232                 rc = -ENOMEM;
 233                 goto cleanup_queue;
 234         }
 235
 236         disk->major = tapeblock_major;
 237         disk->first_minor = device->first_minor;
 238         disk->fops = &tapeblock_fops;
 239         disk->private_data = tape_get_device(device);
 240         disk->queue = blkdat->request_queue;
 241         set_capacity(disk, 0);
 242         sprintf(disk->disk_name, "btibm%d",
 243                 device->first_minor / TAPE_MINORS_PER_DEV);
 244
 245         blkdat->disk = disk;
 246         blkdat->medium_changed = 1;
 247         blkdat->request_queue->queuedata = tape_get_device(device);
 248
 249         add_disk(disk);
 250
 251         tape_get_device(device);
 252         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 253
 254         return 0;
 255
 256 cleanup_queue:
 257         blk_cleanup_queue(blkdat->request_queue);
 258         blkdat->request_queue = NULL;
 259
 260         return rc;
 261 }
 262
 263 void
 264 tapeblock_cleanup_device(struct tape_device *device)
 265 {
 266         flush_work_sync(&device->blk_data.requeue_task);
 267         tape_put_device(device);
 268
 269         if (!device->blk_data.disk) {
 270                 goto cleanup_queue;
 271         }
 272
 273         del_gendisk(device->blk_data.disk);
 274         device->blk_data.disk->private_data = NULL;
 275         tape_put_device(device);
 276         put_disk(device->blk_data.disk);
 277
 278         device->blk_data.disk = NULL;
 279 cleanup_queue:
 280         device->blk_data.request_queue->queuedata = NULL;
 281         tape_put_device(device);
 282
 283         blk_cleanup_queue(device->blk_data.request_queue);
 284         device->blk_data.request_queue = NULL;
 285 }
 286
 287 /*
 288  * Detect number of blocks of the tape.
 289  * FIXME: can we extent this to detect the blocks size as well ?
 290  */
 291 static int
 292 tapeblock_revalidate_disk(struct gendisk *disk)
 293 {
 294         struct tape_device *    device;
 295         unsigned int            nr_of_blks;
 296         int                     rc;
 297
 298         device = (struct tape_device *) disk->private_data;
 299         BUG_ON(!device);
 300
 301         if (!device->blk_data.medium_changed)
 302                 return 0;
 303
 304         rc = tape_mtop(device, MTFSFM, 1);
 305         if (rc)
 306                 return rc;
 307
 308         rc = tape_mtop(device, MTTELL, 1);
 309         if (rc < 0)
 310                 return rc;
 311
 312         pr_info("%s: Determining the size of the recorded area...\n",
 313                 dev_name(&device->cdev->dev));
 314         DBF_LH(3, "Image file ends at %d\n", rc);
 315         nr_of_blks = rc;
 316
 317         /* This will fail for the first file. Catch the error by checking the
 318          * position. */
 319         tape_mtop(device, MTBSF, 1);
 320
 321         rc = tape_mtop(device, MTTELL, 1);
 322         if (rc < 0)
 323                 return rc;
 324
 325         if (rc > nr_of_blks)
 326                 return -EINVAL;
 327
 328         DBF_LH(3, "Image file starts at %d\n", rc);
 329         device->bof = rc;
 330         nr_of_blks -= rc;
 331
 332         pr_info("%s: The size of the recorded area is %i blocks\n",
 333                 dev_name(&device->cdev->dev), nr_of_blks);
 334         set_capacity(device->blk_data.disk,
 335                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 336
 337         device->blk_data.block_position = 0;
 338         device->blk_data.medium_changed = 0;
 339         return 0;
 340 }
 341
 342 static unsigned int
 343 tapeblock_check_events(struct gendisk *disk, unsigned int clearing)
 344 {
 345         struct tape_device *device;
 346
 347         device = (struct tape_device *) disk->private_data;
 348         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 349                 device, device->blk_data.medium_changed);
 350
 351         return device->blk_data.medium_changed ? DISK_EVENT_MEDIA_CHANGE : 0;
 352 }
 353
 354 /*
 355  * Block frontend tape device open function.
 356  */
 357 static int
 358 tapeblock_open(struct block_device *bdev, fmode_t mode)
 359 {
 360         struct gendisk *        disk = bdev->bd_disk;
 361         struct tape_device *    device;
 362         int                     rc;
 363
 364         mutex_lock(&tape_block_mutex);
 365         device = tape_get_device(disk->private_data);
 366
 367         if (device->required_tapemarks) {
 368                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 369                 pr_warning("%s: Opening the tape failed because of missing "
 370                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 371                 rc = -EPERM;
 372                 goto put_device;
 373         }
 374
 375         rc = tape_open(device);
 376         if (rc)
 377                 goto put_device;
 378
 379         rc = tapeblock_revalidate_disk(disk);
 380         if (rc)
 381                 goto release;
 382
 383         /*
 384          * Note: The reference to <device> is hold until the release function
 385          *       is called.
 386          */
 387         tape_state_set(device, TS_BLKUSE);
 388         mutex_unlock(&tape_block_mutex);
 389         return 0;
 390
 391 release:
 392         tape_release(device);
 393  put_device:
 394         tape_put_device(device);
 395         mutex_unlock(&tape_block_mutex);
 396         return rc;
 397 }
 398
 399 /*
 400  * Block frontend tape device release function.
 401  *
 402  * Note: One reference to the tape device was made by the open function. So
 403  *       we just get the pointer here and release the reference.
 404  */
 405 static int
 406 tapeblock_release(struct gendisk *disk, fmode_t mode)
 407 {
 408         struct tape_device *device = disk->private_data;
 409
 410         mutex_lock(&tape_block_mutex);
 411         tape_state_set(device, TS_IN_USE);
 412         tape_release(device);
 413         tape_put_device(device);
 414         mutex_unlock(&tape_block_mutex);
 415
 416         return 0;
 417 }
 418
 419 /*
 420  * Initialize block device frontend.
 421  */
 422 int
 423 tapeblock_init(void)
 424 {
 425         int rc;
 426
 427         /* Register the tape major number to the kernel */
 428         rc = register_blkdev(tapeblock_major, "tBLK");
 429         if (rc < 0)
 430                 return rc;
 431
 432         if (tapeblock_major == 0)
 433                 tapeblock_major = rc;
 434         return 0;
 435 }
 436
 437 /*
 438  * Deregister major for block device frontend
 439  */
 440 void
 441 tapeblock_exit(void)
 442 {
 443         unregister_blkdev(tapeblock_major, "tBLK");
 444 }