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/interrupt.h>
  20 #include <linux/buffer_head.h>
  21 #include <linux/kernel.h>
  22
  23 #include <asm/debug.h>
  24
  25 #define TAPE_DBF_AREA   tape_core_dbf
  26
  27 #include "tape.h"
  28
  29 #define TAPEBLOCK_MAX_SEC       100
  30 #define TAPEBLOCK_MIN_REQUEUE   3
  31
  32 /*
  33  * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
  34  *
  35  * In 2.5/2.6 the block device request function is very likely to be called
  36  * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
  37  * just call any function that tries to allocate CCW requests from that con-
  38  * text since it might sleep. There are two choices to work around this:
  39  *      a) do not allocate with kmalloc but use its own memory pool
  40  *      b) take requests from the queue outside that context, knowing that
  41  *         allocation might sleep
  42  */
  43
  44 /*
  45  * file operation structure for tape block frontend
  46  */
  47 static int tapeblock_open(struct block_device *, fmode_t);
  48 static int tapeblock_release(struct gendisk *, fmode_t);
  49 static int tapeblock_medium_changed(struct gendisk *);
  50 static int tapeblock_revalidate_disk(struct gendisk *);
  51
  52 static const struct block_device_operations tapeblock_fops = {
  53         .owner           = THIS_MODULE,
  54         .open            = tapeblock_open,
  55         .release         = tapeblock_release,
  56         .media_changed   = tapeblock_medium_changed,
  57         .revalidate_disk = tapeblock_revalidate_disk,
  58 };
  59
  60 static int tapeblock_major = 0;
  61
  62 static void
  63 tapeblock_trigger_requeue(struct tape_device *device)
  64 {
  65         /* Protect against rescheduling. */
  66         if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
  67                 return;
  68         schedule_work(&device->blk_data.requeue_task);
  69 }
  70
  71 /*
  72  * Post finished request.
  73  */
  74 static void
  75 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  76 {
  77         struct tape_device *device;
  78         struct request *req;
  79
  80         DBF_LH(6, "__tapeblock_end_request()\n");
  81
  82         device = ccw_req->device;
  83         req = (struct request *) data;
  84         blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
  85         if (ccw_req->rc == 0)
  86                 /* Update position. */
  87                 device->blk_data.block_position =
  88                   (blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
  89         else
  90                 /* We lost the position information due to an error. */
  91                 device->blk_data.block_position = -1;
  92         device->discipline->free_bread(ccw_req);
  93         if (!list_empty(&device->req_queue) ||
  94             blk_peek_request(device->blk_data.request_queue))
  95                 tapeblock_trigger_requeue(device);
  96 }
  97
  98 /*
  99  * Feed the tape device CCW queue with requests supplied in a list.
 100  */
 101 static int
 102 tapeblock_start_request(struct tape_device *device, struct request *req)
 103 {
 104         struct tape_request *   ccw_req;
 105         int                     rc;
 106
 107         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
 108
 109         ccw_req = device->discipline->bread(device, req);
 110         if (IS_ERR(ccw_req)) {
 111                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 112                 blk_end_request_all(req, -EIO);
 113                 return PTR_ERR(ccw_req);
 114         }
 115         ccw_req->callback = __tapeblock_end_request;
 116         ccw_req->callback_data = (void *) req;
 117         ccw_req->retries = TAPEBLOCK_RETRIES;
 118
 119         rc = tape_do_io_async(device, ccw_req);
 120         if (rc) {
 121                 /*
 122                  * Start/enqueueing failed. No retries in
 123                  * this case.
 124                  */
 125                 blk_end_request_all(req, -EIO);
 126                 device->discipline->free_bread(ccw_req);
 127         }
 128
 129         return rc;
 130 }
 131
 132 /*
 133  * Move requests from the block device request queue to the tape device ccw
 134  * queue.
 135  */
 136 static void
 137 tapeblock_requeue(struct work_struct *work) {
 138         struct tape_blk_data *  blkdat;
 139         struct tape_device *    device;
 140         struct request_queue *  queue;
 141         int                     nr_queued;
 142         struct request *        req;
 143         struct list_head *      l;
 144         int                     rc;
 145
 146         blkdat = container_of(work, struct tape_blk_data, requeue_task);
 147         device = blkdat->device;
 148         if (!device)
 149                 return;
 150
 151         spin_lock_irq(get_ccwdev_lock(device->cdev));
 152         queue  = device->blk_data.request_queue;
 153
 154         /* Count number of requests on ccw queue. */
 155         nr_queued = 0;
 156         list_for_each(l, &device->req_queue)
 157                 nr_queued++;
 158         spin_unlock(get_ccwdev_lock(device->cdev));
 159
 160         spin_lock_irq(&device->blk_data.request_queue_lock);
 161         while (
 162                 !blk_queue_plugged(queue) &&
 163                 blk_peek_request(queue) &&
 164                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 165         ) {
 166                 req = blk_fetch_request(queue);
 167                 if (rq_data_dir(req) == WRITE) {
 168                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 169                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 170                         blk_end_request_all(req, -EIO);
 171                         spin_lock_irq(&device->blk_data.request_queue_lock);
 172                         continue;
 173                 }
 174                 nr_queued++;
 175                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 176                 rc = tapeblock_start_request(device, req);
 177                 spin_lock_irq(&device->blk_data.request_queue_lock);
 178         }
 179         spin_unlock_irq(&device->blk_data.request_queue_lock);
 180         atomic_set(&device->blk_data.requeue_scheduled, 0);
 181 }
 182
 183 /*
 184  * Tape request queue function. Called from ll_rw_blk.c
 185  */
 186 static void
 187 tapeblock_request_fn(struct request_queue *queue)
 188 {
 189         struct tape_device *device;
 190
 191         device = (struct tape_device *) queue->queuedata;
 192         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 193         BUG_ON(device == NULL);
 194         tapeblock_trigger_requeue(device);
 195 }
 196
 197 /*
 198  * This function is called for every new tapedevice
 199  */
 200 int
 201 tapeblock_setup_device(struct tape_device * device)
 202 {
 203         struct tape_blk_data *  blkdat;
 204         struct gendisk *        disk;
 205         int                     rc;
 206
 207         blkdat = &device->blk_data;
 208         blkdat->device = device;
 209         spin_lock_init(&blkdat->request_queue_lock);
 210         atomic_set(&blkdat->requeue_scheduled, 0);
 211
 212         blkdat->request_queue = blk_init_queue(
 213                 tapeblock_request_fn,
 214                 &blkdat->request_queue_lock
 215         );
 216         if (!blkdat->request_queue)
 217                 return -ENOMEM;
 218
 219         elevator_exit(blkdat->request_queue->elevator);
 220         rc = elevator_init(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_scheduled_work();
 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 int
 343 tapeblock_medium_changed(struct gendisk *disk)
 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;
 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         device = tape_get_device(disk->private_data);
 365
 366         if (device->required_tapemarks) {
 367                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 368                 pr_warning("%s: Opening the tape failed because of missing "
 369                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 370                 rc = -EPERM;
 371                 goto put_device;
 372         }
 373
 374         rc = tape_open(device);
 375         if (rc)
 376                 goto put_device;
 377
 378         rc = tapeblock_revalidate_disk(disk);
 379         if (rc)
 380                 goto release;
 381
 382         /*
 383          * Note: The reference to <device> is hold until the release function
 384          *       is called.
 385          */
 386         tape_state_set(device, TS_BLKUSE);
 387         return 0;
 388
 389 release:
 390         tape_release(device);
 391  put_device:
 392         tape_put_device(device);
 393         return rc;
 394 }
 395
 396 /*
 397  * Block frontend tape device release function.
 398  *
 399  * Note: One reference to the tape device was made by the open function. So
 400  *       we just get the pointer here and release the reference.
 401  */
 402 static int
 403 tapeblock_release(struct gendisk *disk, fmode_t mode)
 404 {
 405         struct tape_device *device = disk->private_data;
 406
 407         tape_state_set(device, TS_IN_USE);
 408         tape_release(device);
 409         tape_put_device(device);
 410
 411         return 0;
 412 }
 413
 414 /*
 415  * Initialize block device frontend.
 416  */
 417 int
 418 tapeblock_init(void)
 419 {
 420         int rc;
 421
 422         /* Register the tape major number to the kernel */
 423         rc = register_blkdev(tapeblock_major, "tBLK");
 424         if (rc < 0)
 425                 return rc;
 426
 427         if (tapeblock_major == 0)
 428                 tapeblock_major = rc;
 429         return 0;
 430 }
 431
 432 /*
 433  * Deregister major for block device frontend
 434  */
 435 void
 436 tapeblock_exit(void)
 437 {
 438         unregister_blkdev(tapeblock_major, "tBLK");
 439 }