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 int tapeblock_medium_changed(struct gendisk *);
  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         .media_changed   = tapeblock_medium_changed,
  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_queue_plugged(queue) &&
 165                 blk_peek_request(queue) &&
 166                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 167         ) {
 168                 req = blk_fetch_request(queue);
 169                 if (rq_data_dir(req) == WRITE) {
 170                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 171                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 172                         blk_end_request_all(req, -EIO);
 173                         spin_lock_irq(&device->blk_data.request_queue_lock);
 174                         continue;
 175                 }
 176                 nr_queued++;
 177                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 178                 rc = tapeblock_start_request(device, req);
 179                 spin_lock_irq(&device->blk_data.request_queue_lock);
 180         }
 181         spin_unlock_irq(&device->blk_data.request_queue_lock);
 182         atomic_set(&device->blk_data.requeue_scheduled, 0);
 183 }
 184
 185 /*
 186  * Tape request queue function. Called from ll_rw_blk.c
 187  */
 188 static void
 189 tapeblock_request_fn(struct request_queue *queue)
 190 {
 191         struct tape_device *device;
 192
 193         device = (struct tape_device *) queue->queuedata;
 194         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 195         BUG_ON(device == NULL);
 196         tapeblock_trigger_requeue(device);
 197 }
 198
 199 /*
 200  * This function is called for every new tapedevice
 201  */
 202 int
 203 tapeblock_setup_device(struct tape_device * device)
 204 {
 205         struct tape_blk_data *  blkdat;
 206         struct gendisk *        disk;
 207         int                     rc;
 208
 209         blkdat = &device->blk_data;
 210         blkdat->device = device;
 211         spin_lock_init(&blkdat->request_queue_lock);
 212         atomic_set(&blkdat->requeue_scheduled, 0);
 213
 214         blkdat->request_queue = blk_init_queue(
 215                 tapeblock_request_fn,
 216                 &blkdat->request_queue_lock
 217         );
 218         if (!blkdat->request_queue)
 219                 return -ENOMEM;
 220
 221         rc = elevator_change(blkdat->request_queue, "noop");
 222         if (rc)
 223                 goto cleanup_queue;
 224
 225         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 226         blk_queue_max_hw_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 227         blk_queue_max_segments(blkdat->request_queue, -1L);
 228         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 229         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 230
 231         disk = alloc_disk(1);
 232         if (!disk) {
 233                 rc = -ENOMEM;
 234                 goto cleanup_queue;
 235         }
 236
 237         disk->major = tapeblock_major;
 238         disk->first_minor = device->first_minor;
 239         disk->fops = &tapeblock_fops;
 240         disk->private_data = tape_get_device(device);
 241         disk->queue = blkdat->request_queue;
 242         set_capacity(disk, 0);
 243         sprintf(disk->disk_name, "btibm%d",
 244                 device->first_minor / TAPE_MINORS_PER_DEV);
 245
 246         blkdat->disk = disk;
 247         blkdat->medium_changed = 1;
 248         blkdat->request_queue->queuedata = tape_get_device(device);
 249
 250         add_disk(disk);
 251
 252         tape_get_device(device);
 253         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 254
 255         return 0;
 256
 257 cleanup_queue:
 258         blk_cleanup_queue(blkdat->request_queue);
 259         blkdat->request_queue = NULL;
 260
 261         return rc;
 262 }
 263
 264 void
 265 tapeblock_cleanup_device(struct tape_device *device)
 266 {
 267         flush_scheduled_work();
 268         tape_put_device(device);
 269
 270         if (!device->blk_data.disk) {
 271                 goto cleanup_queue;
 272         }
 273
 274         del_gendisk(device->blk_data.disk);
 275         device->blk_data.disk->private_data = NULL;
 276         tape_put_device(device);
 277         put_disk(device->blk_data.disk);
 278
 279         device->blk_data.disk = NULL;
 280 cleanup_queue:
 281         device->blk_data.request_queue->queuedata = NULL;
 282         tape_put_device(device);
 283
 284         blk_cleanup_queue(device->blk_data.request_queue);
 285         device->blk_data.request_queue = NULL;
 286 }
 287
 288 /*
 289  * Detect number of blocks of the tape.
 290  * FIXME: can we extent this to detect the blocks size as well ?
 291  */
 292 static int
 293 tapeblock_revalidate_disk(struct gendisk *disk)
 294 {
 295         struct tape_device *    device;
 296         unsigned int            nr_of_blks;
 297         int                     rc;
 298
 299         device = (struct tape_device *) disk->private_data;
 300         BUG_ON(!device);
 301
 302         if (!device->blk_data.medium_changed)
 303                 return 0;
 304
 305         rc = tape_mtop(device, MTFSFM, 1);
 306         if (rc)
 307                 return rc;
 308
 309         rc = tape_mtop(device, MTTELL, 1);
 310         if (rc < 0)
 311                 return rc;
 312
 313         pr_info("%s: Determining the size of the recorded area...\n",
 314                 dev_name(&device->cdev->dev));
 315         DBF_LH(3, "Image file ends at %d\n", rc);
 316         nr_of_blks = rc;
 317
 318         /* This will fail for the first file. Catch the error by checking the
 319          * position. */
 320         tape_mtop(device, MTBSF, 1);
 321
 322         rc = tape_mtop(device, MTTELL, 1);
 323         if (rc < 0)
 324                 return rc;
 325
 326         if (rc > nr_of_blks)
 327                 return -EINVAL;
 328
 329         DBF_LH(3, "Image file starts at %d\n", rc);
 330         device->bof = rc;
 331         nr_of_blks -= rc;
 332
 333         pr_info("%s: The size of the recorded area is %i blocks\n",
 334                 dev_name(&device->cdev->dev), nr_of_blks);
 335         set_capacity(device->blk_data.disk,
 336                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 337
 338         device->blk_data.block_position = 0;
 339         device->blk_data.medium_changed = 0;
 340         return 0;
 341 }
 342
 343 static int
 344 tapeblock_medium_changed(struct gendisk *disk)
 345 {
 346         struct tape_device *device;
 347
 348         device = (struct tape_device *) disk->private_data;
 349         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 350                 device, device->blk_data.medium_changed);
 351
 352         return device->blk_data.medium_changed;
 353 }
 354
 355 /*
 356  * Block frontend tape device open function.
 357  */
 358 static int
 359 tapeblock_open(struct block_device *bdev, fmode_t mode)
 360 {
 361         struct gendisk *        disk = bdev->bd_disk;
 362         struct tape_device *    device;
 363         int                     rc;
 364
 365         mutex_lock(&tape_block_mutex);
 366         device = tape_get_device(disk->private_data);
 367
 368         if (device->required_tapemarks) {
 369                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 370                 pr_warning("%s: Opening the tape failed because of missing "
 371                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 372                 rc = -EPERM;
 373                 goto put_device;
 374         }
 375
 376         rc = tape_open(device);
 377         if (rc)
 378                 goto put_device;
 379
 380         rc = tapeblock_revalidate_disk(disk);
 381         if (rc)
 382                 goto release;
 383
 384         /*
 385          * Note: The reference to <device> is hold until the release function
 386          *       is called.
 387          */
 388         tape_state_set(device, TS_BLKUSE);
 389         mutex_unlock(&tape_block_mutex);
 390         return 0;
 391
 392 release:
 393         tape_release(device);
 394  put_device:
 395         tape_put_device(device);
 396         mutex_unlock(&tape_block_mutex);
 397         return rc;
 398 }
 399
 400 /*
 401  * Block frontend tape device release function.
 402  *
 403  * Note: One reference to the tape device was made by the open function. So
 404  *       we just get the pointer here and release the reference.
 405  */
 406 static int
 407 tapeblock_release(struct gendisk *disk, fmode_t mode)
 408 {
 409         struct tape_device *device = disk->private_data;
 410
 411         mutex_lock(&tape_block_mutex);
 412         tape_state_set(device, TS_IN_USE);
 413         tape_release(device);
 414         tape_put_device(device);
 415         mutex_unlock(&tape_block_mutex);
 416
 417         return 0;
 418 }
 419
 420 /*
 421  * Initialize block device frontend.
 422  */
 423 int
 424 tapeblock_init(void)
 425 {
 426         int rc;
 427
 428         /* Register the tape major number to the kernel */
 429         rc = register_blkdev(tapeblock_major, "tBLK");
 430         if (rc < 0)
 431                 return rc;
 432
 433         if (tapeblock_major == 0)
 434                 tapeblock_major = rc;
 435         return 0;
 436 }
 437
 438 /*
 439  * Deregister major for block device frontend
 440  */
 441 void
 442 tapeblock_exit(void)
 443 {
 444         unregister_blkdev(tapeblock_major, "tBLK");
 445 }