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_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 226         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
 227         blk_queue_max_hw_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         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         return 0;
 389
 390 release:
 391         tape_release(device);
 392  put_device:
 393         tape_put_device(device);
 394         return rc;
 395 }
 396
 397 /*
 398  * Block frontend tape device release function.
 399  *
 400  * Note: One reference to the tape device was made by the open function. So
 401  *       we just get the pointer here and release the reference.
 402  */
 403 static int
 404 tapeblock_release(struct gendisk *disk, fmode_t mode)
 405 {
 406         struct tape_device *device = disk->private_data;
 407
 408         tape_state_set(device, TS_IN_USE);
 409         tape_release(device);
 410         tape_put_device(device);
 411
 412         return 0;
 413 }
 414
 415 /*
 416  * Initialize block device frontend.
 417  */
 418 int
 419 tapeblock_init(void)
 420 {
 421         int rc;
 422
 423         /* Register the tape major number to the kernel */
 424         rc = register_blkdev(tapeblock_major, "tBLK");
 425         if (rc < 0)
 426                 return rc;
 427
 428         if (tapeblock_major == 0)
 429                 tapeblock_major = rc;
 430         return 0;
 431 }
 432
 433 /*
 434  * Deregister major for block device frontend
 435  */
 436 void
 437 tapeblock_exit(void)
 438 {
 439         unregister_blkdev(tapeblock_major, "tBLK");
 440 }