release/src-rt-6.x.4708/linux/linux-2.6.36/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/smp_lock.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 /*
  35  * file operation structure for tape block frontend
  36  */
  37 static int tapeblock_open(struct block_device *, fmode_t);
  38 static int tapeblock_release(struct gendisk *, fmode_t);
  39 static int tapeblock_medium_changed(struct gendisk *);
  40 static int tapeblock_revalidate_disk(struct gendisk *);
  41
  42 static const struct block_device_operations tapeblock_fops = {
  43         .owner           = THIS_MODULE,
  44         .open            = tapeblock_open,
  45         .release         = tapeblock_release,
  46         .media_changed   = tapeblock_medium_changed,
  47         .revalidate_disk = tapeblock_revalidate_disk,
  48 };
  49
  50 static int tapeblock_major = 0;
  51
  52 static void
  53 tapeblock_trigger_requeue(struct tape_device *device)
  54 {
  55         /* Protect against rescheduling. */
  56         if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
  57                 return;
  58         schedule_work(&device->blk_data.requeue_task);
  59 }
  60
  61 /*
  62  * Post finished request.
  63  */
  64 static void
  65 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
  66 {
  67         struct tape_device *device;
  68         struct request *req;
  69
  70         DBF_LH(6, "__tapeblock_end_request()\n");
  71
  72         device = ccw_req->device;
  73         req = (struct request *) data;
  74         blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
  75         if (ccw_req->rc == 0)
  76                 /* Update position. */
  77                 device->blk_data.block_position =
  78                   (blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
  79         else
  80                 /* We lost the position information due to an error. */
  81                 device->blk_data.block_position = -1;
  82         device->discipline->free_bread(ccw_req);
  83         if (!list_empty(&device->req_queue) ||
  84             blk_peek_request(device->blk_data.request_queue))
  85                 tapeblock_trigger_requeue(device);
  86 }
  87
  88 /*
  89  * Feed the tape device CCW queue with requests supplied in a list.
  90  */
  91 static int
  92 tapeblock_start_request(struct tape_device *device, struct request *req)
  93 {
  94         struct tape_request *   ccw_req;
  95         int                     rc;
  96
  97         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
  98
  99         ccw_req = device->discipline->bread(device, req);
 100         if (IS_ERR(ccw_req)) {
 101                 DBF_EVENT(1, "TBLOCK: bread failed\n");
 102                 blk_end_request_all(req, -EIO);
 103                 return PTR_ERR(ccw_req);
 104         }
 105         ccw_req->callback = __tapeblock_end_request;
 106         ccw_req->callback_data = (void *) req;
 107         ccw_req->retries = TAPEBLOCK_RETRIES;
 108
 109         rc = tape_do_io_async(device, ccw_req);
 110         if (rc) {
 111                 /*
 112                  * Start/enqueueing failed. No retries in
 113                  * this case.
 114                  */
 115                 blk_end_request_all(req, -EIO);
 116                 device->discipline->free_bread(ccw_req);
 117         }
 118
 119         return rc;
 120 }
 121
 122 /*
 123  * Move requests from the block device request queue to the tape device ccw
 124  * queue.
 125  */
 126 static void
 127 tapeblock_requeue(struct work_struct *work) {
 128         struct tape_blk_data *  blkdat;
 129         struct tape_device *    device;
 130         struct request_queue *  queue;
 131         int                     nr_queued;
 132         struct request *        req;
 133         struct list_head *      l;
 134         int                     rc;
 135
 136         blkdat = container_of(work, struct tape_blk_data, requeue_task);
 137         device = blkdat->device;
 138         if (!device)
 139                 return;
 140
 141         spin_lock_irq(get_ccwdev_lock(device->cdev));
 142         queue  = device->blk_data.request_queue;
 143
 144         /* Count number of requests on ccw queue. */
 145         nr_queued = 0;
 146         list_for_each(l, &device->req_queue)
 147                 nr_queued++;
 148         spin_unlock(get_ccwdev_lock(device->cdev));
 149
 150         spin_lock_irq(&device->blk_data.request_queue_lock);
 151         while (
 152                 !blk_queue_plugged(queue) &&
 153                 blk_peek_request(queue) &&
 154                 nr_queued < TAPEBLOCK_MIN_REQUEUE
 155         ) {
 156                 req = blk_fetch_request(queue);
 157                 if (rq_data_dir(req) == WRITE) {
 158                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
 159                         spin_unlock_irq(&device->blk_data.request_queue_lock);
 160                         blk_end_request_all(req, -EIO);
 161                         spin_lock_irq(&device->blk_data.request_queue_lock);
 162                         continue;
 163                 }
 164                 nr_queued++;
 165                 spin_unlock_irq(&device->blk_data.request_queue_lock);
 166                 rc = tapeblock_start_request(device, req);
 167                 spin_lock_irq(&device->blk_data.request_queue_lock);
 168         }
 169         spin_unlock_irq(&device->blk_data.request_queue_lock);
 170         atomic_set(&device->blk_data.requeue_scheduled, 0);
 171 }
 172
 173 /*
 174  * Tape request queue function. Called from ll_rw_blk.c
 175  */
 176 static void
 177 tapeblock_request_fn(struct request_queue *queue)
 178 {
 179         struct tape_device *device;
 180
 181         device = (struct tape_device *) queue->queuedata;
 182         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
 183         BUG_ON(device == NULL);
 184         tapeblock_trigger_requeue(device);
 185 }
 186
 187 /*
 188  * This function is called for every new tapedevice
 189  */
 190 int
 191 tapeblock_setup_device(struct tape_device * device)
 192 {
 193         struct tape_blk_data *  blkdat;
 194         struct gendisk *        disk;
 195         int                     rc;
 196
 197         blkdat = &device->blk_data;
 198         blkdat->device = device;
 199         spin_lock_init(&blkdat->request_queue_lock);
 200         atomic_set(&blkdat->requeue_scheduled, 0);
 201
 202         blkdat->request_queue = blk_init_queue(
 203                 tapeblock_request_fn,
 204                 &blkdat->request_queue_lock
 205         );
 206         if (!blkdat->request_queue)
 207                 return -ENOMEM;
 208
 209         rc = elevator_change(blkdat->request_queue, "noop");
 210         if (rc)
 211                 goto cleanup_queue;
 212
 213         blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
 214         blk_queue_max_hw_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
 215         blk_queue_max_segments(blkdat->request_queue, -1L);
 216         blk_queue_max_segment_size(blkdat->request_queue, -1L);
 217         blk_queue_segment_boundary(blkdat->request_queue, -1L);
 218
 219         disk = alloc_disk(1);
 220         if (!disk) {
 221                 rc = -ENOMEM;
 222                 goto cleanup_queue;
 223         }
 224
 225         disk->major = tapeblock_major;
 226         disk->first_minor = device->first_minor;
 227         disk->fops = &tapeblock_fops;
 228         disk->private_data = tape_get_device(device);
 229         disk->queue = blkdat->request_queue;
 230         set_capacity(disk, 0);
 231         sprintf(disk->disk_name, "btibm%d",
 232                 device->first_minor / TAPE_MINORS_PER_DEV);
 233
 234         blkdat->disk = disk;
 235         blkdat->medium_changed = 1;
 236         blkdat->request_queue->queuedata = tape_get_device(device);
 237
 238         add_disk(disk);
 239
 240         tape_get_device(device);
 241         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 242
 243         return 0;
 244
 245 cleanup_queue:
 246         blk_cleanup_queue(blkdat->request_queue);
 247         blkdat->request_queue = NULL;
 248
 249         return rc;
 250 }
 251
 252 void
 253 tapeblock_cleanup_device(struct tape_device *device)
 254 {
 255         flush_scheduled_work();
 256         tape_put_device(device);
 257
 258         if (!device->blk_data.disk) {
 259                 goto cleanup_queue;
 260         }
 261
 262         del_gendisk(device->blk_data.disk);
 263         device->blk_data.disk->private_data = NULL;
 264         tape_put_device(device);
 265         put_disk(device->blk_data.disk);
 266
 267         device->blk_data.disk = NULL;
 268 cleanup_queue:
 269         device->blk_data.request_queue->queuedata = NULL;
 270         tape_put_device(device);
 271
 272         blk_cleanup_queue(device->blk_data.request_queue);
 273         device->blk_data.request_queue = NULL;
 274 }
 275
 276 static int
 277 tapeblock_revalidate_disk(struct gendisk *disk)
 278 {
 279         struct tape_device *    device;
 280         unsigned int            nr_of_blks;
 281         int                     rc;
 282
 283         device = (struct tape_device *) disk->private_data;
 284         BUG_ON(!device);
 285
 286         if (!device->blk_data.medium_changed)
 287                 return 0;
 288
 289         rc = tape_mtop(device, MTFSFM, 1);
 290         if (rc)
 291                 return rc;
 292
 293         rc = tape_mtop(device, MTTELL, 1);
 294         if (rc < 0)
 295                 return rc;
 296
 297         pr_info("%s: Determining the size of the recorded area...\n",
 298                 dev_name(&device->cdev->dev));
 299         DBF_LH(3, "Image file ends at %d\n", rc);
 300         nr_of_blks = rc;
 301
 302         /* This will fail for the first file. Catch the error by checking the
 303          * position. */
 304         tape_mtop(device, MTBSF, 1);
 305
 306         rc = tape_mtop(device, MTTELL, 1);
 307         if (rc < 0)
 308                 return rc;
 309
 310         if (rc > nr_of_blks)
 311                 return -EINVAL;
 312
 313         DBF_LH(3, "Image file starts at %d\n", rc);
 314         device->bof = rc;
 315         nr_of_blks -= rc;
 316
 317         pr_info("%s: The size of the recorded area is %i blocks\n",
 318                 dev_name(&device->cdev->dev), nr_of_blks);
 319         set_capacity(device->blk_data.disk,
 320                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
 321
 322         device->blk_data.block_position = 0;
 323         device->blk_data.medium_changed = 0;
 324         return 0;
 325 }
 326
 327 static int
 328 tapeblock_medium_changed(struct gendisk *disk)
 329 {
 330         struct tape_device *device;
 331
 332         device = (struct tape_device *) disk->private_data;
 333         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
 334                 device, device->blk_data.medium_changed);
 335
 336         return device->blk_data.medium_changed;
 337 }
 338
 339 /*
 340  * Block frontend tape device open function.
 341  */
 342 static int
 343 tapeblock_open(struct block_device *bdev, fmode_t mode)
 344 {
 345         struct gendisk *        disk = bdev->bd_disk;
 346         struct tape_device *    device;
 347         int                     rc;
 348
 349         lock_kernel();
 350         device = tape_get_device(disk->private_data);
 351
 352         if (device->required_tapemarks) {
 353                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
 354                 pr_warning("%s: Opening the tape failed because of missing "
 355                            "end-of-file marks\n", dev_name(&device->cdev->dev));
 356                 rc = -EPERM;
 357                 goto put_device;
 358         }
 359
 360         rc = tape_open(device);
 361         if (rc)
 362                 goto put_device;
 363
 364         rc = tapeblock_revalidate_disk(disk);
 365         if (rc)
 366                 goto release;
 367
 368         /*
 369          * Note: The reference to <device> is hold until the release function
 370          *       is called.
 371          */
 372         tape_state_set(device, TS_BLKUSE);
 373         unlock_kernel();
 374         return 0;
 375
 376 release:
 377         tape_release(device);
 378  put_device:
 379         tape_put_device(device);
 380         unlock_kernel();
 381         return rc;
 382 }
 383
 384 /*
 385  * Block frontend tape device release function.
 386  *
 387  * Note: One reference to the tape device was made by the open function. So
 388  *       we just get the pointer here and release the reference.
 389  */
 390 static int
 391 tapeblock_release(struct gendisk *disk, fmode_t mode)
 392 {
 393         struct tape_device *device = disk->private_data;
 394
 395         lock_kernel();
 396         tape_state_set(device, TS_IN_USE);
 397         tape_release(device);
 398         tape_put_device(device);
 399         unlock_kernel();
 400
 401         return 0;
 402 }
 403
 404 /*
 405  * Initialize block device frontend.
 406  */
 407 int
 408 tapeblock_init(void)
 409 {
 410         int rc;
 411
 412         /* Register the tape major number to the kernel */
 413         rc = register_blkdev(tapeblock_major, "tBLK");
 414         if (rc < 0)
 415                 return rc;
 416
 417         if (tapeblock_major == 0)
 418                 tapeblock_major = rc;
 419         return 0;
 420 }
 421
 422 /*
 423  * Deregister major for block device frontend
 424  */
 425 void
 426 tapeblock_exit(void)
 427 {
 428         unregister_blkdev(tapeblock_major, "tBLK");
 429 }