i386/linux/linux-2.3.21/drivers/block/ll_rw_blk.c

   1 /*
   2  *  linux/drivers/block/ll_rw_blk.c
   3  *
   4  * Copyright (C) 1991, 1992 Linus Torvalds
   5  * Copyright (C) 1994,      Karl Keyte: Added support for disk statistics
   6  */
   7
   8 /*
   9  * This handles all read/write requests to block devices
  10  */
  11 #include <linux/sched.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kernel_stat.h>
  14 #include <linux/errno.h>
  15 #include <linux/string.h>
  16 #include <linux/config.h>
  17 #include <linux/locks.h>
  18 #include <linux/mm.h>
  19 #include <linux/init.h>
  20 #include <linux/smp_lock.h>
  21
  22 #include <asm/system.h>
  23 #include <asm/io.h>
  24 #include <linux/blk.h>
  25
  26 #include <linux/module.h>
  27
  28 /*
  29  * MAC Floppy IWM hooks
  30  */
  31
  32 #ifdef CONFIG_MAC_FLOPPY_IWM
  33 extern int mac_floppy_init(void);
  34 #endif
  35
  36 /*
  37  * The request-struct contains all necessary data
  38  * to load a nr of sectors into memory
  39  */
  40 static struct request all_requests[NR_REQUEST];
  41
  42 /*
  43  * The "disk" task queue is used to start the actual requests
  44  * after a plug
  45  */
  46 DECLARE_TASK_QUEUE(tq_disk);
  47
  48 /*
  49  * Protect the request list against multiple users..
  50  *
  51  * With this spinlock the Linux block IO subsystem is 100% SMP threaded
  52  * from the IRQ event side, and almost 100% SMP threaded from the syscall
  53  * side (we still have protect against block device array operations, and
  54  * the do_request() side is casually still unsafe. The kernel lock protects
  55  * this part currently.).
  56  *
  57  * there is a fair chance that things will work just OK if these functions
  58  * are called with no global kernel lock held ...
  59  */
  60 spinlock_t io_request_lock = SPIN_LOCK_UNLOCKED;
  61
  62 /*
  63  * used to wait on when there are no free requests
  64  */
  65 DECLARE_WAIT_QUEUE_HEAD(wait_for_request);
  66
  67 /* This specifies how many sectors to read ahead on the disk.  */
  68
  69 int read_ahead[MAX_BLKDEV] = {0, };
  70
  71 /* blk_dev_struct is:
  72  *      *request_fn
  73  *      *current_request
  74  */
  75 struct blk_dev_struct blk_dev[MAX_BLKDEV]; /* initialized by blk_dev_init() */
  76
  77 /*
  78  * blk_size contains the size of all block-devices in units of 1024 byte
  79  * sectors:
  80  *
  81  * blk_size[MAJOR][MINOR]
  82  *
  83  * if (!blk_size[MAJOR]) then no minor size checking is done.
  84  */
  85 int * blk_size[MAX_BLKDEV] = { NULL, NULL, };
  86
  87 /*
  88  * blksize_size contains the size of all block-devices:
  89  *
  90  * blksize_size[MAJOR][MINOR]
  91  *
  92  * if (!blksize_size[MAJOR]) then 1024 bytes is assumed.
  93  */
  94 int * blksize_size[MAX_BLKDEV] = { NULL, NULL, };
  95
  96 /*
  97  * hardsect_size contains the size of the hardware sector of a device.
  98  *
  99  * hardsect_size[MAJOR][MINOR]
 100  *
 101  * if (!hardsect_size[MAJOR])
 102  *              then 512 bytes is assumed.
 103  * else
 104  *              sector_size is hardsect_size[MAJOR][MINOR]
 105  * This is currently set by some scsi devices and read by the msdos fs driver.
 106  * Other uses may appear later.
 107  */
 108 int * hardsect_size[MAX_BLKDEV] = { NULL, NULL, };
 109
 110 /*
 111  * The following tunes the read-ahead algorithm in mm/filemap.c
 112  */
 113 int * max_readahead[MAX_BLKDEV] = { NULL, NULL, };
 114
 115 /*
 116  * Max number of sectors per request
 117  */
 118 int * max_sectors[MAX_BLKDEV] = { NULL, NULL, };
 119
 120 /*
 121  * Max number of segments per request
 122  */
 123 int * max_segments[MAX_BLKDEV] = { NULL, NULL, };
 124
 125 static inline int get_max_sectors(kdev_t dev)
 126 {
 127         if (!max_sectors[MAJOR(dev)])
 128                 return MAX_SECTORS;
 129         return max_sectors[MAJOR(dev)][MINOR(dev)];
 130 }
 131
 132 static inline int get_max_segments(kdev_t dev)
 133 {
 134         if (!max_segments[MAJOR(dev)])
 135                 return MAX_SEGMENTS;
 136         return max_segments[MAJOR(dev)][MINOR(dev)];
 137 }
 138
 139 /*
 140  * Is called with the request spinlock aquired.
 141  * NOTE: the device-specific queue() functions
 142  * have to be atomic!
 143  */
 144 static inline struct request **get_queue(kdev_t dev)
 145 {
 146         int major = MAJOR(dev);
 147         struct blk_dev_struct *bdev = blk_dev + major;
 148
 149         if (bdev->queue)
 150                 return bdev->queue(dev);
 151         return &blk_dev[major].current_request;
 152 }
 153
 154 /*
 155  * remove the plug and let it rip..
 156  */
 157 void unplug_device(void * data)
 158 {
 159         struct blk_dev_struct * dev = (struct blk_dev_struct *) data;
 160         int queue_new_request=0;
 161         unsigned long flags;
 162
 163         spin_lock_irqsave(&io_request_lock,flags);
 164         if (dev->current_request == &dev->plug) {
 165                 struct request * next = dev->plug.next;
 166                 dev->current_request = next;
 167                 if (next || dev->queue) {
 168                         dev->plug.next = NULL;
 169                         queue_new_request = 1;
 170                 }
 171         }
 172         if (queue_new_request)
 173                 (dev->request_fn)();
 174
 175         spin_unlock_irqrestore(&io_request_lock,flags);
 176 }
 177
 178 /*
 179  * "plug" the device if there are no outstanding requests: this will
 180  * force the transfer to start only after we have put all the requests
 181  * on the list.
 182  *
 183  * This is called with interrupts off and no requests on the queue.
 184  * (and with the request spinlock aquired)
 185  */
 186 static inline void plug_device(struct blk_dev_struct * dev)
 187 {
 188         if (dev->current_request)
 189                 return;
 190         dev->current_request = &dev->plug;
 191         queue_task(&dev->plug_tq, &tq_disk);
 192 }
 193
 194 /*
 195  * look for a free request in the first N entries.
 196  * NOTE: interrupts must be disabled on the way in (on SMP the request queue
 197  * spinlock has to be aquired), and will still be disabled on the way out.
 198  */
 199 static inline struct request * get_request(int n, kdev_t dev)
 200 {
 201         static struct request *prev_found = NULL, *prev_limit = NULL;
 202         register struct request *req, *limit;
 203
 204         if (n <= 0)
 205                 panic("get_request(%d): impossible!\n", n);
 206
 207         limit = all_requests + n;
 208         if (limit != prev_limit) {
 209                 prev_limit = limit;
 210                 prev_found = all_requests;
 211         }
 212         req = prev_found;
 213         for (;;) {
 214                 req = ((req > all_requests) ? req : limit) - 1;
 215                 if (req->rq_status == RQ_INACTIVE)
 216                         break;
 217                 if (req == prev_found)
 218                         return NULL;
 219         }
 220         prev_found = req;
 221         req->rq_status = RQ_ACTIVE;
 222         req->rq_dev = dev;
 223         return req;
 224 }
 225
 226 /*
 227  * wait until a free request in the first N entries is available.
 228  */
 229 static struct request * __get_request_wait(int n, kdev_t dev)
 230 {
 231         register struct request *req;
 232         DECLARE_WAITQUEUE(wait, current);
 233         unsigned long flags;
 234
 235         add_wait_queue(&wait_for_request, &wait);
 236         for (;;) {
 237                 current->state = TASK_UNINTERRUPTIBLE;
 238                 spin_lock_irqsave(&io_request_lock,flags);
 239                 req = get_request(n, dev);
 240                 spin_unlock_irqrestore(&io_request_lock,flags);
 241                 if (req)
 242                         break;
 243                 run_task_queue(&tq_disk);
 244                 schedule();
 245         }
 246         remove_wait_queue(&wait_for_request, &wait);
 247         current->state = TASK_RUNNING;
 248         return req;
 249 }
 250
 251 static inline struct request * get_request_wait(int n, kdev_t dev)
 252 {
 253         register struct request *req;
 254         unsigned long flags;
 255
 256         spin_lock_irqsave(&io_request_lock,flags);
 257         req = get_request(n, dev);
 258         spin_unlock_irqrestore(&io_request_lock,flags);
 259         if (req)
 260                 return req;
 261         return __get_request_wait(n, dev);
 262 }
 263
 264 /* RO fail safe mechanism */
 265
 266 static long ro_bits[MAX_BLKDEV][8];
 267
 268 int is_read_only(kdev_t dev)
 269 {
 270         int minor,major;
 271
 272         major = MAJOR(dev);
 273         minor = MINOR(dev);
 274         if (major < 0 || major >= MAX_BLKDEV) return 0;
 275         return ro_bits[major][minor >> 5] & (1 << (minor & 31));
 276 }
 277
 278 void set_device_ro(kdev_t dev,int flag)
 279 {
 280         int minor,major;
 281
 282         major = MAJOR(dev);
 283         minor = MINOR(dev);
 284         if (major < 0 || major >= MAX_BLKDEV) return;
 285         if (flag) ro_bits[major][minor >> 5] |= 1 << (minor & 31);
 286         else ro_bits[major][minor >> 5] &= ~(1 << (minor & 31));
 287 }
 288
 289 static inline void drive_stat_acct(int cmd, unsigned long nr_sectors,
 290                                    short disk_index)
 291 {
 292         kstat.dk_drive[disk_index]++;
 293         if (cmd == READ) {
 294                 kstat.dk_drive_rio[disk_index]++;
 295                 kstat.dk_drive_rblk[disk_index] += nr_sectors;
 296         } else if (cmd == WRITE) {
 297                 kstat.dk_drive_wio[disk_index]++;
 298                 kstat.dk_drive_wblk[disk_index] += nr_sectors;
 299         } else
 300                 printk(KERN_ERR "drive_stat_acct: cmd not R/W?\n");
 301 }
 302
 303 /*
 304  * add-request adds a request to the linked list.
 305  * It disables interrupts (aquires the request spinlock) so that it can muck
 306  * with the request-lists in peace. Thus it should be called with no spinlocks
 307  * held.
 308  *
 309  * By this point, req->cmd is always either READ/WRITE, never READA,
 310  * which is important for drive_stat_acct() above.
 311  */
 312
 313 void add_request(struct blk_dev_struct * dev, struct request * req)
 314 {
 315         int major = MAJOR(req->rq_dev);
 316         int minor = MINOR(req->rq_dev);
 317         struct request * tmp, **current_request;
 318         short            disk_index;
 319         unsigned long flags;
 320         int queue_new_request = 0;
 321
 322         switch (major) {
 323                 case DAC960_MAJOR+0:
 324                         disk_index = (minor & 0x00f8) >> 3;
 325                         if (disk_index < 4)
 326                                 drive_stat_acct(req->cmd, req->nr_sectors, disk_index);
 327                         break;
 328                 case SCSI_DISK0_MAJOR:
 329                         disk_index = (minor & 0x00f0) >> 4;
 330                         if (disk_index < 4)
 331                                 drive_stat_acct(req->cmd, req->nr_sectors, disk_index);
 332                         break;
 333                 case IDE0_MAJOR:        /* same as HD_MAJOR */
 334                 case XT_DISK_MAJOR:
 335                         disk_index = (minor & 0x0040) >> 6;
 336                         drive_stat_acct(req->cmd, req->nr_sectors, disk_index);
 337                         break;
 338                 case IDE1_MAJOR:
 339                         disk_index = ((minor & 0x0040) >> 6) + 2;
 340                         drive_stat_acct(req->cmd, req->nr_sectors, disk_index);
 341                 default:
 342                         break;
 343         }
 344
 345         req->next = NULL;
 346
 347         /*
 348          * We use the goto to reduce locking complexity
 349          */
 350         spin_lock_irqsave(&io_request_lock,flags);
 351         current_request = get_queue(req->rq_dev);
 352
 353         if (!(tmp = *current_request)) {
 354                 *current_request = req;
 355                 if (dev->current_request != &dev->plug)
 356                         queue_new_request = 1;
 357                 goto out;
 358         }
 359         for ( ; tmp->next ; tmp = tmp->next) {
 360                 const int after_current = IN_ORDER(tmp,req);
 361                 const int before_next = IN_ORDER(req,tmp->next);
 362
 363                 if (!IN_ORDER(tmp,tmp->next)) {
 364                         if (after_current || before_next)
 365                                 break;
 366                 } else {
 367                         if (after_current && before_next)
 368                                 break;
 369                 }
 370         }
 371         req->next = tmp->next;
 372         tmp->next = req;
 373
 374 /* for SCSI devices, call request_fn unconditionally */
 375         if (scsi_blk_major(major))
 376                 queue_new_request = 1;
 377         if (major >= COMPAQ_SMART2_MAJOR+0 &&
 378             major <= COMPAQ_SMART2_MAJOR+7)
 379                 queue_new_request = 1;
 380         if (major >= DAC960_MAJOR+0 && major <= DAC960_MAJOR+7)
 381                 queue_new_request = 1;
 382 out:
 383         if (queue_new_request)
 384                 (dev->request_fn)();
 385         spin_unlock_irqrestore(&io_request_lock,flags);
 386 }
 387
 388 /*
 389  * Has to be called with the request spinlock aquired
 390  */
 391 static inline void attempt_merge (struct request *req, int max_sectors)
 392 {
 393         struct request *next = req->next;
 394
 395         if (!next)
 396                 return;
 397         if (req->sector + req->nr_sectors != next->sector)
 398                 return;
 399         if (next->sem || req->cmd != next->cmd || req->rq_dev != next->rq_dev || req->nr_sectors + next->nr_sectors > max_sectors)
 400                 return;
 401         req->bhtail->b_reqnext = next->bh;
 402         req->bhtail = next->bhtail;
 403         req->nr_sectors += next->nr_sectors;
 404         next->rq_status = RQ_INACTIVE;
 405         req->next = next->next;
 406         wake_up (&wait_for_request);
 407 }
 408
 409 void make_request(int major,int rw, struct buffer_head * bh)
 410 {
 411         unsigned int sector, count;
 412         struct request * req;
 413         int rw_ahead, max_req, max_sectors;
 414         unsigned long flags;
 415
 416         count = bh->b_size >> 9;
 417         sector = bh->b_rsector;
 418
 419         /* We'd better have a real physical mapping! */
 420         if (!buffer_mapped(bh))
 421                 BUG();
 422
 423         /* It had better not be a new buffer by the time we see it */
 424         if (buffer_new(bh))
 425                 BUG();
 426
 427         /* Only one thread can actually submit the I/O. */
 428         if (test_and_set_bit(BH_Lock, &bh->b_state))
 429                 return;
 430
 431         if (blk_size[major]) {
 432                 unsigned long maxsector = (blk_size[major][MINOR(bh->b_rdev)] << 1) + 1;
 433
 434                 if (maxsector < count || maxsector - count < sector) {
 435                         bh->b_state &= (1 << BH_Lock) | (1 << BH_Mapped);
 436                         /* This may well happen - the kernel calls bread()
 437                            without checking the size of the device, e.g.,
 438                            when mounting a device. */
 439                         printk(KERN_INFO
 440                                "attempt to access beyond end of device\n");
 441                         printk(KERN_INFO "%s: rw=%d, want=%d, limit=%d\n",
 442                                kdevname(bh->b_rdev), rw,
 443                                (sector + count)>>1,
 444                                blk_size[major][MINOR(bh->b_rdev)]);
 445                         goto end_io;
 446                 }
 447         }
 448
 449         rw_ahead = 0;   /* normal case; gets changed below for READA */
 450         switch (rw) {
 451                 case READA:
 452                         rw_ahead = 1;
 453                         rw = READ;      /* drop into READ */
 454                 case READ:
 455                         if (buffer_uptodate(bh)) /* Hmmph! Already have it */
 456                                 goto end_io;
 457                         kstat.pgpgin++;
 458                         max_req = NR_REQUEST;   /* reads take precedence */
 459                         break;
 460                 case WRITERAW:
 461                         rw = WRITE;
 462                         goto do_write;  /* Skip the buffer refile */
 463                 case WRITE:
 464                         if (!test_and_clear_bit(BH_Dirty, &bh->b_state))
 465                                 goto end_io;    /* Hmmph! Nothing to write */
 466                         refile_buffer(bh);
 467                 do_write:
 468                         /*
 469                          * We don't allow the write-requests to fill up the
 470                          * queue completely:  we want some room for reads,
 471                          * as they take precedence. The last third of the
 472                          * requests are only for reads.
 473                          */
 474                         kstat.pgpgout++;
 475                         max_req = (NR_REQUEST * 2) / 3;
 476                         break;
 477                 default:
 478                         printk(KERN_ERR "make_request: bad block dev cmd,"
 479                                " must be R/W/RA/WA\n");
 480                         goto end_io;
 481         }
 482
 483 /* look for a free request. */
 484        /* Loop uses two requests, 1 for loop and 1 for the real device.
 485         * Cut max_req in half to avoid running out and deadlocking. */
 486          if ((major == LOOP_MAJOR) || (major == NBD_MAJOR))
 487              max_req >>= 1;
 488
 489         /*
 490          * Try to coalesce the new request with old requests
 491          */
 492         max_sectors = get_max_sectors(bh->b_rdev);
 493
 494         /*
 495          * Now we acquire the request spinlock, we have to be mega careful
 496          * not to schedule or do something nonatomic
 497          */
 498         spin_lock_irqsave(&io_request_lock,flags);
 499         req = *get_queue(bh->b_rdev);
 500         if (!req) {
 501                 /* MD and loop can't handle plugging without deadlocking */
 502                 if (major != MD_MAJOR && major != LOOP_MAJOR &&
 503                     major != DDV_MAJOR && major != NBD_MAJOR)
 504                         plug_device(blk_dev + major); /* is atomic */
 505         } else switch (major) {
 506              case IDE0_MAJOR:   /* same as HD_MAJOR */
 507              case IDE1_MAJOR:
 508              case FLOPPY_MAJOR:
 509              case IDE2_MAJOR:
 510              case IDE3_MAJOR:
 511              case IDE4_MAJOR:
 512              case IDE5_MAJOR:
 513              case IDE6_MAJOR:
 514              case IDE7_MAJOR:
 515              case IDE8_MAJOR:
 516              case IDE9_MAJOR:
 517              case ACSI_MAJOR:
 518              case MFM_ACORN_MAJOR:
 519                 /*
 520                  * The scsi disk and cdrom drivers completely remove the request
 521                  * from the queue when they start processing an entry.  For this
 522                  * reason it is safe to continue to add links to the top entry for
 523                  * those devices.
 524                  *
 525                  * All other drivers need to jump over the first entry, as that
 526                  * entry may be busy being processed and we thus can't change it.
 527                  */
 528                 if (req == blk_dev[major].current_request)
 529                         req = req->next;
 530                 if (!req)
 531                         break;
 532                 /* fall through */
 533
 534              case SCSI_DISK0_MAJOR:
 535              case SCSI_DISK1_MAJOR:
 536              case SCSI_DISK2_MAJOR:
 537              case SCSI_DISK3_MAJOR:
 538              case SCSI_DISK4_MAJOR:
 539              case SCSI_DISK5_MAJOR:
 540              case SCSI_DISK6_MAJOR:
 541              case SCSI_DISK7_MAJOR:
 542              case SCSI_CDROM_MAJOR:
 543              case DAC960_MAJOR+0:
 544              case DAC960_MAJOR+1:
 545              case DAC960_MAJOR+2:
 546              case DAC960_MAJOR+3:
 547              case DAC960_MAJOR+4:
 548              case DAC960_MAJOR+5:
 549              case DAC960_MAJOR+6:
 550              case DAC960_MAJOR+7:
 551              case I2O_MAJOR:
 552              case COMPAQ_SMART2_MAJOR+0:
 553              case COMPAQ_SMART2_MAJOR+1:
 554              case COMPAQ_SMART2_MAJOR+2:
 555              case COMPAQ_SMART2_MAJOR+3:
 556              case COMPAQ_SMART2_MAJOR+4:
 557              case COMPAQ_SMART2_MAJOR+5:
 558              case COMPAQ_SMART2_MAJOR+6:
 559              case COMPAQ_SMART2_MAJOR+7:
 560
 561                 do {
 562                         if (req->sem)
 563                                 continue;
 564                         if (req->cmd != rw)
 565                                 continue;
 566                         if (req->nr_sectors + count > max_sectors)
 567                                 continue;
 568                         if (req->rq_dev != bh->b_rdev)
 569                                 continue;
 570                         /* Can we add it to the end of this request? */
 571                         if (req->sector + req->nr_sectors == sector) {
 572                                 req->bhtail->b_reqnext = bh;
 573                                 req->bhtail = bh;
 574                                 req->nr_sectors += count;
 575                                 /* Can we now merge this req with the next? */
 576                                 attempt_merge(req, max_sectors);
 577                         /* or to the beginning? */
 578                         } else if (req->sector - count == sector) {
 579                                 bh->b_reqnext = req->bh;
 580                                 req->bh = bh;
 581                                 req->buffer = bh->b_data;
 582                                 req->current_nr_sectors = count;
 583                                 req->sector = sector;
 584                                 req->nr_sectors += count;
 585                         } else
 586                                 continue;
 587
 588                         spin_unlock_irqrestore(&io_request_lock,flags);
 589                         return;
 590
 591                 } while ((req = req->next) != NULL);
 592         }
 593
 594 /* find an unused request. */
 595         req = get_request(max_req, bh->b_rdev);
 596
 597         spin_unlock_irqrestore(&io_request_lock,flags);
 598
 599 /* if no request available: if rw_ahead, forget it; otherwise try again blocking.. */
 600         if (!req) {
 601                 if (rw_ahead)
 602                         goto end_io;
 603                 req = __get_request_wait(max_req, bh->b_rdev);
 604         }
 605
 606 /* fill up the request-info, and add it to the queue */
 607         req->cmd = rw;
 608         req->errors = 0;
 609         req->sector = sector;
 610         req->nr_sectors = count;
 611         req->current_nr_sectors = count;
 612         req->buffer = bh->b_data;
 613         req->sem = NULL;
 614         req->bh = bh;
 615         req->bhtail = bh;
 616         req->next = NULL;
 617         add_request(major+blk_dev,req);
 618         return;
 619
 620 end_io:
 621         bh->b_end_io(bh, test_bit(BH_Uptodate, &bh->b_state));
 622 }
 623
 624 /* This function can be used to request a number of buffers from a block
 625    device. Currently the only restriction is that all buffers must belong to
 626    the same device */
 627
 628 void ll_rw_block(int rw, int nr, struct buffer_head * bh[])
 629 {
 630         unsigned int major;
 631         int correct_size;
 632         struct blk_dev_struct * dev;
 633         int i;
 634
 635         dev = NULL;
 636         if ((major = MAJOR(bh[0]->b_dev)) < MAX_BLKDEV)
 637                 dev = blk_dev + major;
 638         if (!dev || !dev->request_fn) {
 639                 printk(KERN_ERR
 640         "ll_rw_block: Trying to read nonexistent block-device %s (%ld)\n",
 641                 kdevname(bh[0]->b_dev), bh[0]->b_blocknr);
 642                 goto sorry;
 643         }
 644
 645         /* Determine correct block size for this device.  */
 646         correct_size = BLOCK_SIZE;
 647         if (blksize_size[major]) {
 648                 i = blksize_size[major][MINOR(bh[0]->b_dev)];
 649                 if (i)
 650                         correct_size = i;
 651         }
 652
 653         /* Verify requested block sizes.  */
 654         for (i = 0; i < nr; i++) {
 655                 if (bh[i]->b_size != correct_size) {
 656                         printk(KERN_NOTICE "ll_rw_block: device %s: "
 657                                "only %d-char blocks implemented (%u)\n",
 658                                kdevname(bh[0]->b_dev),
 659                                correct_size, bh[i]->b_size);
 660                         goto sorry;
 661                 }
 662
 663                 /* Md remaps blocks now */
 664                 bh[i]->b_rdev = bh[i]->b_dev;
 665                 bh[i]->b_rsector=bh[i]->b_blocknr*(bh[i]->b_size >> 9);
 666 #ifdef CONFIG_BLK_DEV_MD
 667                 if (major==MD_MAJOR &&
 668                     md_map (MINOR(bh[i]->b_dev), &bh[i]->b_rdev,
 669                             &bh[i]->b_rsector, bh[i]->b_size >> 9)) {
 670                         printk (KERN_ERR
 671                                 "Bad md_map in ll_rw_block\n");
 672                         goto sorry;
 673                 }
 674 #endif
 675         }
 676
 677         if ((rw & WRITE) && is_read_only(bh[0]->b_dev)) {
 678                 printk(KERN_NOTICE "Can't write to read-only device %s\n",
 679                        kdevname(bh[0]->b_dev));
 680                 goto sorry;
 681         }
 682
 683         for (i = 0; i < nr; i++) {
 684                 set_bit(BH_Req, &bh[i]->b_state);
 685 #ifdef CONFIG_BLK_DEV_MD
 686                 if (MAJOR(bh[i]->b_dev) == MD_MAJOR) {
 687                         md_make_request(MINOR (bh[i]->b_dev), rw, bh[i]);
 688                         continue;
 689                 }
 690 #endif
 691                 make_request(MAJOR(bh[i]->b_rdev), rw, bh[i]);
 692         }
 693         return;
 694
 695       sorry:
 696         for (i = 0; i < nr; i++) {
 697                 clear_bit(BH_Dirty, &bh[i]->b_state);
 698                 clear_bit(BH_Uptodate, &bh[i]->b_state);
 699                 bh[i]->b_end_io(bh[i], 0);
 700         }
 701         return;
 702 }
 703
 704 #ifdef CONFIG_STRAM_SWAP
 705 extern int stram_device_init( void );
 706 #endif
 707
 708 /*
 709  * First step of what used to be end_request
 710  *
 711  * 0 means continue with end_that_request_last,
 712  * 1 means we are done
 713  */
 714
 715 int
 716 end_that_request_first( struct request *req, int uptodate, char *name )
 717 {
 718         struct buffer_head * bh;
 719         int nsect;
 720
 721         req->errors = 0;
 722         if (!uptodate) {
 723                 printk("end_request: I/O error, dev %s (%s), sector %lu\n",
 724                         kdevname(req->rq_dev), name, req->sector);
 725                 if ((bh = req->bh) != NULL) {
 726                         nsect = bh->b_size >> 9;
 727                         req->nr_sectors--;
 728                         req->nr_sectors &= ~(nsect - 1);
 729                         req->sector += nsect;
 730                         req->sector &= ~(nsect - 1);
 731                 }
 732         }
 733
 734         if ((bh = req->bh) != NULL) {
 735                 req->bh = bh->b_reqnext;
 736                 bh->b_reqnext = NULL;
 737                 bh->b_end_io(bh, uptodate);
 738                 if ((bh = req->bh) != NULL) {
 739                         req->current_nr_sectors = bh->b_size >> 9;
 740                         if (req->nr_sectors < req->current_nr_sectors) {
 741                                 req->nr_sectors = req->current_nr_sectors;
 742                                 printk("end_request: buffer-list destroyed\n");
 743                         }
 744                         req->buffer = bh->b_data;
 745                         return 1;
 746                 }
 747         }
 748         return 0;
 749 }
 750
 751 void
 752 end_that_request_last( struct request *req )
 753 {
 754         if (req->sem != NULL)
 755                 up(req->sem);
 756         req->rq_status = RQ_INACTIVE;
 757         wake_up(&wait_for_request);
 758 }
 759
 760 int __init blk_dev_init(void)
 761 {
 762         struct request * req;
 763         struct blk_dev_struct *dev;
 764
 765         for (dev = blk_dev + MAX_BLKDEV; dev-- != blk_dev;) {
 766                 dev->request_fn      = NULL;
 767                 dev->queue           = NULL;
 768                 dev->current_request = NULL;
 769                 dev->plug.rq_status  = RQ_INACTIVE;
 770                 dev->plug.cmd        = -1;
 771                 dev->plug.next       = NULL;
 772                 dev->plug_tq.sync    = 0;
 773                 dev->plug_tq.routine = &unplug_device;
 774                 dev->plug_tq.data    = dev;
 775         }
 776
 777         req = all_requests + NR_REQUEST;
 778         while (--req >= all_requests) {
 779                 req->rq_status = RQ_INACTIVE;
 780                 req->next = NULL;
 781         }
 782         memset(ro_bits,0,sizeof(ro_bits));
 783         memset(max_readahead, 0, sizeof(max_readahead));
 784         memset(max_sectors, 0, sizeof(max_sectors));
 785 #ifdef CONFIG_AMIGA_Z2RAM
 786         z2_init();
 787 #endif
 788 #ifdef CONFIG_STRAM_SWAP
 789         stram_device_init();
 790 #endif
 791 #ifdef CONFIG_BLK_DEV_RAM
 792         rd_init();
 793 #endif
 794 #ifdef CONFIG_BLK_DEV_LOOP
 795         loop_init();
 796 #endif
 797 #ifdef CONFIG_ISP16_CDI
 798         isp16_init();
 799 #endif CONFIG_ISP16_CDI
 800 #ifdef CONFIG_BLK_DEV_IDE
 801         ide_init();             /* this MUST precede hd_init */
 802 #endif
 803 #ifdef CONFIG_BLK_DEV_HD
 804         hd_init();
 805 #endif
 806 #ifdef CONFIG_BLK_DEV_PS2
 807         ps2esdi_init();
 808 #endif
 809 #ifdef CONFIG_BLK_DEV_XD
 810         xd_init();
 811 #endif
 812 #ifdef CONFIG_BLK_DEV_MFM
 813         mfm_init();
 814 #endif
 815 #ifdef CONFIG_PARIDE
 816         { extern void paride_init(void); paride_init(); };
 817 #endif
 818 #ifdef CONFIG_MAC_FLOPPY
 819         swim3_init();
 820 #endif
 821 #ifdef CONFIG_BLK_DEV_SWIM_IOP
 822         swimiop_init();
 823 #endif
 824 #ifdef CONFIG_AMIGA_FLOPPY
 825         amiga_floppy_init();
 826 #endif
 827 #ifdef CONFIG_ATARI_FLOPPY
 828         atari_floppy_init();
 829 #endif
 830 #ifdef CONFIG_BLK_DEV_FD
 831         floppy_init();
 832 #else
 833 #if !defined (__mc68000__) && !defined(CONFIG_PPC) && !defined(__sparc__)\
 834     && !defined(CONFIG_APUS) && !defined(__sh__)
 835         outb_p(0xc, 0x3f2);
 836 #endif
 837 #endif
 838 #ifdef CONFIG_CDU31A
 839         cdu31a_init();
 840 #endif CONFIG_CDU31A
 841 #ifdef CONFIG_ATARI_ACSI
 842         acsi_init();
 843 #endif CONFIG_ATARI_ACSI
 844 #ifdef CONFIG_MCD
 845         mcd_init();
 846 #endif CONFIG_MCD
 847 #ifdef CONFIG_MCDX
 848         mcdx_init();
 849 #endif CONFIG_MCDX
 850 #ifdef CONFIG_SBPCD
 851         sbpcd_init();
 852 #endif CONFIG_SBPCD
 853 #ifdef CONFIG_AZTCD
 854         aztcd_init();
 855 #endif CONFIG_AZTCD
 856 #ifdef CONFIG_CDU535
 857         sony535_init();
 858 #endif CONFIG_CDU535
 859 #ifdef CONFIG_GSCD
 860         gscd_init();
 861 #endif CONFIG_GSCD
 862 #ifdef CONFIG_CM206
 863         cm206_init();
 864 #endif
 865 #ifdef CONFIG_OPTCD
 866         optcd_init();
 867 #endif CONFIG_OPTCD
 868 #ifdef CONFIG_SJCD
 869         sjcd_init();
 870 #endif CONFIG_SJCD
 871 #ifdef CONFIG_BLK_DEV_MD
 872         md_init();
 873 #endif CONFIG_BLK_DEV_MD
 874 #ifdef CONFIG_APBLOCK
 875         ap_init();
 876 #endif
 877 #ifdef CONFIG_DDV
 878         ddv_init();
 879 #endif
 880 #ifdef CONFIG_BLK_DEV_NBD
 881         nbd_init();
 882 #endif
 883         return 0;
 884 };
 885
 886 EXPORT_SYMBOL(io_request_lock);
 887 EXPORT_SYMBOL(end_that_request_first);
 888 EXPORT_SYMBOL(end_that_request_last);