drivers/scsi/sd.c

/* */
This source file includes following definitions.
sd_open
sd_release
sd_geninit
rw_intr
do_sd_request
requeue_sd_request
check_scsidisk_media_change
sd_init_done
sd_init_onedisk
sd_init
sd_finish
sd_detect
sd_attach
revalidate_scsidisk
fop_revalidate_scsidisk
sd_detach
init_module
cleanup_module
   1 /*
   2  *      sd.c Copyright (C) 1992 Drew Eckhardt 
   3  *           Copyright (C) 1993, 1994, 1995 Eric Youngdale
   4  *
   5  *      Linux scsi disk driver
   6  *              Initial versions: Drew Eckhardt 
   7  *              Subsequent revisions: Eric Youngdale
   8  *
   9  *      <drew@colorado.edu>
  10  *
  11  *       Modified by Eric Youngdale ericy@cais.com to
  12  *       add scatter-gather, multiple outstanding request, and other
  13  *       enhancements.
  14  *
  15  *       Modified by Eric Youngdale eric@aib.com to support loadable
  16  *       low-level scsi drivers.
  17  */
  18 
  19 #ifdef MODULE
  20 #include <linux/autoconf.h>
  21 #include <linux/module.h>
  22 #include <linux/version.h>
  23 /*
  24  * This is a variable in scsi.c that is set when we are processing something
  25  * after boot time.  By definition, this is true when we are a loadable module
  26  * ourselves.
  27  */
  28 #define MODULE_FLAG 1
  29 #else
  30 #define MODULE_FLAG scsi_loadable_module_flag
  31 #endif /* MODULE */
  32 
  33 #include <linux/fs.h>
  34 #include <linux/kernel.h>
  35 #include <linux/sched.h>
  36 #include <linux/mm.h>
  37 #include <linux/string.h>
  38 #include <linux/errno.h>
  39 #include <asm/system.h>
  40 
  41 #define MAJOR_NR SCSI_DISK_MAJOR
  42 #include "../block/blk.h"
  43 #include "scsi.h"
  44 #include "hosts.h"
  45 #include "sd.h"
  46 #include "scsi_ioctl.h"
  47 #include "constants.h"
  48 
  49 #include <linux/genhd.h>
  50 
  51 /*
  52  *  static const char RCSid[] = "$Header:";
  53  */
  54 
  55 #define MAX_RETRIES 5
  56 
  57 /*
  58  *  Time out in seconds for disks and Magneto-opticals (which are slower).
  59  */
  60 
  61 #define SD_TIMEOUT (7 * HZ)
  62 #define SD_MOD_TIMEOUT (8 * HZ)
  63 
  64 #define CLUSTERABLE_DEVICE(SC) (SC->host->use_clustering && \
  65                                 SC->device->type != TYPE_MOD)
  66 
  67 struct hd_struct * sd;
  68 int revalidate_scsidisk(int dev, int maxusage);
  69 
  70 Scsi_Disk * rscsi_disks = NULL;
  71 static int * sd_sizes;
  72 static int * sd_blocksizes;
  73 static int * sd_hardsizes;              /* Hardware sector size */
  74 
  75 extern int sd_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
  76 
  77 static int check_scsidisk_media_change(dev_t);
  78 static int fop_revalidate_scsidisk(dev_t);
  79 
  80 static sd_init_onedisk(int);
  81 
  82 static void requeue_sd_request (Scsi_Cmnd * SCpnt);
  83 
  84 static int sd_init(void);
  85 static void sd_finish(void);
  86 static int sd_attach(Scsi_Device *);
  87 static int sd_detect(Scsi_Device *);
  88 static void sd_detach(Scsi_Device *);
  89 
  90 struct Scsi_Device_Template sd_template = 
  91 { NULL, "disk", "sd", NULL, TYPE_DISK, 
  92       SCSI_DISK_MAJOR, 0, 0, 0, 1,
  93       sd_detect, sd_init,
  94       sd_finish, sd_attach, sd_detach
  95 };
  96 
  97 static int sd_open(struct inode * inode, struct file * filp)
     /*  */
  98 {
  99     int target;
 100     target =  DEVICE_NR(MINOR(inode->i_rdev));
 101     
 102     if(target >= sd_template.dev_max || !rscsi_disks[target].device)
 103         return -ENXIO;   /* No such device */
 104     
 105     /* 
 106      * Make sure that only one process can do a check_change_disk at one time.
 107      * This is also used to lock out further access when the partition table 
 108      * is being re-read. 
 109      */
 110     
 111     while (rscsi_disks[target].device->busy)
 112     barrier();   
 113     if(rscsi_disks[target].device->removable) {
 114         check_disk_change(inode->i_rdev);
 115         
 116         if(!rscsi_disks[target].device->access_count)
 117             sd_ioctl(inode, NULL, SCSI_IOCTL_DOORLOCK, 0);
 118     };
 119 
 120     /*
 121      * See if we are requesting a non-existent partition.  Do this
 122      * after checking for disk change.
 123      */
 124     if(sd_sizes[MINOR(inode->i_rdev)] == 0)
 125         return -ENXIO;
 126     
 127     rscsi_disks[target].device->access_count++;
 128     if (rscsi_disks[target].device->host->hostt->usage_count)
 129         (*rscsi_disks[target].device->host->hostt->usage_count)++;
 130     if(sd_template.usage_count) (*sd_template.usage_count)++;
 131     return 0;
 132 }
 133 
 134 static void sd_release(struct inode * inode, struct file * file)
     /*  */
 135 {
 136     int target;
 137     sync_dev(inode->i_rdev);
 138     
 139     target =  DEVICE_NR(MINOR(inode->i_rdev));
 140     
 141     rscsi_disks[target].device->access_count--;
 142     if (rscsi_disks[target].device->host->hostt->usage_count)
 143         (*rscsi_disks[target].device->host->hostt->usage_count)--;
 144     if(sd_template.usage_count) (*sd_template.usage_count)--;
 145     
 146     if(rscsi_disks[target].device->removable) {
 147         if(!rscsi_disks[target].device->access_count)
 148             sd_ioctl(inode, NULL, SCSI_IOCTL_DOORUNLOCK, 0);
 149     }
 150 }
 151 
 152 static void sd_geninit(struct gendisk *);
 153 
 154 static struct file_operations sd_fops = {
 155     NULL,                        /* lseek - default */
 156     block_read,                  /* read - general block-dev read */
 157     block_write,                 /* write - general block-dev write */
 158     NULL,                        /* readdir - bad */
 159     NULL,                        /* select */
 160     sd_ioctl,                    /* ioctl */
 161     NULL,                        /* mmap */
 162     sd_open,                     /* open code */
 163     sd_release,                  /* release */
 164     block_fsync,                 /* fsync */
 165     NULL,                        /* fasync */
 166     check_scsidisk_media_change, /* Disk change */
 167     fop_revalidate_scsidisk      /* revalidate */
 168 };
 169 
 170 static struct gendisk sd_gendisk = {
 171     MAJOR_NR,                    /* Major number */
 172     "sd",                        /* Major name */
 173     4,                           /* Bits to shift to get real from partition */
 174     1 << 4,                      /* Number of partitions per real */
 175     0,                           /* maximum number of real */
 176     sd_geninit,                  /* init function */
 177     NULL,                        /* hd struct */
 178     NULL,                        /* block sizes */
 179     0,                           /* number */
 180     NULL,                        /* internal */
 181     NULL                         /* next */
 182 };
 183 
 184 static void sd_geninit (struct gendisk *ignored)
     /*  */
 185 {
 186     int i;
 187     
 188     for (i = 0; i < sd_template.dev_max; ++i)
 189         if(rscsi_disks[i].device) 
 190             sd[i << 4].nr_sects = rscsi_disks[i].capacity;
 191 #if 0
 192     /* No longer needed - we keep track of this as we attach/detach */
 193     sd_gendisk.nr_real = sd_template.dev_max;
 194 #endif
 195 }
 196 
 197 /*
 198  * rw_intr is the interrupt routine for the device driver.  It will
 199  * be notified on the end of a SCSI read / write, and
 200  * will take on of several actions based on success or failure.
 201  */
 202 
 203 static void rw_intr (Scsi_Cmnd *SCpnt)
     /*  */
 204 {
 205     int result = SCpnt->result;
 206     int this_count = SCpnt->bufflen >> 9;
 207     
 208 #ifdef DEBUG
 209     printk("sd%c : rw_intr(%d, %d)\n", 'a' + MINOR(SCpnt->request.dev), 
 210            SCpnt->host->host_no, result);
 211 #endif
 212     
 213     /*
 214      * First case : we assume that the command succeeded.  One of two things 
 215      * will happen here.  Either we will be finished, or there will be more
 216      * sectors that we were unable to read last time.
 217      */
 218 
 219     if (!result) {
 220         
 221 #ifdef DEBUG
 222         printk("sd%c : %d sectors remain.\n", 'a' + MINOR(SCpnt->request.dev),
 223                SCpnt->request.nr_sectors);
 224         printk("use_sg is %d\n ",SCpnt->use_sg);
 225 #endif
 226         if (SCpnt->use_sg) {
 227             struct scatterlist * sgpnt;
 228             int i;
 229             sgpnt = (struct scatterlist *) SCpnt->buffer;
 230             for(i=0; i<SCpnt->use_sg; i++) {
 231 #ifdef DEBUG
 232                 printk(":%x %x %d\n",sgpnt[i].alt_address, sgpnt[i].address, 
 233                        sgpnt[i].length);
 234 #endif
 235                 if (sgpnt[i].alt_address) {
 236                     if (SCpnt->request.cmd == READ)
 237                         memcpy(sgpnt[i].alt_address, sgpnt[i].address, 
 238                                sgpnt[i].length);
 239                     scsi_free(sgpnt[i].address, sgpnt[i].length);
 240                 };
 241             };
 242 
 243             /* Free list of scatter-gather pointers */
 244             scsi_free(SCpnt->buffer, SCpnt->sglist_len);  
 245         } else {
 246             if (SCpnt->buffer != SCpnt->request.buffer) {
 247 #ifdef DEBUG
 248                 printk("nosg: %x %x %d\n",SCpnt->request.buffer, SCpnt->buffer,
 249                        SCpnt->bufflen);
 250 #endif  
 251                 if (SCpnt->request.cmd == READ)
 252                     memcpy(SCpnt->request.buffer, SCpnt->buffer,
 253                            SCpnt->bufflen);
 254                 scsi_free(SCpnt->buffer, SCpnt->bufflen);
 255             };
 256         };
 257         /*
 258          * If multiple sectors are requested in one buffer, then
 259          * they will have been finished off by the first command.
 260          * If not, then we have a multi-buffer command.
 261          */
 262         if (SCpnt->request.nr_sectors > this_count)
 263         {
 264             SCpnt->request.errors = 0;
 265             
 266             if (!SCpnt->request.bh)
 267             {
 268 #ifdef DEBUG
 269                 printk("sd%c : handling page request, no buffer\n",
 270                        'a' + MINOR(SCpnt->request.dev));
 271 #endif
 272                 /*
 273                  * The SCpnt->request.nr_sectors field is always done in 
 274                  * 512 byte sectors, even if this really isn't the case.
 275                  */
 276                 panic("sd.c: linked page request (%lx %x)",
 277                       SCpnt->request.sector, this_count);
 278             }
 279         }
 280         SCpnt = end_scsi_request(SCpnt, 1, this_count);
 281         requeue_sd_request(SCpnt);
 282         return;
 283     }
 284     
 285     /* Free up any indirection buffers we allocated for DMA purposes. */
 286     if (SCpnt->use_sg) {
 287         struct scatterlist * sgpnt;
 288         int i;
 289         sgpnt = (struct scatterlist *) SCpnt->buffer;
 290         for(i=0; i<SCpnt->use_sg; i++) {
 291 #ifdef DEBUG
 292             printk("err: %x %x %d\n",SCpnt->request.buffer, SCpnt->buffer,
 293                    SCpnt->bufflen);
 294 #endif
 295             if (sgpnt[i].alt_address) {
 296                 scsi_free(sgpnt[i].address, sgpnt[i].length);
 297             };
 298         };
 299         scsi_free(SCpnt->buffer, SCpnt->sglist_len);  /* Free list of scatter-gather pointers */
 300     } else {
 301 #ifdef DEBUG
 302         printk("nosgerr: %x %x %d\n",SCpnt->request.buffer, SCpnt->buffer,
 303                SCpnt->bufflen);
 304 #endif
 305         if (SCpnt->buffer != SCpnt->request.buffer)
 306             scsi_free(SCpnt->buffer, SCpnt->bufflen);
 307     };
 308     
 309     /*
 310      * Now, if we were good little boys and girls, Santa left us a request
 311      * sense buffer.  We can extract information from this, so we
 312      * can choose a block to remap, etc.
 313      */
 314 
 315     if (driver_byte(result) != 0) {
 316         if (suggestion(result) == SUGGEST_REMAP) {
 317 #ifdef REMAP
 318             /*
 319              * Not yet implemented.  A read will fail after being remapped,
 320              * a write will call the strategy routine again.
 321              */
 322             if rscsi_disks[DEVICE_NR(SCpnt->request.dev)].remap
 323             {
 324                 result = 0;
 325             }
 326             else
 327 #endif
 328         }
 329         
 330         if ((SCpnt->sense_buffer[0] & 0x7f) == 0x70) {
 331             if ((SCpnt->sense_buffer[2] & 0xf) == UNIT_ATTENTION) {
 332                 if(rscsi_disks[DEVICE_NR(SCpnt->request.dev)].device->removable) {
 333                     /* detected disc change.  set a bit and quietly refuse
 334                      * further access.
 335                      */  
 336                     rscsi_disks[DEVICE_NR(SCpnt->request.dev)].device->changed = 1;
 337                     SCpnt = end_scsi_request(SCpnt, 0, this_count);
 338                     requeue_sd_request(SCpnt);
 339                     return;
 340                 }
 341                 else
 342                 {
 343                     /*
 344                      * Must have been a power glitch, or a bus reset.
 345                      * Could not have been a media change, so we just retry
 346                      * the request and see what happens.
 347                      */
 348                     requeue_sd_request(SCpnt);
 349                     return;
 350                 }
 351             }
 352         }
 353         
 354         
 355         /* If we had an ILLEGAL REQUEST returned, then we may have
 356          * performed an unsupported command.  The only thing this should be 
 357          * would be a ten byte read where only a six byte read was supported.
 358          * Also, on a system where READ CAPACITY failed, we have have read 
 359          * past the end of the disk. 
 360          */
 361 
 362         if (SCpnt->sense_buffer[2] == ILLEGAL_REQUEST) {
 363             if (rscsi_disks[DEVICE_NR(SCpnt->request.dev)].ten) {
 364                 rscsi_disks[DEVICE_NR(SCpnt->request.dev)].ten = 0;
 365                 requeue_sd_request(SCpnt);
 366                 result = 0;
 367             } else {
 368                 /* ???? */
 369             }
 370         }
 371     }  /* driver byte != 0 */
 372     if (result) {
 373         printk("SCSI disk error : host %d channel %d id %d lun %d return code = %x\n",
 374                rscsi_disks[DEVICE_NR(SCpnt->request.dev)].device->host->host_no,
 375                rscsi_disks[DEVICE_NR(SCpnt->request.dev)].device->channel,
 376            rscsi_disks[DEVICE_NR(SCpnt->request.dev)].device->id,
 377              rscsi_disks[DEVICE_NR(SCpnt->request.dev)].device->lun, result);
 378         
 379         if (driver_byte(result) & DRIVER_SENSE)
 380             print_sense("sd", SCpnt);
 381         SCpnt = end_scsi_request(SCpnt, 0, SCpnt->request.current_nr_sectors);
 382         requeue_sd_request(SCpnt);
 383         return;
 384     }
 385 }
 386 
 387 /*
 388  * requeue_sd_request() is the request handler function for the sd driver.
 389  * Its function in life is to take block device requests, and translate
 390  * them to SCSI commands.
 391  */
 392 
 393 static void do_sd_request (void)
     /*  */
 394 {
 395     Scsi_Cmnd * SCpnt = NULL;
 396     Scsi_Device * SDev;
 397     struct request * req = NULL;
 398     unsigned long flags;
 399     int flag = 0;
 400     
 401     save_flags(flags);
 402     while (1==1){
 403         cli();
 404         if (CURRENT != NULL && CURRENT->dev == -1) {
 405             restore_flags(flags);
 406             return;
 407         };
 408         
 409         INIT_SCSI_REQUEST;
 410         SDev = rscsi_disks[DEVICE_NR(MINOR(CURRENT->dev))].device;
 411         
 412         /*
 413          * I am not sure where the best place to do this is.  We need
 414          * to hook in a place where we are likely to come if in user
 415          * space.
 416          */
 417         if( SDev->was_reset )
 418         {
 419             /*
 420              * We need to relock the door, but we might
 421              * be in an interrupt handler.  Only do this
 422              * from user space, since we do not want to
 423              * sleep from an interrupt.
 424              */
 425             if( SDev->removable && !intr_count )
 426             {
 427                 scsi_ioctl(SDev, SCSI_IOCTL_DOORLOCK, 0);
 428             }
 429             SDev->was_reset = 0;
 430         }
 431                 
 432         /* We have to be careful here. allocate_device will get a free pointer,
 433          * but there is no guarantee that it is queueable.  In normal usage, 
 434          * we want to call this, because other types of devices may have the 
 435          * host all tied up, and we want to make sure that we have at least 
 436          * one request pending for this type of device. We can also come 
 437          * through here while servicing an interrupt, because of the need to 
 438          * start another command. If we call allocate_device more than once, 
 439          * then the system can wedge if the command is not queueable. The 
 440          * request_queueable function is safe because it checks to make sure 
 441          * that the host is able to take another command before it returns
 442          * a pointer.  
 443          */
 444 
 445         if (flag++ == 0)
 446             SCpnt = allocate_device(&CURRENT,
 447                                     rscsi_disks[DEVICE_NR(MINOR(CURRENT->dev))].device, 0); 
 448         else SCpnt = NULL;
 449         
 450         /*
 451          * The following restore_flags leads to latency problems.  FIXME.
 452          * Using a "sti()" gets rid of the latency problems but causes
 453          * race conditions and crashes.
 454          */
 455         restore_flags(flags);
 456 
 457         /* This is a performance enhancement. We dig down into the request 
 458          * list and try and find a queueable request (i.e. device not busy, 
 459          * and host able to accept another command. If we find one, then we 
 460          * queue it. This can make a big difference on systems with more than 
 461          * one disk drive.  We want to have the interrupts off when monkeying 
 462          * with the request list, because otherwise the kernel might try and 
 463          * slip in a request in between somewhere. 
 464          */
 465 
 466         if (!SCpnt && sd_template.nr_dev > 1){
 467             struct request *req1;
 468             req1 = NULL;
 469             cli();
 470             req = CURRENT;
 471             while(req){
 472                 SCpnt = request_queueable(req, rscsi_disks[DEVICE_NR(MINOR(req->dev))].device);
 473                 if(SCpnt) break;
 474                 req1 = req;
 475                 req = req->next;
 476             };
 477             if (SCpnt && req->dev == -1) {
 478                 if (req == CURRENT) 
 479                     CURRENT = CURRENT->next;
 480                 else
 481                     req1->next = req->next;
 482             };
 483             restore_flags(flags);
 484         };
 485         
 486         if (!SCpnt) return; /* Could not find anything to do */
 487         
 488         /* Queue command */
 489         requeue_sd_request(SCpnt);
 490     };  /* While */
 491 }    
 492 
 493 static void requeue_sd_request (Scsi_Cmnd * SCpnt)
     /*  */
 494 {
 495     int dev, block, this_count;
 496     unsigned char cmd[10];
 497     int bounce_size, contiguous;
 498     int max_sg;
 499     struct buffer_head * bh, *bhp;
 500     char * buff, *bounce_buffer;
 501     
 502  repeat:
 503     
 504     if(!SCpnt || SCpnt->request.dev <= 0) {
 505         do_sd_request();
 506         return;
 507     }
 508     
 509     dev =  MINOR(SCpnt->request.dev);
 510     block = SCpnt->request.sector;
 511     this_count = 0;
 512 
 513 #ifdef DEBUG
 514     printk("Doing sd request, dev = %d, block = %d\n", dev, block);
 515 #endif
 516     
 517     if (dev >= (sd_template.dev_max << 4) || 
 518         !rscsi_disks[DEVICE_NR(dev)].device ||
 519         block + SCpnt->request.nr_sectors > sd[dev].nr_sects)
 520     {
 521         SCpnt = end_scsi_request(SCpnt, 0, SCpnt->request.nr_sectors);
 522         goto repeat;
 523     }
 524     
 525     block += sd[dev].start_sect;
 526     dev = DEVICE_NR(dev);
 527     
 528     if (rscsi_disks[dev].device->changed)
 529     {
 530         /*
 531          * quietly refuse to do anything to a changed disc until the changed 
 532          * bit has been reset
 533          */
 534         /* printk("SCSI disk has been changed. Prohibiting further I/O.\n"); */
 535         SCpnt = end_scsi_request(SCpnt, 0, SCpnt->request.nr_sectors);
 536         goto repeat;
 537     }
 538     
 539 #ifdef DEBUG
 540     printk("sd%c : real dev = /dev/sd%c, block = %d\n", 
 541            'a' + MINOR(SCpnt->request.dev), dev, block);
 542 #endif
 543     
 544     /*
 545      * If we have a 1K hardware sectorsize, prevent access to single
 546      * 512 byte sectors.  In theory we could handle this - in fact
 547      * the scsi cdrom driver must be able to handle this because
 548      * we typically use 1K blocksizes, and cdroms typically have
 549      * 2K hardware sectorsizes.  Of course, things are simpler
 550      * with the cdrom, since it is read-only.  For performance
 551      * reasons, the filesystems should be able to handle this
 552      * and not force the scsi disk driver to use bounce buffers
 553      * for this.
 554      */
 555     if (rscsi_disks[dev].sector_size == 1024)
 556         if((block & 1) || (SCpnt->request.nr_sectors & 1)) {
 557             printk("sd.c:Bad block number requested");
 558             SCpnt = end_scsi_request(SCpnt, 0, SCpnt->request.nr_sectors);
 559             goto repeat;
 560         }
 561     
 562     switch (SCpnt->request.cmd)
 563     {
 564     case WRITE :
 565         if (!rscsi_disks[dev].device->writeable)
 566         {
 567             SCpnt = end_scsi_request(SCpnt, 0, SCpnt->request.nr_sectors);
 568             goto repeat;
 569         }
 570         cmd[0] = WRITE_6;
 571         break;
 572     case READ :
 573         cmd[0] = READ_6;
 574         break;
 575     default :
 576         panic ("Unknown sd command %d\n", SCpnt->request.cmd);
 577     }
 578     
 579     SCpnt->this_count = 0;
 580     
 581     /* If the host adapter can deal with very large scatter-gather
 582      * requests, it is a waste of time to cluster 
 583      */
 584     contiguous = (!CLUSTERABLE_DEVICE(SCpnt) ? 0 :1);
 585     bounce_buffer = NULL;
 586     bounce_size = (SCpnt->request.nr_sectors << 9);
 587     
 588     /* First see if we need a bounce buffer for this request. If we do, make 
 589      * sure that we can allocate a buffer. Do not waste space by allocating 
 590      * a bounce buffer if we are straddling the 16Mb line 
 591      */ 
 592     if (contiguous && SCpnt->request.bh &&
 593         ((long) SCpnt->request.bh->b_data) 
 594         + (SCpnt->request.nr_sectors << 9) - 1 > ISA_DMA_THRESHOLD 
 595         && SCpnt->host->unchecked_isa_dma) {
 596         if(((long) SCpnt->request.bh->b_data) > ISA_DMA_THRESHOLD)
 597             bounce_buffer = (char *) scsi_malloc(bounce_size);
 598         if(!bounce_buffer) contiguous = 0;
 599     };
 600     
 601     if(contiguous && SCpnt->request.bh && SCpnt->request.bh->b_reqnext)
 602         for(bh = SCpnt->request.bh, bhp = bh->b_reqnext; bhp; bh = bhp, 
 603             bhp = bhp->b_reqnext) {
 604             if(!CONTIGUOUS_BUFFERS(bh,bhp)) { 
 605                 if(bounce_buffer) scsi_free(bounce_buffer, bounce_size);
 606                 contiguous = 0;
 607                 break;
 608             } 
 609         };
 610     if (!SCpnt->request.bh || contiguous) {
 611         
 612         /* case of page request (i.e. raw device), or unlinked buffer */
 613         this_count = SCpnt->request.nr_sectors;
 614         buff = SCpnt->request.buffer;
 615         SCpnt->use_sg = 0;
 616         
 617     } else if (SCpnt->host->sg_tablesize == 0 ||
 618                (need_isa_buffer && dma_free_sectors <= 10)) {
 619         
 620         /* Case of host adapter that cannot scatter-gather.  We also
 621          * come here if we are running low on DMA buffer memory.  We set
 622          * a threshold higher than that we would need for this request so
 623          * we leave room for other requests.  Even though we would not need
 624          * it all, we need to be conservative, because if we run low enough
 625          * we have no choice but to panic. 
 626          */
 627         if (SCpnt->host->sg_tablesize != 0 &&
 628             need_isa_buffer && 
 629             dma_free_sectors <= 10)
 630             printk("Warning: SCSI DMA buffer space running low.  Using non scatter-gather I/O.\n");
 631         
 632         this_count = SCpnt->request.current_nr_sectors;
 633         buff = SCpnt->request.buffer;
 634         SCpnt->use_sg = 0;
 635         
 636     } else {
 637         
 638         /* Scatter-gather capable host adapter */
 639         struct scatterlist * sgpnt;
 640         int count, this_count_max;
 641         int counted;
 642         
 643         bh = SCpnt->request.bh;
 644         this_count = 0;
 645         this_count_max = (rscsi_disks[dev].ten ? 0xffff : 0xff);
 646         count = 0;
 647         bhp = NULL;
 648         while(bh) {
 649             if ((this_count + (bh->b_size >> 9)) > this_count_max) break;
 650             if(!bhp || !CONTIGUOUS_BUFFERS(bhp,bh) ||
 651                !CLUSTERABLE_DEVICE(SCpnt) ||
 652                (SCpnt->host->unchecked_isa_dma &&
 653                 ((unsigned long) bh->b_data-1) == ISA_DMA_THRESHOLD)) {
 654                 if (count < SCpnt->host->sg_tablesize) count++;
 655                 else break;
 656             };
 657             this_count += (bh->b_size >> 9);
 658             bhp = bh;
 659             bh = bh->b_reqnext;
 660         };
 661 #if 0
 662         if(SCpnt->host->unchecked_isa_dma &&
 663            ((unsigned int) SCpnt->request.bh->b_data-1) == ISA_DMA_THRESHOLD) count--;
 664 #endif
 665         SCpnt->use_sg = count;  /* Number of chains */
 666         count = 512;/* scsi_malloc can only allocate in chunks of 512 bytes */
 667         while( count < (SCpnt->use_sg * sizeof(struct scatterlist))) 
 668             count = count << 1;
 669         SCpnt->sglist_len = count;
 670         max_sg = count / sizeof(struct scatterlist);
 671         if(SCpnt->host->sg_tablesize < max_sg) 
 672             max_sg = SCpnt->host->sg_tablesize;
 673         sgpnt = (struct scatterlist * ) scsi_malloc(count);
 674         if (!sgpnt) {
 675             printk("Warning - running *really* short on DMA buffers\n");
 676             SCpnt->use_sg = 0;    /* No memory left - bail out */
 677             this_count = SCpnt->request.current_nr_sectors;
 678             buff = SCpnt->request.buffer;
 679         } else {
 680             memset(sgpnt, 0, count);  /* Zero so it is easy to fill, but only
 681                                        * if memory is available 
 682                                        */
 683             buff = (char *) sgpnt;
 684             counted = 0;
 685             for(count = 0, bh = SCpnt->request.bh, bhp = bh->b_reqnext;
 686                 count < SCpnt->use_sg && bh; 
 687                 count++, bh = bhp) {
 688                 
 689                 bhp = bh->b_reqnext;
 690                 
 691                 if(!sgpnt[count].address) sgpnt[count].address = bh->b_data;
 692                 sgpnt[count].length += bh->b_size;
 693                 counted += bh->b_size >> 9;
 694                 
 695                 if (((long) sgpnt[count].address) + sgpnt[count].length - 1 > 
 696                     ISA_DMA_THRESHOLD && (SCpnt->host->unchecked_isa_dma) &&
 697                     !sgpnt[count].alt_address) {
 698                     sgpnt[count].alt_address = sgpnt[count].address;
 699                     /* We try and avoid exhausting the DMA pool, since it is 
 700                      * easier to control usage here. In other places we might 
 701                      * have a more pressing need, and we would be screwed if 
 702                      * we ran out */
 703                     if(dma_free_sectors < (sgpnt[count].length >> 9) + 10) {
 704                         sgpnt[count].address = NULL;
 705                     } else {
 706                         sgpnt[count].address = 
 707                             (char *) scsi_malloc(sgpnt[count].length);
 708                     };
 709                     /* If we start running low on DMA buffers, we abort the 
 710                      * scatter-gather operation, and free all of the memory 
 711                      * we have allocated.  We want to ensure that all scsi 
 712                      * operations are able to do at least a non-scatter/gather
 713                      * operation */
 714                     if(sgpnt[count].address == NULL){ /* Out of dma memory */
 715 #if 0
 716                         printk("Warning: Running low on SCSI DMA buffers");
 717                         /* Try switching back to a non s-g operation. */
 718                         while(--count >= 0){
 719                             if(sgpnt[count].alt_address) 
 720                                 scsi_free(sgpnt[count].address, 
 721                                           sgpnt[count].length);
 722                         };
 723                         this_count = SCpnt->request.current_nr_sectors;
 724                         buff = SCpnt->request.buffer;
 725                         SCpnt->use_sg = 0;
 726                         scsi_free(sgpnt, SCpnt->sglist_len);
 727 #endif
 728                         SCpnt->use_sg = count;
 729                         this_count = counted -= bh->b_size >> 9;
 730                         break;
 731                     };
 732                     
 733                 };
 734                 
 735                 /* Only cluster buffers if we know that we can supply DMA 
 736                  * buffers large enough to satisfy the request. Do not cluster
 737                  * a new request if this would mean that we suddenly need to 
 738                  * start using DMA bounce buffers */
 739                 if(bhp && CONTIGUOUS_BUFFERS(bh,bhp) 
 740                    && CLUSTERABLE_DEVICE(SCpnt)) {
 741                     char * tmp;
 742                     
 743                     if (((long) sgpnt[count].address) + sgpnt[count].length +
 744                         bhp->b_size - 1 > ISA_DMA_THRESHOLD && 
 745                         (SCpnt->host->unchecked_isa_dma) &&
 746                         !sgpnt[count].alt_address) continue;
 747                     
 748                     if(!sgpnt[count].alt_address) {count--; continue; }
 749                     if(dma_free_sectors > 10)
 750                         tmp = (char *) scsi_malloc(sgpnt[count].length 
 751                                                    + bhp->b_size);
 752                     else {
 753                         tmp = NULL;
 754                         max_sg = SCpnt->use_sg;
 755                     };
 756                     if(tmp){
 757                         scsi_free(sgpnt[count].address, sgpnt[count].length);
 758                         sgpnt[count].address = tmp;
 759                         count--;
 760                         continue;
 761                     };
 762                     
 763                     /* If we are allowed another sg chain, then increment 
 764                      * counter so we can insert it.  Otherwise we will end 
 765                      up truncating */
 766                     
 767                     if (SCpnt->use_sg < max_sg) SCpnt->use_sg++;
 768                 };  /* contiguous buffers */
 769             }; /* for loop */
 770             
 771             /* This is actually how many we are going to transfer */
 772             this_count = counted; 
 773             
 774             if(count < SCpnt->use_sg || SCpnt->use_sg 
 775                > SCpnt->host->sg_tablesize){
 776                 bh = SCpnt->request.bh;
 777                 printk("Use sg, count %d %x %d\n", 
 778                        SCpnt->use_sg, count, dma_free_sectors);
 779                 printk("maxsg = %x, counted = %d this_count = %d\n", 
 780                        max_sg, counted, this_count);
 781                 while(bh){
 782                     printk("[%p %lx] ", bh->b_data, bh->b_size);
 783                     bh = bh->b_reqnext;
 784                 };
 785                 if(SCpnt->use_sg < 16)
 786                     for(count=0; count<SCpnt->use_sg; count++)
 787                         printk("{%d:%p %p %d}  ", count,
 788                                sgpnt[count].address,
 789                                sgpnt[count].alt_address,
 790                                sgpnt[count].length);
 791                 panic("Ooops");
 792             };
 793             
 794             if (SCpnt->request.cmd == WRITE)
 795                 for(count=0; count<SCpnt->use_sg; count++)
 796                     if(sgpnt[count].alt_address)
 797                         memcpy(sgpnt[count].address, sgpnt[count].alt_address, 
 798                                sgpnt[count].length);
 799         };  /* Able to malloc sgpnt */
 800     };  /* Host adapter capable of scatter-gather */
 801     
 802     /* Now handle the possibility of DMA to addresses > 16Mb */
 803     
 804     if(SCpnt->use_sg == 0){
 805         if (((long) buff) + (this_count << 9) - 1 > ISA_DMA_THRESHOLD && 
 806             (SCpnt->host->unchecked_isa_dma)) {
 807             if(bounce_buffer)
 808                 buff = bounce_buffer;
 809             else
 810                 buff = (char *) scsi_malloc(this_count << 9);
 811             if(buff == NULL) {  /* Try backing off a bit if we are low on mem*/
 812                 this_count = SCpnt->request.current_nr_sectors;
 813                 buff = (char *) scsi_malloc(this_count << 9);
 814                 if(!buff) panic("Ran out of DMA buffers.");
 815             };
 816             if (SCpnt->request.cmd == WRITE)
 817                 memcpy(buff, (char *)SCpnt->request.buffer, this_count << 9);
 818         };
 819     };
 820 #ifdef DEBUG
 821     printk("sd%c : %s %d/%d 512 byte blocks.\n", 
 822            'a' + MINOR(SCpnt->request.dev),
 823            (SCpnt->request.cmd == WRITE) ? "writing" : "reading",
 824            this_count, SCpnt->request.nr_sectors);
 825 #endif
 826     
 827     cmd[1] = (SCpnt->lun << 5) & 0xe0;
 828     
 829     if (rscsi_disks[dev].sector_size == 1024){
 830         if(block & 1) panic("sd.c:Bad block number requested");
 831         if(this_count & 1) panic("sd.c:Bad block number requested");
 832         block = block >> 1;
 833         this_count = this_count >> 1;
 834     };
 835     
 836     if (rscsi_disks[dev].sector_size == 256){
 837         block = block << 1;
 838         this_count = this_count << 1;
 839     };
 840     
 841     if (((this_count > 0xff) ||  (block > 0x1fffff)) && rscsi_disks[dev].ten)
 842     {
 843         if (this_count > 0xffff)
 844             this_count = 0xffff;
 845         
 846         cmd[0] += READ_10 - READ_6 ;
 847         cmd[2] = (unsigned char) (block >> 24) & 0xff;
 848         cmd[3] = (unsigned char) (block >> 16) & 0xff;
 849         cmd[4] = (unsigned char) (block >> 8) & 0xff;
 850         cmd[5] = (unsigned char) block & 0xff;
 851         cmd[6] = cmd[9] = 0;
 852         cmd[7] = (unsigned char) (this_count >> 8) & 0xff;
 853         cmd[8] = (unsigned char) this_count & 0xff;
 854     }
 855     else
 856     {
 857         if (this_count > 0xff)
 858             this_count = 0xff;
 859         
 860         cmd[1] |= (unsigned char) ((block >> 16) & 0x1f);
 861         cmd[2] = (unsigned char) ((block >> 8) & 0xff);
 862         cmd[3] = (unsigned char) block & 0xff;
 863         cmd[4] = (unsigned char) this_count;
 864         cmd[5] = 0;
 865     }
 866     
 867     /*
 868      * We shouldn't disconnect in the middle of a sector, so with a dumb 
 869      * host adapter, it's safe to assume that we can at least transfer 
 870      * this many bytes between each connect / disconnect.  
 871      */
 872     
 873     SCpnt->transfersize = rscsi_disks[dev].sector_size;
 874     SCpnt->underflow = this_count << 9; 
 875     scsi_do_cmd (SCpnt, (void *) cmd, buff, 
 876                  this_count * rscsi_disks[dev].sector_size,
 877                  rw_intr, 
 878                  (SCpnt->device->type == TYPE_DISK ? 
 879                   SD_TIMEOUT : SD_MOD_TIMEOUT),
 880                  MAX_RETRIES);
 881 }
 882 
 883 static int check_scsidisk_media_change(dev_t full_dev){
     /*  */
 884     int retval;
 885     int target;
 886     struct inode inode;
 887     int flag = 0;
 888     
 889     target =  DEVICE_NR(MINOR(full_dev));
 890     
 891     if (target >= sd_template.dev_max ||
 892         !rscsi_disks[target].device) {
 893         printk("SCSI disk request error: invalid device.\n");
 894         return 0;
 895     };
 896     
 897     if(!rscsi_disks[target].device->removable) return 0;
 898     
 899     inode.i_rdev = full_dev;  /* This is all we really need here */
 900     retval = sd_ioctl(&inode, NULL, SCSI_IOCTL_TEST_UNIT_READY, 0);
 901     
 902     if(retval){ /* Unable to test, unit probably not ready.  This usually
 903                  * means there is no disc in the drive.  Mark as changed,
 904                  * and we will figure it out later once the drive is
 905                  * available again.  */
 906         
 907         rscsi_disks[target].device->changed = 1;
 908         return 1; /* This will force a flush, if called from
 909                    * check_disk_change */
 910     };
 911     
 912     retval = rscsi_disks[target].device->changed;
 913     if(!flag) rscsi_disks[target].device->changed = 0;
 914     return retval;
 915 }
 916 
 917 static void sd_init_done (Scsi_Cmnd * SCpnt)
     /*  */
 918 {
 919     struct request * req;
 920     
 921     req = &SCpnt->request;
 922     req->dev = 0xfffe; /* Busy, but indicate request done */
 923     
 924     if (req->sem != NULL) {
 925         up(req->sem);
 926     }
 927 }
 928 
 929 static int sd_init_onedisk(int i)
     /*  */
 930 {
 931     unsigned char cmd[10];
 932     unsigned char *buffer;
 933     unsigned long spintime;
 934     int the_result, retries;
 935     Scsi_Cmnd * SCpnt;
 936     
 937     /* We need to retry the READ_CAPACITY because a UNIT_ATTENTION is 
 938      * considered a fatal error, and many devices report such an error 
 939      * just after a scsi bus reset. 
 940      */
 941     
 942     SCpnt = allocate_device(NULL, rscsi_disks[i].device, 1);
 943     buffer = (unsigned char *) scsi_malloc(512);
 944     
 945     spintime = 0;
 946     
 947     /* Spin up drives, as required.  Only do this at boot time */
 948     if (current->pid == 0){
 949         do{
 950             retries = 0;
 951             while(retries < 3)
 952             {
 953                 cmd[0] = TEST_UNIT_READY;
 954                 cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
 955                 memset ((void *) &cmd[2], 0, 8);
 956                 SCpnt->request.dev = 0xffff;  /* Mark as really busy again */
 957                 SCpnt->cmd_len = 0;
 958                 SCpnt->sense_buffer[0] = 0;
 959                 SCpnt->sense_buffer[2] = 0;
 960                 
 961                 scsi_do_cmd (SCpnt,
 962                              (void *) cmd, (void *) buffer,
 963                              512, sd_init_done,  SD_TIMEOUT,
 964                              MAX_RETRIES);
 965                 
 966                 while(SCpnt->request.dev != 0xfffe) barrier();
 967                 
 968                 the_result = SCpnt->result;
 969                 retries++;
 970                 if(   the_result == 0
 971                    || SCpnt->sense_buffer[2] != UNIT_ATTENTION)
 972                     break;
 973             }
 974             
 975             /* Look for non-removable devices that return NOT_READY.  
 976              * Issue command to spin up drive for these cases. */
 977             if(the_result && !rscsi_disks[i].device->removable && 
 978                SCpnt->sense_buffer[2] == NOT_READY) {
 979                 int time1;
 980                 if(!spintime){
 981                     printk( "sd%c: Spinning up disk...", 'a' + i );
 982                     cmd[0] = START_STOP;
 983                     cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
 984                     cmd[1] |= 1;  /* Return immediately */
 985                     memset ((void *) &cmd[2], 0, 8);
 986                     cmd[4] = 1; /* Start spin cycle */
 987                     /* Mark as really busy again */
 988                     SCpnt->request.dev = 0xffff; 
 989                     SCpnt->cmd_len = 0;
 990                     SCpnt->sense_buffer[0] = 0;
 991                     SCpnt->sense_buffer[2] = 0;
 992                     
 993                     scsi_do_cmd (SCpnt,
 994                                  (void *) cmd, (void *) buffer,
 995                                  512, sd_init_done,  SD_TIMEOUT,
 996                                  MAX_RETRIES);
 997                     
 998                     while(SCpnt->request.dev != 0xfffe)
 999             barrier();
1000                     
1001                     spintime = jiffies;
1002                 };
1003                 
1004                 time1 = jiffies;
1005                 while(jiffies < time1 + HZ); /* Wait 1 second for next try */
1006                 printk( "." );
1007             };
1008         } while(the_result && spintime && spintime+100*HZ > jiffies);
1009         if (spintime) {
1010             if (the_result)
1011                 printk( "not responding...\n" );
1012             else
1013                 printk( "ready\n" );
1014         }
1015     };  /* current->pid == 0 */
1016     
1017     
1018     retries = 3;
1019     do {
1020         cmd[0] = READ_CAPACITY;
1021         cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
1022         memset ((void *) &cmd[2], 0, 8);
1023         memset ((void *) buffer, 0, 8);
1024         SCpnt->request.dev = 0xffff;  /* Mark as really busy again */
1025         SCpnt->cmd_len = 0;
1026         SCpnt->sense_buffer[0] = 0;
1027         SCpnt->sense_buffer[2] = 0;
1028         
1029         scsi_do_cmd (SCpnt,
1030                      (void *) cmd, (void *) buffer,
1031                      8, sd_init_done,  SD_TIMEOUT,
1032                      MAX_RETRIES);
1033         
1034         if (current->pid == 0)
1035             while(SCpnt->request.dev != 0xfffe)
1036         barrier();
1037         else
1038             if (SCpnt->request.dev != 0xfffe){
1039                 struct semaphore sem = MUTEX_LOCKED;
1040                 SCpnt->request.sem = &sem;
1041                 down(&sem);
1042                 /* Hmm.. Have to ask about this one.. */
1043                 while (SCpnt->request.dev != 0xfffe) 
1044             schedule();
1045             };
1046         
1047         the_result = SCpnt->result;
1048         retries--;
1049         
1050     } while(the_result && retries);
1051     
1052     SCpnt->request.dev = -1;  /* Mark as not busy */
1053     
1054     wake_up(&SCpnt->device->device_wait); 
1055     
1056     /* Wake up a process waiting for device */
1057     
1058     /*
1059      * The SCSI standard says: 
1060      * "READ CAPACITY is necessary for self configuring software"
1061      *  While not mandatory, support of READ CAPACITY is strongly encouraged.
1062      *  We used to die if we couldn't successfully do a READ CAPACITY.
1063      *  But, now we go on about our way.  The side effects of this are
1064      *
1065      *  1. We can't know block size with certainty. I have said "512 bytes 
1066      *     is it" as this is most common.
1067      *
1068      *  2. Recovery from when some one attempts to read past the end of the 
1069      *     raw device will be slower.
1070      */
1071     
1072     if (the_result)
1073     {
1074         printk ("sd%c : READ CAPACITY failed.\n"
1075                 "sd%c : status = %x, message = %02x, host = %d, driver = %02x \n",
1076                 'a' + i, 'a' + i,
1077                 status_byte(the_result),
1078                 msg_byte(the_result),
1079                 host_byte(the_result),
1080                 driver_byte(the_result)
1081                 );
1082         if (driver_byte(the_result)  & DRIVER_SENSE)
1083             printk("sd%c : extended sense code = %1x \n", 
1084                    'a' + i, SCpnt->sense_buffer[2] & 0xf);
1085         else
1086             printk("sd%c : sense not available. \n", 'a' + i);
1087         
1088         printk("sd%c : block size assumed to be 512 bytes, disk size 1GB.  \n",
1089                'a' + i);
1090         rscsi_disks[i].capacity = 0x1fffff;
1091         rscsi_disks[i].sector_size = 512;
1092         
1093         /* Set dirty bit for removable devices if not ready - sometimes drives
1094          * will not report this properly. */
1095         if(rscsi_disks[i].device->removable && 
1096            SCpnt->sense_buffer[2] == NOT_READY)
1097             rscsi_disks[i].device->changed = 1;
1098         
1099     }
1100     else
1101     {
1102         rscsi_disks[i].capacity = (buffer[0] << 24) |
1103             (buffer[1] << 16) |
1104                 (buffer[2] << 8) |
1105                     buffer[3];
1106         
1107         rscsi_disks[i].sector_size = (buffer[4] << 24) |
1108             (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
1109         
1110         if (rscsi_disks[i].sector_size != 512 &&
1111             rscsi_disks[i].sector_size != 1024 &&
1112             rscsi_disks[i].sector_size != 256)
1113         {
1114             printk ("sd%c : unsupported sector size %d.\n",
1115                     'a' + i, rscsi_disks[i].sector_size);
1116             if(rscsi_disks[i].device->removable){
1117                 rscsi_disks[i].capacity = 0;
1118             } else {
1119                 printk ("scsi : deleting disk entry.\n");
1120                 rscsi_disks[i].device = NULL;
1121                 sd_template.nr_dev--;
1122                 return i;
1123             };
1124         }
1125     {
1126         /*
1127          * The msdos fs need to know the hardware sector size
1128          * So I have created this table. See ll_rw_blk.c
1129          * Jacques Gelinas (Jacques@solucorp.qc.ca)
1130          */
1131         int m;
1132         int hard_sector = rscsi_disks[i].sector_size;
1133         /* There is 16 minor allocated for each devices */
1134         for (m=i<<4; m<((i+1)<<4); m++){
1135             sd_hardsizes[m] = hard_sector;
1136         }
1137         printk ("SCSI Hardware sector size is %d bytes on device sd%c\n",
1138                 hard_sector,i+'a');
1139     }
1140         if(rscsi_disks[i].sector_size == 1024)
1141             rscsi_disks[i].capacity <<= 1;  /* Change into 512 byte sectors */
1142         if(rscsi_disks[i].sector_size == 256)
1143             rscsi_disks[i].capacity >>= 1;  /* Change into 512 byte sectors */
1144     }
1145     
1146     rscsi_disks[i].ten = 1;
1147     rscsi_disks[i].remap = 1;
1148     scsi_free(buffer, 512);
1149     return i;
1150 }
1151 
1152 /*
1153  * The sd_init() function looks at all SCSI drives present, determines
1154  * their size, and reads partition table entries for them.
1155  */
1156 
1157 static int sd_registered = 0;
1158 
1159 static int sd_init()
     /*  */
1160 {
1161     int i;
1162     
1163     if (sd_template.dev_noticed == 0) return 0;
1164     
1165     if(!sd_registered) {
1166           if (register_blkdev(MAJOR_NR,"sd",&sd_fops)) {
1167               printk("Unable to get major %d for SCSI disk\n",MAJOR_NR);
1168               return 1;
1169           }
1170           sd_registered++;
1171       }
1172     
1173     /* We do not support attaching loadable devices yet. */
1174     if(rscsi_disks) return 0;
1175     
1176     sd_template.dev_max = sd_template.dev_noticed + SD_EXTRA_DEVS;
1177     
1178     rscsi_disks = (Scsi_Disk *) 
1179         scsi_init_malloc(sd_template.dev_max * sizeof(Scsi_Disk), GFP_ATOMIC);
1180     memset(rscsi_disks, 0, sd_template.dev_max * sizeof(Scsi_Disk));
1181     
1182     sd_sizes = (int *) scsi_init_malloc((sd_template.dev_max << 4) * 
1183                                         sizeof(int), GFP_ATOMIC);
1184     memset(sd_sizes, 0, (sd_template.dev_max << 4) * sizeof(int));
1185     
1186     sd_blocksizes = (int *) scsi_init_malloc((sd_template.dev_max << 4) * 
1187                                              sizeof(int), GFP_ATOMIC);
1188     
1189     sd_hardsizes = (int *) scsi_init_malloc((sd_template.dev_max << 4) * 
1190                                             sizeof(int), GFP_ATOMIC);
1191     
1192     for(i=0;i<(sd_template.dev_max << 4);i++){
1193         sd_blocksizes[i] = 1024;
1194         sd_hardsizes[i] = 512;
1195     }
1196     blksize_size[MAJOR_NR] = sd_blocksizes;
1197     hardsect_size[MAJOR_NR] = sd_hardsizes;
1198     sd = (struct hd_struct *) scsi_init_malloc((sd_template.dev_max << 4) *
1199                                                sizeof(struct hd_struct),
1200                                                GFP_ATOMIC);
1201     
1202     
1203     sd_gendisk.max_nr = sd_template.dev_max;
1204     sd_gendisk.part = sd;
1205     sd_gendisk.sizes = sd_sizes;
1206     sd_gendisk.real_devices = (void *) rscsi_disks;
1207     return 0;
1208 }
1209 
1210 static void sd_finish()
     /*  */
1211 {
1212     int i;
1213 
1214     blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
1215     
1216     sd_gendisk.next = gendisk_head;
1217     gendisk_head = &sd_gendisk;
1218     
1219     for (i = 0; i < sd_template.dev_max; ++i)
1220         if (!rscsi_disks[i].capacity && 
1221             rscsi_disks[i].device)
1222         {
1223             i = sd_init_onedisk(i);
1224             if (MODULE_FLAG
1225                 && !rscsi_disks[i].has_part_table) {
1226                 sd_sizes[i << 4] = rscsi_disks[i].capacity;
1227                 revalidate_scsidisk(i << 4, 0);
1228             }
1229             rscsi_disks[i].has_part_table = 1;
1230         }
1231     
1232     /* If our host adapter is capable of scatter-gather, then we increase
1233      * the read-ahead to 16 blocks (32 sectors).  If not, we use
1234      * a two block (4 sector) read ahead. 
1235      */
1236     if(rscsi_disks[0].device && rscsi_disks[0].device->host->sg_tablesize)
1237         read_ahead[MAJOR_NR] = 120;  /* 120 sector read-ahead */
1238     else
1239         read_ahead[MAJOR_NR] = 4;  /* 4 sector read-ahead */
1240 
1241     return;
1242 }
1243 
1244 static int sd_detect(Scsi_Device * SDp){
     /*  */
1245     if(SDp->type != TYPE_DISK && SDp->type != TYPE_MOD) return 0;
1246     
1247     printk("Detected scsi disk sd%c at scsi%d, channel %d, id %d, lun %d\n", 
1248            'a'+ (sd_template.dev_noticed++),
1249            SDp->host->host_no, SDp->channel, SDp->id, SDp->lun); 
1250     
1251     return 1;
1252 }
1253 
1254 static int sd_attach(Scsi_Device * SDp){
     /*  */
1255     Scsi_Disk * dpnt;
1256     int i;
1257     
1258     if(SDp->type != TYPE_DISK && SDp->type != TYPE_MOD) return 0;
1259     
1260     if(sd_template.nr_dev >= sd_template.dev_max) {
1261         SDp->attached--;
1262         return 1;
1263     }
1264     
1265     for(dpnt = rscsi_disks, i=0; i<sd_template.dev_max; i++, dpnt++) 
1266         if(!dpnt->device) break;
1267     
1268     if(i >= sd_template.dev_max) panic ("scsi_devices corrupt (sd)");
1269     
1270     SDp->scsi_request_fn = do_sd_request;
1271     rscsi_disks[i].device = SDp;
1272     rscsi_disks[i].has_part_table = 0;
1273     sd_template.nr_dev++;
1274     sd_gendisk.nr_real++;
1275     return 0;
1276 }
1277 
1278 #define DEVICE_BUSY rscsi_disks[target].device->busy
1279 #define USAGE rscsi_disks[target].device->access_count
1280 #define CAPACITY rscsi_disks[target].capacity
1281 #define MAYBE_REINIT  sd_init_onedisk(target)
1282 #define GENDISK_STRUCT sd_gendisk
1283 
1284 /* This routine is called to flush all partitions and partition tables
1285  * for a changed scsi disk, and then re-read the new partition table.
1286  * If we are revalidating a disk because of a media change, then we
1287  * enter with usage == 0.  If we are using an ioctl, we automatically have
1288  * usage == 1 (we need an open channel to use an ioctl :-), so this
1289  * is our limit.
1290  */
1291 int revalidate_scsidisk(int dev, int maxusage){
     /*  */
1292     int target, major;
1293     struct gendisk * gdev;
1294     unsigned long flags;
1295     int max_p;
1296     int start;
1297     int i;
1298     
1299     target =  DEVICE_NR(MINOR(dev));
1300     gdev = &GENDISK_STRUCT;
1301     
1302     save_flags(flags);
1303     cli();
1304     if (DEVICE_BUSY || USAGE > maxusage) {
1305         restore_flags(flags);
1306         printk("Device busy for revalidation (usage=%d)\n", USAGE);
1307         return -EBUSY;
1308     };
1309     DEVICE_BUSY = 1;
1310     restore_flags(flags);
1311     
1312     max_p = gdev->max_p;
1313     start = target << gdev->minor_shift;
1314     major = MAJOR_NR << 8;
1315     
1316     for (i=max_p - 1; i >=0 ; i--) {
1317         sync_dev(major | start | i);
1318         invalidate_inodes(major | start | i);
1319         invalidate_buffers(major | start | i);
1320         gdev->part[start+i].start_sect = 0;
1321         gdev->part[start+i].nr_sects = 0;
1322         /*
1323          * Reset the blocksize for everything so that we can read
1324          * the partition table.
1325          */
1326         blksize_size[MAJOR_NR][i] = 1024;
1327     };
1328     
1329 #ifdef MAYBE_REINIT
1330     MAYBE_REINIT;
1331 #endif
1332     
1333     gdev->part[start].nr_sects = CAPACITY;
1334     resetup_one_dev(gdev, target);
1335     
1336     DEVICE_BUSY = 0;
1337     return 0;
1338 }
1339 
1340 static int fop_revalidate_scsidisk(dev_t dev){
     /*  */
1341     return revalidate_scsidisk(dev, 0);
1342 }
1343 
1344 
1345 static void sd_detach(Scsi_Device * SDp)
     /*  */
1346 {
1347     Scsi_Disk * dpnt;
1348     int i;
1349     int max_p;
1350     int major;
1351     int start;
1352     
1353     for(dpnt = rscsi_disks, i=0; i<sd_template.dev_max; i++, dpnt++) 
1354         if(dpnt->device == SDp) {
1355             
1356             /* If we are disconnecting a disk driver, sync and invalidate 
1357              * everything */
1358             max_p = sd_gendisk.max_p;
1359             start = i << sd_gendisk.minor_shift;
1360             major = MAJOR_NR << 8;
1361             
1362             for (i=max_p - 1; i >=0 ; i--) {
1363                 sync_dev(major | start | i);
1364                 invalidate_inodes(major | start | i);
1365                 invalidate_buffers(major | start | i);
1366                 sd_gendisk.part[start+i].start_sect = 0;
1367                 sd_gendisk.part[start+i].nr_sects = 0;
1368                 sd_sizes[start+i] = 0;
1369             };
1370             
1371             dpnt->has_part_table = 0;
1372             dpnt->device = NULL;
1373             dpnt->capacity = 0;
1374             SDp->attached--;
1375             sd_template.dev_noticed--;
1376             sd_template.nr_dev--;
1377             sd_gendisk.nr_real--;
1378             return;
1379         }
1380     return;
1381 }
1382 
1383 #ifdef MODULE
1384 #include <linux/module.h>
1385 #include <linux/version.h>
1386 
1387 char kernel_version[] = UTS_RELEASE;
1388 
1389 int init_module(void) {
     /*  */
1390     sd_template.usage_count = &mod_use_count_;
1391     return scsi_register_module(MODULE_SCSI_DEV, &sd_template);
1392 }
1393 
1394 void cleanup_module( void) 
     /*  */
1395 {
1396     struct gendisk * prev_sdgd;
1397     struct gendisk * sdgd;
1398     
1399     if (MOD_IN_USE) {
1400         printk(KERN_INFO __FILE__ ": module is in use, remove rejected\n");
1401         return;
1402     }
1403     scsi_unregister_module(MODULE_SCSI_DEV, &sd_template);
1404     unregister_blkdev(SCSI_DISK_MAJOR, "sd");
1405     sd_registered--;
1406     if( rscsi_disks != NULL )
1407     {
1408         scsi_init_free((char *) rscsi_disks,
1409                        (sd_template.dev_noticed + SD_EXTRA_DEVS) 
1410                        * sizeof(Scsi_Disk));
1411         
1412         scsi_init_free((char *) sd_sizes, sd_template.dev_max * sizeof(int));
1413         scsi_init_free((char *) sd_blocksizes, sd_template.dev_max * sizeof(int));
1414         scsi_init_free((char *) sd_hardsizes, sd_template.dev_max * sizeof(int));
1415         scsi_init_free((char *) sd, 
1416                        (sd_template.dev_max << 4) * sizeof(struct hd_struct));
1417         /*
1418          * Now remove sd_gendisk from the linked list
1419          */
1420         sdgd = gendisk_head;
1421         prev_sdgd = NULL;
1422         while(sdgd != &sd_gendisk)
1423         {
1424             prev_sdgd = sdgd;
1425             sdgd = sdgd->next;
1426         }
1427         
1428         if(sdgd != &sd_gendisk)
1429             printk("sd_gendisk not in disk chain.\n");
1430         else {
1431             if(prev_sdgd != NULL)
1432                 prev_sdgd->next = sdgd->next;
1433             else
1434                 gendisk_head = sdgd->next;
1435         }
1436     }
1437     
1438     blksize_size[MAJOR_NR] = NULL;
1439     blk_dev[MAJOR_NR].request_fn = NULL;
1440     blk_size[MAJOR_NR] = NULL;  
1441     hardsect_size[MAJOR_NR] = NULL;
1442     read_ahead[MAJOR_NR] = 0;
1443     sd_template.dev_max = 0;
1444 }
1445 #endif /* MODULE */
1446 
1447 /*
1448  * Overrides for Emacs so that we almost follow Linus's tabbing style.
1449  * Emacs will notice this stuff at the end of the file and automatically
1450  * adjust the settings for this buffer only.  This must remain at the end
1451  * of the file.
1452  * ---------------------------------------------------------------------------
1453  * Local variables:
1454  * c-indent-level: 4
1455  * c-brace-imaginary-offset: 0
1456  * c-brace-offset: -4
1457  * c-argdecl-indent: 4
1458  * c-label-offset: -4
1459  * c-continued-statement-offset: 4
1460  * c-continued-brace-offset: 0
1461  * indent-tabs-mode: nil
1462  * tab-width: 8
1463  * End:
1464  */
/* */
root/drivers/scsi/sd.c

DEFINITIONS
