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sd.c

/*
 *      sd.c Copyright (C) 1992 Drew Eckhardt
 *           Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
 *
 *      Linux scsi disk driver
 *              Initial versions: Drew Eckhardt
 *              Subsequent revisions: Eric Youngdale
 *    Modification history:
 *       - Drew Eckhardt <drew@colorado.edu> original
 *       - Eric Youngdale <eric@andante.org> add scatter-gather, multiple 
 *         outstanding request, and other enhancements.
 *         Support loadable low-level scsi drivers.
 *       - Jirka Hanika <geo@ff.cuni.cz> support more scsi disks using 
 *         eight major numbers.
 *       - Richard Gooch <rgooch@atnf.csiro.au> support devfs.
 *     - Torben Mathiasen <tmm@image.dk> Resource allocation fixes in 
 *       sd_init and cleanups.
 *     - Alex Davis <letmein@erols.com> Fix problem where partition info
 *       not being read in sd_open. Fix problem where removable media 
 *       could be ejected after sd_open.
 *     - Douglas Gilbert <dgilbert@interlog.com> cleanup for lk 2.5.x
 *     - Badari Pulavarty <pbadari@us.ibm.com>, Matthew Wilcox 
 *       <willy@debian.org>, Kurt Garloff <garloff@suse.de>: 
 *       Support 32k/1M disks.
 *
 *    Logging policy (needs CONFIG_SCSI_LOGGING defined):
 *     - setting up transfer: SCSI_LOG_HLQUEUE levels 1 and 2
 *     - end of transfer (bh + scsi_lib): SCSI_LOG_HLCOMPLETE level 1
 *     - entering sd_ioctl: SCSI_LOG_IOCTL level 1
 *     - entering other commands: SCSI_LOG_HLQUEUE level 3
 *    Note: when the logging level is set by the user, it must be greater
 *    than the level indicated above to trigger output.     
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/bio.h>
#include <linux/genhd.h>
#include <linux/hdreg.h>
#include <linux/errno.h>
#include <linux/idr.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsicam.h>
#include <scsi/sd.h>

#include "scsi_logging.h"

MODULE_AUTHOR("Eric Youngdale");
MODULE_DESCRIPTION("SCSI disk (sd) driver");
MODULE_LICENSE("GPL");

MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK0_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK1_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK2_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK3_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK4_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK5_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK6_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK7_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK8_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK9_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK10_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK11_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK12_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK13_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK14_MAJOR);
MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_DISK15_MAJOR);
MODULE_ALIAS_SCSI_DEVICE(TYPE_DISK);
MODULE_ALIAS_SCSI_DEVICE(TYPE_MOD);
MODULE_ALIAS_SCSI_DEVICE(TYPE_RBC);

static int  sd_revalidate_disk(struct gendisk *);
static int  sd_probe(struct device *);
static int  sd_remove(struct device *);
static void sd_shutdown(struct device *);
static int sd_suspend(struct device *, pm_message_t state);
static int sd_resume(struct device *);
static void sd_rescan(struct device *);
static int sd_done(struct scsi_cmnd *);
static void sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer);
static void scsi_disk_release(struct class_device *cdev);
static void sd_print_sense_hdr(struct scsi_disk *, struct scsi_sense_hdr *);
static void sd_print_result(struct scsi_disk *, int);

static DEFINE_IDR(sd_index_idr);
static DEFINE_SPINLOCK(sd_index_lock);

/* This semaphore is used to mediate the 0->1 reference get in the
 * face of object destruction (i.e. we can't allow a get on an
 * object after last put) */
static DEFINE_MUTEX(sd_ref_mutex);

static const char *sd_cache_types[] = {
      "write through", "none", "write back",
      "write back, no read (daft)"
};

static ssize_t sd_store_cache_type(struct class_device *cdev, const char *buf,
                           size_t count)
{
      int i, ct = -1, rcd, wce, sp;
      struct scsi_disk *sdkp = to_scsi_disk(cdev);
      struct scsi_device *sdp = sdkp->device;
      char buffer[64];
      char *buffer_data;
      struct scsi_mode_data data;
      struct scsi_sense_hdr sshdr;
      int len;

      if (sdp->type != TYPE_DISK)
            /* no cache control on RBC devices; theoretically they
             * can do it, but there's probably so many exceptions
             * it's not worth the risk */
            return -EINVAL;

      for (i = 0; i < ARRAY_SIZE(sd_cache_types); i++) {
            const int len = strlen(sd_cache_types[i]);
            if (strncmp(sd_cache_types[i], buf, len) == 0 &&
                buf[len] == '\n') {
                  ct = i;
                  break;
            }
      }
      if (ct < 0)
            return -EINVAL;
      rcd = ct & 0x01 ? 1 : 0;
      wce = ct & 0x02 ? 1 : 0;
      if (scsi_mode_sense(sdp, 0x08, 8, buffer, sizeof(buffer), SD_TIMEOUT,
                      SD_MAX_RETRIES, &data, NULL))
            return -EINVAL;
      len = min_t(size_t, sizeof(buffer), data.length - data.header_length -
              data.block_descriptor_length);
      buffer_data = buffer + data.header_length +
            data.block_descriptor_length;
      buffer_data[2] &= ~0x05;
      buffer_data[2] |= wce << 2 | rcd;
      sp = buffer_data[0] & 0x80 ? 1 : 0;

      if (scsi_mode_select(sdp, 1, sp, 8, buffer_data, len, SD_TIMEOUT,
                       SD_MAX_RETRIES, &data, &sshdr)) {
            if (scsi_sense_valid(&sshdr))
                  sd_print_sense_hdr(sdkp, &sshdr);
            return -EINVAL;
      }
      sd_revalidate_disk(sdkp->disk);
      return count;
}

static ssize_t sd_store_manage_start_stop(struct class_device *cdev,
                                const char *buf, size_t count)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);
      struct scsi_device *sdp = sdkp->device;

      if (!capable(CAP_SYS_ADMIN))
            return -EACCES;

      sdp->manage_start_stop = simple_strtoul(buf, NULL, 10);

      return count;
}

static ssize_t sd_store_allow_restart(struct class_device *cdev, const char *buf,
                              size_t count)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);
      struct scsi_device *sdp = sdkp->device;

      if (!capable(CAP_SYS_ADMIN))
            return -EACCES;

      if (sdp->type != TYPE_DISK)
            return -EINVAL;

      sdp->allow_restart = simple_strtoul(buf, NULL, 10);

      return count;
}

static ssize_t sd_show_cache_type(struct class_device *cdev, char *buf)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);
      int ct = sdkp->RCD + 2*sdkp->WCE;

      return snprintf(buf, 40, "%s\n", sd_cache_types[ct]);
}

static ssize_t sd_show_fua(struct class_device *cdev, char *buf)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);

      return snprintf(buf, 20, "%u\n", sdkp->DPOFUA);
}

static ssize_t sd_show_manage_start_stop(struct class_device *cdev, char *buf)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);
      struct scsi_device *sdp = sdkp->device;

      return snprintf(buf, 20, "%u\n", sdp->manage_start_stop);
}

static ssize_t sd_show_allow_restart(struct class_device *cdev, char *buf)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);

      return snprintf(buf, 40, "%d\n", sdkp->device->allow_restart);
}

static struct class_device_attribute sd_disk_attrs[] = {
      __ATTR(cache_type, S_IRUGO|S_IWUSR, sd_show_cache_type,
             sd_store_cache_type),
      __ATTR(FUA, S_IRUGO, sd_show_fua, NULL),
      __ATTR(allow_restart, S_IRUGO|S_IWUSR, sd_show_allow_restart,
             sd_store_allow_restart),
      __ATTR(manage_start_stop, S_IRUGO|S_IWUSR, sd_show_manage_start_stop,
             sd_store_manage_start_stop),
      __ATTR_NULL,
};

static struct class sd_disk_class = {
      .name       = "scsi_disk",
      .owner            = THIS_MODULE,
      .release    = scsi_disk_release,
      .class_dev_attrs = sd_disk_attrs,
};

static struct scsi_driver sd_template = {
      .owner                  = THIS_MODULE,
      .gendrv = {
            .name       = "sd",
            .probe            = sd_probe,
            .remove           = sd_remove,
            .suspend    = sd_suspend,
            .resume           = sd_resume,
            .shutdown   = sd_shutdown,
      },
      .rescan                 = sd_rescan,
      .done             = sd_done,
};

/*
 * Device no to disk mapping:
 * 
 *       major         disc2     disc  p1
 *   |............|.............|....|....| <- dev_t
 *    31        20 19          8 7  4 3  0
 * 
 * Inside a major, we have 16k disks, however mapped non-
 * contiguously. The first 16 disks are for major0, the next
 * ones with major1, ... Disk 256 is for major0 again, disk 272 
 * for major1, ... 
 * As we stay compatible with our numbering scheme, we can reuse 
 * the well-know SCSI majors 8, 65--71, 136--143.
 */
static int sd_major(int major_idx)
{
      switch (major_idx) {
      case 0:
            return SCSI_DISK0_MAJOR;
      case 1 ... 7:
            return SCSI_DISK1_MAJOR + major_idx - 1;
      case 8 ... 15:
            return SCSI_DISK8_MAJOR + major_idx - 8;
      default:
            BUG();
            return 0;   /* shut up gcc */
      }
}

static inline struct scsi_disk *scsi_disk(struct gendisk *disk)
{
      return container_of(disk->private_data, struct scsi_disk, driver);
}

static struct scsi_disk *__scsi_disk_get(struct gendisk *disk)
{
      struct scsi_disk *sdkp = NULL;

      if (disk->private_data) {
            sdkp = scsi_disk(disk);
            if (scsi_device_get(sdkp->device) == 0)
                  class_device_get(&sdkp->cdev);
            else
                  sdkp = NULL;
      }
      return sdkp;
}

static struct scsi_disk *scsi_disk_get(struct gendisk *disk)
{
      struct scsi_disk *sdkp;

      mutex_lock(&sd_ref_mutex);
      sdkp = __scsi_disk_get(disk);
      mutex_unlock(&sd_ref_mutex);
      return sdkp;
}

static struct scsi_disk *scsi_disk_get_from_dev(struct device *dev)
{
      struct scsi_disk *sdkp;

      mutex_lock(&sd_ref_mutex);
      sdkp = dev_get_drvdata(dev);
      if (sdkp)
            sdkp = __scsi_disk_get(sdkp->disk);
      mutex_unlock(&sd_ref_mutex);
      return sdkp;
}

static void scsi_disk_put(struct scsi_disk *sdkp)
{
      struct scsi_device *sdev = sdkp->device;

      mutex_lock(&sd_ref_mutex);
      class_device_put(&sdkp->cdev);
      scsi_device_put(sdev);
      mutex_unlock(&sd_ref_mutex);
}

/**
 *    sd_init_command - build a scsi (read or write) command from
 *    information in the request structure.
 *    @SCpnt: pointer to mid-level's per scsi command structure that
 *    contains request and into which the scsi command is written
 *
 *    Returns 1 if successful and 0 if error (or cannot be done now).
 **/
static int sd_prep_fn(struct request_queue *q, struct request *rq)
{
      struct scsi_cmnd *SCpnt;
      struct scsi_device *sdp = q->queuedata;
      struct gendisk *disk = rq->rq_disk;
      sector_t block = rq->sector;
      unsigned int this_count = rq->nr_sectors;
      unsigned int timeout = sdp->timeout;
      int ret;

      if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
            ret = scsi_setup_blk_pc_cmnd(sdp, rq);
            goto out;
      } else if (rq->cmd_type != REQ_TYPE_FS) {
            ret = BLKPREP_KILL;
            goto out;
      }
      ret = scsi_setup_fs_cmnd(sdp, rq);
      if (ret != BLKPREP_OK)
            goto out;
      SCpnt = rq->special;

      /* from here on until we're complete, any goto out
       * is used for a killable error condition */
      ret = BLKPREP_KILL;

      SCSI_LOG_HLQUEUE(1, scmd_printk(KERN_INFO, SCpnt,
                              "sd_init_command: block=%llu, "
                              "count=%d\n",
                              (unsigned long long)block,
                              this_count));

      if (!sdp || !scsi_device_online(sdp) ||
          block + rq->nr_sectors > get_capacity(disk)) {
            SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
                                    "Finishing %ld sectors\n",
                                    rq->nr_sectors));
            SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
                                    "Retry with 0x%p\n", SCpnt));
            goto out;
      }

      if (sdp->changed) {
            /*
             * quietly refuse to do anything to a changed disc until 
             * the changed bit has been reset
             */
            /* printk("SCSI disk has been changed. Prohibiting further I/O.\n"); */
            goto out;
      }

      SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt, "block=%llu\n",
                              (unsigned long long)block));

      /*
       * If we have a 1K hardware sectorsize, prevent access to single
       * 512 byte sectors.  In theory we could handle this - in fact
       * the scsi cdrom driver must be able to handle this because
       * we typically use 1K blocksizes, and cdroms typically have
       * 2K hardware sectorsizes.  Of course, things are simpler
       * with the cdrom, since it is read-only.  For performance
       * reasons, the filesystems should be able to handle this
       * and not force the scsi disk driver to use bounce buffers
       * for this.
       */
      if (sdp->sector_size == 1024) {
            if ((block & 1) || (rq->nr_sectors & 1)) {
                  scmd_printk(KERN_ERR, SCpnt,
                            "Bad block number requested\n");
                  goto out;
            } else {
                  block = block >> 1;
                  this_count = this_count >> 1;
            }
      }
      if (sdp->sector_size == 2048) {
            if ((block & 3) || (rq->nr_sectors & 3)) {
                  scmd_printk(KERN_ERR, SCpnt,
                            "Bad block number requested\n");
                  goto out;
            } else {
                  block = block >> 2;
                  this_count = this_count >> 2;
            }
      }
      if (sdp->sector_size == 4096) {
            if ((block & 7) || (rq->nr_sectors & 7)) {
                  scmd_printk(KERN_ERR, SCpnt,
                            "Bad block number requested\n");
                  goto out;
            } else {
                  block = block >> 3;
                  this_count = this_count >> 3;
            }
      }
      if (rq_data_dir(rq) == WRITE) {
            if (!sdp->writeable) {
                  goto out;
            }
            SCpnt->cmnd[0] = WRITE_6;
            SCpnt->sc_data_direction = DMA_TO_DEVICE;
      } else if (rq_data_dir(rq) == READ) {
            SCpnt->cmnd[0] = READ_6;
            SCpnt->sc_data_direction = DMA_FROM_DEVICE;
      } else {
            scmd_printk(KERN_ERR, SCpnt, "Unknown command %x\n", rq->cmd_flags);
            goto out;
      }

      SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
                              "%s %d/%ld 512 byte blocks.\n",
                              (rq_data_dir(rq) == WRITE) ?
                              "writing" : "reading", this_count,
                              rq->nr_sectors));

      SCpnt->cmnd[1] = 0;
      
      if (block > 0xffffffff) {
            SCpnt->cmnd[0] += READ_16 - READ_6;
            SCpnt->cmnd[1] |= blk_fua_rq(rq) ? 0x8 : 0;
            SCpnt->cmnd[2] = sizeof(block) > 4 ? (unsigned char) (block >> 56) & 0xff : 0;
            SCpnt->cmnd[3] = sizeof(block) > 4 ? (unsigned char) (block >> 48) & 0xff : 0;
            SCpnt->cmnd[4] = sizeof(block) > 4 ? (unsigned char) (block >> 40) & 0xff : 0;
            SCpnt->cmnd[5] = sizeof(block) > 4 ? (unsigned char) (block >> 32) & 0xff : 0;
            SCpnt->cmnd[6] = (unsigned char) (block >> 24) & 0xff;
            SCpnt->cmnd[7] = (unsigned char) (block >> 16) & 0xff;
            SCpnt->cmnd[8] = (unsigned char) (block >> 8) & 0xff;
            SCpnt->cmnd[9] = (unsigned char) block & 0xff;
            SCpnt->cmnd[10] = (unsigned char) (this_count >> 24) & 0xff;
            SCpnt->cmnd[11] = (unsigned char) (this_count >> 16) & 0xff;
            SCpnt->cmnd[12] = (unsigned char) (this_count >> 8) & 0xff;
            SCpnt->cmnd[13] = (unsigned char) this_count & 0xff;
            SCpnt->cmnd[14] = SCpnt->cmnd[15] = 0;
      } else if ((this_count > 0xff) || (block > 0x1fffff) ||
               SCpnt->device->use_10_for_rw) {
            if (this_count > 0xffff)
                  this_count = 0xffff;

            SCpnt->cmnd[0] += READ_10 - READ_6;
            SCpnt->cmnd[1] |= blk_fua_rq(rq) ? 0x8 : 0;
            SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
            SCpnt->cmnd[3] = (unsigned char) (block >> 16) & 0xff;
            SCpnt->cmnd[4] = (unsigned char) (block >> 8) & 0xff;
            SCpnt->cmnd[5] = (unsigned char) block & 0xff;
            SCpnt->cmnd[6] = SCpnt->cmnd[9] = 0;
            SCpnt->cmnd[7] = (unsigned char) (this_count >> 8) & 0xff;
            SCpnt->cmnd[8] = (unsigned char) this_count & 0xff;
      } else {
            if (unlikely(blk_fua_rq(rq))) {
                  /*
                   * This happens only if this drive failed
                   * 10byte rw command with ILLEGAL_REQUEST
                   * during operation and thus turned off
                   * use_10_for_rw.
                   */
                  scmd_printk(KERN_ERR, SCpnt,
                            "FUA write on READ/WRITE(6) drive\n");
                  goto out;
            }

            SCpnt->cmnd[1] |= (unsigned char) ((block >> 16) & 0x1f);
            SCpnt->cmnd[2] = (unsigned char) ((block >> 8) & 0xff);
            SCpnt->cmnd[3] = (unsigned char) block & 0xff;
            SCpnt->cmnd[4] = (unsigned char) this_count;
            SCpnt->cmnd[5] = 0;
      }
      SCpnt->request_bufflen = this_count * sdp->sector_size;

      /*
       * We shouldn't disconnect in the middle of a sector, so with a dumb
       * host adapter, it's safe to assume that we can at least transfer
       * this many bytes between each connect / disconnect.
       */
      SCpnt->transfersize = sdp->sector_size;
      SCpnt->underflow = this_count << 9;
      SCpnt->allowed = SD_MAX_RETRIES;
      SCpnt->timeout_per_command = timeout;

      /*
       * This indicates that the command is ready from our end to be
       * queued.
       */
      ret = BLKPREP_OK;
 out:
      return scsi_prep_return(q, rq, ret);
}

/**
 *    sd_open - open a scsi disk device
 *    @inode: only i_rdev member may be used
 *    @filp: only f_mode and f_flags may be used
 *
 *    Returns 0 if successful. Returns a negated errno value in case 
 *    of error.
 *
 *    Note: This can be called from a user context (e.g. fsck(1) )
 *    or from within the kernel (e.g. as a result of a mount(1) ).
 *    In the latter case @inode and @filp carry an abridged amount
 *    of information as noted above.
 **/
static int sd_open(struct inode *inode, struct file *filp)
{
      struct gendisk *disk = inode->i_bdev->bd_disk;
      struct scsi_disk *sdkp;
      struct scsi_device *sdev;
      int retval;

      if (!(sdkp = scsi_disk_get(disk)))
            return -ENXIO;


      SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_open\n"));

      sdev = sdkp->device;

      /*
       * If the device is in error recovery, wait until it is done.
       * If the device is offline, then disallow any access to it.
       */
      retval = -ENXIO;
      if (!scsi_block_when_processing_errors(sdev))
            goto error_out;

      if (sdev->removable || sdkp->write_prot)
            check_disk_change(inode->i_bdev);

      /*
       * If the drive is empty, just let the open fail.
       */
      retval = -ENOMEDIUM;
      if (sdev->removable && !sdkp->media_present &&
          !(filp->f_flags & O_NDELAY))
            goto error_out;

      /*
       * If the device has the write protect tab set, have the open fail
       * if the user expects to be able to write to the thing.
       */
      retval = -EROFS;
      if (sdkp->write_prot && (filp->f_mode & FMODE_WRITE))
            goto error_out;

      /*
       * It is possible that the disk changing stuff resulted in
       * the device being taken offline.  If this is the case,
       * report this to the user, and don't pretend that the
       * open actually succeeded.
       */
      retval = -ENXIO;
      if (!scsi_device_online(sdev))
            goto error_out;

      if (!sdkp->openers++ && sdev->removable) {
            if (scsi_block_when_processing_errors(sdev))
                  scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);
      }

      return 0;

error_out:
      scsi_disk_put(sdkp);
      return retval;    
}

/**
 *    sd_release - invoked when the (last) close(2) is called on this
 *    scsi disk.
 *    @inode: only i_rdev member may be used
 *    @filp: only f_mode and f_flags may be used
 *
 *    Returns 0. 
 *
 *    Note: may block (uninterruptible) if error recovery is underway
 *    on this disk.
 **/
static int sd_release(struct inode *inode, struct file *filp)
{
      struct gendisk *disk = inode->i_bdev->bd_disk;
      struct scsi_disk *sdkp = scsi_disk(disk);
      struct scsi_device *sdev = sdkp->device;

      SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n"));

      if (!--sdkp->openers && sdev->removable) {
            if (scsi_block_when_processing_errors(sdev))
                  scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
      }

      /*
       * XXX and what if there are packets in flight and this close()
       * XXX is followed by a "rmmod sd_mod"?
       */
      scsi_disk_put(sdkp);
      return 0;
}

static int sd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
      struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
      struct scsi_device *sdp = sdkp->device;
      struct Scsi_Host *host = sdp->host;
      int diskinfo[4];

      /* default to most commonly used values */
        diskinfo[0] = 0x40;   /* 1 << 6 */
            diskinfo[1] = 0x20;     /* 1 << 5 */
            diskinfo[2] = sdkp->capacity >> 11;
      
      /* override with calculated, extended default, or driver values */
      if (host->hostt->bios_param)
            host->hostt->bios_param(sdp, bdev, sdkp->capacity, diskinfo);
      else
            scsicam_bios_param(bdev, sdkp->capacity, diskinfo);

      geo->heads = diskinfo[0];
      geo->sectors = diskinfo[1];
      geo->cylinders = diskinfo[2];
      return 0;
}

/**
 *    sd_ioctl - process an ioctl
 *    @inode: only i_rdev/i_bdev members may be used
 *    @filp: only f_mode and f_flags may be used
 *    @cmd: ioctl command number
 *    @arg: this is third argument given to ioctl(2) system call.
 *    Often contains a pointer.
 *
 *    Returns 0 if successful (some ioctls return postive numbers on
 *    success as well). Returns a negated errno value in case of error.
 *
 *    Note: most ioctls are forward onto the block subsystem or further
 *    down in the scsi subsystem.
 **/
static int sd_ioctl(struct inode * inode, struct file * filp, 
                unsigned int cmd, unsigned long arg)
{
      struct block_device *bdev = inode->i_bdev;
      struct gendisk *disk = bdev->bd_disk;
      struct scsi_device *sdp = scsi_disk(disk)->device;
      void __user *p = (void __user *)arg;
      int error;
    
      SCSI_LOG_IOCTL(1, printk("sd_ioctl: disk=%s, cmd=0x%x\n",
                                    disk->disk_name, cmd));

      /*
       * If we are in the middle of error recovery, don't let anyone
       * else try and use this device.  Also, if error recovery fails, it
       * may try and take the device offline, in which case all further
       * access to the device is prohibited.
       */
      error = scsi_nonblockable_ioctl(sdp, cmd, p, filp);
      if (!scsi_block_when_processing_errors(sdp) || !error)
            return error;

      /*
       * Send SCSI addressing ioctls directly to mid level, send other
       * ioctls to block level and then onto mid level if they can't be
       * resolved.
       */
      switch (cmd) {
            case SCSI_IOCTL_GET_IDLUN:
            case SCSI_IOCTL_GET_BUS_NUMBER:
                  return scsi_ioctl(sdp, cmd, p);
            default:
                  error = scsi_cmd_ioctl(filp, disk->queue, disk, cmd, p);
                  if (error != -ENOTTY)
                        return error;
      }
      return scsi_ioctl(sdp, cmd, p);
}

static void set_media_not_present(struct scsi_disk *sdkp)
{
      sdkp->media_present = 0;
      sdkp->capacity = 0;
      sdkp->device->changed = 1;
}

/**
 *    sd_media_changed - check if our medium changed
 *    @disk: kernel device descriptor 
 *
 *    Returns 0 if not applicable or no change; 1 if change
 *
 *    Note: this function is invoked from the block subsystem.
 **/
static int sd_media_changed(struct gendisk *disk)
{
      struct scsi_disk *sdkp = scsi_disk(disk);
      struct scsi_device *sdp = sdkp->device;
      int retval;

      SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_media_changed\n"));

      if (!sdp->removable)
            return 0;

      /*
       * If the device is offline, don't send any commands - just pretend as
       * if the command failed.  If the device ever comes back online, we
       * can deal with it then.  It is only because of unrecoverable errors
       * that we would ever take a device offline in the first place.
       */
      if (!scsi_device_online(sdp))
            goto not_present;

      /*
       * Using TEST_UNIT_READY enables differentiation between drive with
       * no cartridge loaded - NOT READY, drive with changed cartridge -
       * UNIT ATTENTION, or with same cartridge - GOOD STATUS.
       *
       * Drives that auto spin down. eg iomega jaz 1G, will be started
       * by sd_spinup_disk() from sd_revalidate_disk(), which happens whenever
       * sd_revalidate() is called.
       */
      retval = -ENODEV;
      if (scsi_block_when_processing_errors(sdp))
            retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, SD_MAX_RETRIES);

      /*
       * Unable to test, unit probably not ready.   This usually
       * means there is no disc in the drive.  Mark as changed,
       * and we will figure it out later once the drive is
       * available again.
       */
      if (retval)
             goto not_present;

      /*
       * For removable scsi disk we have to recognise the presence
       * of a disk in the drive. This is kept in the struct scsi_disk
       * struct and tested at open !  Daniel Roche (dan@lectra.fr)
       */
      sdkp->media_present = 1;

      retval = sdp->changed;
      sdp->changed = 0;

      return retval;

not_present:
      set_media_not_present(sdkp);
      return 1;
}

static int sd_sync_cache(struct scsi_disk *sdkp)
{
      int retries, res;
      struct scsi_device *sdp = sdkp->device;
      struct scsi_sense_hdr sshdr;

      if (!scsi_device_online(sdp))
            return -ENODEV;


      for (retries = 3; retries > 0; --retries) {
            unsigned char cmd[10] = { 0 };

            cmd[0] = SYNCHRONIZE_CACHE;
            /*
             * Leave the rest of the command zero to indicate
             * flush everything.
             */
            res = scsi_execute_req(sdp, cmd, DMA_NONE, NULL, 0, &sshdr,
                               SD_TIMEOUT, SD_MAX_RETRIES);
            if (res == 0)
                  break;
      }

      if (res) {
            sd_print_result(sdkp, res);
            if (driver_byte(res) & DRIVER_SENSE)
                  sd_print_sense_hdr(sdkp, &sshdr);
      }

      if (res)
            return -EIO;
      return 0;
}

static void sd_prepare_flush(struct request_queue *q, struct request *rq)
{
      memset(rq->cmd, 0, sizeof(rq->cmd));
      rq->cmd_type = REQ_TYPE_BLOCK_PC;
      rq->timeout = SD_TIMEOUT;
      rq->cmd[0] = SYNCHRONIZE_CACHE;
      rq->cmd_len = 10;
}

static void sd_rescan(struct device *dev)
{
      struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);

      if (sdkp) {
            sd_revalidate_disk(sdkp->disk);
            scsi_disk_put(sdkp);
      }
}


#ifdef CONFIG_COMPAT
/* 
 * This gets directly called from VFS. When the ioctl 
 * is not recognized we go back to the other translation paths. 
 */
static long sd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
      struct block_device *bdev = file->f_path.dentry->d_inode->i_bdev;
      struct gendisk *disk = bdev->bd_disk;
      struct scsi_device *sdev = scsi_disk(disk)->device;

      /*
       * If we are in the middle of error recovery, don't let anyone
       * else try and use this device.  Also, if error recovery fails, it
       * may try and take the device offline, in which case all further
       * access to the device is prohibited.
       */
      if (!scsi_block_when_processing_errors(sdev))
            return -ENODEV;
             
      if (sdev->host->hostt->compat_ioctl) {
            int ret;

            ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg);

            return ret;
      }

      /* 
       * Let the static ioctl translation table take care of it.
       */
      return -ENOIOCTLCMD; 
}
#endif

static struct block_device_operations sd_fops = {
      .owner                  = THIS_MODULE,
      .open             = sd_open,
      .release          = sd_release,
      .ioctl                  = sd_ioctl,
      .getgeo                 = sd_getgeo,
#ifdef CONFIG_COMPAT
      .compat_ioctl           = sd_compat_ioctl,
#endif
      .media_changed          = sd_media_changed,
      .revalidate_disk  = sd_revalidate_disk,
};

/**
 *    sd_done - bottom half handler: called when the lower level
 *    driver has completed (successfully or otherwise) a scsi command.
 *    @SCpnt: mid-level's per command structure.
 *
 *    Note: potentially run from within an ISR. Must not block.
 **/
static int sd_done(struct scsi_cmnd *SCpnt)
{
      int result = SCpnt->result;
      unsigned int xfer_size = SCpnt->request_bufflen;
      unsigned int good_bytes = result ? 0 : xfer_size;
      u64 start_lba = SCpnt->request->sector;
      u64 bad_lba;
      struct scsi_sense_hdr sshdr;
      int sense_valid = 0;
      int sense_deferred = 0;
      int info_valid;

      if (result) {
            sense_valid = scsi_command_normalize_sense(SCpnt, &sshdr);
            if (sense_valid)
                  sense_deferred = scsi_sense_is_deferred(&sshdr);
      }
#ifdef CONFIG_SCSI_LOGGING
      SCSI_LOG_HLCOMPLETE(1, scsi_print_result(SCpnt));
      if (sense_valid) {
            SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, SCpnt,
                                       "sd_done: sb[respc,sk,asc,"
                                       "ascq]=%x,%x,%x,%x\n",
                                       sshdr.response_code,
                                       sshdr.sense_key, sshdr.asc,
                                       sshdr.ascq));
      }
#endif
      if (driver_byte(result) != DRIVER_SENSE &&
          (!sense_valid || sense_deferred))
            goto out;

      switch (sshdr.sense_key) {
      case HARDWARE_ERROR:
      case MEDIUM_ERROR:
            if (!blk_fs_request(SCpnt->request))
                  goto out;
            info_valid = scsi_get_sense_info_fld(SCpnt->sense_buffer,
                                         SCSI_SENSE_BUFFERSIZE,
                                         &bad_lba);
            if (!info_valid)
                  goto out;
            if (xfer_size <= SCpnt->device->sector_size)
                  goto out;
            switch (SCpnt->device->sector_size) {
            case 256:
                  start_lba <<= 1;
                  break;
            case 512:
                  break;
            case 1024:
                  start_lba >>= 1;
                  break;
            case 2048:
                  start_lba >>= 2;
                  break;
            case 4096:
                  start_lba >>= 3;
                  break;
            default:
                  /* Print something here with limiting frequency. */
                  goto out;
                  break;
            }
            /* This computation should always be done in terms of
             * the resolution of the device's medium.
             */
            good_bytes = (bad_lba - start_lba)*SCpnt->device->sector_size;
            break;
      case RECOVERED_ERROR:
      case NO_SENSE:
            /* Inform the user, but make sure that it's not treated
             * as a hard error.
             */
            scsi_print_sense("sd", SCpnt);
            SCpnt->result = 0;
            memset(SCpnt->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
            good_bytes = xfer_size;
            break;
      case ILLEGAL_REQUEST:
            if (SCpnt->device->use_10_for_rw &&
                (SCpnt->cmnd[0] == READ_10 ||
                 SCpnt->cmnd[0] == WRITE_10))
                  SCpnt->device->use_10_for_rw = 0;
            if (SCpnt->device->use_10_for_ms &&
                (SCpnt->cmnd[0] == MODE_SENSE_10 ||
                 SCpnt->cmnd[0] == MODE_SELECT_10))
                  SCpnt->device->use_10_for_ms = 0;
            break;
      default:
            break;
      }
 out:
      return good_bytes;
}

static int media_not_present(struct scsi_disk *sdkp,
                       struct scsi_sense_hdr *sshdr)
{

      if (!scsi_sense_valid(sshdr))
            return 0;
      /* not invoked for commands that could return deferred errors */
      if (sshdr->sense_key != NOT_READY &&
          sshdr->sense_key != UNIT_ATTENTION)
            return 0;
      if (sshdr->asc != 0x3A) /* medium not present */
            return 0;

      set_media_not_present(sdkp);
      return 1;
}

/*
 * spinup disk - called only in sd_revalidate_disk()
 */
static void
sd_spinup_disk(struct scsi_disk *sdkp)
{
      unsigned char cmd[10];
      unsigned long spintime_expire = 0;
      int retries, spintime;
      unsigned int the_result;
      struct scsi_sense_hdr sshdr;
      int sense_valid = 0;

      spintime = 0;

      /* Spin up drives, as required.  Only do this at boot time */
      /* Spinup needs to be done for module loads too. */
      do {
            retries = 0;

            do {
                  cmd[0] = TEST_UNIT_READY;
                  memset((void *) &cmd[1], 0, 9);

                  the_result = scsi_execute_req(sdkp->device, cmd,
                                          DMA_NONE, NULL, 0,
                                          &sshdr, SD_TIMEOUT,
                                          SD_MAX_RETRIES);

                  /*
                   * If the drive has indicated to us that it
                   * doesn't have any media in it, don't bother
                   * with any more polling.
                   */
                  if (media_not_present(sdkp, &sshdr))
                        return;

                  if (the_result)
                        sense_valid = scsi_sense_valid(&sshdr);
                  retries++;
            } while (retries < 3 && 
                   (!scsi_status_is_good(the_result) ||
                    ((driver_byte(the_result) & DRIVER_SENSE) &&
                    sense_valid && sshdr.sense_key == UNIT_ATTENTION)));

            if ((driver_byte(the_result) & DRIVER_SENSE) == 0) {
                  /* no sense, TUR either succeeded or failed
                   * with a status error */
                  if(!spintime && !scsi_status_is_good(the_result)) {
                        sd_printk(KERN_NOTICE, sdkp, "Unit Not Ready\n");
                        sd_print_result(sdkp, the_result);
                  }
                  break;
            }
                              
            /*
             * The device does not want the automatic start to be issued.
             */
            if (sdkp->device->no_start_on_add) {
                  break;
            }

            /*
             * If manual intervention is required, or this is an
             * absent USB storage device, a spinup is meaningless.
             */
            if (sense_valid &&
                sshdr.sense_key == NOT_READY &&
                sshdr.asc == 4 && sshdr.ascq == 3) {
                  break;            /* manual intervention required */

            /*
             * Issue command to spin up drive when not ready
             */
            } else if (sense_valid && sshdr.sense_key == NOT_READY) {
                  if (!spintime) {
                        sd_printk(KERN_NOTICE, sdkp, "Spinning up disk...");
                        cmd[0] = START_STOP;
                        cmd[1] = 1; /* Return immediately */
                        memset((void *) &cmd[2], 0, 8);
                        cmd[4] = 1; /* Start spin cycle */
                        scsi_execute_req(sdkp->device, cmd, DMA_NONE,
                                     NULL, 0, &sshdr,
                                     SD_TIMEOUT, SD_MAX_RETRIES);
                        spintime_expire = jiffies + 100 * HZ;
                        spintime = 1;
                  }
                  /* Wait 1 second for next try */
                  msleep(1000);
                  printk(".");

            /*
             * Wait for USB flash devices with slow firmware.
             * Yes, this sense key/ASC combination shouldn't
             * occur here.  It's characteristic of these devices.
             */
            } else if (sense_valid &&
                        sshdr.sense_key == UNIT_ATTENTION &&
                        sshdr.asc == 0x28) {
                  if (!spintime) {
                        spintime_expire = jiffies + 5 * HZ;
                        spintime = 1;
                  }
                  /* Wait 1 second for next try */
                  msleep(1000);
            } else {
                  /* we don't understand the sense code, so it's
                   * probably pointless to loop */
                  if(!spintime) {
                        sd_printk(KERN_NOTICE, sdkp, "Unit Not Ready\n");
                        sd_print_sense_hdr(sdkp, &sshdr);
                  }
                  break;
            }
                        
      } while (spintime && time_before_eq(jiffies, spintime_expire));

      if (spintime) {
            if (scsi_status_is_good(the_result))
                  printk("ready\n");
            else
                  printk("not responding...\n");
      }
}

/*
 * read disk capacity
 */
static void
sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)
{
      unsigned char cmd[16];
      int the_result, retries;
      int sector_size = 0;
      int longrc = 0;
      struct scsi_sense_hdr sshdr;
      int sense_valid = 0;
      struct scsi_device *sdp = sdkp->device;

repeat:
      retries = 3;
      do {
            if (longrc) {
                  memset((void *) cmd, 0, 16);
                  cmd[0] = SERVICE_ACTION_IN;
                  cmd[1] = SAI_READ_CAPACITY_16;
                  cmd[13] = 12;
                  memset((void *) buffer, 0, 12);
            } else {
                  cmd[0] = READ_CAPACITY;
                  memset((void *) &cmd[1], 0, 9);
                  memset((void *) buffer, 0, 8);
            }
            
            the_result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE,
                                    buffer, longrc ? 12 : 8, &sshdr,
                                    SD_TIMEOUT, SD_MAX_RETRIES);

            if (media_not_present(sdkp, &sshdr))
                  return;

            if (the_result)
                  sense_valid = scsi_sense_valid(&sshdr);
            retries--;

      } while (the_result && retries);

      if (the_result && !longrc) {
            sd_printk(KERN_NOTICE, sdkp, "READ CAPACITY failed\n");
            sd_print_result(sdkp, the_result);
            if (driver_byte(the_result) & DRIVER_SENSE)
                  sd_print_sense_hdr(sdkp, &sshdr);
            else
                  sd_printk(KERN_NOTICE, sdkp, "Sense not available.\n");

            /* Set dirty bit for removable devices if not ready -
             * sometimes drives will not report this properly. */
            if (sdp->removable &&
                sense_valid && sshdr.sense_key == NOT_READY)
                  sdp->changed = 1;

            /* Either no media are present but the drive didn't tell us,
               or they are present but the read capacity command fails */
            /* sdkp->media_present = 0; -- not always correct */
            sdkp->capacity = 0; /* unknown mapped to zero - as usual */

            return;
      } else if (the_result && longrc) {
            /* READ CAPACITY(16) has been failed */
            sd_printk(KERN_NOTICE, sdkp, "READ CAPACITY(16) failed\n");
            sd_print_result(sdkp, the_result);
            sd_printk(KERN_NOTICE, sdkp, "Use 0xffffffff as device size\n");

            sdkp->capacity = 1 + (sector_t) 0xffffffff;           
            goto got_data;
      }     
      
      if (!longrc) {
            sector_size = (buffer[4] << 24) |
                  (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
            if (buffer[0] == 0xff && buffer[1] == 0xff &&
                buffer[2] == 0xff && buffer[3] == 0xff) {
                  if(sizeof(sdkp->capacity) > 4) {
                        sd_printk(KERN_NOTICE, sdkp, "Very big device. "
                                "Trying to use READ CAPACITY(16).\n");
                        longrc = 1;
                        goto repeat;
                  }
                  sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use "
                          "a kernel compiled with support for large "
                          "block devices.\n");
                  sdkp->capacity = 0;
                  goto got_data;
            }
            sdkp->capacity = 1 + (((sector_t)buffer[0] << 24) |
                  (buffer[1] << 16) |
                  (buffer[2] << 8) |
                  buffer[3]);             
      } else {
            sdkp->capacity = 1 + (((u64)buffer[0] << 56) |
                  ((u64)buffer[1] << 48) |
                  ((u64)buffer[2] << 40) |
                  ((u64)buffer[3] << 32) |
                  ((sector_t)buffer[4] << 24) |
                  ((sector_t)buffer[5] << 16) |
                  ((sector_t)buffer[6] << 8)  |
                  (sector_t)buffer[7]);
                  
            sector_size = (buffer[8] << 24) |
                  (buffer[9] << 16) | (buffer[10] << 8) | buffer[11];
      }     

      /* Some devices return the total number of sectors, not the
       * highest sector number.  Make the necessary adjustment. */
      if (sdp->fix_capacity) {
            --sdkp->capacity;

      /* Some devices have version which report the correct sizes
       * and others which do not. We guess size according to a heuristic
       * and err on the side of lowering the capacity. */
      } else {
            if (sdp->guess_capacity)
                  if (sdkp->capacity & 0x01) /* odd sizes are odd */
                        --sdkp->capacity;
      }

got_data:
      if (sector_size == 0) {
            sector_size = 512;
            sd_printk(KERN_NOTICE, sdkp, "Sector size 0 reported, "
                    "assuming 512.\n");
      }

      if (sector_size != 512 &&
          sector_size != 1024 &&
          sector_size != 2048 &&
          sector_size != 4096 &&
          sector_size != 256) {
            sd_printk(KERN_NOTICE, sdkp, "Unsupported sector size %d.\n",
                    sector_size);
            /*
             * The user might want to re-format the drive with
             * a supported sectorsize.  Once this happens, it
             * would be relatively trivial to set the thing up.
             * For this reason, we leave the thing in the table.
             */
            sdkp->capacity = 0;
            /*
             * set a bogus sector size so the normal read/write
             * logic in the block layer will eventually refuse any
             * request on this device without tripping over power
             * of two sector size assumptions
             */
            sector_size = 512;
      }
      {
            /*
             * The msdos fs needs to know the hardware sector size
             * So I have created this table. See ll_rw_blk.c
             * Jacques Gelinas (Jacques@solucorp.qc.ca)
             */
            int hard_sector = sector_size;
            sector_t sz = (sdkp->capacity/2) * (hard_sector/256);
            struct request_queue *queue = sdp->request_queue;
            sector_t mb = sz;

            blk_queue_hardsect_size(queue, hard_sector);
            /* avoid 64-bit division on 32-bit platforms */
            sector_div(sz, 625);
            mb -= sz - 974;
            sector_div(mb, 1950);

            sd_printk(KERN_NOTICE, sdkp,
                    "%llu %d-byte hardware sectors (%llu MB)\n",
                    (unsigned long long)sdkp->capacity,
                    hard_sector, (unsigned long long)mb);
      }

      /* Rescale capacity to 512-byte units */
      if (sector_size == 4096)
            sdkp->capacity <<= 3;
      else if (sector_size == 2048)
            sdkp->capacity <<= 2;
      else if (sector_size == 1024)
            sdkp->capacity <<= 1;
      else if (sector_size == 256)
            sdkp->capacity >>= 1;

      sdkp->device->sector_size = sector_size;
}

/* called with buffer of length 512 */
static inline int
sd_do_mode_sense(struct scsi_device *sdp, int dbd, int modepage,
             unsigned char *buffer, int len, struct scsi_mode_data *data,
             struct scsi_sense_hdr *sshdr)
{
      return scsi_mode_sense(sdp, dbd, modepage, buffer, len,
                         SD_TIMEOUT, SD_MAX_RETRIES, data,
                         sshdr);
}

/*
 * read write protect setting, if possible - called only in sd_revalidate_disk()
 * called with buffer of length SD_BUF_SIZE
 */
static void
sd_read_write_protect_flag(struct scsi_disk *sdkp, unsigned char *buffer)
{
      int res;
      struct scsi_device *sdp = sdkp->device;
      struct scsi_mode_data data;

      set_disk_ro(sdkp->disk, 0);
      if (sdp->skip_ms_page_3f) {
            sd_printk(KERN_NOTICE, sdkp, "Assuming Write Enabled\n");
            return;
      }

      if (sdp->use_192_bytes_for_3f) {
            res = sd_do_mode_sense(sdp, 0, 0x3F, buffer, 192, &data, NULL);
      } else {
            /*
             * First attempt: ask for all pages (0x3F), but only 4 bytes.
             * We have to start carefully: some devices hang if we ask
             * for more than is available.
             */
            res = sd_do_mode_sense(sdp, 0, 0x3F, buffer, 4, &data, NULL);

            /*
             * Second attempt: ask for page 0 When only page 0 is
             * implemented, a request for page 3F may return Sense Key
             * 5: Illegal Request, Sense Code 24: Invalid field in
             * CDB.
             */
            if (!scsi_status_is_good(res))
                  res = sd_do_mode_sense(sdp, 0, 0, buffer, 4, &data, NULL);

            /*
             * Third attempt: ask 255 bytes, as we did earlier.
             */
            if (!scsi_status_is_good(res))
                  res = sd_do_mode_sense(sdp, 0, 0x3F, buffer, 255,
                                     &data, NULL);
      }

      if (!scsi_status_is_good(res)) {
            sd_printk(KERN_WARNING, sdkp,
                    "Test WP failed, assume Write Enabled\n");
      } else {
            sdkp->write_prot = ((data.device_specific & 0x80) != 0);
            set_disk_ro(sdkp->disk, sdkp->write_prot);
            sd_printk(KERN_NOTICE, sdkp, "Write Protect is %s\n",
                    sdkp->write_prot ? "on" : "off");
            sd_printk(KERN_DEBUG, sdkp,
                    "Mode Sense: %02x %02x %02x %02x\n",
                    buffer[0], buffer[1], buffer[2], buffer[3]);
      }
}

/*
 * sd_read_cache_type - called only from sd_revalidate_disk()
 * called with buffer of length SD_BUF_SIZE
 */
static void
sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
{
      int len = 0, res;
      struct scsi_device *sdp = sdkp->device;

      int dbd;
      int modepage;
      struct scsi_mode_data data;
      struct scsi_sense_hdr sshdr;

      if (sdp->skip_ms_page_8)
            goto defaults;

      if (sdp->type == TYPE_RBC) {
            modepage = 6;
            dbd = 8;
      } else {
            modepage = 8;
            dbd = 0;
      }

      /* cautiously ask */
      res = sd_do_mode_sense(sdp, dbd, modepage, buffer, 4, &data, &sshdr);

      if (!scsi_status_is_good(res))
            goto bad_sense;

      if (!data.header_length) {
            modepage = 6;
            sd_printk(KERN_ERR, sdkp, "Missing header in MODE_SENSE response\n");
      }

      /* that went OK, now ask for the proper length */
      len = data.length;

      /*
       * We're only interested in the first three bytes, actually.
       * But the data cache page is defined for the first 20.
       */
      if (len < 3)
            goto bad_sense;
      if (len > 20)
            len = 20;

      /* Take headers and block descriptors into account */
      len += data.header_length + data.block_descriptor_length;
      if (len > SD_BUF_SIZE)
            goto bad_sense;

      /* Get the data */
      res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len, &data, &sshdr);

      if (scsi_status_is_good(res)) {
            int offset = data.header_length + data.block_descriptor_length;

            if (offset >= SD_BUF_SIZE - 2) {
                  sd_printk(KERN_ERR, sdkp, "Malformed MODE SENSE response\n");
                  goto defaults;
            }

            if ((buffer[offset] & 0x3f) != modepage) {
                  sd_printk(KERN_ERR, sdkp, "Got wrong page\n");
                  goto defaults;
            }

            if (modepage == 8) {
                  sdkp->WCE = ((buffer[offset + 2] & 0x04) != 0);
                  sdkp->RCD = ((buffer[offset + 2] & 0x01) != 0);
            } else {
                  sdkp->WCE = ((buffer[offset + 2] & 0x01) == 0);
                  sdkp->RCD = 0;
            }

            sdkp->DPOFUA = (data.device_specific & 0x10) != 0;
            if (sdkp->DPOFUA && !sdkp->device->use_10_for_rw) {
                  sd_printk(KERN_NOTICE, sdkp,
                          "Uses READ/WRITE(6), disabling FUA\n");
                  sdkp->DPOFUA = 0;
            }

            sd_printk(KERN_NOTICE, sdkp,
                   "Write cache: %s, read cache: %s, %s\n",
                   sdkp->WCE ? "enabled" : "disabled",
                   sdkp->RCD ? "disabled" : "enabled",
                   sdkp->DPOFUA ? "supports DPO and FUA"
                   : "doesn't support DPO or FUA");

            return;
      }

bad_sense:
      if (scsi_sense_valid(&sshdr) &&
          sshdr.sense_key == ILLEGAL_REQUEST &&
          sshdr.asc == 0x24 && sshdr.ascq == 0x0)
            /* Invalid field in CDB */
            sd_printk(KERN_NOTICE, sdkp, "Cache data unavailable\n");
      else
            sd_printk(KERN_ERR, sdkp, "Asking for cache data failed\n");

defaults:
      sd_printk(KERN_ERR, sdkp, "Assuming drive cache: write through\n");
      sdkp->WCE = 0;
      sdkp->RCD = 0;
      sdkp->DPOFUA = 0;
}

/**
 *    sd_revalidate_disk - called the first time a new disk is seen,
 *    performs disk spin up, read_capacity, etc.
 *    @disk: struct gendisk we care about
 **/
static int sd_revalidate_disk(struct gendisk *disk)
{
      struct scsi_disk *sdkp = scsi_disk(disk);
      struct scsi_device *sdp = sdkp->device;
      unsigned char *buffer;
      unsigned ordered;

      SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
                              "sd_revalidate_disk\n"));

      /*
       * If the device is offline, don't try and read capacity or any
       * of the other niceties.
       */
      if (!scsi_device_online(sdp))
            goto out;

      buffer = kmalloc(SD_BUF_SIZE, GFP_KERNEL);
      if (!buffer) {
            sd_printk(KERN_WARNING, sdkp, "sd_revalidate_disk: Memory "
                    "allocation failure.\n");
            goto out;
      }

      /* defaults, until the device tells us otherwise */
      sdp->sector_size = 512;
      sdkp->capacity = 0;
      sdkp->media_present = 1;
      sdkp->write_prot = 0;
      sdkp->WCE = 0;
      sdkp->RCD = 0;

      sd_spinup_disk(sdkp);

      /*
       * Without media there is no reason to ask; moreover, some devices
       * react badly if we do.
       */
      if (sdkp->media_present) {
            sd_read_capacity(sdkp, buffer);
            sd_read_write_protect_flag(sdkp, buffer);
            sd_read_cache_type(sdkp, buffer);
      }

      /*
       * We now have all cache related info, determine how we deal
       * with ordered requests.  Note that as the current SCSI
       * dispatch function can alter request order, we cannot use
       * QUEUE_ORDERED_TAG_* even when ordered tag is supported.
       */
      if (sdkp->WCE)
            ordered = sdkp->DPOFUA
                  ? QUEUE_ORDERED_DRAIN_FUA : QUEUE_ORDERED_DRAIN_FLUSH;
      else
            ordered = QUEUE_ORDERED_DRAIN;

      blk_queue_ordered(sdkp->disk->queue, ordered, sd_prepare_flush);

      set_capacity(disk, sdkp->capacity);
      kfree(buffer);

 out:
      return 0;
}

/**
 *    sd_probe - called during driver initialization and whenever a
 *    new scsi device is attached to the system. It is called once
 *    for each scsi device (not just disks) present.
 *    @dev: pointer to device object
 *
 *    Returns 0 if successful (or not interested in this scsi device 
 *    (e.g. scanner)); 1 when there is an error.
 *
 *    Note: this function is invoked from the scsi mid-level.
 *    This function sets up the mapping between a given 
 *    <host,channel,id,lun> (found in sdp) and new device name 
 *    (e.g. /dev/sda). More precisely it is the block device major 
 *    and minor number that is chosen here.
 *
 *    Assume sd_attach is not re-entrant (for time being)
 *    Also think about sd_attach() and sd_remove() running coincidentally.
 **/
static int sd_probe(struct device *dev)
{
      struct scsi_device *sdp = to_scsi_device(dev);
      struct scsi_disk *sdkp;
      struct gendisk *gd;
      u32 index;
      int error;

      error = -ENODEV;
      if (sdp->type != TYPE_DISK && sdp->type != TYPE_MOD && sdp->type != TYPE_RBC)
            goto out;

      SCSI_LOG_HLQUEUE(3, sdev_printk(KERN_INFO, sdp,
                              "sd_attach\n"));

      error = -ENOMEM;
      sdkp = kzalloc(sizeof(*sdkp), GFP_KERNEL);
      if (!sdkp)
            goto out;

      gd = alloc_disk(16);
      if (!gd)
            goto out_free;

      if (!idr_pre_get(&sd_index_idr, GFP_KERNEL))
            goto out_put;

      spin_lock(&sd_index_lock);
      error = idr_get_new(&sd_index_idr, NULL, &index);
      spin_unlock(&sd_index_lock);

      if (index >= SD_MAX_DISKS)
            error = -EBUSY;
      if (error)
            goto out_put;

      sdkp->device = sdp;
      sdkp->driver = &sd_template;
      sdkp->disk = gd;
      sdkp->index = index;
      sdkp->openers = 0;

      if (!sdp->timeout) {
            if (sdp->type != TYPE_MOD)
                  sdp->timeout = SD_TIMEOUT;
            else
                  sdp->timeout = SD_MOD_TIMEOUT;
      }

      class_device_initialize(&sdkp->cdev);
      sdkp->cdev.dev = &sdp->sdev_gendev;
      sdkp->cdev.class = &sd_disk_class;
      strncpy(sdkp->cdev.class_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);

      if (class_device_add(&sdkp->cdev))
            goto out_put;

      get_device(&sdp->sdev_gendev);

      gd->major = sd_major((index & 0xf0) >> 4);
      gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
      gd->minors = 16;
      gd->fops = &sd_fops;

      if (index < 26) {
            sprintf(gd->disk_name, "sd%c", 'a' + index % 26);
      } else if (index < (26 + 1) * 26) {
            sprintf(gd->disk_name, "sd%c%c",
                  'a' + index / 26 - 1,'a' + index % 26);
      } else {
            const unsigned int m1 = (index / 26 - 1) / 26 - 1;
            const unsigned int m2 = (index / 26 - 1) % 26;
            const unsigned int m3 =  index % 26;
            sprintf(gd->disk_name, "sd%c%c%c",
                  'a' + m1, 'a' + m2, 'a' + m3);
      }

      gd->private_data = &sdkp->driver;
      gd->queue = sdkp->device->request_queue;

      sd_revalidate_disk(gd);

      blk_queue_prep_rq(sdp->request_queue, sd_prep_fn);

      gd->driverfs_dev = &sdp->sdev_gendev;
      gd->flags = GENHD_FL_DRIVERFS;
      if (sdp->removable)
            gd->flags |= GENHD_FL_REMOVABLE;

      dev_set_drvdata(dev, sdkp);
      add_disk(gd);

      sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
              sdp->removable ? "removable " : "");

      return 0;

 out_put:
      put_disk(gd);
 out_free:
      kfree(sdkp);
 out:
      return error;
}

/**
 *    sd_remove - called whenever a scsi disk (previously recognized by
 *    sd_probe) is detached from the system. It is called (potentially
 *    multiple times) during sd module unload.
 *    @sdp: pointer to mid level scsi device object
 *
 *    Note: this function is invoked from the scsi mid-level.
 *    This function potentially frees up a device name (e.g. /dev/sdc)
 *    that could be re-used by a subsequent sd_probe().
 *    This function is not called when the built-in sd driver is "exit-ed".
 **/
static int sd_remove(struct device *dev)
{
      struct scsi_disk *sdkp = dev_get_drvdata(dev);

      class_device_del(&sdkp->cdev);
      del_gendisk(sdkp->disk);
      sd_shutdown(dev);

      mutex_lock(&sd_ref_mutex);
      dev_set_drvdata(dev, NULL);
      class_device_put(&sdkp->cdev);
      mutex_unlock(&sd_ref_mutex);

      return 0;
}

/**
 *    scsi_disk_release - Called to free the scsi_disk structure
 *    @cdev: pointer to embedded class device
 *
 *    sd_ref_mutex must be held entering this routine.  Because it is
 *    called on last put, you should always use the scsi_disk_get()
 *    scsi_disk_put() helpers which manipulate the semaphore directly
 *    and never do a direct class_device_put().
 **/
static void scsi_disk_release(struct class_device *cdev)
{
      struct scsi_disk *sdkp = to_scsi_disk(cdev);
      struct gendisk *disk = sdkp->disk;
      
      spin_lock(&sd_index_lock);
      idr_remove(&sd_index_idr, sdkp->index);
      spin_unlock(&sd_index_lock);

      disk->private_data = NULL;
      put_disk(disk);
      put_device(&sdkp->device->sdev_gendev);

      kfree(sdkp);
}

static int sd_start_stop_device(struct scsi_disk *sdkp, int start)
{
      unsigned char cmd[6] = { START_STOP };    /* START_VALID */
      struct scsi_sense_hdr sshdr;
      struct scsi_device *sdp = sdkp->device;
      int res;

      if (start)
            cmd[4] |= 1;      /* START */

      if (!scsi_device_online(sdp))
            return -ENODEV;

      res = scsi_execute_req(sdp, cmd, DMA_NONE, NULL, 0, &sshdr,
                         SD_TIMEOUT, SD_MAX_RETRIES);
      if (res) {
            sd_printk(KERN_WARNING, sdkp, "START_STOP FAILED\n");
            sd_print_result(sdkp, res);
            if (driver_byte(res) & DRIVER_SENSE)
                  sd_print_sense_hdr(sdkp, &sshdr);
      }

      return res;
}

/*
 * Send a SYNCHRONIZE CACHE instruction down to the device through
 * the normal SCSI command structure.  Wait for the command to
 * complete.
 */
static void sd_shutdown(struct device *dev)
{
      struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);

      if (!sdkp)
            return;         /* this can happen */

      if (sdkp->WCE) {
            sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");
            sd_sync_cache(sdkp);
      }

      if (system_state != SYSTEM_RESTART && sdkp->device->manage_start_stop) {
            sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
            sd_start_stop_device(sdkp, 0);
      }

      scsi_disk_put(sdkp);
}

static int sd_suspend(struct device *dev, pm_message_t mesg)
{
      struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
      int ret = 0;

      if (!sdkp)
            return 0;   /* this can happen */

      if (sdkp->WCE) {
            sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");
            ret = sd_sync_cache(sdkp);
            if (ret)
                  goto done;
      }

      if (mesg.event == PM_EVENT_SUSPEND &&
          sdkp->device->manage_start_stop) {
            sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
            ret = sd_start_stop_device(sdkp, 0);
      }

done:
      scsi_disk_put(sdkp);
      return ret;
}

static int sd_resume(struct device *dev)
{
      struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
      int ret = 0;

      if (!sdkp->device->manage_start_stop)
            goto done;

      sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
      ret = sd_start_stop_device(sdkp, 1);

done:
      scsi_disk_put(sdkp);
      return ret;
}

/**
 *    init_sd - entry point for this driver (both when built in or when
 *    a module).
 *
 *    Note: this function registers this driver with the scsi mid-level.
 **/
static int __init init_sd(void)
{
      int majors = 0, i, err;

      SCSI_LOG_HLQUEUE(3, printk("init_sd: sd driver entry point\n"));

      for (i = 0; i < SD_MAJORS; i++)
            if (register_blkdev(sd_major(i), "sd") == 0)
                  majors++;

      if (!majors)
            return -ENODEV;

      err = class_register(&sd_disk_class);
      if (err)
            goto err_out;

      err = scsi_register_driver(&sd_template.gendrv);
      if (err)
            goto err_out_class;

      return 0;

err_out_class:
      class_unregister(&sd_disk_class);
err_out:
      for (i = 0; i < SD_MAJORS; i++)
            unregister_blkdev(sd_major(i), "sd");
      return err;
}

/**
 *    exit_sd - exit point for this driver (when it is a module).
 *
 *    Note: this function unregisters this driver from the scsi mid-level.
 **/
static void __exit exit_sd(void)
{
      int i;

      SCSI_LOG_HLQUEUE(3, printk("exit_sd: exiting sd driver\n"));

      scsi_unregister_driver(&sd_template.gendrv);
      class_unregister(&sd_disk_class);

      for (i = 0; i < SD_MAJORS; i++)
            unregister_blkdev(sd_major(i), "sd");
}

module_init(init_sd);
module_exit(exit_sd);

static void sd_print_sense_hdr(struct scsi_disk *sdkp,
                         struct scsi_sense_hdr *sshdr)
{
      sd_printk(KERN_INFO, sdkp, "");
      scsi_show_sense_hdr(sshdr);
      sd_printk(KERN_INFO, sdkp, "");
      scsi_show_extd_sense(sshdr->asc, sshdr->ascq);
}

static void sd_print_result(struct scsi_disk *sdkp, int result)
{
      sd_printk(KERN_INFO, sdkp, "");
      scsi_show_result(result);
}


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