dasd_genhd.c

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/*
 * Author(s)......: Holger Smolinski <[email protected]>
 *          Horst Hummel <[email protected]>
 *          Carsten Otte <[email protected]>
 *          Martin Schwidefsky <[email protected]>
 * Bugreports.to..: <[email protected]>
 * Copyright IBM Corp. 1999, 2001
 *
 * gendisk related functions for the dasd driver.
 *
 */

#define KMSG_COMPONENT "dasd"

#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/blkpg.h>

#include <asm/uaccess.h>

/* This is ugly... */
#define PRINTK_HEADER "dasd_gendisk:"

#include "dasd_int.h"

/*
 * Allocate and register gendisk structure for device.
 */
int dasd_gendisk_alloc(struct dasd_block *block)
{
    struct gendisk *gdp;
    struct dasd_device *base;
    int len;

    /* Make sure the minor for this device exists. */
    base = block->base;
    if (base->devindex >= DASD_PER_MAJOR)
        return -EBUSY;

    gdp = alloc_disk(1 << DASD_PARTN_BITS);
    if (!gdp)
        return -ENOMEM;

    /* Initialize gendisk structure. */
    gdp->major = DASD_MAJOR;
    gdp->first_minor = base->devindex << DASD_PARTN_BITS;
    gdp->fops = &dasd_device_operations;
    gdp->driverfs_dev = &base->cdev->dev;

    /*
     * Set device name.
     *   dasda - dasdz : 26 devices
     *   dasdaa - dasdzz : 676 devices, added up = 702
     *   dasdaaa - dasdzzz : 17576 devices, added up = 18278
     *   dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
     */
    len = sprintf(gdp->disk_name, "dasd");
    if (base->devindex > 25) {
        if (base->devindex > 701) {
            if (base->devindex > 18277)
                    len += sprintf(gdp->disk_name + len, "%c",
                           'a'+(((base->devindex-18278)
                             /17576)%26));
            len += sprintf(gdp->disk_name + len, "%c",
                       'a'+(((base->devindex-702)/676)%26));
        }
        len += sprintf(gdp->disk_name + len, "%c",
                   'a'+(((base->devindex-26)/26)%26));
    }
    len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));

    if (base->features & DASD_FEATURE_READONLY ||
        test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
        set_disk_ro(gdp, 1);
    dasd_add_link_to_gendisk(gdp, base);
    gdp->queue = block->request_queue;
    block->gdp = gdp;
    set_capacity(block->gdp, 0);
    add_disk(block->gdp);
    return 0;
}

/*
 * Unregister and free gendisk structure for device.
 */
void dasd_gendisk_free(struct dasd_block *block)
{
    if (block->gdp) {
        del_gendisk(block->gdp);
        block->gdp->queue = NULL;
        block->gdp->private_data = NULL;
        put_disk(block->gdp);
        block->gdp = NULL;
    }
}

/*
 * Trigger a partition detection.
 */
int dasd_scan_partitions(struct dasd_block *block)
{
    struct block_device *bdev;

    bdev = bdget_disk(block->gdp, 0);
    if (!bdev || blkdev_get(bdev, FMODE_READ, NULL) < 0)
        return -ENODEV;
    /*
     * See fs/partition/check.c:register_disk,rescan_partitions
     * Can't call rescan_partitions directly. Use ioctl.
     */
    ioctl_by_bdev(bdev, BLKRRPART, 0);
    /*
     * Since the matching blkdev_put call to the blkdev_get in
     * this function is not called before dasd_destroy_partitions
     * the offline open_count limit needs to be increased from
     * 0 to 1. This is done by setting device->bdev (see
     * dasd_generic_set_offline). As long as the partition
     * detection is running no offline should be allowed. That
     * is why the assignment to device->bdev is done AFTER
     * the BLKRRPART ioctl.
     */
    block->bdev = bdev;
    return 0;
}

/*
 * Remove all inodes in the system for a device, delete the
 * partitions and make device unusable by setting its size to zero.
 */
void dasd_destroy_partitions(struct dasd_block *block)
{
    /* The two structs have 168/176 byte on 31/64 bit. */
    struct blkpg_partition bpart;
    struct blkpg_ioctl_arg barg;
    struct block_device *bdev;

    /*
     * Get the bdev pointer from the device structure and clear
     * device->bdev to lower the offline open_count limit again.
     */
    bdev = block->bdev;
    block->bdev = NULL;

    /*
     * See fs/partition/check.c:delete_partition
     * Can't call delete_partitions directly. Use ioctl.
     * The ioctl also does locking and invalidation.
     */
    memset(&bpart, 0, sizeof(struct blkpg_partition));
    memset(&barg, 0, sizeof(struct blkpg_ioctl_arg));
    barg.data = (void __force __user *) &bpart;
    barg.op = BLKPG_DEL_PARTITION;
    for (bpart.pno = block->gdp->minors - 1; bpart.pno > 0; bpart.pno--)
        ioctl_by_bdev(bdev, BLKPG, (unsigned long) &barg);

    invalidate_partition(block->gdp, 0);
    /* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
    blkdev_put(bdev, FMODE_READ);
    set_capacity(block->gdp, 0);
}

int dasd_gendisk_init(void)
{
    int rc;

    /* Register to static dasd major 94 */
    rc = register_blkdev(DASD_MAJOR, "dasd");
    if (rc != 0) {
        pr_warning("Registering the device driver with major number "
               "%d failed\n", DASD_MAJOR);
        return rc;
    }
    return 0;
}

void dasd_gendisk_exit(void)
{
    unregister_blkdev(DASD_MAJOR, "dasd");
}