linux/drivers/s390/block/dasd_genhd.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
   4 *                  Horst Hummel <Horst.Hummel@de.ibm.com>
   5 *                  Carsten Otte <Cotte@de.ibm.com>
   6 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
   7 * Bugreports.to..: <Linux390@de.ibm.com>
   8 * Copyright IBM Corp. 1999, 2001
   9 *
  10 * gendisk related functions for the dasd driver.
  11 *
  12 */
  13
  14#define KMSG_COMPONENT "dasd"
  15
  16#include <linux/interrupt.h>
  17#include <linux/fs.h>
  18#include <linux/blkpg.h>
  19
  20#include <linux/uaccess.h>
  21
  22/* This is ugly... */
  23#define PRINTK_HEADER "dasd_gendisk:"
  24
  25#include "dasd_int.h"
  26
  27/*
  28 * Allocate and register gendisk structure for device.
  29 */
  30int dasd_gendisk_alloc(struct dasd_block *block)
  31{
  32        struct gendisk *gdp;
  33        struct dasd_device *base;
  34        int len;
  35
  36        /* Make sure the minor for this device exists. */
  37        base = block->base;
  38        if (base->devindex >= DASD_PER_MAJOR)
  39                return -EBUSY;
  40
  41        gdp = alloc_disk(1 << DASD_PARTN_BITS);
  42        if (!gdp)
  43                return -ENOMEM;
  44
  45        /* Initialize gendisk structure. */
  46        gdp->major = DASD_MAJOR;
  47        gdp->first_minor = base->devindex << DASD_PARTN_BITS;
  48        gdp->fops = &dasd_device_operations;
  49
  50        /*
  51         * Set device name.
  52         *   dasda - dasdz : 26 devices
  53         *   dasdaa - dasdzz : 676 devices, added up = 702
  54         *   dasdaaa - dasdzzz : 17576 devices, added up = 18278
  55         *   dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
  56         */
  57        len = sprintf(gdp->disk_name, "dasd");
  58        if (base->devindex > 25) {
  59                if (base->devindex > 701) {
  60                        if (base->devindex > 18277)
  61                                len += sprintf(gdp->disk_name + len, "%c",
  62                                               'a'+(((base->devindex-18278)
  63                                                     /17576)%26));
  64                        len += sprintf(gdp->disk_name + len, "%c",
  65                                       'a'+(((base->devindex-702)/676)%26));
  66                }
  67                len += sprintf(gdp->disk_name + len, "%c",
  68                               'a'+(((base->devindex-26)/26)%26));
  69        }
  70        len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));
  71
  72        if (base->features & DASD_FEATURE_READONLY ||
  73            test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
  74                set_disk_ro(gdp, 1);
  75        dasd_add_link_to_gendisk(gdp, base);
  76        gdp->queue = block->request_queue;
  77        block->gdp = gdp;
  78        set_capacity(block->gdp, 0);
  79        device_add_disk(&base->cdev->dev, block->gdp, NULL);
  80        return 0;
  81}
  82
  83/*
  84 * Unregister and free gendisk structure for device.
  85 */
  86void dasd_gendisk_free(struct dasd_block *block)
  87{
  88        if (block->gdp) {
  89                del_gendisk(block->gdp);
  90                block->gdp->private_data = NULL;
  91                put_disk(block->gdp);
  92                block->gdp = NULL;
  93        }
  94}
  95
  96/*
  97 * Trigger a partition detection.
  98 */
  99int dasd_scan_partitions(struct dasd_block *block)
 100{
 101        struct block_device *bdev;
 102        int rc;
 103
 104        bdev = blkdev_get_by_dev(disk_devt(block->gdp), FMODE_READ, NULL);
 105        if (IS_ERR(bdev)) {
 106                DBF_DEV_EVENT(DBF_ERR, block->base,
 107                              "scan partitions error, blkdev_get returned %ld",
 108                              PTR_ERR(bdev));
 109                return -ENODEV;
 110        }
 111
 112        mutex_lock(&bdev->bd_mutex);
 113        rc = bdev_disk_changed(bdev, false);
 114        mutex_unlock(&bdev->bd_mutex);
 115        if (rc)
 116                DBF_DEV_EVENT(DBF_ERR, block->base,
 117                                "scan partitions error, rc %d", rc);
 118
 119        /*
 120         * Since the matching blkdev_put call to the blkdev_get in
 121         * this function is not called before dasd_destroy_partitions
 122         * the offline open_count limit needs to be increased from
 123         * 0 to 1. This is done by setting device->bdev (see
 124         * dasd_generic_set_offline). As long as the partition
 125         * detection is running no offline should be allowed. That
 126         * is why the assignment to device->bdev is done AFTER
 127         * the BLKRRPART ioctl.
 128         */
 129        block->bdev = bdev;
 130        return 0;
 131}
 132
 133/*
 134 * Remove all inodes in the system for a device, delete the
 135 * partitions and make device unusable by setting its size to zero.
 136 */
 137void dasd_destroy_partitions(struct dasd_block *block)
 138{
 139        struct block_device *bdev;
 140
 141        /*
 142         * Get the bdev pointer from the device structure and clear
 143         * device->bdev to lower the offline open_count limit again.
 144         */
 145        bdev = block->bdev;
 146        block->bdev = NULL;
 147
 148        mutex_lock(&bdev->bd_mutex);
 149        bdev_disk_changed(bdev, true);
 150        mutex_unlock(&bdev->bd_mutex);
 151
 152        /* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
 153        blkdev_put(bdev, FMODE_READ);
 154}
 155
 156int dasd_gendisk_init(void)
 157{
 158        int rc;
 159
 160        /* Register to static dasd major 94 */
 161        rc = register_blkdev(DASD_MAJOR, "dasd");
 162        if (rc != 0) {
 163                pr_warn("Registering the device driver with major number %d failed\n",
 164                        DASD_MAJOR);
 165                return rc;
 166        }
 167        return 0;
 168}
 169
 170void dasd_gendisk_exit(void)
 171{
 172        unregister_blkdev(DASD_MAJOR, "dasd");
 173}
 174