// SPDX-License-Identifier: GPL-2.0
/*
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 *                  Horst Hummel <Horst.Hummel@de.ibm.com>
 *                  Carsten Otte <Cotte@de.ibm.com>
 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * 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 <linux/uaccess.h>

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

#include "dasd_int.h"

static struct lock_class_key dasd_bio_compl_lkclass;

/*
 * 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_node(block->request_queue, NUMA_NO_NODE,
                                &dasd_bio_compl_lkclass);
        if (!gdp)
                return -ENOMEM;

        /* Initialize gendisk structure. */
        gdp->major = DASD_MAJOR;
        gdp->first_minor = base->devindex << DASD_PARTN_BITS;
        gdp->minors = 1 << DASD_PARTN_BITS;
        gdp->fops = &dasd_device_operations;

        /*
         * 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);
        block->gdp = gdp;
        set_capacity(block->gdp, 0);
        device_add_disk(&base->cdev->dev, block->gdp, NULL);
        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->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;
        int rc;

        bdev = blkdev_get_by_dev(disk_devt(block->gdp), FMODE_READ, NULL);
        if (IS_ERR(bdev)) {
                DBF_DEV_EVENT(DBF_ERR, block->base,
                              "scan partitions error, blkdev_get returned %ld",
                              PTR_ERR(bdev));
                return -ENODEV;
        }

        mutex_lock(&block->gdp->open_mutex);
        rc = bdev_disk_changed(block->gdp, false);
        mutex_unlock(&block->gdp->open_mutex);
        if (rc)
                DBF_DEV_EVENT(DBF_ERR, block->base,
                                "scan partitions error, rc %d", rc);

        /*
         * 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)
{
        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;

        mutex_lock(&bdev->bd_disk->open_mutex);
        bdev_disk_changed(bdev->bd_disk, true);
        mutex_unlock(&bdev->bd_disk->open_mutex);

        /* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
        blkdev_put(bdev, FMODE_READ);
}

int dasd_gendisk_init(void)
{
        int rc;

        /* Register to static dasd major 94 */
        rc = register_blkdev(DASD_MAJOR, "dasd");
        if (rc != 0) {
                pr_warn("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");
}