// 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"

/*
 * 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;

        /*
         * 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);
        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 = bdget_disk(block->gdp, 0);
        if (!bdev) {
                DBF_DEV_EVENT(DBF_ERR, block->base, "%s",
                              "scan partitions error, bdget returned NULL");
                return -ENODEV;
        }

        rc = blkdev_get(bdev, FMODE_READ, NULL);
        if (rc < 0) {
                DBF_DEV_EVENT(DBF_ERR, block->base,
                              "scan partitions error, blkdev_get returned %d",
                              rc);
                return -ENODEV;
        }

        rc = blkdev_reread_part(bdev);
        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)
{
        /* 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_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");
}