drivers/s390/block/dasd_genhd.c

   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  */
  30 int 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  */
  86 void 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  */
  99 int 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  */
 137 void 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         blk_drop_partitions(bdev);
 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         set_capacity(block->gdp, 0);
 155 }
 156
 157 int dasd_gendisk_init(void)
 158 {
 159         int rc;
 160
 161         /* Register to static dasd major 94 */
 162         rc = register_blkdev(DASD_MAJOR, "dasd");
 163         if (rc != 0) {
 164                 pr_warn("Registering the device driver with major number %d failed\n",
 165                         DASD_MAJOR);
 166                 return rc;
 167         }
 168         return 0;
 169 }
 170
 171 void dasd_gendisk_exit(void)
 172 {
 173         unregister_blkdev(DASD_MAJOR, "dasd");
 174 }