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 #include <linux/interrupt.h>
  15 #include <linux/major.h>
  16 #include <linux/fs.h>
  17 #include <linux/blkpg.h>
  18
  19 #include <linux/uaccess.h>
  20
  21 #include "dasd_int.h"
  22
  23 static unsigned int queue_depth = 32;
  24 static unsigned int nr_hw_queues = 4;
  25
  26 module_param(queue_depth, uint, 0444);
  27 MODULE_PARM_DESC(queue_depth, "Default queue depth for new DASD devices");
  28
  29 module_param(nr_hw_queues, uint, 0444);
  30 MODULE_PARM_DESC(nr_hw_queues, "Default number of hardware queues for new DASD devices");
  31
  32 /*
  33  * Allocate and register gendisk structure for device.
  34  */
  35 int dasd_gendisk_alloc(struct dasd_block *block)
  36 {
  37         struct queue_limits lim = {
  38                 /*
  39                  * With page sized segments, each segment can be translated into
  40                  * one idaw/tidaw.
  41                  */
  42                 .max_segment_size = PAGE_SIZE,
  43                 .seg_boundary_mask = PAGE_SIZE - 1,
  44                 .max_segments = USHRT_MAX,
  45         };
  46         struct gendisk *gdp;
  47         struct dasd_device *base;
  48         int len, rc;
  49
  50         /* Make sure the minor for this device exists. */
  51         base = block->base;
  52         if (base->devindex >= DASD_PER_MAJOR)
  53                 return -EBUSY;
  54
  55         block->tag_set.ops = &dasd_mq_ops;
  56         block->tag_set.cmd_size = sizeof(struct dasd_ccw_req);
  57         block->tag_set.nr_hw_queues = nr_hw_queues;
  58         block->tag_set.queue_depth = queue_depth;
  59         block->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
  60         block->tag_set.numa_node = NUMA_NO_NODE;
  61         rc = blk_mq_alloc_tag_set(&block->tag_set);
  62         if (rc)
  63                 return rc;
  64
  65         gdp = blk_mq_alloc_disk(&block->tag_set, &lim, block);
  66         if (IS_ERR(gdp)) {
  67                 blk_mq_free_tag_set(&block->tag_set);
  68                 return PTR_ERR(gdp);
  69         }
  70
  71         /* Initialize gendisk structure. */
  72         gdp->major = DASD_MAJOR;
  73         gdp->first_minor = base->devindex << DASD_PARTN_BITS;
  74         gdp->minors = 1 << DASD_PARTN_BITS;
  75         gdp->fops = &dasd_device_operations;
  76
  77         /*
  78          * Set device name.
  79          *   dasda - dasdz : 26 devices
  80          *   dasdaa - dasdzz : 676 devices, added up = 702
  81          *   dasdaaa - dasdzzz : 17576 devices, added up = 18278
  82          *   dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
  83          */
  84         len = sprintf(gdp->disk_name, "dasd");
  85         if (base->devindex > 25) {
  86                 if (base->devindex > 701) {
  87                         if (base->devindex > 18277)
  88                                 len += sprintf(gdp->disk_name + len, "%c",
  89                                                'a'+(((base->devindex-18278)
  90                                                      /17576)%26));
  91                         len += sprintf(gdp->disk_name + len, "%c",
  92                                        'a'+(((base->devindex-702)/676)%26));
  93                 }
  94                 len += sprintf(gdp->disk_name + len, "%c",
  95                                'a'+(((base->devindex-26)/26)%26));
  96         }
  97         len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));
  98
  99         if (base->features & DASD_FEATURE_READONLY ||
 100             test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
 101                 set_disk_ro(gdp, 1);
 102         dasd_add_link_to_gendisk(gdp, base);
 103         block->gdp = gdp;
 104         set_capacity(block->gdp, 0);
 105
 106         rc = device_add_disk(&base->cdev->dev, block->gdp, NULL);
 107         if (rc) {
 108                 dasd_gendisk_free(block);
 109                 return rc;
 110         }
 111
 112         return 0;
 113 }
 114
 115 /*
 116  * Unregister and free gendisk structure for device.
 117  */
 118 void dasd_gendisk_free(struct dasd_block *block)
 119 {
 120         if (block->gdp) {
 121                 del_gendisk(block->gdp);
 122                 block->gdp->private_data = NULL;
 123                 put_disk(block->gdp);
 124                 block->gdp = NULL;
 125                 blk_mq_free_tag_set(&block->tag_set);
 126         }
 127 }
 128
 129 /*
 130  * Trigger a partition detection.
 131  */
 132 int dasd_scan_partitions(struct dasd_block *block)
 133 {
 134         struct file *bdev_file;
 135         int rc;
 136
 137         bdev_file = bdev_file_open_by_dev(disk_devt(block->gdp), BLK_OPEN_READ,
 138                                        NULL, NULL);
 139         if (IS_ERR(bdev_file)) {
 140                 DBF_DEV_EVENT(DBF_ERR, block->base,
 141                               "scan partitions error, blkdev_get returned %ld",
 142                               PTR_ERR(bdev_file));
 143                 return -ENODEV;
 144         }
 145
 146         mutex_lock(&block->gdp->open_mutex);
 147         rc = bdev_disk_changed(block->gdp, false);
 148         mutex_unlock(&block->gdp->open_mutex);
 149         if (rc)
 150                 DBF_DEV_EVENT(DBF_ERR, block->base,
 151                                 "scan partitions error, rc %d", rc);
 152
 153         /*
 154          * Since the matching fput() call to the
 155          * bdev_file_open_by_path() in this function is not called before
 156          * dasd_destroy_partitions the offline open_count limit needs to be
 157          * increased from 0 to 1. This is done by setting device->bdev_file
 158          * (see dasd_generic_set_offline). As long as the partition detection
 159          * is running no offline should be allowed. That is why the assignment
 160          * to block->bdev_file is done AFTER the BLKRRPART ioctl.
 161          */
 162         block->bdev_file = bdev_file;
 163         return 0;
 164 }
 165
 166 /*
 167  * Remove all inodes in the system for a device, delete the
 168  * partitions and make device unusable by setting its size to zero.
 169  */
 170 void dasd_destroy_partitions(struct dasd_block *block)
 171 {
 172         struct file *bdev_file;
 173
 174         /*
 175          * Get the bdev_file pointer from the device structure and clear
 176          * device->bdev_file to lower the offline open_count limit again.
 177          */
 178         bdev_file = block->bdev_file;
 179         block->bdev_file = NULL;
 180
 181         mutex_lock(&file_bdev(bdev_file)->bd_disk->open_mutex);
 182         bdev_disk_changed(file_bdev(bdev_file)->bd_disk, true);
 183         mutex_unlock(&file_bdev(bdev_file)->bd_disk->open_mutex);
 184
 185         /* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
 186         fput(bdev_file);
 187 }
 188
 189 int dasd_gendisk_init(void)
 190 {
 191         int rc;
 192
 193         /* Register to static dasd major 94 */
 194         rc = register_blkdev(DASD_MAJOR, "dasd");
 195         if (rc != 0) {
 196                 pr_warn("Registering the device driver with major number %d failed\n",
 197                         DASD_MAJOR);
 198                 return rc;
 199         }
 200         return 0;
 201 }
 202
 203 void dasd_gendisk_exit(void)
 204 {
 205         unregister_blkdev(DASD_MAJOR, "dasd");
 206 }