block/blk-ia-ranges.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Block device concurrent positioning ranges.
   4  *
   5  *  Copyright (C) 2021 Western Digital Corporation or its Affiliates.
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/slab.h>
  10 #include <linux/init.h>
  11
  12 #include "blk.h"
  13
  14 static ssize_t
  15 blk_ia_range_sector_show(struct blk_independent_access_range *iar,
  16                          char *buf)
  17 {
  18         return sprintf(buf, "%llu\n", iar->sector);
  19 }
  20
  21 static ssize_t
  22 blk_ia_range_nr_sectors_show(struct blk_independent_access_range *iar,
  23                              char *buf)
  24 {
  25         return sprintf(buf, "%llu\n", iar->nr_sectors);
  26 }
  27
  28 struct blk_ia_range_sysfs_entry {
  29         struct attribute attr;
  30         ssize_t (*show)(struct blk_independent_access_range *iar, char *buf);
  31 };
  32
  33 static struct blk_ia_range_sysfs_entry blk_ia_range_sector_entry = {
  34         .attr = { .name = "sector", .mode = 0444 },
  35         .show = blk_ia_range_sector_show,
  36 };
  37
  38 static struct blk_ia_range_sysfs_entry blk_ia_range_nr_sectors_entry = {
  39         .attr = { .name = "nr_sectors", .mode = 0444 },
  40         .show = blk_ia_range_nr_sectors_show,
  41 };
  42
  43 static struct attribute *blk_ia_range_attrs[] = {
  44         &blk_ia_range_sector_entry.attr,
  45         &blk_ia_range_nr_sectors_entry.attr,
  46         NULL,
  47 };
  48 ATTRIBUTE_GROUPS(blk_ia_range);
  49
  50 static ssize_t blk_ia_range_sysfs_show(struct kobject *kobj,
  51                                       struct attribute *attr, char *buf)
  52 {
  53         struct blk_ia_range_sysfs_entry *entry =
  54                 container_of(attr, struct blk_ia_range_sysfs_entry, attr);
  55         struct blk_independent_access_range *iar =
  56                 container_of(kobj, struct blk_independent_access_range, kobj);
  57
  58         return entry->show(iar, buf);
  59 }
  60
  61 static const struct sysfs_ops blk_ia_range_sysfs_ops = {
  62         .show   = blk_ia_range_sysfs_show,
  63 };
  64
  65 /*
  66  * Independent access range entries are not freed individually, but alltogether
  67  * with struct blk_independent_access_ranges and its array of ranges. Since
  68  * kobject_add() takes a reference on the parent kobject contained in
  69  * struct blk_independent_access_ranges, the array of independent access range
  70  * entries cannot be freed until kobject_del() is called for all entries.
  71  * So we do not need to do anything here, but still need this no-op release
  72  * operation to avoid complaints from the kobject code.
  73  */
  74 static void blk_ia_range_sysfs_nop_release(struct kobject *kobj)
  75 {
  76 }
  77
  78 static const struct kobj_type blk_ia_range_ktype = {
  79         .sysfs_ops      = &blk_ia_range_sysfs_ops,
  80         .default_groups = blk_ia_range_groups,
  81         .release        = blk_ia_range_sysfs_nop_release,
  82 };
  83
  84 /*
  85  * This will be executed only after all independent access range entries are
  86  * removed with kobject_del(), at which point, it is safe to free everything,
  87  * including the array of ranges.
  88  */
  89 static void blk_ia_ranges_sysfs_release(struct kobject *kobj)
  90 {
  91         struct blk_independent_access_ranges *iars =
  92                 container_of(kobj, struct blk_independent_access_ranges, kobj);
  93
  94         kfree(iars);
  95 }
  96
  97 static const struct kobj_type blk_ia_ranges_ktype = {
  98         .release        = blk_ia_ranges_sysfs_release,
  99 };
 100
 101 /**
 102  * disk_register_independent_access_ranges - register with sysfs a set of
 103  *              independent access ranges
 104  * @disk:       Target disk
 105  *
 106  * Register with sysfs a set of independent access ranges for @disk.
 107  */
 108 int disk_register_independent_access_ranges(struct gendisk *disk)
 109 {
 110         struct blk_independent_access_ranges *iars = disk->ia_ranges;
 111         struct request_queue *q = disk->queue;
 112         int i, ret;
 113
 114         lockdep_assert_held(&q->sysfs_dir_lock);
 115         lockdep_assert_held(&q->sysfs_lock);
 116
 117         if (!iars)
 118                 return 0;
 119
 120         /*
 121          * At this point, iars is the new set of sector access ranges that needs
 122          * to be registered with sysfs.
 123          */
 124         WARN_ON(iars->sysfs_registered);
 125         ret = kobject_init_and_add(&iars->kobj, &blk_ia_ranges_ktype,
 126                                    &disk->queue_kobj, "%s",
 127                                    "independent_access_ranges");
 128         if (ret) {
 129                 disk->ia_ranges = NULL;
 130                 kobject_put(&iars->kobj);
 131                 return ret;
 132         }
 133
 134         for (i = 0; i < iars->nr_ia_ranges; i++) {
 135                 ret = kobject_init_and_add(&iars->ia_range[i].kobj,
 136                                            &blk_ia_range_ktype, &iars->kobj,
 137                                            "%d", i);
 138                 if (ret) {
 139                         while (--i >= 0)
 140                                 kobject_del(&iars->ia_range[i].kobj);
 141                         kobject_del(&iars->kobj);
 142                         kobject_put(&iars->kobj);
 143                         return ret;
 144                 }
 145         }
 146
 147         iars->sysfs_registered = true;
 148
 149         return 0;
 150 }
 151
 152 void disk_unregister_independent_access_ranges(struct gendisk *disk)
 153 {
 154         struct request_queue *q = disk->queue;
 155         struct blk_independent_access_ranges *iars = disk->ia_ranges;
 156         int i;
 157
 158         lockdep_assert_held(&q->sysfs_dir_lock);
 159         lockdep_assert_held(&q->sysfs_lock);
 160
 161         if (!iars)
 162                 return;
 163
 164         if (iars->sysfs_registered) {
 165                 for (i = 0; i < iars->nr_ia_ranges; i++)
 166                         kobject_del(&iars->ia_range[i].kobj);
 167                 kobject_del(&iars->kobj);
 168                 kobject_put(&iars->kobj);
 169         } else {
 170                 kfree(iars);
 171         }
 172
 173         disk->ia_ranges = NULL;
 174 }
 175
 176 static struct blk_independent_access_range *
 177 disk_find_ia_range(struct blk_independent_access_ranges *iars,
 178                   sector_t sector)
 179 {
 180         struct blk_independent_access_range *iar;
 181         int i;
 182
 183         for (i = 0; i < iars->nr_ia_ranges; i++) {
 184                 iar = &iars->ia_range[i];
 185                 if (sector >= iar->sector &&
 186                     sector < iar->sector + iar->nr_sectors)
 187                         return iar;
 188         }
 189
 190         return NULL;
 191 }
 192
 193 static bool disk_check_ia_ranges(struct gendisk *disk,
 194                                 struct blk_independent_access_ranges *iars)
 195 {
 196         struct blk_independent_access_range *iar, *tmp;
 197         sector_t capacity = get_capacity(disk);
 198         sector_t sector = 0;
 199         int i;
 200
 201         if (WARN_ON_ONCE(!iars->nr_ia_ranges))
 202                 return false;
 203
 204         /*
 205          * While sorting the ranges in increasing LBA order, check that the
 206          * ranges do not overlap, that there are no sector holes and that all
 207          * sectors belong to one range.
 208          */
 209         for (i = 0; i < iars->nr_ia_ranges; i++) {
 210                 tmp = disk_find_ia_range(iars, sector);
 211                 if (!tmp || tmp->sector != sector) {
 212                         pr_warn("Invalid non-contiguous independent access ranges\n");
 213                         return false;
 214                 }
 215
 216                 iar = &iars->ia_range[i];
 217                 if (tmp != iar) {
 218                         swap(iar->sector, tmp->sector);
 219                         swap(iar->nr_sectors, tmp->nr_sectors);
 220                 }
 221
 222                 sector += iar->nr_sectors;
 223         }
 224
 225         if (sector != capacity) {
 226                 pr_warn("Independent access ranges do not match disk capacity\n");
 227                 return false;
 228         }
 229
 230         return true;
 231 }
 232
 233 static bool disk_ia_ranges_changed(struct gendisk *disk,
 234                                    struct blk_independent_access_ranges *new)
 235 {
 236         struct blk_independent_access_ranges *old = disk->ia_ranges;
 237         int i;
 238
 239         if (!old)
 240                 return true;
 241
 242         if (old->nr_ia_ranges != new->nr_ia_ranges)
 243                 return true;
 244
 245         for (i = 0; i < old->nr_ia_ranges; i++) {
 246                 if (new->ia_range[i].sector != old->ia_range[i].sector ||
 247                     new->ia_range[i].nr_sectors != old->ia_range[i].nr_sectors)
 248                         return true;
 249         }
 250
 251         return false;
 252 }
 253
 254 /**
 255  * disk_alloc_independent_access_ranges - Allocate an independent access ranges
 256  *                                        data structure
 257  * @disk:               target disk
 258  * @nr_ia_ranges:       Number of independent access ranges
 259  *
 260  * Allocate a struct blk_independent_access_ranges structure with @nr_ia_ranges
 261  * access range descriptors.
 262  */
 263 struct blk_independent_access_ranges *
 264 disk_alloc_independent_access_ranges(struct gendisk *disk, int nr_ia_ranges)
 265 {
 266         struct blk_independent_access_ranges *iars;
 267
 268         iars = kzalloc_node(struct_size(iars, ia_range, nr_ia_ranges),
 269                             GFP_KERNEL, disk->queue->node);
 270         if (iars)
 271                 iars->nr_ia_ranges = nr_ia_ranges;
 272         return iars;
 273 }
 274 EXPORT_SYMBOL_GPL(disk_alloc_independent_access_ranges);
 275
 276 /**
 277  * disk_set_independent_access_ranges - Set a disk independent access ranges
 278  * @disk:       target disk
 279  * @iars:       independent access ranges structure
 280  *
 281  * Set the independent access ranges information of the request queue
 282  * of @disk to @iars. If @iars is NULL and the independent access ranges
 283  * structure already set is cleared. If there are no differences between
 284  * @iars and the independent access ranges structure already set, @iars
 285  * is freed.
 286  */
 287 void disk_set_independent_access_ranges(struct gendisk *disk,
 288                                 struct blk_independent_access_ranges *iars)
 289 {
 290         struct request_queue *q = disk->queue;
 291
 292         mutex_lock(&q->sysfs_dir_lock);
 293         mutex_lock(&q->sysfs_lock);
 294         if (iars && !disk_check_ia_ranges(disk, iars)) {
 295                 kfree(iars);
 296                 iars = NULL;
 297         }
 298         if (iars && !disk_ia_ranges_changed(disk, iars)) {
 299                 kfree(iars);
 300                 goto unlock;
 301         }
 302
 303         /*
 304          * This may be called for a registered queue. E.g. during a device
 305          * revalidation. If that is the case, we need to unregister the old
 306          * set of independent access ranges and register the new set. If the
 307          * queue is not registered, registration of the device request queue
 308          * will register the independent access ranges.
 309          */
 310         disk_unregister_independent_access_ranges(disk);
 311         disk->ia_ranges = iars;
 312         if (blk_queue_registered(q))
 313                 disk_register_independent_access_ranges(disk);
 314 unlock:
 315         mutex_unlock(&q->sysfs_lock);
 316         mutex_unlock(&q->sysfs_dir_lock);
 317 }
 318 EXPORT_SYMBOL_GPL(disk_set_independent_access_ranges);