1 files changed, 318 insertions, 0 deletions
diff --git a/block/blk-ia-ranges.c b/block/blk-ia-ranges.c
new file mode 100644
index 000000000000..c9eb4241e048
--- /dev/null
+++ b/block/blk-ia-ranges.c
@@ -0,0 +1,318 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Block device concurrent positioning ranges.
+ *
+ *  Copyright (C) 2021 Western Digital Corporation or its Affiliates.
+ */
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+
+#include "blk.h"
+
+static ssize_t
+blk_ia_range_sector_show(struct blk_independent_access_range *iar,
+			 char *buf)
+{
+	return sprintf(buf, "%llu\n", iar->sector);
+}
+
+static ssize_t
+blk_ia_range_nr_sectors_show(struct blk_independent_access_range *iar,
+			     char *buf)
+{
+	return sprintf(buf, "%llu\n", iar->nr_sectors);
+}
+
+struct blk_ia_range_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct blk_independent_access_range *iar, char *buf);
+};
+
+static struct blk_ia_range_sysfs_entry blk_ia_range_sector_entry = {
+	.attr = { .name = "sector", .mode = 0444 },
+	.show = blk_ia_range_sector_show,
+};
+
+static struct blk_ia_range_sysfs_entry blk_ia_range_nr_sectors_entry = {
+	.attr = { .name = "nr_sectors", .mode = 0444 },
+	.show = blk_ia_range_nr_sectors_show,
+};
+
+static struct attribute *blk_ia_range_attrs[] = {
+	&blk_ia_range_sector_entry.attr,
+	&blk_ia_range_nr_sectors_entry.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(blk_ia_range);
+
+static ssize_t blk_ia_range_sysfs_show(struct kobject *kobj,
+				      struct attribute *attr, char *buf)
+{
+	struct blk_ia_range_sysfs_entry *entry =
+		container_of(attr, struct blk_ia_range_sysfs_entry, attr);
+	struct blk_independent_access_range *iar =
+		container_of(kobj, struct blk_independent_access_range, kobj);
+
+	return entry->show(iar, buf);
+}
+
+static const struct sysfs_ops blk_ia_range_sysfs_ops = {
+	.show	= blk_ia_range_sysfs_show,
+};
+
+/*
+ * Independent access range entries are not freed individually, but alltogether
+ * with struct blk_independent_access_ranges and its array of ranges. Since
+ * kobject_add() takes a reference on the parent kobject contained in
+ * struct blk_independent_access_ranges, the array of independent access range
+ * entries cannot be freed until kobject_del() is called for all entries.
+ * So we do not need to do anything here, but still need this no-op release
+ * operation to avoid complaints from the kobject code.
+ */
+static void blk_ia_range_sysfs_nop_release(struct kobject *kobj)
+{
+}
+
+static const struct kobj_type blk_ia_range_ktype = {
+	.sysfs_ops	= &blk_ia_range_sysfs_ops,
+	.default_groups	= blk_ia_range_groups,
+	.release	= blk_ia_range_sysfs_nop_release,
+};
+
+/*
+ * This will be executed only after all independent access range entries are
+ * removed with kobject_del(), at which point, it is safe to free everything,
+ * including the array of ranges.
+ */
+static void blk_ia_ranges_sysfs_release(struct kobject *kobj)
+{
+	struct blk_independent_access_ranges *iars =
+		container_of(kobj, struct blk_independent_access_ranges, kobj);
+
+	kfree(iars);
+}
+
+static const struct kobj_type blk_ia_ranges_ktype = {
+	.release	= blk_ia_ranges_sysfs_release,
+};
+
+/**
+ * disk_register_independent_access_ranges - register with sysfs a set of
+ *		independent access ranges
+ * @disk:	Target disk
+ *
+ * Register with sysfs a set of independent access ranges for @disk.
+ */
+int disk_register_independent_access_ranges(struct gendisk *disk)
+{
+	struct blk_independent_access_ranges *iars = disk->ia_ranges;
+	struct request_queue *q = disk->queue;
+	int i, ret;
+
+	lockdep_assert_held(&q->sysfs_dir_lock);
+	lockdep_assert_held(&q->sysfs_lock);
+
+	if (!iars)
+		return 0;
+
+	/*
+	 * At this point, iars is the new set of sector access ranges that needs
+	 * to be registered with sysfs.
+	 */
+	WARN_ON(iars->sysfs_registered);
+	ret = kobject_init_and_add(&iars->kobj, &blk_ia_ranges_ktype,
+				   &disk->queue_kobj, "%s",
+				   "independent_access_ranges");
+	if (ret) {
+		disk->ia_ranges = NULL;
+		kobject_put(&iars->kobj);
+		return ret;
+	}
+
+	for (i = 0; i < iars->nr_ia_ranges; i++) {
+		ret = kobject_init_and_add(&iars->ia_range[i].kobj,
+					   &blk_ia_range_ktype, &iars->kobj,
+					   "%d", i);
+		if (ret) {
+			while (--i >= 0)
+				kobject_del(&iars->ia_range[i].kobj);
+			kobject_del(&iars->kobj);
+			kobject_put(&iars->kobj);
+			return ret;
+		}
+	}
+
+	iars->sysfs_registered = true;
+
+	return 0;
+}
+
+void disk_unregister_independent_access_ranges(struct gendisk *disk)
+{
+	struct request_queue *q = disk->queue;
+	struct blk_independent_access_ranges *iars = disk->ia_ranges;
+	int i;
+
+	lockdep_assert_held(&q->sysfs_dir_lock);
+	lockdep_assert_held(&q->sysfs_lock);
+
+	if (!iars)
+		return;
+
+	if (iars->sysfs_registered) {
+		for (i = 0; i < iars->nr_ia_ranges; i++)
+			kobject_del(&iars->ia_range[i].kobj);
+		kobject_del(&iars->kobj);
+		kobject_put(&iars->kobj);
+	} else {
+		kfree(iars);
+	}
+
+	disk->ia_ranges = NULL;
+}
+
+static struct blk_independent_access_range *
+disk_find_ia_range(struct blk_independent_access_ranges *iars,
+		  sector_t sector)
+{
+	struct blk_independent_access_range *iar;
+	int i;
+
+	for (i = 0; i < iars->nr_ia_ranges; i++) {
+		iar = &iars->ia_range[i];
+		if (sector >= iar->sector &&
+		    sector < iar->sector + iar->nr_sectors)
+			return iar;
+	}
+
+	return NULL;
+}
+
+static bool disk_check_ia_ranges(struct gendisk *disk,
+				struct blk_independent_access_ranges *iars)
+{
+	struct blk_independent_access_range *iar, *tmp;
+	sector_t capacity = get_capacity(disk);
+	sector_t sector = 0;
+	int i;
+
+	if (WARN_ON_ONCE(!iars->nr_ia_ranges))
+		return false;
+
+	/*
+	 * While sorting the ranges in increasing LBA order, check that the
+	 * ranges do not overlap, that there are no sector holes and that all
+	 * sectors belong to one range.
+	 */
+	for (i = 0; i < iars->nr_ia_ranges; i++) {
+		tmp = disk_find_ia_range(iars, sector);
+		if (!tmp || tmp->sector != sector) {
+			pr_warn("Invalid non-contiguous independent access ranges\n");
+			return false;
+		}
+
+		iar = &iars->ia_range[i];
+		if (tmp != iar) {
+			swap(iar->sector, tmp->sector);
+			swap(iar->nr_sectors, tmp->nr_sectors);
+		}
+
+		sector += iar->nr_sectors;
+	}
+
+	if (sector != capacity) {
+		pr_warn("Independent access ranges do not match disk capacity\n");
+		return false;
+	}
+
+	return true;
+}
+
+static bool disk_ia_ranges_changed(struct gendisk *disk,
+				   struct blk_independent_access_ranges *new)
+{
+	struct blk_independent_access_ranges *old = disk->ia_ranges;
+	int i;
+
+	if (!old)
+		return true;
+
+	if (old->nr_ia_ranges != new->nr_ia_ranges)
+		return true;
+
+	for (i = 0; i < old->nr_ia_ranges; i++) {
+		if (new->ia_range[i].sector != old->ia_range[i].sector ||
+		    new->ia_range[i].nr_sectors != old->ia_range[i].nr_sectors)
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * disk_alloc_independent_access_ranges - Allocate an independent access ranges
+ *                                        data structure
+ * @disk:		target disk
+ * @nr_ia_ranges:	Number of independent access ranges
+ *
+ * Allocate a struct blk_independent_access_ranges structure with @nr_ia_ranges
+ * access range descriptors.
+ */
+struct blk_independent_access_ranges *
+disk_alloc_independent_access_ranges(struct gendisk *disk, int nr_ia_ranges)
+{
+	struct blk_independent_access_ranges *iars;
+
+	iars = kzalloc_node(struct_size(iars, ia_range, nr_ia_ranges),
+			    GFP_KERNEL, disk->queue->node);
+	if (iars)
+		iars->nr_ia_ranges = nr_ia_ranges;
+	return iars;
+}
+EXPORT_SYMBOL_GPL(disk_alloc_independent_access_ranges);
+
+/**
+ * disk_set_independent_access_ranges - Set a disk independent access ranges
+ * @disk:	target disk
+ * @iars:	independent access ranges structure
+ *
+ * Set the independent access ranges information of the request queue
+ * of @disk to @iars. If @iars is NULL and the independent access ranges
+ * structure already set is cleared. If there are no differences between
+ * @iars and the independent access ranges structure already set, @iars
+ * is freed.
+ */
+void disk_set_independent_access_ranges(struct gendisk *disk,
+				struct blk_independent_access_ranges *iars)
+{
+	struct request_queue *q = disk->queue;
+
+	mutex_lock(&q->sysfs_dir_lock);
+	mutex_lock(&q->sysfs_lock);
+	if (iars && !disk_check_ia_ranges(disk, iars)) {
+		kfree(iars);
+		iars = NULL;
+	}
+	if (iars && !disk_ia_ranges_changed(disk, iars)) {
+		kfree(iars);
+		goto unlock;
+	}
+
+	/*
+	 * This may be called for a registered queue. E.g. during a device
+	 * revalidation. If that is the case, we need to unregister the old
+	 * set of independent access ranges and register the new set. If the
+	 * queue is not registered, registration of the device request queue
+	 * will register the independent access ranges.
+	 */
+	disk_unregister_independent_access_ranges(disk);
+	disk->ia_ranges = iars;
+	if (blk_queue_registered(q))
+		disk_register_independent_access_ranges(disk);
+unlock:
+	mutex_unlock(&q->sysfs_lock);
+	mutex_unlock(&q->sysfs_dir_lock);
+}
+EXPORT_SYMBOL_GPL(disk_set_independent_access_ranges);