netfilter: conntrack: refine gc worker heuristics, redux

[mirror_ubuntu-artful-kernel.git] / drivers / nvdimm / region_devs.c

/*
 * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
#include <linux/scatterlist.h>
#include <linux/highmem.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/hash.h>
#include <linux/pmem.h>
#include <linux/sort.h>
#include <linux/io.h>
#include <linux/nd.h>
#include "nd-core.h"
#include "nd.h"

/*
 * For readq() and writeq() on 32-bit builds, the hi-lo, lo-hi order is
 * irrelevant.
 */
#include <linux/io-64-nonatomic-hi-lo.h>

static DEFINE_IDA(region_ida);
static DEFINE_PER_CPU(int, flush_idx);

static int nvdimm_map_flush(struct device *dev, struct nvdimm *nvdimm, int dimm,
                struct nd_region_data *ndrd)
{
        int i, j;

        dev_dbg(dev, "%s: map %d flush address%s\n", nvdimm_name(nvdimm),
                        nvdimm->num_flush, nvdimm->num_flush == 1 ? "" : "es");
        for (i = 0; i < (1 << ndrd->hints_shift); i++) {
                struct resource *res = &nvdimm->flush_wpq[i];
                unsigned long pfn = PHYS_PFN(res->start);
                void __iomem *flush_page;

                /* check if flush hints share a page */
                for (j = 0; j < i; j++) {
                        struct resource *res_j = &nvdimm->flush_wpq[j];
                        unsigned long pfn_j = PHYS_PFN(res_j->start);

                        if (pfn == pfn_j)
                                break;
                }

                if (j < i)
                        flush_page = (void __iomem *) ((unsigned long)
                                        ndrd_get_flush_wpq(ndrd, dimm, j)
                                        & PAGE_MASK);
                else
                        flush_page = devm_nvdimm_ioremap(dev,
                                        PFN_PHYS(pfn), PAGE_SIZE);
                if (!flush_page)
                        return -ENXIO;
                ndrd_set_flush_wpq(ndrd, dimm, i, flush_page
                                + (res->start & ~PAGE_MASK));
        }

        return 0;
}

int nd_region_activate(struct nd_region *nd_region)
{
        int i, j, num_flush = 0;
        struct nd_region_data *ndrd;
        struct device *dev = &nd_region->dev;
        size_t flush_data_size = sizeof(void *);

        nvdimm_bus_lock(&nd_region->dev);
        for (i = 0; i < nd_region->ndr_mappings; i++) {
                struct nd_mapping *nd_mapping = &nd_region->mapping[i];
                struct nvdimm *nvdimm = nd_mapping->nvdimm;

                /* at least one null hint slot per-dimm for the "no-hint" case */
                flush_data_size += sizeof(void *);
                num_flush = min_not_zero(num_flush, nvdimm->num_flush);
                if (!nvdimm->num_flush)
                        continue;
                flush_data_size += nvdimm->num_flush * sizeof(void *);
        }
        nvdimm_bus_unlock(&nd_region->dev);

        ndrd = devm_kzalloc(dev, sizeof(*ndrd) + flush_data_size, GFP_KERNEL);
        if (!ndrd)
                return -ENOMEM;
        dev_set_drvdata(dev, ndrd);

        if (!num_flush)
                return 0;

        ndrd->hints_shift = ilog2(num_flush);
        for (i = 0; i < nd_region->ndr_mappings; i++) {
                struct nd_mapping *nd_mapping = &nd_region->mapping[i];
                struct nvdimm *nvdimm = nd_mapping->nvdimm;
                int rc = nvdimm_map_flush(&nd_region->dev, nvdimm, i, ndrd);

                if (rc)
                        return rc;
        }

        /*
         * Clear out entries that are duplicates. This should prevent the
         * extra flushings.
         */
        for (i = 0; i < nd_region->ndr_mappings - 1; i++) {
                /* ignore if NULL already */
                if (!ndrd_get_flush_wpq(ndrd, i, 0))
                        continue;

                for (j = i + 1; j < nd_region->ndr_mappings; j++)
                        if (ndrd_get_flush_wpq(ndrd, i, 0) ==
                            ndrd_get_flush_wpq(ndrd, j, 0))
                                ndrd_set_flush_wpq(ndrd, j, 0, NULL);
        }

        return 0;
}

static void nd_region_release(struct device *dev)
{
        struct nd_region *nd_region = to_nd_region(dev);
        u16 i;

        for (i = 0; i < nd_region->ndr_mappings; i++) {
                struct nd_mapping *nd_mapping = &nd_region->mapping[i];
                struct nvdimm *nvdimm = nd_mapping->nvdimm;

                put_device(&nvdimm->dev);
        }
        free_percpu(nd_region->lane);
        ida_simple_remove(&region_ida, nd_region->id);
        if (is_nd_blk(dev))
                kfree(to_nd_blk_region(dev));
        else
                kfree(nd_region);
}

static struct device_type nd_blk_device_type = {
        .name = "nd_blk",
        .release = nd_region_release,
};

static struct device_type nd_pmem_device_type = {
        .name = "nd_pmem",
        .release = nd_region_release,
};

static struct device_type nd_volatile_device_type = {
        .name = "nd_volatile",
        .release = nd_region_release,
};

bool is_nd_pmem(struct device *dev)
{
        return dev ? dev->type == &nd_pmem_device_type : false;
}

bool is_nd_blk(struct device *dev)
{
        return dev ? dev->type == &nd_blk_device_type : false;
}

struct nd_region *to_nd_region(struct device *dev)
{
        struct nd_region *nd_region = container_of(dev, struct nd_region, dev);

        WARN_ON(dev->type->release != nd_region_release);
        return nd_region;
}
EXPORT_SYMBOL_GPL(to_nd_region);

struct nd_blk_region *to_nd_blk_region(struct device *dev)
{
        struct nd_region *nd_region = to_nd_region(dev);

        WARN_ON(!is_nd_blk(dev));
        return container_of(nd_region, struct nd_blk_region, nd_region);
}
EXPORT_SYMBOL_GPL(to_nd_blk_region);

void *nd_region_provider_data(struct nd_region *nd_region)
{
        return nd_region->provider_data;
}
EXPORT_SYMBOL_GPL(nd_region_provider_data);

void *nd_blk_region_provider_data(struct nd_blk_region *ndbr)
{
        return ndbr->blk_provider_data;
}
EXPORT_SYMBOL_GPL(nd_blk_region_provider_data);

void nd_blk_region_set_provider_data(struct nd_blk_region *ndbr, void *data)
{
        ndbr->blk_provider_data = data;
}
EXPORT_SYMBOL_GPL(nd_blk_region_set_provider_data);

/**
 * nd_region_to_nstype() - region to an integer namespace type
 * @nd_region: region-device to interrogate
 *
 * This is the 'nstype' attribute of a region as well, an input to the
 * MODALIAS for namespace devices, and bit number for a nvdimm_bus to match
 * namespace devices with namespace drivers.
 */
int nd_region_to_nstype(struct nd_region *nd_region)
{
        if (is_nd_pmem(&nd_region->dev)) {
                u16 i, alias;

                for (i = 0, alias = 0; i < nd_region->ndr_mappings; i++) {
                        struct nd_mapping *nd_mapping = &nd_region->mapping[i];
                        struct nvdimm *nvdimm = nd_mapping->nvdimm;

                        if (nvdimm->flags & NDD_ALIASING)
                                alias++;
                }
                if (alias)
                        return ND_DEVICE_NAMESPACE_PMEM;
                else
                        return ND_DEVICE_NAMESPACE_IO;
        } else if (is_nd_blk(&nd_region->dev)) {
                return ND_DEVICE_NAMESPACE_BLK;
        }

        return 0;
}
EXPORT_SYMBOL(nd_region_to_nstype);

static ssize_t size_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        unsigned long long size = 0;

        if (is_nd_pmem(dev)) {
                size = nd_region->ndr_size;
        } else if (nd_region->ndr_mappings == 1) {
                struct nd_mapping *nd_mapping = &nd_region->mapping[0];

                size = nd_mapping->size;
        }

        return sprintf(buf, "%llu\n", size);
}
static DEVICE_ATTR_RO(size);

static ssize_t mappings_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);

        return sprintf(buf, "%d\n", nd_region->ndr_mappings);
}
static DEVICE_ATTR_RO(mappings);

static ssize_t nstype_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);

        return sprintf(buf, "%d\n", nd_region_to_nstype(nd_region));
}
static DEVICE_ATTR_RO(nstype);

static ssize_t set_cookie_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        struct nd_interleave_set *nd_set = nd_region->nd_set;

        if (is_nd_pmem(dev) && nd_set)
                /* pass, should be precluded by region_visible */;
        else
                return -ENXIO;

        return sprintf(buf, "%#llx\n", nd_set->cookie);
}
static DEVICE_ATTR_RO(set_cookie);

resource_size_t nd_region_available_dpa(struct nd_region *nd_region)
{
        resource_size_t blk_max_overlap = 0, available, overlap;
        int i;

        WARN_ON(!is_nvdimm_bus_locked(&nd_region->dev));

 retry:
        available = 0;
        overlap = blk_max_overlap;
        for (i = 0; i < nd_region->ndr_mappings; i++) {
                struct nd_mapping *nd_mapping = &nd_region->mapping[i];
                struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);

                /* if a dimm is disabled the available capacity is zero */
                if (!ndd)
                        return 0;

                if (is_nd_pmem(&nd_region->dev)) {
                        available += nd_pmem_available_dpa(nd_region,
                                        nd_mapping, &overlap);
                        if (overlap > blk_max_overlap) {
                                blk_max_overlap = overlap;
                                goto retry;
                        }
                } else if (is_nd_blk(&nd_region->dev))
                        available += nd_blk_available_dpa(nd_region);
        }

        return available;
}

static ssize_t available_size_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        unsigned long long available = 0;

        /*
         * Flush in-flight updates and grab a snapshot of the available
         * size.  Of course, this value is potentially invalidated the
         * memory nvdimm_bus_lock() is dropped, but that's userspace's
         * problem to not race itself.
         */
        nvdimm_bus_lock(dev);
        wait_nvdimm_bus_probe_idle(dev);
        available = nd_region_available_dpa(nd_region);
        nvdimm_bus_unlock(dev);

        return sprintf(buf, "%llu\n", available);
}
static DEVICE_ATTR_RO(available_size);

static ssize_t init_namespaces_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region_data *ndrd = dev_get_drvdata(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        if (ndrd)
                rc = sprintf(buf, "%d/%d\n", ndrd->ns_active, ndrd->ns_count);
        else
                rc = -ENXIO;
        nvdimm_bus_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RO(init_namespaces);

static ssize_t namespace_seed_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        if (nd_region->ns_seed)
                rc = sprintf(buf, "%s\n", dev_name(nd_region->ns_seed));
        else
                rc = sprintf(buf, "\n");
        nvdimm_bus_unlock(dev);
        return rc;
}
static DEVICE_ATTR_RO(namespace_seed);

static ssize_t btt_seed_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        if (nd_region->btt_seed)
                rc = sprintf(buf, "%s\n", dev_name(nd_region->btt_seed));
        else
                rc = sprintf(buf, "\n");
        nvdimm_bus_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RO(btt_seed);

static ssize_t pfn_seed_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        if (nd_region->pfn_seed)
                rc = sprintf(buf, "%s\n", dev_name(nd_region->pfn_seed));
        else
                rc = sprintf(buf, "\n");
        nvdimm_bus_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RO(pfn_seed);

static ssize_t dax_seed_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        if (nd_region->dax_seed)
                rc = sprintf(buf, "%s\n", dev_name(nd_region->dax_seed));
        else
                rc = sprintf(buf, "\n");
        nvdimm_bus_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RO(dax_seed);

static ssize_t read_only_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_region *nd_region = to_nd_region(dev);

        return sprintf(buf, "%d\n", nd_region->ro);
}

static ssize_t read_only_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        bool ro;
        int rc = strtobool(buf, &ro);
        struct nd_region *nd_region = to_nd_region(dev);

        if (rc)
                return rc;

        nd_region->ro = ro;
        return len;
}
static DEVICE_ATTR_RW(read_only);

static struct attribute *nd_region_attributes[] = {
        &dev_attr_size.attr,
        &dev_attr_nstype.attr,
        &dev_attr_mappings.attr,
        &dev_attr_btt_seed.attr,
        &dev_attr_pfn_seed.attr,
        &dev_attr_dax_seed.attr,
        &dev_attr_read_only.attr,
        &dev_attr_set_cookie.attr,
        &dev_attr_available_size.attr,
        &dev_attr_namespace_seed.attr,
        &dev_attr_init_namespaces.attr,
        NULL,
};

static umode_t region_visible(struct kobject *kobj, struct attribute *a, int n)
{
        struct device *dev = container_of(kobj, typeof(*dev), kobj);
        struct nd_region *nd_region = to_nd_region(dev);
        struct nd_interleave_set *nd_set = nd_region->nd_set;
        int type = nd_region_to_nstype(nd_region);

        if (!is_nd_pmem(dev) && a == &dev_attr_pfn_seed.attr)
                return 0;

        if (!is_nd_pmem(dev) && a == &dev_attr_dax_seed.attr)
                return 0;

        if (a != &dev_attr_set_cookie.attr
                        && a != &dev_attr_available_size.attr)
                return a->mode;

        if ((type == ND_DEVICE_NAMESPACE_PMEM
                                || type == ND_DEVICE_NAMESPACE_BLK)
                        && a == &dev_attr_available_size.attr)
                return a->mode;
        else if (is_nd_pmem(dev) && nd_set)
                return a->mode;

        return 0;
}

struct attribute_group nd_region_attribute_group = {
        .attrs = nd_region_attributes,
        .is_visible = region_visible,
};
EXPORT_SYMBOL_GPL(nd_region_attribute_group);

u64 nd_region_interleave_set_cookie(struct nd_region *nd_region)
{
        struct nd_interleave_set *nd_set = nd_region->nd_set;

        if (nd_set)
                return nd_set->cookie;
        return 0;
}

void nd_mapping_free_labels(struct nd_mapping *nd_mapping)
{
        struct nd_label_ent *label_ent, *e;

        lockdep_assert_held(&nd_mapping->lock);
        list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
                list_del(&label_ent->list);
                kfree(label_ent);
        }
}

/*
 * Upon successful probe/remove, take/release a reference on the
 * associated interleave set (if present), and plant new btt + namespace
 * seeds.  Also, on the removal of a BLK region, notify the provider to
 * disable the region.
 */
static void nd_region_notify_driver_action(struct nvdimm_bus *nvdimm_bus,
                struct device *dev, bool probe)
{
        struct nd_region *nd_region;

        if (!probe && (is_nd_pmem(dev) || is_nd_blk(dev))) {
                int i;

                nd_region = to_nd_region(dev);
                for (i = 0; i < nd_region->ndr_mappings; i++) {
                        struct nd_mapping *nd_mapping = &nd_region->mapping[i];
                        struct nvdimm_drvdata *ndd = nd_mapping->ndd;
                        struct nvdimm *nvdimm = nd_mapping->nvdimm;

                        mutex_lock(&nd_mapping->lock);
                        nd_mapping_free_labels(nd_mapping);
                        mutex_unlock(&nd_mapping->lock);

                        put_ndd(ndd);
                        nd_mapping->ndd = NULL;
                        if (ndd)
                                atomic_dec(&nvdimm->busy);
                }

                if (is_nd_pmem(dev))
                        return;
        }
        if (dev->parent && (is_nd_blk(dev->parent) || is_nd_pmem(dev->parent))
                        && probe) {
                nd_region = to_nd_region(dev->parent);
                nvdimm_bus_lock(dev);
                if (nd_region->ns_seed == dev)
                        nd_region_create_ns_seed(nd_region);
                nvdimm_bus_unlock(dev);
        }
        if (is_nd_btt(dev) && probe) {
                struct nd_btt *nd_btt = to_nd_btt(dev);

                nd_region = to_nd_region(dev->parent);
                nvdimm_bus_lock(dev);
                if (nd_region->btt_seed == dev)
                        nd_region_create_btt_seed(nd_region);
                if (nd_region->ns_seed == &nd_btt->ndns->dev)
                        nd_region_create_ns_seed(nd_region);
                nvdimm_bus_unlock(dev);
        }
        if (is_nd_pfn(dev) && probe) {
                struct nd_pfn *nd_pfn = to_nd_pfn(dev);

                nd_region = to_nd_region(dev->parent);
                nvdimm_bus_lock(dev);
                if (nd_region->pfn_seed == dev)
                        nd_region_create_pfn_seed(nd_region);
                if (nd_region->ns_seed == &nd_pfn->ndns->dev)
                        nd_region_create_ns_seed(nd_region);
                nvdimm_bus_unlock(dev);
        }
        if (is_nd_dax(dev) && probe) {
                struct nd_dax *nd_dax = to_nd_dax(dev);

                nd_region = to_nd_region(dev->parent);
                nvdimm_bus_lock(dev);
                if (nd_region->dax_seed == dev)
                        nd_region_create_dax_seed(nd_region);
                if (nd_region->ns_seed == &nd_dax->nd_pfn.ndns->dev)
                        nd_region_create_ns_seed(nd_region);
                nvdimm_bus_unlock(dev);
        }
}

void nd_region_probe_success(struct nvdimm_bus *nvdimm_bus, struct device *dev)
{
        nd_region_notify_driver_action(nvdimm_bus, dev, true);
}

void nd_region_disable(struct nvdimm_bus *nvdimm_bus, struct device *dev)
{
        nd_region_notify_driver_action(nvdimm_bus, dev, false);
}

static ssize_t mappingN(struct device *dev, char *buf, int n)
{
        struct nd_region *nd_region = to_nd_region(dev);
        struct nd_mapping *nd_mapping;
        struct nvdimm *nvdimm;

        if (n >= nd_region->ndr_mappings)
                return -ENXIO;
        nd_mapping = &nd_region->mapping[n];
        nvdimm = nd_mapping->nvdimm;

        return sprintf(buf, "%s,%llu,%llu\n", dev_name(&nvdimm->dev),
                        nd_mapping->start, nd_mapping->size);
}

#define REGION_MAPPING(idx) \
static ssize_t mapping##idx##_show(struct device *dev,          \
                struct device_attribute *attr, char *buf)       \
{                                                               \
        return mappingN(dev, buf, idx);                         \
}                                                               \
static DEVICE_ATTR_RO(mapping##idx)

/*
 * 32 should be enough for a while, even in the presence of socket
 * interleave a 32-way interleave set is a degenerate case.
 */
REGION_MAPPING(0);
REGION_MAPPING(1);
REGION_MAPPING(2);
REGION_MAPPING(3);
REGION_MAPPING(4);
REGION_MAPPING(5);
REGION_MAPPING(6);
REGION_MAPPING(7);
REGION_MAPPING(8);
REGION_MAPPING(9);
REGION_MAPPING(10);
REGION_MAPPING(11);
REGION_MAPPING(12);
REGION_MAPPING(13);
REGION_MAPPING(14);
REGION_MAPPING(15);
REGION_MAPPING(16);
REGION_MAPPING(17);
REGION_MAPPING(18);
REGION_MAPPING(19);
REGION_MAPPING(20);
REGION_MAPPING(21);
REGION_MAPPING(22);
REGION_MAPPING(23);
REGION_MAPPING(24);
REGION_MAPPING(25);
REGION_MAPPING(26);
REGION_MAPPING(27);
REGION_MAPPING(28);
REGION_MAPPING(29);
REGION_MAPPING(30);
REGION_MAPPING(31);

static umode_t mapping_visible(struct kobject *kobj, struct attribute *a, int n)
{
        struct device *dev = container_of(kobj, struct device, kobj);
        struct nd_region *nd_region = to_nd_region(dev);

        if (n < nd_region->ndr_mappings)
                return a->mode;
        return 0;
}

static struct attribute *mapping_attributes[] = {
        &dev_attr_mapping0.attr,
        &dev_attr_mapping1.attr,
        &dev_attr_mapping2.attr,
        &dev_attr_mapping3.attr,
        &dev_attr_mapping4.attr,
        &dev_attr_mapping5.attr,
        &dev_attr_mapping6.attr,
        &dev_attr_mapping7.attr,
        &dev_attr_mapping8.attr,
        &dev_attr_mapping9.attr,
        &dev_attr_mapping10.attr,
        &dev_attr_mapping11.attr,
        &dev_attr_mapping12.attr,
        &dev_attr_mapping13.attr,
        &dev_attr_mapping14.attr,
        &dev_attr_mapping15.attr,
        &dev_attr_mapping16.attr,
        &dev_attr_mapping17.attr,
        &dev_attr_mapping18.attr,
        &dev_attr_mapping19.attr,
        &dev_attr_mapping20.attr,
        &dev_attr_mapping21.attr,
        &dev_attr_mapping22.attr,
        &dev_attr_mapping23.attr,
        &dev_attr_mapping24.attr,
        &dev_attr_mapping25.attr,
        &dev_attr_mapping26.attr,
        &dev_attr_mapping27.attr,
        &dev_attr_mapping28.attr,
        &dev_attr_mapping29.attr,
        &dev_attr_mapping30.attr,
        &dev_attr_mapping31.attr,
        NULL,
};

struct attribute_group nd_mapping_attribute_group = {
        .is_visible = mapping_visible,
        .attrs = mapping_attributes,
};
EXPORT_SYMBOL_GPL(nd_mapping_attribute_group);

int nd_blk_region_init(struct nd_region *nd_region)
{
        struct device *dev = &nd_region->dev;
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);

        if (!is_nd_blk(dev))
                return 0;

        if (nd_region->ndr_mappings < 1) {
                dev_err(dev, "invalid BLK region\n");
                return -ENXIO;
        }

        return to_nd_blk_region(dev)->enable(nvdimm_bus, dev);
}

/**
 * nd_region_acquire_lane - allocate and lock a lane
 * @nd_region: region id and number of lanes possible
 *
 * A lane correlates to a BLK-data-window and/or a log slot in the BTT.
 * We optimize for the common case where there are 256 lanes, one
 * per-cpu.  For larger systems we need to lock to share lanes.  For now
 * this implementation assumes the cost of maintaining an allocator for
 * free lanes is on the order of the lock hold time, so it implements a
 * static lane = cpu % num_lanes mapping.
 *
 * In the case of a BTT instance on top of a BLK namespace a lane may be
 * acquired recursively.  We lock on the first instance.
 *
 * In the case of a BTT instance on top of PMEM, we only acquire a lane
 * for the BTT metadata updates.
 */
unsigned int nd_region_acquire_lane(struct nd_region *nd_region)
{
        unsigned int cpu, lane;

        cpu = get_cpu();
        if (nd_region->num_lanes < nr_cpu_ids) {
                struct nd_percpu_lane *ndl_lock, *ndl_count;

                lane = cpu % nd_region->num_lanes;
                ndl_count = per_cpu_ptr(nd_region->lane, cpu);
                ndl_lock = per_cpu_ptr(nd_region->lane, lane);
                if (ndl_count->count++ == 0)
                        spin_lock(&ndl_lock->lock);
        } else
                lane = cpu;

        return lane;
}
EXPORT_SYMBOL(nd_region_acquire_lane);

void nd_region_release_lane(struct nd_region *nd_region, unsigned int lane)
{
        if (nd_region->num_lanes < nr_cpu_ids) {
                unsigned int cpu = get_cpu();
                struct nd_percpu_lane *ndl_lock, *ndl_count;

                ndl_count = per_cpu_ptr(nd_region->lane, cpu);
                ndl_lock = per_cpu_ptr(nd_region->lane, lane);
                if (--ndl_count->count == 0)
                        spin_unlock(&ndl_lock->lock);
                put_cpu();
        }
        put_cpu();
}
EXPORT_SYMBOL(nd_region_release_lane);

static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
                struct nd_region_desc *ndr_desc, struct device_type *dev_type,
                const char *caller)
{
        struct nd_region *nd_region;
        struct device *dev;
        void *region_buf;
        unsigned int i;
        int ro = 0;

        for (i = 0; i < ndr_desc->num_mappings; i++) {
                struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
                struct nvdimm *nvdimm = mapping->nvdimm;

                if ((mapping->start | mapping->size) % SZ_4K) {
                        dev_err(&nvdimm_bus->dev, "%s: %s mapping%d is not 4K aligned\n",
                                        caller, dev_name(&nvdimm->dev), i);

                        return NULL;
                }

                if (nvdimm->flags & NDD_UNARMED)
                        ro = 1;
        }

        if (dev_type == &nd_blk_device_type) {
                struct nd_blk_region_desc *ndbr_desc;
                struct nd_blk_region *ndbr;

                ndbr_desc = to_blk_region_desc(ndr_desc);
                ndbr = kzalloc(sizeof(*ndbr) + sizeof(struct nd_mapping)
                                * ndr_desc->num_mappings,
                                GFP_KERNEL);
                if (ndbr) {
                        nd_region = &ndbr->nd_region;
                        ndbr->enable = ndbr_desc->enable;
                        ndbr->do_io = ndbr_desc->do_io;
                }
                region_buf = ndbr;
        } else {
                nd_region = kzalloc(sizeof(struct nd_region)
                                + sizeof(struct nd_mapping)
                                * ndr_desc->num_mappings,
                                GFP_KERNEL);
                region_buf = nd_region;
        }

        if (!region_buf)
                return NULL;
        nd_region->id = ida_simple_get(&region_ida, 0, 0, GFP_KERNEL);
        if (nd_region->id < 0)
                goto err_id;

        nd_region->lane = alloc_percpu(struct nd_percpu_lane);
        if (!nd_region->lane)
                goto err_percpu;

        for (i = 0; i < nr_cpu_ids; i++) {
                struct nd_percpu_lane *ndl;

                ndl = per_cpu_ptr(nd_region->lane, i);
                spin_lock_init(&ndl->lock);
                ndl->count = 0;
        }

        for (i = 0; i < ndr_desc->num_mappings; i++) {
                struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
                struct nvdimm *nvdimm = mapping->nvdimm;

                nd_region->mapping[i].nvdimm = nvdimm;
                nd_region->mapping[i].start = mapping->start;
                nd_region->mapping[i].size = mapping->size;
                INIT_LIST_HEAD(&nd_region->mapping[i].labels);
                mutex_init(&nd_region->mapping[i].lock);

                get_device(&nvdimm->dev);
        }
        nd_region->ndr_mappings = ndr_desc->num_mappings;
        nd_region->provider_data = ndr_desc->provider_data;
        nd_region->nd_set = ndr_desc->nd_set;
        nd_region->num_lanes = ndr_desc->num_lanes;
        nd_region->flags = ndr_desc->flags;
        nd_region->ro = ro;
        nd_region->numa_node = ndr_desc->numa_node;
        ida_init(&nd_region->ns_ida);
        ida_init(&nd_region->btt_ida);
        ida_init(&nd_region->pfn_ida);
        ida_init(&nd_region->dax_ida);
        dev = &nd_region->dev;
        dev_set_name(dev, "region%d", nd_region->id);
        dev->parent = &nvdimm_bus->dev;
        dev->type = dev_type;
        dev->groups = ndr_desc->attr_groups;
        nd_region->ndr_size = resource_size(ndr_desc->res);
        nd_region->ndr_start = ndr_desc->res->start;
        nd_device_register(dev);

        return nd_region;

 err_percpu:
        ida_simple_remove(&region_ida, nd_region->id);
 err_id:
        kfree(region_buf);
        return NULL;
}

struct nd_region *nvdimm_pmem_region_create(struct nvdimm_bus *nvdimm_bus,
                struct nd_region_desc *ndr_desc)
{
        ndr_desc->num_lanes = ND_MAX_LANES;
        return nd_region_create(nvdimm_bus, ndr_desc, &nd_pmem_device_type,
                        __func__);
}
EXPORT_SYMBOL_GPL(nvdimm_pmem_region_create);

struct nd_region *nvdimm_blk_region_create(struct nvdimm_bus *nvdimm_bus,
                struct nd_region_desc *ndr_desc)
{
        if (ndr_desc->num_mappings > 1)
                return NULL;
        ndr_desc->num_lanes = min(ndr_desc->num_lanes, ND_MAX_LANES);
        return nd_region_create(nvdimm_bus, ndr_desc, &nd_blk_device_type,
                        __func__);
}
EXPORT_SYMBOL_GPL(nvdimm_blk_region_create);

struct nd_region *nvdimm_volatile_region_create(struct nvdimm_bus *nvdimm_bus,
                struct nd_region_desc *ndr_desc)
{
        ndr_desc->num_lanes = ND_MAX_LANES;
        return nd_region_create(nvdimm_bus, ndr_desc, &nd_volatile_device_type,
                        __func__);
}
EXPORT_SYMBOL_GPL(nvdimm_volatile_region_create);

/**
 * nvdimm_flush - flush any posted write queues between the cpu and pmem media
 * @nd_region: blk or interleaved pmem region
 */
void nvdimm_flush(struct nd_region *nd_region)
{
        struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev);
        int i, idx;

        /*
         * Try to encourage some diversity in flush hint addresses
         * across cpus assuming a limited number of flush hints.
         */
        idx = this_cpu_read(flush_idx);
        idx = this_cpu_add_return(flush_idx, hash_32(current->pid + idx, 8));

        /*
         * The first wmb() is needed to 'sfence' all previous writes
         * such that they are architecturally visible for the platform
         * buffer flush.  Note that we've already arranged for pmem
         * writes to avoid the cache via arch_memcpy_to_pmem().  The
         * final wmb() ensures ordering for the NVDIMM flush write.
         */
        wmb();
        for (i = 0; i < nd_region->ndr_mappings; i++)
                if (ndrd_get_flush_wpq(ndrd, i, 0))
                        writeq(1, ndrd_get_flush_wpq(ndrd, i, idx));
        wmb();
}
EXPORT_SYMBOL_GPL(nvdimm_flush);

/**
 * nvdimm_has_flush - determine write flushing requirements
 * @nd_region: blk or interleaved pmem region
 *
 * Returns 1 if writes require flushing
 * Returns 0 if writes do not require flushing
 * Returns -ENXIO if flushing capability can not be determined
 */
int nvdimm_has_flush(struct nd_region *nd_region)
{
        struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev);
        int i;

        /* no nvdimm == flushing capability unknown */
        if (nd_region->ndr_mappings == 0)
                return -ENXIO;

        for (i = 0; i < nd_region->ndr_mappings; i++)
                /* flush hints present, flushing required */
                if (ndrd_get_flush_wpq(ndrd, i, 0))
                        return 1;

        /*
         * The platform defines dimm devices without hints, assume
         * platform persistence mechanism like ADR
         */
        return 0;
}
EXPORT_SYMBOL_GPL(nvdimm_has_flush);

void __exit nd_region_devs_exit(void)
{
        ida_destroy(&region_ida);
}