/*
 * 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/device.h>
#include <linux/ndctl.h>
#include <linux/uuid.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/nd.h>
#include "nd-core.h"
#include "label.h"
#include "nd.h"

static guid_t nvdimm_btt_guid;
static guid_t nvdimm_btt2_guid;
static guid_t nvdimm_pfn_guid;
static guid_t nvdimm_dax_guid;

static u32 best_seq(u32 a, u32 b)
{
        a &= NSINDEX_SEQ_MASK;
        b &= NSINDEX_SEQ_MASK;

        if (a == 0 || a == b)
                return b;
        else if (b == 0)
                return a;
        else if (nd_inc_seq(a) == b)
                return b;
        else
                return a;
}

unsigned sizeof_namespace_label(struct nvdimm_drvdata *ndd)
{
        return ndd->nslabel_size;
}

static size_t __sizeof_namespace_index(u32 nslot)
{
        return ALIGN(sizeof(struct nd_namespace_index) + DIV_ROUND_UP(nslot, 8),
                        NSINDEX_ALIGN);
}

static int __nvdimm_num_label_slots(struct nvdimm_drvdata *ndd,
                size_t index_size)
{
        return (ndd->nsarea.config_size - index_size * 2) /
                        sizeof_namespace_label(ndd);
}

int nvdimm_num_label_slots(struct nvdimm_drvdata *ndd)
{
        u32 tmp_nslot, n;

        tmp_nslot = ndd->nsarea.config_size / sizeof_namespace_label(ndd);
        n = __sizeof_namespace_index(tmp_nslot) / NSINDEX_ALIGN;

        return __nvdimm_num_label_slots(ndd, NSINDEX_ALIGN * n);
}

size_t sizeof_namespace_index(struct nvdimm_drvdata *ndd)
{
        u32 nslot, space, size;

        /*
         * Per UEFI 2.7, the minimum size of the Label Storage Area is large
         * enough to hold 2 index blocks and 2 labels.  The minimum index
         * block size is 256 bytes. The label size is 128 for namespaces
         * prior to version 1.2 and at minimum 256 for version 1.2 and later.
         */
        nslot = nvdimm_num_label_slots(ndd);
        space = ndd->nsarea.config_size - nslot * sizeof_namespace_label(ndd);
        size = __sizeof_namespace_index(nslot) * 2;
        if (size <= space && nslot >= 2)
                return size / 2;

        dev_err(ndd->dev, "label area (%d) too small to host (%d byte) labels\n",
                        ndd->nsarea.config_size, sizeof_namespace_label(ndd));
        return 0;
}

static int __nd_label_validate(struct nvdimm_drvdata *ndd)
{
        /*
         * On media label format consists of two index blocks followed
         * by an array of labels.  None of these structures are ever
         * updated in place.  A sequence number tracks the current
         * active index and the next one to write, while labels are
         * written to free slots.
         *
         *     +------------+
         *     |            |
         *     |  nsindex0  |
         *     |            |
         *     +------------+
         *     |            |
         *     |  nsindex1  |
         *     |            |
         *     +------------+
         *     |   label0   |
         *     +------------+
         *     |   label1   |
         *     +------------+
         *     |            |
         *      ....nslot...
         *     |            |
         *     +------------+
         *     |   labelN   |
         *     +------------+
         */
        struct nd_namespace_index *nsindex[] = {
                to_namespace_index(ndd, 0),
                to_namespace_index(ndd, 1),
        };
        const int num_index = ARRAY_SIZE(nsindex);
        struct device *dev = ndd->dev;
        bool valid[2] = { 0 };
        int i, num_valid = 0;
        u32 seq;

        for (i = 0; i < num_index; i++) {
                u32 nslot;
                u8 sig[NSINDEX_SIG_LEN];
                u64 sum_save, sum, size;
                unsigned int version, labelsize;

                memcpy(sig, nsindex[i]->sig, NSINDEX_SIG_LEN);
                if (memcmp(sig, NSINDEX_SIGNATURE, NSINDEX_SIG_LEN) != 0) {
                        dev_dbg(dev, "nsindex%d signature invalid\n", i);
                        continue;
                }

                /* label sizes larger than 128 arrived with v1.2 */
                version = __le16_to_cpu(nsindex[i]->major) * 100
                        + __le16_to_cpu(nsindex[i]->minor);
                if (version >= 102)
                        labelsize = 1 << (7 + nsindex[i]->labelsize);
                else
                        labelsize = 128;

                if (labelsize != sizeof_namespace_label(ndd)) {
                        dev_dbg(dev, "nsindex%d labelsize %d invalid\n",
                                        i, nsindex[i]->labelsize);
                        continue;
                }

                sum_save = __le64_to_cpu(nsindex[i]->checksum);
                nsindex[i]->checksum = __cpu_to_le64(0);
                sum = nd_fletcher64(nsindex[i], sizeof_namespace_index(ndd), 1);
                nsindex[i]->checksum = __cpu_to_le64(sum_save);
                if (sum != sum_save) {
                        dev_dbg(dev, "nsindex%d checksum invalid\n", i);
                        continue;
                }

                seq = __le32_to_cpu(nsindex[i]->seq);
                if ((seq & NSINDEX_SEQ_MASK) == 0) {
                        dev_dbg(dev, "nsindex%d sequence: %#x invalid\n", i, seq);
                        continue;
                }

                /* sanity check the index against expected values */
                if (__le64_to_cpu(nsindex[i]->myoff)
                                != i * sizeof_namespace_index(ndd)) {
                        dev_dbg(dev, "nsindex%d myoff: %#llx invalid\n",
                                        i, (unsigned long long)
                                        __le64_to_cpu(nsindex[i]->myoff));
                        continue;
                }
                if (__le64_to_cpu(nsindex[i]->otheroff)
                                != (!i) * sizeof_namespace_index(ndd)) {
                        dev_dbg(dev, "nsindex%d otheroff: %#llx invalid\n",
                                        i, (unsigned long long)
                                        __le64_to_cpu(nsindex[i]->otheroff));
                        continue;
                }
                if (__le64_to_cpu(nsindex[i]->labeloff)
                                != 2 * sizeof_namespace_index(ndd)) {
                        dev_dbg(dev, "nsindex%d labeloff: %#llx invalid\n",
                                        i, (unsigned long long)
                                        __le64_to_cpu(nsindex[i]->labeloff));
                        continue;
                }

                size = __le64_to_cpu(nsindex[i]->mysize);
                if (size > sizeof_namespace_index(ndd)
                                || size < sizeof(struct nd_namespace_index)) {
                        dev_dbg(dev, "nsindex%d mysize: %#llx invalid\n", i, size);
                        continue;
                }

                nslot = __le32_to_cpu(nsindex[i]->nslot);
                if (nslot * sizeof_namespace_label(ndd)
                                + 2 * sizeof_namespace_index(ndd)
                                > ndd->nsarea.config_size) {
                        dev_dbg(dev, "nsindex%d nslot: %u invalid, config_size: %#x\n",
                                        i, nslot, ndd->nsarea.config_size);
                        continue;
                }
                valid[i] = true;
                num_valid++;
        }

        switch (num_valid) {
        case 0:
                break;
        case 1:
                for (i = 0; i < num_index; i++)
                        if (valid[i])
                                return i;
                /* can't have num_valid > 0 but valid[] = { false, false } */
                WARN_ON(1);
                break;
        default:
                /* pick the best index... */
                seq = best_seq(__le32_to_cpu(nsindex[0]->seq),
                                __le32_to_cpu(nsindex[1]->seq));
                if (seq == (__le32_to_cpu(nsindex[1]->seq) & NSINDEX_SEQ_MASK))
                        return 1;
                else
                        return 0;
                break;
        }

        return -1;
}

static int nd_label_validate(struct nvdimm_drvdata *ndd)
{
        /*
         * In order to probe for and validate namespace index blocks we
         * need to know the size of the labels, and we can't trust the
         * size of the labels until we validate the index blocks.
         * Resolve this dependency loop by probing for known label
         * sizes, but default to v1.2 256-byte namespace labels if
         * discovery fails.
         */
        int label_size[] = { 128, 256 };
        int i, rc;

        for (i = 0; i < ARRAY_SIZE(label_size); i++) {
                ndd->nslabel_size = label_size[i];
                rc = __nd_label_validate(ndd);
                if (rc >= 0)
                        return rc;
        }

        return -1;
}

static void nd_label_copy(struct nvdimm_drvdata *ndd,
                          struct nd_namespace_index *dst,
                          struct nd_namespace_index *src)
{
        /* just exit if either destination or source is NULL */
        if (!dst || !src)
                return;

        memcpy(dst, src, sizeof_namespace_index(ndd));
}

static struct nd_namespace_label *nd_label_base(struct nvdimm_drvdata *ndd)
{
        void *base = to_namespace_index(ndd, 0);

        return base + 2 * sizeof_namespace_index(ndd);
}

static int to_slot(struct nvdimm_drvdata *ndd,
                struct nd_namespace_label *nd_label)
{
        unsigned long label, base;

        label = (unsigned long) nd_label;
        base = (unsigned long) nd_label_base(ndd);

        return (label - base) / sizeof_namespace_label(ndd);
}

static struct nd_namespace_label *to_label(struct nvdimm_drvdata *ndd, int slot)
{
        unsigned long label, base;

        base = (unsigned long) nd_label_base(ndd);
        label = base + sizeof_namespace_label(ndd) * slot;

        return (struct nd_namespace_label *) label;
}

#define for_each_clear_bit_le(bit, addr, size) \
        for ((bit) = find_next_zero_bit_le((addr), (size), 0);  \
             (bit) < (size);                                    \
             (bit) = find_next_zero_bit_le((addr), (size), (bit) + 1))

/**
 * preamble_index - common variable initialization for nd_label_* routines
 * @ndd: dimm container for the relevant label set
 * @idx: namespace_index index
 * @nsindex_out: on return set to the currently active namespace index
 * @free: on return set to the free label bitmap in the index
 * @nslot: on return set to the number of slots in the label space
 */
static bool preamble_index(struct nvdimm_drvdata *ndd, int idx,
                struct nd_namespace_index **nsindex_out,
                unsigned long **free, u32 *nslot)
{
        struct nd_namespace_index *nsindex;

        nsindex = to_namespace_index(ndd, idx);
        if (nsindex == NULL)
                return false;

        *free = (unsigned long *) nsindex->free;
        *nslot = __le32_to_cpu(nsindex->nslot);
        *nsindex_out = nsindex;

        return true;
}

char *nd_label_gen_id(struct nd_label_id *label_id, u8 *uuid, u32 flags)
{
        if (!label_id || !uuid)
                return NULL;
        snprintf(label_id->id, ND_LABEL_ID_SIZE, "%s-%pUb",
                        flags & NSLABEL_FLAG_LOCAL ? "blk" : "pmem", uuid);
        return label_id->id;
}

static bool preamble_current(struct nvdimm_drvdata *ndd,
                struct nd_namespace_index **nsindex,
                unsigned long **free, u32 *nslot)
{
        return preamble_index(ndd, ndd->ns_current, nsindex,
                        free, nslot);
}

static bool preamble_next(struct nvdimm_drvdata *ndd,
                struct nd_namespace_index **nsindex,
                unsigned long **free, u32 *nslot)
{
        return preamble_index(ndd, ndd->ns_next, nsindex,
                        free, nslot);
}

static bool slot_valid(struct nvdimm_drvdata *ndd,
                struct nd_namespace_label *nd_label, u32 slot)
{
        /* check that we are written where we expect to be written */
        if (slot != __le32_to_cpu(nd_label->slot))
                return false;

        /* check that DPA allocations are page aligned */
        if ((__le64_to_cpu(nd_label->dpa)
                                | __le64_to_cpu(nd_label->rawsize)) % SZ_4K)
                return false;

        /* check checksum */
        if (namespace_label_has(ndd, checksum)) {
                u64 sum, sum_save;

                sum_save = __le64_to_cpu(nd_label->checksum);
                nd_label->checksum = __cpu_to_le64(0);
                sum = nd_fletcher64(nd_label, sizeof_namespace_label(ndd), 1);
                nd_label->checksum = __cpu_to_le64(sum_save);
                if (sum != sum_save) {
                        dev_dbg(ndd->dev, "fail checksum. slot: %d expect: %#llx\n",
                                slot, sum);
                        return false;
                }
        }

        return true;
}

int nd_label_reserve_dpa(struct nvdimm_drvdata *ndd)
{
        struct nd_namespace_index *nsindex;
        unsigned long *free;
        u32 nslot, slot;

        if (!preamble_current(ndd, &nsindex, &free, &nslot))
                return 0; /* no label, nothing to reserve */

        for_each_clear_bit_le(slot, free, nslot) {
                struct nd_namespace_label *nd_label;
                struct nd_region *nd_region = NULL;
                u8 label_uuid[NSLABEL_UUID_LEN];
                struct nd_label_id label_id;
                struct resource *res;
                u32 flags;

                nd_label = to_label(ndd, slot);

                if (!slot_valid(ndd, nd_label, slot))
                        continue;

                memcpy(label_uuid, nd_label->uuid, NSLABEL_UUID_LEN);
                flags = __le32_to_cpu(nd_label->flags);
                nd_label_gen_id(&label_id, label_uuid, flags);
                res = nvdimm_allocate_dpa(ndd, &label_id,
                                __le64_to_cpu(nd_label->dpa),
                                __le64_to_cpu(nd_label->rawsize));
                nd_dbg_dpa(nd_region, ndd, res, "reserve\n");
                if (!res)
                        return -EBUSY;
        }

        return 0;
}

int nd_label_data_init(struct nvdimm_drvdata *ndd)
{
        size_t config_size, read_size, max_xfer, offset;
        struct nd_namespace_index *nsindex;
        unsigned int i;
        int rc = 0;
        u32 nslot;

        if (ndd->data)
                return 0;

        if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0) {
                dev_dbg(ndd->dev, "failed to init config data area: (%u:%u)\n",
                        ndd->nsarea.max_xfer, ndd->nsarea.config_size);
                return -ENXIO;
        }

        /*
         * We need to determine the maximum index area as this is the section
         * we must read and validate before we can start processing labels.
         *
         * If the area is too small to contain the two indexes and 2 labels
         * then we abort.
         *
         * Start at a label size of 128 as this should result in the largest
         * possible namespace index size.
         */
        ndd->nslabel_size = 128;
        read_size = sizeof_namespace_index(ndd) * 2;
        if (!read_size)
                return -ENXIO;

        /* Allocate config data */
        config_size = ndd->nsarea.config_size;
        ndd->data = kvzalloc(config_size, GFP_KERNEL);
        if (!ndd->data)
                return -ENOMEM;

        /*
         * We want to guarantee as few reads as possible while conserving
         * memory. To do that we figure out how much unused space will be left
         * in the last read, divide that by the total number of reads it is
         * going to take given our maximum transfer size, and then reduce our
         * maximum transfer size based on that result.
         */
        max_xfer = min_t(size_t, ndd->nsarea.max_xfer, config_size);
        if (read_size < max_xfer) {
                /* trim waste */
                max_xfer -= ((max_xfer - 1) - (config_size - 1) % max_xfer) /
                            DIV_ROUND_UP(config_size, max_xfer);
                /* make certain we read indexes in exactly 1 read */
                if (max_xfer < read_size)
                        max_xfer = read_size;
        }

        /* Make our initial read size a multiple of max_xfer size */
        read_size = min(DIV_ROUND_UP(read_size, max_xfer) * max_xfer,
                        config_size);

        /* Read the index data */
        rc = nvdimm_get_config_data(ndd, ndd->data, 0, read_size);
        if (rc)
                goto out_err;

        /* Validate index data, if not valid assume all labels are invalid */
        ndd->ns_current = nd_label_validate(ndd);
        if (ndd->ns_current < 0)
                return 0;

        /* Record our index values */
        ndd->ns_next = nd_label_next_nsindex(ndd->ns_current);

        /* Copy "current" index on top of the "next" index */
        nsindex = to_current_namespace_index(ndd);
        nd_label_copy(ndd, to_next_namespace_index(ndd), nsindex);

        /* Determine starting offset for label data */
        offset = __le64_to_cpu(nsindex->labeloff);
        nslot = __le32_to_cpu(nsindex->nslot);

        /* Loop through the free list pulling in any active labels */
        for (i = 0; i < nslot; i++, offset += ndd->nslabel_size) {
                size_t label_read_size;

                /* zero out the unused labels */
                if (test_bit_le(i, nsindex->free)) {
                        memset(ndd->data + offset, 0, ndd->nslabel_size);
                        continue;
                }

                /* if we already read past here then just continue */
                if (offset + ndd->nslabel_size <= read_size)
                        continue;

                /* if we haven't read in a while reset our read_size offset */
                if (read_size < offset)
                        read_size = offset;

                /* determine how much more will be read after this next call. */
                label_read_size = offset + ndd->nslabel_size - read_size;
                label_read_size = DIV_ROUND_UP(label_read_size, max_xfer) *
                                  max_xfer;

                /* truncate last read if needed */
                if (read_size + label_read_size > config_size)
                        label_read_size = config_size - read_size;

                /* Read the label data */
                rc = nvdimm_get_config_data(ndd, ndd->data + read_size,
                                            read_size, label_read_size);
                if (rc)
                        goto out_err;

                /* push read_size to next read offset */
                read_size += label_read_size;
        }

        dev_dbg(ndd->dev, "len: %zu rc: %d\n", offset, rc);
out_err:
        return rc;
}

int nd_label_active_count(struct nvdimm_drvdata *ndd)
{
        struct nd_namespace_index *nsindex;
        unsigned long *free;
        u32 nslot, slot;
        int count = 0;

        if (!preamble_current(ndd, &nsindex, &free, &nslot))
                return 0;

        for_each_clear_bit_le(slot, free, nslot) {
                struct nd_namespace_label *nd_label;

                nd_label = to_label(ndd, slot);

                if (!slot_valid(ndd, nd_label, slot)) {
                        u32 label_slot = __le32_to_cpu(nd_label->slot);
                        u64 size = __le64_to_cpu(nd_label->rawsize);
                        u64 dpa = __le64_to_cpu(nd_label->dpa);

                        dev_dbg(ndd->dev,
                                "slot%d invalid slot: %d dpa: %llx size: %llx\n",
                                        slot, label_slot, dpa, size);
                        continue;
                }
                count++;
        }
        return count;
}

struct nd_namespace_label *nd_label_active(struct nvdimm_drvdata *ndd, int n)
{
        struct nd_namespace_index *nsindex;
        unsigned long *free;
        u32 nslot, slot;

        if (!preamble_current(ndd, &nsindex, &free, &nslot))
                return NULL;

        for_each_clear_bit_le(slot, free, nslot) {
                struct nd_namespace_label *nd_label;

                nd_label = to_label(ndd, slot);
                if (!slot_valid(ndd, nd_label, slot))
                        continue;

                if (n-- == 0)
                        return to_label(ndd, slot);
        }

        return NULL;
}

u32 nd_label_alloc_slot(struct nvdimm_drvdata *ndd)
{
        struct nd_namespace_index *nsindex;
        unsigned long *free;
        u32 nslot, slot;

        if (!preamble_next(ndd, &nsindex, &free, &nslot))
                return UINT_MAX;

        WARN_ON(!is_nvdimm_bus_locked(ndd->dev));

        slot = find_next_bit_le(free, nslot, 0);
        if (slot == nslot)
                return UINT_MAX;

        clear_bit_le(slot, free);

        return slot;
}

bool nd_label_free_slot(struct nvdimm_drvdata *ndd, u32 slot)
{
        struct nd_namespace_index *nsindex;
        unsigned long *free;
        u32 nslot;

        if (!preamble_next(ndd, &nsindex, &free, &nslot))
                return false;

        WARN_ON(!is_nvdimm_bus_locked(ndd->dev));

        if (slot < nslot)
                return !test_and_set_bit_le(slot, free);
        return false;
}

u32 nd_label_nfree(struct nvdimm_drvdata *ndd)
{
        struct nd_namespace_index *nsindex;
        unsigned long *free;
        u32 nslot;

        WARN_ON(!is_nvdimm_bus_locked(ndd->dev));

        if (!preamble_next(ndd, &nsindex, &free, &nslot))
                return nvdimm_num_label_slots(ndd);

        return bitmap_weight(free, nslot);
}

static int nd_label_write_index(struct nvdimm_drvdata *ndd, int index, u32 seq,
                unsigned long flags)
{
        struct nd_namespace_index *nsindex;
        unsigned long offset;
        u64 checksum;
        u32 nslot;
        int rc;

        nsindex = to_namespace_index(ndd, index);
        if (flags & ND_NSINDEX_INIT)
                nslot = nvdimm_num_label_slots(ndd);
        else
                nslot = __le32_to_cpu(nsindex->nslot);

        memcpy(nsindex->sig, NSINDEX_SIGNATURE, NSINDEX_SIG_LEN);
        memset(&nsindex->flags, 0, 3);
        nsindex->labelsize = sizeof_namespace_label(ndd) >> 8;
        nsindex->seq = __cpu_to_le32(seq);
        offset = (unsigned long) nsindex
                - (unsigned long) to_namespace_index(ndd, 0);
        nsindex->myoff = __cpu_to_le64(offset);
        nsindex->mysize = __cpu_to_le64(sizeof_namespace_index(ndd));
        offset = (unsigned long) to_namespace_index(ndd,
                        nd_label_next_nsindex(index))
                - (unsigned long) to_namespace_index(ndd, 0);
        nsindex->otheroff = __cpu_to_le64(offset);
        offset = (unsigned long) nd_label_base(ndd)
                - (unsigned long) to_namespace_index(ndd, 0);
        nsindex->labeloff = __cpu_to_le64(offset);
        nsindex->nslot = __cpu_to_le32(nslot);
        nsindex->major = __cpu_to_le16(1);
        if (sizeof_namespace_label(ndd) < 256)
                nsindex->minor = __cpu_to_le16(1);
        else
                nsindex->minor = __cpu_to_le16(2);
        nsindex->checksum = __cpu_to_le64(0);
        if (flags & ND_NSINDEX_INIT) {
                unsigned long *free = (unsigned long *) nsindex->free;
                u32 nfree = ALIGN(nslot, BITS_PER_LONG);
                int last_bits, i;

                memset(nsindex->free, 0xff, nfree / 8);
                for (i = 0, last_bits = nfree - nslot; i < last_bits; i++)
                        clear_bit_le(nslot + i, free);
        }
        checksum = nd_fletcher64(nsindex, sizeof_namespace_index(ndd), 1);
        nsindex->checksum = __cpu_to_le64(checksum);
        rc = nvdimm_set_config_data(ndd, __le64_to_cpu(nsindex->myoff),
                        nsindex, sizeof_namespace_index(ndd));
        if (rc < 0)
                return rc;

        if (flags & ND_NSINDEX_INIT)
                return 0;

        /* copy the index we just wrote to the new 'next' */
        WARN_ON(index != ndd->ns_next);
        nd_label_copy(ndd, to_current_namespace_index(ndd), nsindex);
        ndd->ns_current = nd_label_next_nsindex(ndd->ns_current);
        ndd->ns_next = nd_label_next_nsindex(ndd->ns_next);
        WARN_ON(ndd->ns_current == ndd->ns_next);

        return 0;
}

static unsigned long nd_label_offset(struct nvdimm_drvdata *ndd,
                struct nd_namespace_label *nd_label)
{
        return (unsigned long) nd_label
                - (unsigned long) to_namespace_index(ndd, 0);
}

enum nvdimm_claim_class to_nvdimm_cclass(guid_t *guid)
{
        if (guid_equal(guid, &nvdimm_btt_guid))
                return NVDIMM_CCLASS_BTT;
        else if (guid_equal(guid, &nvdimm_btt2_guid))
                return NVDIMM_CCLASS_BTT2;
        else if (guid_equal(guid, &nvdimm_pfn_guid))
                return NVDIMM_CCLASS_PFN;
        else if (guid_equal(guid, &nvdimm_dax_guid))
                return NVDIMM_CCLASS_DAX;
        else if (guid_equal(guid, &guid_null))
                return NVDIMM_CCLASS_NONE;

        return NVDIMM_CCLASS_UNKNOWN;
}

static const guid_t *to_abstraction_guid(enum nvdimm_claim_class claim_class,
        guid_t *target)
{
        if (claim_class == NVDIMM_CCLASS_BTT)
                return &nvdimm_btt_guid;
        else if (claim_class == NVDIMM_CCLASS_BTT2)
                return &nvdimm_btt2_guid;
        else if (claim_class == NVDIMM_CCLASS_PFN)
                return &nvdimm_pfn_guid;
        else if (claim_class == NVDIMM_CCLASS_DAX)
                return &nvdimm_dax_guid;
        else if (claim_class == NVDIMM_CCLASS_UNKNOWN) {
                /*
                 * If we're modifying a namespace for which we don't
                 * know the claim_class, don't touch the existing guid.
                 */
                return target;
        } else
                return &guid_null;
}

static int __pmem_label_update(struct nd_region *nd_region,
                struct nd_mapping *nd_mapping, struct nd_namespace_pmem *nspm,
                int pos)
{
        struct nd_namespace_common *ndns = &nspm->nsio.common;
        struct nd_interleave_set *nd_set = nd_region->nd_set;
        struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
        struct nd_label_ent *label_ent, *victim = NULL;
        struct nd_namespace_label *nd_label;
        struct nd_namespace_index *nsindex;
        struct nd_label_id label_id;
        struct resource *res;
        unsigned long *free;
        u32 nslot, slot;
        size_t offset;
        u64 cookie;
        int rc;

        if (!preamble_next(ndd, &nsindex, &free, &nslot))
                return -ENXIO;

        cookie = nd_region_interleave_set_cookie(nd_region, nsindex);
        nd_label_gen_id(&label_id, nspm->uuid, 0);
        for_each_dpa_resource(ndd, res)
                if (strcmp(res->name, label_id.id) == 0)
                        break;

        if (!res) {
                WARN_ON_ONCE(1);
                return -ENXIO;
        }

        /* allocate and write the label to the staging (next) index */
        slot = nd_label_alloc_slot(ndd);
        if (slot == UINT_MAX)
                return -ENXIO;
        dev_dbg(ndd->dev, "allocated: %d\n", slot);

        nd_label = to_label(ndd, slot);
        memset(nd_label, 0, sizeof_namespace_label(ndd));
        memcpy(nd_label->uuid, nspm->uuid, NSLABEL_UUID_LEN);
        if (nspm->alt_name)
                memcpy(nd_label->name, nspm->alt_name, NSLABEL_NAME_LEN);
        nd_label->flags = __cpu_to_le32(NSLABEL_FLAG_UPDATING);
        nd_label->nlabel = __cpu_to_le16(nd_region->ndr_mappings);
        nd_label->position = __cpu_to_le16(pos);
        nd_label->isetcookie = __cpu_to_le64(cookie);
        nd_label->rawsize = __cpu_to_le64(resource_size(res));
        nd_label->lbasize = __cpu_to_le64(nspm->lbasize);
        nd_label->dpa = __cpu_to_le64(res->start);
        nd_label->slot = __cpu_to_le32(slot);
        if (namespace_label_has(ndd, type_guid))
                guid_copy(&nd_label->type_guid, &nd_set->type_guid);
        if (namespace_label_has(ndd, abstraction_guid))
                guid_copy(&nd_label->abstraction_guid,
                                to_abstraction_guid(ndns->claim_class,
                                        &nd_label->abstraction_guid));
        if (namespace_label_has(ndd, checksum)) {
                u64 sum;

                nd_label->checksum = __cpu_to_le64(0);
                sum = nd_fletcher64(nd_label, sizeof_namespace_label(ndd), 1);
                nd_label->checksum = __cpu_to_le64(sum);
        }
        nd_dbg_dpa(nd_region, ndd, res, "\n");

        /* update label */
        offset = nd_label_offset(ndd, nd_label);
        rc = nvdimm_set_config_data(ndd, offset, nd_label,
                        sizeof_namespace_label(ndd));
        if (rc < 0)
                return rc;

        /* Garbage collect the previous label */
        mutex_lock(&nd_mapping->lock);
        list_for_each_entry(label_ent, &nd_mapping->labels, list) {
                if (!label_ent->label)
                        continue;
                if (memcmp(nspm->uuid, label_ent->label->uuid,
                                        NSLABEL_UUID_LEN) != 0)
                        continue;
                victim = label_ent;
                list_move_tail(&victim->list, &nd_mapping->labels);
                break;
        }
        if (victim) {
                dev_dbg(ndd->dev, "free: %d\n", slot);
                slot = to_slot(ndd, victim->label);
                nd_label_free_slot(ndd, slot);
                victim->label = NULL;
        }

        /* update index */
        rc = nd_label_write_index(ndd, ndd->ns_next,
                        nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
        if (rc == 0) {
                list_for_each_entry(label_ent, &nd_mapping->labels, list)
                        if (!label_ent->label) {
                                label_ent->label = nd_label;
                                nd_label = NULL;
                                break;
                        }
                dev_WARN_ONCE(&nspm->nsio.common.dev, nd_label,
                                "failed to track label: %d\n",
                                to_slot(ndd, nd_label));
                if (nd_label)
                        rc = -ENXIO;
        }
        mutex_unlock(&nd_mapping->lock);

        return rc;
}

static bool is_old_resource(struct resource *res, struct resource **list, int n)
{
        int i;

        if (res->flags & DPA_RESOURCE_ADJUSTED)
                return false;
        for (i = 0; i < n; i++)
                if (res == list[i])
                        return true;
        return false;
}

static struct resource *to_resource(struct nvdimm_drvdata *ndd,
                struct nd_namespace_label *nd_label)
{
        struct resource *res;

        for_each_dpa_resource(ndd, res) {
                if (res->start != __le64_to_cpu(nd_label->dpa))
                        continue;
                if (resource_size(res) != __le64_to_cpu(nd_label->rawsize))
                        continue;
                return res;
        }

        return NULL;
}

/*
 * 1/ Account all the labels that can be freed after this update
 * 2/ Allocate and write the label to the staging (next) index
 * 3/ Record the resources in the namespace device
 */
static int __blk_label_update(struct nd_region *nd_region,
                struct nd_mapping *nd_mapping, struct nd_namespace_blk *nsblk,
                int num_labels)
{
        int i, alloc, victims, nfree, old_num_resources, nlabel, rc = -ENXIO;
        struct nd_interleave_set *nd_set = nd_region->nd_set;
        struct nd_namespace_common *ndns = &nsblk->common;
        struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
        struct nd_namespace_label *nd_label;
        struct nd_label_ent *label_ent, *e;
        struct nd_namespace_index *nsindex;
        unsigned long *free, *victim_map = NULL;
        struct resource *res, **old_res_list;
        struct nd_label_id label_id;
        u8 uuid[NSLABEL_UUID_LEN];
        int min_dpa_idx = 0;
        LIST_HEAD(list);
        u32 nslot, slot;

        if (!preamble_next(ndd, &nsindex, &free, &nslot))
                return -ENXIO;

        old_res_list = nsblk->res;
        nfree = nd_label_nfree(ndd);
        old_num_resources = nsblk->num_resources;
        nd_label_gen_id(&label_id, nsblk->uuid, NSLABEL_FLAG_LOCAL);

        /*
         * We need to loop over the old resources a few times, which seems a
         * bit inefficient, but we need to know that we have the label
         * space before we start mutating the tracking structures.
         * Otherwise the recovery method of last resort for userspace is
         * disable and re-enable the parent region.
         */
        alloc = 0;
        for_each_dpa_resource(ndd, res) {
                if (strcmp(res->name, label_id.id) != 0)
                        continue;
                if (!is_old_resource(res, old_res_list, old_num_resources))
                        alloc++;
        }

        victims = 0;
        if (old_num_resources) {
                /* convert old local-label-map to dimm-slot victim-map */
                victim_map = bitmap_zalloc(nslot, GFP_KERNEL);
                if (!victim_map)
                        return -ENOMEM;

                /* mark unused labels for garbage collection */
                for_each_clear_bit_le(slot, free, nslot) {
                        nd_label = to_label(ndd, slot);
                        memcpy(uuid, nd_label->uuid, NSLABEL_UUID_LEN);
                        if (memcmp(uuid, nsblk->uuid, NSLABEL_UUID_LEN) != 0)
                                continue;
                        res = to_resource(ndd, nd_label);
                        if (res && is_old_resource(res, old_res_list,
                                                old_num_resources))
                                continue;
                        slot = to_slot(ndd, nd_label);
                        set_bit(slot, victim_map);
                        victims++;
                }
        }

        /* don't allow updates that consume the last label */
        if (nfree - alloc < 0 || nfree - alloc + victims < 1) {
                dev_info(&nsblk->common.dev, "insufficient label space\n");
                bitmap_free(victim_map);
                return -ENOSPC;
        }
        /* from here on we need to abort on error */


        /* assign all resources to the namespace before writing the labels */
        nsblk->res = NULL;
        nsblk->num_resources = 0;
        for_each_dpa_resource(ndd, res) {
                if (strcmp(res->name, label_id.id) != 0)
                        continue;
                if (!nsblk_add_resource(nd_region, ndd, nsblk, res->start)) {
                        rc = -ENOMEM;
                        goto abort;
                }
        }

        /*
         * Find the resource associated with the first label in the set
         * per the v1.2 namespace specification.
         */
        for (i = 0; i < nsblk->num_resources; i++) {
                struct resource *min = nsblk->res[min_dpa_idx];

                res = nsblk->res[i];
                if (res->start < min->start)
                        min_dpa_idx = i;
        }

        for (i = 0; i < nsblk->num_resources; i++) {

                size_t offset;

                res = nsblk->res[i];
                if (is_old_resource(res, old_res_list, old_num_resources))
                        continue; /* carry-over */
                slot = nd_label_alloc_slot(ndd);
                if (slot == UINT_MAX)
                        goto abort;
                dev_dbg(ndd->dev, "allocated: %d\n", slot);

                nd_label = to_label(ndd, slot);
                memset(nd_label, 0, sizeof_namespace_label(ndd));
                memcpy(nd_label->uuid, nsblk->uuid, NSLABEL_UUID_LEN);
                if (nsblk->alt_name)
                        memcpy(nd_label->name, nsblk->alt_name,
                                        NSLABEL_NAME_LEN);
                nd_label->flags = __cpu_to_le32(NSLABEL_FLAG_LOCAL);

                /*
                 * Use the presence of the type_guid as a flag to
                 * determine isetcookie usage and nlabel + position
                 * policy for blk-aperture namespaces.
                 */
                if (namespace_label_has(ndd, type_guid)) {
                        if (i == min_dpa_idx) {
                                nd_label->nlabel = __cpu_to_le16(nsblk->num_resources);
                                nd_label->position = __cpu_to_le16(0);
                        } else {
                                nd_label->nlabel = __cpu_to_le16(0xffff);
                                nd_label->position = __cpu_to_le16(0xffff);
                        }
                        nd_label->isetcookie = __cpu_to_le64(nd_set->cookie2);
                } else {
                        nd_label->nlabel = __cpu_to_le16(0); /* N/A */
                        nd_label->position = __cpu_to_le16(0); /* N/A */
                        nd_label->isetcookie = __cpu_to_le64(0); /* N/A */
                }

                nd_label->dpa = __cpu_to_le64(res->start);
                nd_label->rawsize = __cpu_to_le64(resource_size(res));
                nd_label->lbasize = __cpu_to_le64(nsblk->lbasize);
                nd_label->slot = __cpu_to_le32(slot);
                if (namespace_label_has(ndd, type_guid))
                        guid_copy(&nd_label->type_guid, &nd_set->type_guid);
                if (namespace_label_has(ndd, abstraction_guid))
                        guid_copy(&nd_label->abstraction_guid,
                                        to_abstraction_guid(ndns->claim_class,
                                                &nd_label->abstraction_guid));

                if (namespace_label_has(ndd, checksum)) {
                        u64 sum;

                        nd_label->checksum = __cpu_to_le64(0);
                        sum = nd_fletcher64(nd_label,
                                        sizeof_namespace_label(ndd), 1);
                        nd_label->checksum = __cpu_to_le64(sum);
                }

                /* update label */
                offset = nd_label_offset(ndd, nd_label);
                rc = nvdimm_set_config_data(ndd, offset, nd_label,
                                sizeof_namespace_label(ndd));
                if (rc < 0)
                        goto abort;
        }

        /* free up now unused slots in the new index */
        for_each_set_bit(slot, victim_map, victim_map ? nslot : 0) {
                dev_dbg(ndd->dev, "free: %d\n", slot);
                nd_label_free_slot(ndd, slot);
        }

        /* update index */
        rc = nd_label_write_index(ndd, ndd->ns_next,
                        nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
        if (rc)
                goto abort;

        /*
         * Now that the on-dimm labels are up to date, fix up the tracking
         * entries in nd_mapping->labels
         */
        nlabel = 0;
        mutex_lock(&nd_mapping->lock);
        list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
                nd_label = label_ent->label;
                if (!nd_label)
                        continue;
                nlabel++;
                memcpy(uuid, nd_label->uuid, NSLABEL_UUID_LEN);
                if (memcmp(uuid, nsblk->uuid, NSLABEL_UUID_LEN) != 0)
                        continue;
                nlabel--;
                list_move(&label_ent->list, &list);
                label_ent->label = NULL;
        }
        list_splice_tail_init(&list, &nd_mapping->labels);
        mutex_unlock(&nd_mapping->lock);

        if (nlabel + nsblk->num_resources > num_labels) {
                /*
                 * Bug, we can't end up with more resources than
                 * available labels
                 */
                WARN_ON_ONCE(1);
                rc = -ENXIO;
                goto out;
        }

        mutex_lock(&nd_mapping->lock);
        label_ent = list_first_entry_or_null(&nd_mapping->labels,
                        typeof(*label_ent), list);
        if (!label_ent) {
                WARN_ON(1);
                mutex_unlock(&nd_mapping->lock);
                rc = -ENXIO;
                goto out;
        }
        for_each_clear_bit_le(slot, free, nslot) {
                nd_label = to_label(ndd, slot);
                memcpy(uuid, nd_label->uuid, NSLABEL_UUID_LEN);
                if (memcmp(uuid, nsblk->uuid, NSLABEL_UUID_LEN) != 0)
                        continue;
                res = to_resource(ndd, nd_label);
                res->flags &= ~DPA_RESOURCE_ADJUSTED;
                dev_vdbg(&nsblk->common.dev, "assign label slot: %d\n", slot);
                list_for_each_entry_from(label_ent, &nd_mapping->labels, list) {
                        if (label_ent->label)
                                continue;
                        label_ent->label = nd_label;
                        nd_label = NULL;
                        break;
                }
                if (nd_label)
                        dev_WARN(&nsblk->common.dev,
                                        "failed to track label slot%d\n", slot);
        }
        mutex_unlock(&nd_mapping->lock);

 out:
        kfree(old_res_list);
        bitmap_free(victim_map);
        return rc;

 abort:
        /*
         * 1/ repair the allocated label bitmap in the index
         * 2/ restore the resource list
         */
        nd_label_copy(ndd, nsindex, to_current_namespace_index(ndd));
        kfree(nsblk->res);
        nsblk->res = old_res_list;
        nsblk->num_resources = old_num_resources;
        old_res_list = NULL;
        goto out;
}

static int init_labels(struct nd_mapping *nd_mapping, int num_labels)
{
        int i, old_num_labels = 0;
        struct nd_label_ent *label_ent;
        struct nd_namespace_index *nsindex;
        struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);

        mutex_lock(&nd_mapping->lock);
        list_for_each_entry(label_ent, &nd_mapping->labels, list)
                old_num_labels++;
        mutex_unlock(&nd_mapping->lock);

        /*
         * We need to preserve all the old labels for the mapping so
         * they can be garbage collected after writing the new labels.
         */
        for (i = old_num_labels; i < num_labels; i++) {
                label_ent = kzalloc(sizeof(*label_ent), GFP_KERNEL);
                if (!label_ent)
                        return -ENOMEM;
                mutex_lock(&nd_mapping->lock);
                list_add_tail(&label_ent->list, &nd_mapping->labels);
                mutex_unlock(&nd_mapping->lock);
        }

        if (ndd->ns_current == -1 || ndd->ns_next == -1)
                /* pass */;
        else
                return max(num_labels, old_num_labels);

        nsindex = to_namespace_index(ndd, 0);
        memset(nsindex, 0, ndd->nsarea.config_size);
        for (i = 0; i < 2; i++) {
                int rc = nd_label_write_index(ndd, i, 3 - i, ND_NSINDEX_INIT);

                if (rc)
                        return rc;
        }
        ndd->ns_next = 1;
        ndd->ns_current = 0;

        return max(num_labels, old_num_labels);
}

static int del_labels(struct nd_mapping *nd_mapping, u8 *uuid)
{
        struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
        struct nd_label_ent *label_ent, *e;
        struct nd_namespace_index *nsindex;
        u8 label_uuid[NSLABEL_UUID_LEN];
        unsigned long *free;
        LIST_HEAD(list);
        u32 nslot, slot;
        int active = 0;

        if (!uuid)
                return 0;

        /* no index || no labels == nothing to delete */
        if (!preamble_next(ndd, &nsindex, &free, &nslot))
                return 0;

        mutex_lock(&nd_mapping->lock);
        list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
                struct nd_namespace_label *nd_label = label_ent->label;

                if (!nd_label)
                        continue;
                active++;
                memcpy(label_uuid, nd_label->uuid, NSLABEL_UUID_LEN);
                if (memcmp(label_uuid, uuid, NSLABEL_UUID_LEN) != 0)
                        continue;
                active--;
                slot = to_slot(ndd, nd_label);
                nd_label_free_slot(ndd, slot);
                dev_dbg(ndd->dev, "free: %d\n", slot);
                list_move_tail(&label_ent->list, &list);
                label_ent->label = NULL;
        }
        list_splice_tail_init(&list, &nd_mapping->labels);

        if (active == 0) {
                nd_mapping_free_labels(nd_mapping);
                dev_dbg(ndd->dev, "no more active labels\n");
        }
        mutex_unlock(&nd_mapping->lock);

        return nd_label_write_index(ndd, ndd->ns_next,
                        nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
}

int nd_pmem_namespace_label_update(struct nd_region *nd_region,
                struct nd_namespace_pmem *nspm, resource_size_t size)
{
        int i;

        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);
                struct resource *res;
                int rc, count = 0;

                if (size == 0) {
                        rc = del_labels(nd_mapping, nspm->uuid);
                        if (rc)
                                return rc;
                        continue;
                }

                for_each_dpa_resource(ndd, res)
                        if (strncmp(res->name, "pmem", 4) == 0)
                                count++;
                WARN_ON_ONCE(!count);

                rc = init_labels(nd_mapping, count);
                if (rc < 0)
                        return rc;

                rc = __pmem_label_update(nd_region, nd_mapping, nspm, i);
                if (rc)
                        return rc;
        }

        return 0;
}

int nd_blk_namespace_label_update(struct nd_region *nd_region,
                struct nd_namespace_blk *nsblk, resource_size_t size)
{
        struct nd_mapping *nd_mapping = &nd_region->mapping[0];
        struct resource *res;
        int count = 0;

        if (size == 0)
                return del_labels(nd_mapping, nsblk->uuid);

        for_each_dpa_resource(to_ndd(nd_mapping), res)
                count++;

        count = init_labels(nd_mapping, count);
        if (count < 0)
                return count;

        return __blk_label_update(nd_region, nd_mapping, nsblk, count);
}

int __init nd_label_init(void)
{
        WARN_ON(guid_parse(NVDIMM_BTT_GUID, &nvdimm_btt_guid));
        WARN_ON(guid_parse(NVDIMM_BTT2_GUID, &nvdimm_btt2_guid));
        WARN_ON(guid_parse(NVDIMM_PFN_GUID, &nvdimm_pfn_guid));
        WARN_ON(guid_parse(NVDIMM_DAX_GUID, &nvdimm_dax_guid));

        return 0;
}