#ifdef __KERNEL__
# include <linux/string.h>
# include <linux/slab.h>
# include <linux/bug.h>
# include <linux/kernel.h>
# ifndef dprintk
#  define dprintk(args...)
# endif
#else
# include <string.h>
# include <stdio.h>
# include <stdlib.h>
# include <assert.h>
# define BUG_ON(x) assert(!(x))
# define dprintk(args...) /* printf(args) */
# define kmalloc(x, f) malloc(x)
# define kfree(x) free(x)
#endif

#include <linux/crush/crush.h>
#include <linux/crush/hash.h>
#include <linux/crush/mapper.h>

/*
 * Implement the core CRUSH mapping algorithm.
 */

/**
 * crush_find_rule - find a crush_rule id for a given ruleset, type, and size.
 * @map: the crush_map
 * @ruleset: the storage ruleset id (user defined)
 * @type: storage ruleset type (user defined)
 * @size: output set size
 */
int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size)
{
        __u32 i;

        for (i = 0; i < map->max_rules; i++) {
                if (map->rules[i] &&
                    map->rules[i]->mask.ruleset == ruleset &&
                    map->rules[i]->mask.type == type &&
                    map->rules[i]->mask.min_size <= size &&
                    map->rules[i]->mask.max_size >= size)
                        return i;
        }
        return -1;
}


/*
 * bucket choose methods
 *
 * For each bucket algorithm, we have a "choose" method that, given a
 * crush input @x and replica position (usually, position in output set) @r,
 * will produce an item in the bucket.
 */

/*
 * Choose based on a random permutation of the bucket.
 *
 * We used to use some prime number arithmetic to do this, but it
 * wasn't very random, and had some other bad behaviors.  Instead, we
 * calculate an actual random permutation of the bucket members.
 * Since this is expensive, we optimize for the r=0 case, which
 * captures the vast majority of calls.
 */
static int bucket_perm_choose(struct crush_bucket *bucket,
                              int x, int r)
{
        unsigned int pr = r % bucket->size;
        unsigned int i, s;

        /* start a new permutation if @x has changed */
        if (bucket->perm_x != (__u32)x || bucket->perm_n == 0) {
                dprintk("bucket %d new x=%d\n", bucket->id, x);
                bucket->perm_x = x;

                /* optimize common r=0 case */
                if (pr == 0) {
                        s = crush_hash32_3(bucket->hash, x, bucket->id, 0) %
                                bucket->size;
                        bucket->perm[0] = s;
                        bucket->perm_n = 0xffff;   /* magic value, see below */
                        goto out;
                }

                for (i = 0; i < bucket->size; i++)
                        bucket->perm[i] = i;
                bucket->perm_n = 0;
        } else if (bucket->perm_n == 0xffff) {
                /* clean up after the r=0 case above */
                for (i = 1; i < bucket->size; i++)
                        bucket->perm[i] = i;
                bucket->perm[bucket->perm[0]] = 0;
                bucket->perm_n = 1;
        }

        /* calculate permutation up to pr */
        for (i = 0; i < bucket->perm_n; i++)
                dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]);
        while (bucket->perm_n <= pr) {
                unsigned int p = bucket->perm_n;
                /* no point in swapping the final entry */
                if (p < bucket->size - 1) {
                        i = crush_hash32_3(bucket->hash, x, bucket->id, p) %
                                (bucket->size - p);
                        if (i) {
                                unsigned int t = bucket->perm[p + i];
                                bucket->perm[p + i] = bucket->perm[p];
                                bucket->perm[p] = t;
                        }
                        dprintk(" perm_choose swap %d with %d\n", p, p+i);
                }
                bucket->perm_n++;
        }
        for (i = 0; i < bucket->size; i++)
                dprintk(" perm_choose  %d: %d\n", i, bucket->perm[i]);

        s = bucket->perm[pr];
out:
        dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id,
                bucket->size, x, r, pr, s);
        return bucket->items[s];
}

/* uniform */
static int bucket_uniform_choose(struct crush_bucket_uniform *bucket,
                                 int x, int r)
{
        return bucket_perm_choose(&bucket->h, x, r);
}

/* list */
static int bucket_list_choose(struct crush_bucket_list *bucket,
                              int x, int r)
{
        int i;

        for (i = bucket->h.size-1; i >= 0; i--) {
                __u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i],
                                         r, bucket->h.id);
                w &= 0xffff;
                dprintk("list_choose i=%d x=%d r=%d item %d weight %x "
                        "sw %x rand %llx",
                        i, x, r, bucket->h.items[i], bucket->item_weights[i],
                        bucket->sum_weights[i], w);
                w *= bucket->sum_weights[i];
                w = w >> 16;
                /*dprintk(" scaled %llx\n", w);*/
                if (w < bucket->item_weights[i])
                        return bucket->h.items[i];
        }

        dprintk("bad list sums for bucket %d\n", bucket->h.id);
        return bucket->h.items[0];
}


/* (binary) tree */
static int height(int n)
{
        int h = 0;
        while ((n & 1) == 0) {
                h++;
                n = n >> 1;
        }
        return h;
}

static int left(int x)
{
        int h = height(x);
        return x - (1 << (h-1));
}

static int right(int x)
{
        int h = height(x);
        return x + (1 << (h-1));
}

static int terminal(int x)
{
        return x & 1;
}

static int bucket_tree_choose(struct crush_bucket_tree *bucket,
                              int x, int r)
{
        int n;
        __u32 w;
        __u64 t;

        /* start at root */
        n = bucket->num_nodes >> 1;

        while (!terminal(n)) {
                int l;
                /* pick point in [0, w) */
                w = bucket->node_weights[n];
                t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r,
                                          bucket->h.id) * (__u64)w;
                t = t >> 32;

                /* descend to the left or right? */
                l = left(n);
                if (t < bucket->node_weights[l])
                        n = l;
                else
                        n = right(n);
        }

        return bucket->h.items[n >> 1];
}


/* straw */

static int bucket_straw_choose(struct crush_bucket_straw *bucket,
                               int x, int r)
{
        __u32 i;
        int high = 0;
        __u64 high_draw = 0;
        __u64 draw;

        for (i = 0; i < bucket->h.size; i++) {
                draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r);
                draw &= 0xffff;
                draw *= bucket->straws[i];
                if (i == 0 || draw > high_draw) {
                        high = i;
                        high_draw = draw;
                }
        }
        return bucket->h.items[high];
}

static int crush_bucket_choose(struct crush_bucket *in, int x, int r)
{
        dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r);
        BUG_ON(in->size == 0);
        switch (in->alg) {
        case CRUSH_BUCKET_UNIFORM:
                return bucket_uniform_choose((struct crush_bucket_uniform *)in,
                                          x, r);
        case CRUSH_BUCKET_LIST:
                return bucket_list_choose((struct crush_bucket_list *)in,
                                          x, r);
        case CRUSH_BUCKET_TREE:
                return bucket_tree_choose((struct crush_bucket_tree *)in,
                                          x, r);
        case CRUSH_BUCKET_STRAW:
                return bucket_straw_choose((struct crush_bucket_straw *)in,
                                           x, r);
        default:
                dprintk("unknown bucket %d alg %d\n", in->id, in->alg);
                return in->items[0];
        }
}

/*
 * true if device is marked "out" (failed, fully offloaded)
 * of the cluster
 */
static int is_out(const struct crush_map *map,
                  const __u32 *weight, int weight_max,
                  int item, int x)
{
        if (item >= weight_max)
                return 1;
        if (weight[item] >= 0x10000)
                return 0;
        if (weight[item] == 0)
                return 1;
        if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
            < weight[item])
                return 0;
        return 1;
}

/**
 * crush_choose_firstn - choose numrep distinct items of given type
 * @map: the crush_map
 * @bucket: the bucket we are choose an item from
 * @x: crush input value
 * @numrep: the number of items to choose
 * @type: the type of item to choose
 * @out: pointer to output vector
 * @outpos: our position in that vector
 * @tries: number of attempts to make
 * @recurse_tries: number of attempts to have recursive chooseleaf make
 * @local_retries: localized retries
 * @local_fallback_retries: localized fallback retries
 * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose)
 * @vary_r: pass r to recursive calls
 * @out2: second output vector for leaf items (if @recurse_to_leaf)
 * @parent_r: r value passed from the parent
 */
static int crush_choose_firstn(const struct crush_map *map,
                               struct crush_bucket *bucket,
                               const __u32 *weight, int weight_max,
                               int x, int numrep, int type,
                               int *out, int outpos,
                               unsigned int tries,
                               unsigned int recurse_tries,
                               unsigned int local_retries,
                               unsigned int local_fallback_retries,
                               int recurse_to_leaf,
                               unsigned int vary_r,
                               int *out2,
                               int parent_r)
{
        int rep;
        unsigned int ftotal, flocal;
        int retry_descent, retry_bucket, skip_rep;
        struct crush_bucket *in = bucket;
        int r;
        int i;
        int item = 0;
        int itemtype;
        int collide, reject;

        dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d tries %d recurse_tries %d local_retries %d local_fallback_retries %d parent_r %d\n",
                recurse_to_leaf ? "_LEAF" : "",
                bucket->id, x, outpos, numrep,
                tries, recurse_tries, local_retries, local_fallback_retries,
                parent_r);

        for (rep = outpos; rep < numrep; rep++) {
                /* keep trying until we get a non-out, non-colliding item */
                ftotal = 0;
                skip_rep = 0;
                do {
                        retry_descent = 0;
                        in = bucket;               /* initial bucket */

                        /* choose through intervening buckets */
                        flocal = 0;
                        do {
                                collide = 0;
                                retry_bucket = 0;
                                r = rep + parent_r;
                                /* r' = r + f_total */
                                r += ftotal;

                                /* bucket choose */
                                if (in->size == 0) {
                                        reject = 1;
                                        goto reject;
                                }
                                if (local_fallback_retries > 0 &&
                                    flocal >= (in->size>>1) &&
                                    flocal > local_fallback_retries)
                                        item = bucket_perm_choose(in, x, r);
                                else
                                        item = crush_bucket_choose(in, x, r);
                                if (item >= map->max_devices) {
                                        dprintk("   bad item %d\n", item);
                                        skip_rep = 1;
                                        break;
                                }

                                /* desired type? */
                                if (item < 0)
                                        itemtype = map->buckets[-1-item]->type;
                                else
                                        itemtype = 0;
                                dprintk("  item %d type %d\n", item, itemtype);

                                /* keep going? */
                                if (itemtype != type) {
                                        if (item >= 0 ||
                                            (-1-item) >= map->max_buckets) {
                                                dprintk("   bad item type %d\n", type);
                                                skip_rep = 1;
                                                break;
                                        }
                                        in = map->buckets[-1-item];
                                        retry_bucket = 1;
                                        continue;
                                }

                                /* collision? */
                                for (i = 0; i < outpos; i++) {
                                        if (out[i] == item) {
                                                collide = 1;
                                                break;
                                        }
                                }

                                reject = 0;
                                if (!collide && recurse_to_leaf) {
                                        if (item < 0) {
                                                int sub_r;
                                                if (vary_r)
                                                        sub_r = r >> (vary_r-1);
                                                else
                                                        sub_r = 0;
                                                if (crush_choose_firstn(map,
                                                         map->buckets[-1-item],
                                                         weight, weight_max,
                                                         x, outpos+1, 0,
                                                         out2, outpos,
                                                         recurse_tries, 0,
                                                         local_retries,
                                                         local_fallback_retries,
                                                         0,
                                                         vary_r,
                                                         NULL,
                                                         sub_r) <= outpos)
                                                        /* didn't get leaf */
                                                        reject = 1;
                                        } else {
                                                /* we already have a leaf! */
                                                out2[outpos] = item;
                                        }
                                }

                                if (!reject) {
                                        /* out? */
                                        if (itemtype == 0)
                                                reject = is_out(map, weight,
                                                                weight_max,
                                                                item, x);
                                        else
                                                reject = 0;
                                }

reject:
                                if (reject || collide) {
                                        ftotal++;
                                        flocal++;

                                        if (collide && flocal <= local_retries)
                                                /* retry locally a few times */
                                                retry_bucket = 1;
                                        else if (local_fallback_retries > 0 &&
                                                 flocal <= in->size + local_fallback_retries)
                                                /* exhaustive bucket search */
                                                retry_bucket = 1;
                                        else if (ftotal < tries)
                                                /* then retry descent */
                                                retry_descent = 1;
                                        else
                                                /* else give up */
                                                skip_rep = 1;
                                        dprintk("  reject %d  collide %d  "
                                                "ftotal %u  flocal %u\n",
                                                reject, collide, ftotal,
                                                flocal);
                                }
                        } while (retry_bucket);
                } while (retry_descent);

                if (skip_rep) {
                        dprintk("skip rep\n");
                        continue;
                }

                dprintk("CHOOSE got %d\n", item);
                out[outpos] = item;
                outpos++;
        }

        dprintk("CHOOSE returns %d\n", outpos);
        return outpos;
}


/**
 * crush_choose_indep: alternative breadth-first positionally stable mapping
 *
 */
static void crush_choose_indep(const struct crush_map *map,
                               struct crush_bucket *bucket,
                               const __u32 *weight, int weight_max,
                               int x, int left, int numrep, int type,
                               int *out, int outpos,
                               unsigned int tries,
                               unsigned int recurse_tries,
                               int recurse_to_leaf,
                               int *out2,
                               int parent_r)
{
        struct crush_bucket *in = bucket;
        int endpos = outpos + left;
        int rep;
        unsigned int ftotal;
        int r;
        int i;
        int item = 0;
        int itemtype;
        int collide;

        dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",
                bucket->id, x, outpos, numrep);

        /* initially my result is undefined */
        for (rep = outpos; rep < endpos; rep++) {
                out[rep] = CRUSH_ITEM_UNDEF;
                if (out2)
                        out2[rep] = CRUSH_ITEM_UNDEF;
        }

        for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) {
                for (rep = outpos; rep < endpos; rep++) {
                        if (out[rep] != CRUSH_ITEM_UNDEF)
                                continue;

                        in = bucket;  /* initial bucket */

                        /* choose through intervening buckets */
                        for (;;) {
                                /* note: we base the choice on the position
                                 * even in the nested call.  that means that
                                 * if the first layer chooses the same bucket
                                 * in a different position, we will tend to
                                 * choose a different item in that bucket.
                                 * this will involve more devices in data
                                 * movement and tend to distribute the load.
                                 */
                                r = rep + parent_r;

                                /* be careful */
                                if (in->alg == CRUSH_BUCKET_UNIFORM &&
                                    in->size % numrep == 0)
                                        /* r'=r+(n+1)*f_total */
                                        r += (numrep+1) * ftotal;
                                else
                                        /* r' = r + n*f_total */
                                        r += numrep * ftotal;

                                /* bucket choose */
                                if (in->size == 0) {
                                        dprintk("   empty bucket\n");
                                        break;
                                }

                                item = crush_bucket_choose(in, x, r);
                                if (item >= map->max_devices) {
                                        dprintk("   bad item %d\n", item);
                                        out[rep] = CRUSH_ITEM_NONE;
                                        if (out2)
                                                out2[rep] = CRUSH_ITEM_NONE;
                                        left--;
                                        break;
                                }

                                /* desired type? */
                                if (item < 0)
                                        itemtype = map->buckets[-1-item]->type;
                                else
                                        itemtype = 0;
                                dprintk("  item %d type %d\n", item, itemtype);

                                /* keep going? */
                                if (itemtype != type) {
                                        if (item >= 0 ||
                                            (-1-item) >= map->max_buckets) {
                                                dprintk("   bad item type %d\n", type);
                                                out[rep] = CRUSH_ITEM_NONE;
                                                if (out2)
                                                        out2[rep] =
                                                                CRUSH_ITEM_NONE;
                                                left--;
                                                break;
                                        }
                                        in = map->buckets[-1-item];
                                        continue;
                                }

                                /* collision? */
                                collide = 0;
                                for (i = outpos; i < endpos; i++) {
                                        if (out[i] == item) {
                                                collide = 1;
                                                break;
                                        }
                                }
                                if (collide)
                                        break;

                                if (recurse_to_leaf) {
                                        if (item < 0) {
                                                crush_choose_indep(map,
                                                   map->buckets[-1-item],
                                                   weight, weight_max,
                                                   x, 1, numrep, 0,
                                                   out2, rep,
                                                   recurse_tries, 0,
                                                   0, NULL, r);
                                                if (out2[rep] == CRUSH_ITEM_NONE) {
                                                        /* placed nothing; no leaf */
                                                        break;
                                                }
                                        } else {
                                                /* we already have a leaf! */
                                                out2[rep] = item;
                                        }
                                }

                                /* out? */
                                if (itemtype == 0 &&
                                    is_out(map, weight, weight_max, item, x))
                                        break;

                                /* yay! */
                                out[rep] = item;
                                left--;
                                break;
                        }
                }
        }
        for (rep = outpos; rep < endpos; rep++) {
                if (out[rep] == CRUSH_ITEM_UNDEF) {
                        out[rep] = CRUSH_ITEM_NONE;
                }
                if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) {
                        out2[rep] = CRUSH_ITEM_NONE;
                }
        }
}

/**
 * crush_do_rule - calculate a mapping with the given input and rule
 * @map: the crush_map
 * @ruleno: the rule id
 * @x: hash input
 * @result: pointer to result vector
 * @result_max: maximum result size
 * @weight: weight vector (for map leaves)
 * @weight_max: size of weight vector
 * @scratch: scratch vector for private use; must be >= 3 * result_max
 */
int crush_do_rule(const struct crush_map *map,
                  int ruleno, int x, int *result, int result_max,
                  const __u32 *weight, int weight_max,
                  int *scratch)
{
        int result_len;
        int *a = scratch;
        int *b = scratch + result_max;
        int *c = scratch + result_max*2;
        int recurse_to_leaf;
        int *w;
        int wsize = 0;
        int *o;
        int osize;
        int *tmp;
        struct crush_rule *rule;
        __u32 step;
        int i, j;
        int numrep;
        /*
         * the original choose_total_tries value was off by one (it
         * counted "retries" and not "tries").  add one.
         */
        int choose_tries = map->choose_total_tries + 1;
        int choose_leaf_tries = 0;
        /*
         * the local tries values were counted as "retries", though,
         * and need no adjustment
         */
        int choose_local_retries = map->choose_local_tries;
        int choose_local_fallback_retries = map->choose_local_fallback_tries;

        int vary_r = map->chooseleaf_vary_r;

        if ((__u32)ruleno >= map->max_rules) {
                dprintk(" bad ruleno %d\n", ruleno);
                return 0;
        }

        rule = map->rules[ruleno];
        result_len = 0;
        w = a;
        o = b;

        for (step = 0; step < rule->len; step++) {
                int firstn = 0;
                struct crush_rule_step *curstep = &rule->steps[step];

                switch (curstep->op) {
                case CRUSH_RULE_TAKE:
                        w[0] = curstep->arg1;
                        wsize = 1;
                        break;

                case CRUSH_RULE_SET_CHOOSE_TRIES:
                        if (curstep->arg1 > 0)
                                choose_tries = curstep->arg1;
                        break;

                case CRUSH_RULE_SET_CHOOSELEAF_TRIES:
                        if (curstep->arg1 > 0)
                                choose_leaf_tries = curstep->arg1;
                        break;

                case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES:
                        if (curstep->arg1 >= 0)
                                choose_local_retries = curstep->arg1;
                        break;

                case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES:
                        if (curstep->arg1 >= 0)
                                choose_local_fallback_retries = curstep->arg1;
                        break;

                case CRUSH_RULE_SET_CHOOSELEAF_VARY_R:
                        if (curstep->arg1 >= 0)
                                vary_r = curstep->arg1;
                        break;

                case CRUSH_RULE_CHOOSELEAF_FIRSTN:
                case CRUSH_RULE_CHOOSE_FIRSTN:
                        firstn = 1;
                        /* fall through */
                case CRUSH_RULE_CHOOSELEAF_INDEP:
                case CRUSH_RULE_CHOOSE_INDEP:
                        if (wsize == 0)
                                break;

                        recurse_to_leaf =
                                curstep->op ==
                                 CRUSH_RULE_CHOOSELEAF_FIRSTN ||
                                curstep->op ==
                                CRUSH_RULE_CHOOSELEAF_INDEP;

                        /* reset output */
                        osize = 0;

                        for (i = 0; i < wsize; i++) {
                                /*
                                 * see CRUSH_N, CRUSH_N_MINUS macros.
                                 * basically, numrep <= 0 means relative to
                                 * the provided result_max
                                 */
                                numrep = curstep->arg1;
                                if (numrep <= 0) {
                                        numrep += result_max;
                                        if (numrep <= 0)
                                                continue;
                                }
                                j = 0;
                                if (firstn) {
                                        int recurse_tries;
                                        if (choose_leaf_tries)
                                                recurse_tries =
                                                        choose_leaf_tries;
                                        else if (map->chooseleaf_descend_once)
                                                recurse_tries = 1;
                                        else
                                                recurse_tries = choose_tries;
                                        osize += crush_choose_firstn(
                                                map,
                                                map->buckets[-1-w[i]],
                                                weight, weight_max,
                                                x, numrep,
                                                curstep->arg2,
                                                o+osize, j,
                                                choose_tries,
                                                recurse_tries,
                                                choose_local_retries,
                                                choose_local_fallback_retries,
                                                recurse_to_leaf,
                                                vary_r,
                                                c+osize,
                                                0);
                                } else {
                                        crush_choose_indep(
                                                map,
                                                map->buckets[-1-w[i]],
                                                weight, weight_max,
                                                x, numrep, numrep,
                                                curstep->arg2,
                                                o+osize, j,
                                                choose_tries,
                                                choose_leaf_tries ?
                                                   choose_leaf_tries : 1,
                                                recurse_to_leaf,
                                                c+osize,
                                                0);
                                        osize += numrep;
                                }
                        }

                        if (recurse_to_leaf)
                                /* copy final _leaf_ values to output set */
                                memcpy(o, c, osize*sizeof(*o));

                        /* swap o and w arrays */
                        tmp = o;
                        o = w;
                        w = tmp;
                        wsize = osize;
                        break;


                case CRUSH_RULE_EMIT:
                        for (i = 0; i < wsize && result_len < result_max; i++) {
                                result[result_len] = w[i];
                                result_len++;
                        }
                        wsize = 0;
                        break;

                default:
                        dprintk(" unknown op %d at step %d\n",
                                curstep->op, step);
                        break;
                }
        }
        return result_len;
}