--- /dev/null
+#ifndef CEPH_CRUSH_BUILDER_H
+#define CEPH_CRUSH_BUILDER_H
+
+#include "include/int_types.h"
+
+struct crush_bucket;
+struct crush_choose_arg;
+struct crush_map;
+struct crush_rule;
+
+/** @ingroup API
+ *
+ * Allocate a crush_map with __malloc(3)__ and initialize it. The
+ * caller is responsible for deallocating the crush_map with
+ * crush_destroy().
+ *
+ * The content of the allocated crush_map is set with
+ * set_optimal_crush_map(). The caller is responsible for setting each
+ * tunable in the __crush_map__ for backward compatibility or mapping
+ * stability.
+ *
+ * @returns a pointer to the newly created crush_map or NULL
+ */
+extern struct crush_map *crush_create();
+/** @ingroup API
+ *
+ * Analyze the content of __map__ and set the internal values required
+ * before it can be used to map values with crush_do_rule(). The caller
+ * must make sure it is run before crush_do_rule() and after any
+ * function that modifies the __map__ (crush_add_bucket(), etc.).
+ *
+ * @param map the crush_map
+ */
+extern void crush_finalize(struct crush_map *map);
+
+/* rules */
+/** @ingroup API
+ *
+ * Allocate an empty crush_rule structure large enough to store __len__ steps.
+ * Steps can be added to a rule via crush_rule_set_step(). The __ruleset__
+ * is a user defined integer, not used by __libcrush__ and stored in
+ * the allocated rule at __rule->mask.ruleset__.
+ *
+ * The rule is designed to allow crush_do_rule() to get at least __minsize__ items
+ * and at most __maxsize__ items.
+ *
+ * The __type__ is defined by the caller and will be used by
+ * crush_find_rule() when looking for a rule and by
+ * __CRUSH_RULE_CHOOSE*__ steps when looking for items.
+ *
+ * The caller is responsible for deallocating the returned pointer via
+ * crush_destroy_rule().
+ *
+ * If __malloc(3)__ fails, return NULL.
+ *
+ * @param len number of steps in the rule
+ * @param ruleset user defined value
+ * @param type user defined value
+ * @param minsize minimum number of items the rule can map
+ * @param maxsize maximum number of items the rule can map
+ *
+ * @returns a pointer to the newly created rule or NULL
+ */
+extern struct crush_rule *crush_make_rule(int len, int ruleset, int type, int minsize, int maxsize);
+/** @ingroup API
+ *
+ * Set the __pos__ step of the __rule__ to an operand and up to two arguments.
+ * The value of the operand __op__ determines if the arguments are used and how:
+ *
+ * - __CRUSH_RULE_NOOP__ do nothing.
+ * - __CRUSH_RULE_TAKE__ select the __arg1__ item
+ * - __CRUSH_RULE_EMIT__ append the selection to the results and clear
+ * the selection
+ *
+ * - __CRUSH_RULE_CHOOSE_FIRSTN__ and __CRUSH_RULE_CHOOSE_INDEP__
+ * recursively explore each bucket currently selected, looking for
+ * __arg1__ items of type __arg2__ and select them.
+ * - __CRUSH_RULE_CHOOSELEAF_FIRSTN__ and __CRUSH_RULE_CHOOSELEAF_INDEP__
+ * recursively explore each bucket currently selected, looking for
+ * __arg1__ leaves within all the buckets of type __arg2__ and
+ * select them.
+ *
+ * In all __CHOOSE__ steps, if __arg1__ is less than or equal to zero,
+ * the number of items to select is equal to the __max_result__ argument
+ * of crush_do_rule() minus __arg1__. It is common to set __arg1__ to zero
+ * to select as many items as requested by __max_result__.
+ *
+ * - __CRUSH_RULE_SET_CHOOSE_TRIES__ and __CRUSH_RULE_SET_CHOOSELEAF_TRIES__
+ *
+ * The CHOOSE_FIRSTN and CHOOSE_INDEP rule step look for buckets of
+ * a given type, randomly selecting them. If they are unlucky and
+ * find the same bucket twice, they will try N+1 times (N being the
+ * value of the choose_total_tries tunable). If there is a previous
+ * SET_CHOOSE_TRIES step in the same rule, it will try C times
+ * instead (C being the value of the argument of the
+ * SET_CHOOSE_TRIES step).
+ *
+ * Note: the __choose_total_tries__ tunable defined in crush_map is
+ * the number of retry, not the number of tries. The number of tries
+ * is the number of retry+1. The SET_CHOOSE_TRIES rule step sets the
+ * number of tries and does not need the + 1. This confusing
+ * difference is inherited from an off-by-one bug from years ago.
+ *
+ * The CHOOSELEAF_FIRSTN and CHOOSELEAF_INDEP rule step do the same
+ * as CHOOSE_FIRSTN and CHOOSE_INDEP but also recursively explore
+ * each bucket found, looking for a single device. The same device
+ * may be found in two different buckets because the crush map is
+ * not a strict hierarchy, it is a DAG. When such a collision
+ * happens, they will try again. The number of times they try to
+ * find a non colliding device is:
+ *
+ * - If FIRSTN and there is no previous SET_CHOOSELEAF_TRIES rule
+ * step: try N + 1 times (N being the value of the
+ * __choose_total_tries__ tunable defined in crush_map)
+ *
+ * - If FIRSTN and there is a previous SET_CHOOSELEAF_TRIES rule
+ * step: try P times (P being the value of the argument of the
+ * SET_CHOOSELEAF_TRIES rule step)
+ *
+ * - If INDEP and there is no previous SET_CHOOSELEAF_TRIES rule
+ * step: try 1 time.
+ *
+ * - If INDEP and there is a previous SET_CHOOSELEAF_TRIES rule step: try
+ * P times (P being the value of the argument of the SET_CHOOSELEAF_TRIES
+ * rule step)
+ *
+ * @param rule the rule in which the step is inserted
+ * @param pos the zero based step index
+ * @param op one of __CRUSH_RULE_NOOP__, __CRUSH_RULE_TAKE__, __CRUSH_RULE_CHOOSE_FIRSTN__, __CRUSH_RULE_CHOOSE_INDEP__, __CRUSH_RULE_CHOOSELEAF_FIRSTN__, __CRUSH_RULE_CHOOSELEAF_INDEP__, __CRUSH_RULE_SET_CHOOSE_TRIES__, __CRUSH_RULE_SET_CHOOSELEAF_TRIES__ or __CRUSH_RULE_EMIT__
+ * @param arg1 first argument for __op__
+ * @param arg2 second argument for __op__
+ */
+extern void crush_rule_set_step(struct crush_rule *rule, int pos, int op, int arg1, int arg2);
+/** @ingroup API
+ *
+ * Add the __rule__ into the crush __map__ and assign it the
+ * __ruleno__ unique identifier. If __ruleno__ is -1, the function will
+ * assign the lowest available identifier. The __ruleno__ value must be
+ * a positive integer lower than __CRUSH_MAX_RULES__.
+ *
+ * - return -ENOSPC if the rule identifier is >= __CRUSH_MAX_RULES__
+ * - return -ENOMEM if __realloc(3)__ fails to expand the array of
+ * rules in the __map__
+ *
+ * @param map the crush_map
+ * @param rule the rule to add to the __map__
+ * @param ruleno a positive integer < __CRUSH_MAX_RULES__ or -1
+ *
+ * @returns the rule unique identifier on success, < 0 on error
+ */
+extern int crush_add_rule(struct crush_map *map, struct crush_rule *rule, int ruleno);
+
+/* buckets */
+extern int crush_get_next_bucket_id(struct crush_map *map);
+/** @ingroup API
+ *
+ * Add __bucket__ into the crush __map__ and assign it the
+ * __bucketno__ unique identifier. If __bucketno__ is 0, the function
+ * will assign the lowest available identifier. The bucket identifier
+ * must be a negative integer. The bucket identifier is returned via
+ * __idout__.
+ *
+ * - return -ENOMEM if __realloc(3)__ fails to expand the array of
+ * buckets in the __map__
+ * - return -EEXIST if the __bucketno__ identifier is already assigned
+ * to another bucket.
+ *
+ * @param[in] map the crush_map
+ * @param[in] bucketno the bucket unique identifer or 0
+ * @param[in] bucket the bucket to add to the __map__
+ * @param[out] idout a pointer to the bucket identifier
+ *
+ * @returns 0 on success, < 0 on error
+ */
+extern int crush_add_bucket(struct crush_map *map,
+ int bucketno,
+ struct crush_bucket *bucket, int *idout);
+/** @ingroup API
+ *
+ * Allocate a crush_bucket with __malloc(3)__ and initialize it. The
+ * content of the bucket is filled with __size__ items from
+ * __items__. The item selection is set to use __alg__ which is one of
+ * ::CRUSH_BUCKET_UNIFORM , ::CRUSH_BUCKET_LIST or
+ * ::CRUSH_BUCKET_STRAW2. The initial __items__ are assigned a
+ * weight from the __weights__ array, depending on the value of
+ * __alg__. If __alg__ is ::CRUSH_BUCKET_UNIFORM, all items are set
+ * to have a weight equal to __weights[0]__, otherwise the weight of
+ * __items[x]__ is set to be the value of __weights[x]__.
+ *
+ * The caller is responsible for deallocating the returned pointer via
+ * crush_destroy_bucket().
+ *
+ * @param map __unused__
+ * @param alg algorithm for item selection
+ * @param hash always set to CRUSH_HASH_RJENKINS1
+ * @param type user defined bucket type
+ * @param size of the __items__ array
+ * @param items array of __size__ items
+ * @param weights the weight of each item in __items__, depending on __alg__
+ *
+ * @returns a pointer to the newly created bucket or NULL
+ */
+struct crush_bucket *crush_make_bucket(struct crush_map *map, int alg, int hash, int type, int size, int *items, int *weights);
+extern struct crush_choose_arg *crush_make_choose_args(struct crush_map *map, int num_positions);
+extern void crush_destroy_choose_args(struct crush_choose_arg *args);
+/** @ingroup API
+ *
+ * Add __item__ to __bucket__ with __weight__. The weight of the new
+ * item is added to the weight of the bucket so that it reflects
+ * the total weight of all items.
+ *
+ * If __bucket->alg__ is ::CRUSH_BUCKET_UNIFORM, the value of __weight__ must be equal to
+ * __(struct crush_bucket_uniform *)bucket->item_weight__.
+ *
+ * - return -ENOMEM if the __bucket__ cannot be resized with __realloc(3)__.
+ * - return -ERANGE if adding __weight__ to the weight of the bucket overflows.
+ * - return -EINVAL if __bucket->alg__ is ::CRUSH_BUCKET_UNIFORM and
+ * the __weight__ is not equal to __(struct crush_bucket_uniform *)bucket->item_weight__.
+ * - return -1 if the value of __bucket->alg__ is unknown.
+ *
+ * @returns 0 on success, < 0 on error
+ */
+extern int crush_bucket_add_item(struct crush_map *map, struct crush_bucket *bucket, int item, int weight);
+/** @ingroup API
+ *
+ * If __bucket->alg__ is ::CRUSH_BUCKET_UNIFORM,
+ * __(struct crush_bucket_uniform *)bucket->item_weight__ is set to __weight__ and the
+ * weight of the bucket is set to be the number of items in the bucket times the weight.
+ * The return value is the difference between the new bucket weight and the former
+ * bucket weight. The __item__ argument is ignored.
+ *
+ * If __bucket->alg__ is different from ::CRUSH_BUCKET_UNIFORM,
+ * set the __weight__ of __item__ in __bucket__. The former weight of the
+ * item is subtracted from the weight of the bucket and the new weight is added.
+ * The return value is the difference between the new item weight and the former
+ * item weight.
+ *
+ * @returns the difference between the new weight and the former weight
+ */
+extern int crush_bucket_adjust_item_weight(struct crush_map *map, struct crush_bucket *bucket, int item, int weight);
+/** @ingroup API
+ *
+ * Recursively update the weight of __bucket__ and its children, deep
+ * first. The __bucket__ weight is set to the sum of the weight of the
+ * items it contains.
+ *
+ * - return -ERANGE if the sum of the weight of the items in __bucket__ overflows.
+ * - return -1 if the value of __bucket->alg__ is unknown.
+ *
+ * @param map a crush_map containing __bucket__
+ * @param bucket the root of the tree to reweight
+ * @returns 0 on success, < 0 on error
+ */
+extern int crush_reweight_bucket(struct crush_map *map, struct crush_bucket *bucket);
+/** @ingroup API
+ *
+ * Remove __bucket__ from __map__ and deallocate it via crush_destroy_bucket().
+ * __assert(3)__ that __bucket__ is in __map__. The caller is responsible for
+ * making sure the bucket is not the child of any other bucket in the __map__.
+ *
+ * @param map a crush_map containing __bucket__
+ * @param bucket the bucket to remove from __map__
+ * @returns 0
+ */
+extern int crush_remove_bucket(struct crush_map *map, struct crush_bucket *bucket);
+/** @ingroup API
+ *
+ * Remove __item__ from __bucket__ and subtract the item weight from
+ * the bucket weight. If the weight of the item is greater than the
+ * weight of the bucket, silentely set the bucket weight to zero.
+ *
+ * - return -ENOMEM if the __bucket__ cannot be sized down with __realloc(3)__.
+ * - return -1 if the value of __bucket->alg__ is unknown.
+ *
+ * @param map __unused__
+ * @param bucket the bucket from which __item__ is removed
+ * @param item the item to remove from __bucket__
+ * @returns 0 on success, < 0 on error
+ */
+extern int crush_bucket_remove_item(struct crush_map *map, struct crush_bucket *bucket, int item);
+
+struct crush_bucket_uniform *
+crush_make_uniform_bucket(int hash, int type, int size,
+ int *items,
+ int item_weight);
+struct crush_bucket_list*
+crush_make_list_bucket(int hash, int type, int size,
+ int *items,
+ int *weights);
+struct crush_bucket_tree*
+crush_make_tree_bucket(int hash, int type, int size,
+ int *items, /* in leaf order */
+ int *weights);
+struct crush_bucket_straw *
+crush_make_straw_bucket(struct crush_map *map,
+ int hash, int type, int size,
+ int *items,
+ int *weights);
+
+extern int crush_addition_is_unsafe(__u32 a, __u32 b);
+extern int crush_multiplication_is_unsafe(__u32 a, __u32 b);
+
+/** @ingroup API
+ *
+ * Set the __map__ tunables to implement the most ancient behavior,
+ * for backward compatibility purposes only.
+ *
+ * - choose_local_tries == 2
+ * - choose_local_fallback_tries == 5
+ * - choose_total_tries == 19
+ * - chooseleaf_descend_once == 0
+ * - chooseleaf_vary_r == 0
+ * - straw_calc_version == 0
+ * - chooseleaf_stable = 0
+ *
+ * See the __crush_map__ documentation for more information about
+ * each tunable.
+ *
+ * @param map a crush_map
+ */
+extern void set_legacy_crush_map(struct crush_map *map);
+/** @ingroup API
+ *
+ * Set the __map__ tunables to implement the optimal behavior. These
+ * are the values set by crush_create(). It does not guarantee a
+ * stable mapping after an upgrade.
+ *
+ * For instance when a bug is fixed it may significantly change the
+ * mapping. In that case a new tunable (say tunable_new) is added so
+ * the caller can control when the bug fix is activated. The
+ * set_optimal_crush_map() function will always set all tunables,
+ * including tunable_new, to fix all bugs even if it means changing
+ * the mapping. If the caller needs fine grained control on the
+ * tunables to upgrade to a new version without changing the mapping,
+ * it needs to set the __crush_map__ tunables individually.
+ *
+ * See the __crush_map__ documentation for more information about
+ * each tunable.
+ *
+ * @param map a crush_map
+ */
+extern void set_optimal_crush_map(struct crush_map *map);
+
+#endif
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