1 files changed, 180 insertions, 0 deletions

diff --git a/include/linux/crush/crush.h b/include/linux/crush/crush.h
new file mode 100644
index 000000000000..97e435b191f4
--- /dev/null
+++ b/include/linux/crush/crush.h
@@ -0,0 +1,180 @@
+#ifndef CEPH_CRUSH_CRUSH_H
+#define CEPH_CRUSH_CRUSH_H
+
+#include <linux/types.h>
+
+/*
+ * CRUSH is a pseudo-random data distribution algorithm that
+ * efficiently distributes input values (typically, data objects)
+ * across a heterogeneous, structured storage cluster.
+ *
+ * The algorithm was originally described in detail in this paper
+ * (although the algorithm has evolved somewhat since then):
+ *
+ *     http://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf
+ *
+ * LGPL2
+ */
+
+
+#define CRUSH_MAGIC 0x00010000ul   /* for detecting algorithm revisions */
+
+
+#define CRUSH_MAX_DEPTH 10  /* max crush hierarchy depth */
+#define CRUSH_MAX_SET   10  /* max size of a mapping result */
+
+
+/*
+ * CRUSH uses user-defined "rules" to describe how inputs should be
+ * mapped to devices.  A rule consists of sequence of steps to perform
+ * to generate the set of output devices.
+ */
+struct crush_rule_step {
+        __u32 op;
+        __s32 arg1;
+        __s32 arg2;
+};
+
+/* step op codes */
+enum {
+        CRUSH_RULE_NOOP = 0,
+        CRUSH_RULE_TAKE = 1,          /* arg1 = value to start with */
+        CRUSH_RULE_CHOOSE_FIRSTN = 2, /* arg1 = num items to pick */
+                                      /* arg2 = type */
+        CRUSH_RULE_CHOOSE_INDEP = 3,  /* same */
+        CRUSH_RULE_EMIT = 4,          /* no args */
+        CRUSH_RULE_CHOOSE_LEAF_FIRSTN = 6,
+        CRUSH_RULE_CHOOSE_LEAF_INDEP = 7,
+};
+
+/*
+ * for specifying choose num (arg1) relative to the max parameter
+ * passed to do_rule
+ */
+#define CRUSH_CHOOSE_N            0
+#define CRUSH_CHOOSE_N_MINUS(x)   (-(x))
+
+/*
+ * The rule mask is used to describe what the rule is intended for.
+ * Given a ruleset and size of output set, we search through the
+ * rule list for a matching rule_mask.
+ */
+struct crush_rule_mask {
+        __u8 ruleset;
+        __u8 type;
+        __u8 min_size;
+        __u8 max_size;
+};
+
+struct crush_rule {
+        __u32 len;
+        struct crush_rule_mask mask;
+        struct crush_rule_step steps[0];
+};
+
+#define crush_rule_size(len) (sizeof(struct crush_rule) + \
+                              (len)*sizeof(struct crush_rule_step))
+
+
+
+/*
+ * A bucket is a named container of other items (either devices or
+ * other buckets).  Items within a bucket are chosen using one of a
+ * few different algorithms.  The table summarizes how the speed of
+ * each option measures up against mapping stability when items are
+ * added or removed.
+ *
+ *  Bucket Alg     Speed       Additions    Removals
+ *  ------------------------------------------------
+ *  uniform         O(1)       poor         poor
+ *  list            O(n)       optimal      poor
+ *  tree            O(log n)   good         good
+ *  straw           O(n)       optimal      optimal
+ */
+enum {
+        CRUSH_BUCKET_UNIFORM = 1,
+        CRUSH_BUCKET_LIST = 2,
+        CRUSH_BUCKET_TREE = 3,
+        CRUSH_BUCKET_STRAW = 4
+};
+extern const char *crush_bucket_alg_name(int alg);
+
+struct crush_bucket {
+        __s32 id;        /* this'll be negative */
+        __u16 type;      /* non-zero; type=0 is reserved for devices */
+        __u8 alg;        /* one of CRUSH_BUCKET_* */
+        __u8 hash;       /* which hash function to use, CRUSH_HASH_* */
+        __u32 weight;    /* 16-bit fixed point */
+        __u32 size;      /* num items */
+        __s32 *items;
+
+        /*
+         * cached random permutation: used for uniform bucket and for
+         * the linear search fallback for the other bucket types.
+         */
+        __u32 perm_x;  /* @x for which *perm is defined */
+        __u32 perm_n;  /* num elements of *perm that are permuted/defined */
+        __u32 *perm;
+};
+
+struct crush_bucket_uniform {
+        struct crush_bucket h;
+        __u32 item_weight;  /* 16-bit fixed point; all items equally weighted */
+};
+
+struct crush_bucket_list {
+        struct crush_bucket h;
+        __u32 *item_weights;  /* 16-bit fixed point */
+        __u32 *sum_weights;   /* 16-bit fixed point.  element i is sum
+                                 of weights 0..i, inclusive */
+};
+
+struct crush_bucket_tree {
+        struct crush_bucket h;  /* note: h.size is _tree_ size, not number of
+                                   actual items */
+        __u8 num_nodes;
+        __u32 *node_weights;
+};
+
+struct crush_bucket_straw {
+        struct crush_bucket h;
+        __u32 *item_weights;   /* 16-bit fixed point */
+        __u32 *straws;         /* 16-bit fixed point */
+};
+
+
+
+/*
+ * CRUSH map includes all buckets, rules, etc.
+ */
+struct crush_map {
+        struct crush_bucket **buckets;
+        struct crush_rule **rules;
+
+        /*
+         * Parent pointers to identify the parent bucket a device or
+         * bucket in the hierarchy.  If an item appears more than
+         * once, this is the _last_ time it appeared (where buckets
+         * are processed in bucket id order, from -1 on down to
+         * -max_buckets.
+         */
+        __u32 *bucket_parents;
+        __u32 *device_parents;
+
+        __s32 max_buckets;
+        __u32 max_rules;
+        __s32 max_devices;
+};
+
+
+/* crush.c */
+extern int crush_get_bucket_item_weight(struct crush_bucket *b, int pos);
+extern void crush_calc_parents(struct crush_map *map);
+extern void crush_destroy_bucket_uniform(struct crush_bucket_uniform *b);
+extern void crush_destroy_bucket_list(struct crush_bucket_list *b);
+extern void crush_destroy_bucket_tree(struct crush_bucket_tree *b);
+extern void crush_destroy_bucket_straw(struct crush_bucket_straw *b);
+extern void crush_destroy_bucket(struct crush_bucket *b);
+extern void crush_destroy(struct crush_map *map);
+
+#endif