crush: fix force to behave with non-root TAKE

If the (first) TAKE in the crush rule is not the root, see if they picked
a point somewhere beneath the appropriate part of the hierachy.  If not,
continue with a normal mapping.

Previously we would simply error out in this case and map nothing.

Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/src/crush/mapper.c b/src/crush/mapper.c
index 52ece9c5a899d9aef9e2c588c96242e51a488a9e..79a9814ceb6ca048c80658a305640e4e1bcad57c 100644 (file)
--- a/src/crush/mapper.c
+++ b/src/crush/mapper.c
@@ -489,7 +489,8 @@ int crush_do_rule(const struct crush_map *map,
        /*
         * determine hierarchical context of force, if any.  note
         * that this may or may not correspond to the specific types
-        * referenced by the crush rule.
+        * referenced by the crush rule.  it will also only affect
+        * the first descent (TAKE).
         */
        if (force >= 0 &&
            force < map->max_devices &&
@@ -511,13 +512,14 @@ int crush_do_rule(const struct crush_map *map,
                switch (rule->steps[step].op) {
                case CRUSH_RULE_TAKE:
                        w[0] = rule->steps[step].arg1;
-                       if (force_pos >= 0) {
-                               if (force_context[force_pos] != w[0]) {
-                                       rc = -1;  /* forced mapping dne */
-                                       goto out;
-                               }
+
+                       /* find position in force_context/hierarchy */
+                       while (force_pos >= 0 && force_context[force_pos] != w[0])
                                force_pos--;
-                       }
+                       /* and move past it */
+                       if (force_pos >= 0)
+                               force_pos--;
+
                        wsize = 1;
                        break;