Crush: Ensuring at most num-rep osds are selected

Crush temporary buffers are allocated as per replica size configured
by the user.When there are more final osds (to be selected as per
rule) than the replicas, buffer overlaps and it causes crash.Now, it
ensures that at most num-rep osds are selected even if more number of
osds are allowed by the rule.

Fixes: #9492
Signed-off-by: Johnu George <johnugeo@cisco.com>

diff --git a/src/crush/mapper.c b/src/crush/mapper.c
index e610f3108ac4f6bf7d729fd609a3c75a2bcb5a28..f2ca9ea543ab27f6e75dec1a423011bdc944d1a5 100644 (file)
--- a/src/crush/mapper.c
+++ b/src/crush/mapper.c
@@ -291,6 +291,7 @@ static int is_out(const struct crush_map *map,
  * @type: the type of item to choose
  * @out: pointer to output vector
  * @outpos: our position in that vector
+ * @out_size: size of the out vector
  * @tries: number of attempts to make
  * @recurse_tries: number of attempts to have recursive chooseleaf make
  * @local_retries: localized retries
@@ -305,6 +306,7 @@ static int crush_choose_firstn(const struct crush_map *map,
                               const __u32 *weight, int weight_max,
                               int x, int numrep, int type,
                               int *out, int outpos,
+                              int out_size,
                               unsigned int tries,
                               unsigned int recurse_tries,
                               unsigned int local_retries,
@@ -323,6 +325,7 @@ static int crush_choose_firstn(const struct crush_map *map,
        int item = 0;
        int itemtype;
        int collide, reject;
+       int count = out_size;
 
        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" : "",
@@ -330,7 +333,7 @@ static int crush_choose_firstn(const struct crush_map *map,
                tries, recurse_tries, local_retries, local_fallback_retries,
                parent_r);
 
-       for (rep = outpos; rep < numrep; rep++) {
+       for (rep = outpos; rep < numrep && count > 0 ; rep++) {
                /* keep trying until we get a non-out, non-colliding item */
                ftotal = 0;
                skip_rep = 0;
@@ -404,7 +407,7 @@ static int crush_choose_firstn(const struct crush_map *map,
                                                         map->buckets[-1-item],
                                                         weight, weight_max,
                                                         x, outpos+1, 0,
-                                                        out2, outpos,
+                                                        out2, outpos, count,
                                                         recurse_tries, 0,
                                                         local_retries,
                                                         local_fallback_retries,
@@ -464,6 +467,7 @@ reject:
                dprintk("CHOOSE got %d\n", item);
                out[outpos] = item;
                outpos++;
+               count--;
 
                if (map->choose_tries && ftotal <= map->choose_total_tries)
                        map->choose_tries[ftotal]++;
@@ -793,6 +797,7 @@ int crush_do_rule(const struct crush_map *map,
                                                x, numrep,
                                                curstep->arg2,
                                                o+osize, j,
+                                               result_max-osize,
                                                choose_tries,
                                                recurse_tries,
                                                choose_local_retries,