1 files changed, 25 insertions, 10 deletions

diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index f358d0bfa76b..79d14d70b7ea 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -2445,19 +2445,34 @@ static void apply_upmap(struct ceph_osdmap *osdmap,
 
         pg = lookup_pg_mapping(&osdmap->pg_upmap_items, pgid);
         if (pg) {
-                for (i = 0; i < raw->size; i++) {
-                        for (j = 0; j < pg->pg_upmap_items.len; j++) {
-                                int from = pg->pg_upmap_items.from_to[j][0];
-                                int to = pg->pg_upmap_items.from_to[j][1];
-
-                                if (from == raw->osds[i]) {
-                                        if (!(to != CRUSH_ITEM_NONE &&
-                                              to < osdmap->max_osd &&
-                                              osdmap->osd_weight[to] == 0))
-                                                raw->osds[i] = to;
+                /*
+                 * Note: this approach does not allow a bidirectional swap,
+                 * e.g., [[1,2],[2,1]] applied to [0,1,2] -> [0,2,1].
+                 */
+                for (i = 0; i < pg->pg_upmap_items.len; i++) {
+                        int from = pg->pg_upmap_items.from_to[i][0];
+                        int to = pg->pg_upmap_items.from_to[i][1];
+                        int pos = -1;
+                        bool exists = false;
+
+                        /* make sure replacement doesn't already appear */
+                        for (j = 0; j < raw->size; j++) {
+                                int osd = raw->osds[j];
+
+                                if (osd == to) {
+                                        exists = true;
                                         break;
                                 }
+                                /* ignore mapping if target is marked out */
+                                if (osd == from && pos < 0 &&
+                                    !(to != CRUSH_ITEM_NONE &&
+                                      to < osdmap->max_osd &&
+                                      osdmap->osd_weight[to] == 0)) {
+                                        pos = j;
+                                }
                         }
+                        if (!exists && pos >= 0)
+                                raw->osds[pos] = to;
                 }
         }
 }