mdb_page_get() can ignore the toplevel spill list

...when we search dirty list before instead of after spill list.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 3fd47ddcb41c2464184810fe97f1ec9876621eb9..cd150cf89d23364137fd4fc55c37bcdf2ff47203 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -6664,26 +6664,17 @@ mdb_page_get(MDB_cursor *mc, pgno_t pgno,
 #endif
        MDB_page **ret)
 {
-       MDB_txn *txn = mc->mc_txn;
+       MDB_txn *txn = mc->mc_txn, *tx2;
        MDB_page *p = NULL;
 
        if (! (mc->mc_flags & (C_ORIG_RDONLY|C_WRITEMAP))) {
-               MDB_txn *tx2 = txn;
-               do {
+               for (tx2 = txn;; ) {
                        MDB_ID2L dl = tx2->mt_u.dirty_list;
+                       MDB_IDL  sl;
                        unsigned x;
-                       /* Spilled pages were dirtied in this txn and flushed
-                        * because the dirty list got full. Bring this page
-                        * back in from the map (but don't unspill it here,
-                        * leave that unless page_touch happens again).
+                       /* tx2 may have malloced its own "dirty" version of the
+                        * page, with the same page number.
                         */
-                       if (tx2->mt_spill_pgs) {
-                               MDB_ID pn = pgno << 1;
-                               x = mdb_midl_search(tx2->mt_spill_pgs, pn);
-                               if (x <= tx2->mt_spill_pgs[0] && tx2->mt_spill_pgs[x] == pn) {
-                                       goto mapped;
-                               }
-                       }
                        if (dl[0].mid) {
                                unsigned x = mdb_mid2l_search(dl, pgno);
                                if (x <= dl[0].mid && dl[x].mid == pgno) {
@@ -6691,7 +6682,23 @@ mdb_page_get(MDB_cursor *mc, pgno_t pgno,
                                        goto done;
                                }
                        }
-               } while ((tx2 = tx2->mt_parent) != NULL);
+                       /* Spilled pages were dirtied in this txn, then cleaned
+                        * and flushed to the map when dirty_list got full.
+                        * Check if tx2 spilled the page before moving on to
+                        * search the parent.  (But don't unspill here, leave
+                        * that unless page_touch happens again.)
+                        */
+                       sl = tx2->mt_spill_pgs;
+                       if ((tx2 = tx2->mt_parent) == NULL)
+                               break;
+                       if (sl) {
+                               MDB_ID pn = pgno << 1;
+                               x = mdb_midl_search(sl, pn);
+                               if (x <= sl[0] && sl[x] == pn) {
+                                       goto mapped;
+                               }
+                       }
+               }
        }
 
        if (pgno >= txn->mt_next_pgno) {