There are four possible states for the WT_PAGE.dsk memory: the WT_PAGE

disk-image is mapped into memory (unmap on page discard), is in allocated
memory (free on page discard), is in memory belonging to a caller (ignore on
page discard), or isn't set at all (ignore on page discard).

We've been trying to figure out which based on the state of WT_PAGE.dsk and
a single flag, and that's not enough.  Use two explicit flags, one for
mapped memory and one for allocated memory, and neither flag is set for the
latter two states.

8 files changed, 21 insertions, 23 deletions

diff --git a/src/btree/bt_discard.c b/src/btree/bt_discard.c
index e91234c050e..1f500960468 100644
--- a/src/btree/bt_discard.c
+++ b/src/btree/bt_discard.c
@@ -77,15 +77,12 @@ __wt_page_out(WT_SESSION_IMPL *session, WT_PAGE **pagep)
 		break;
 	}
 
-	/* Free any allocated disk image. */
-	if (page->dsk != NULL) {
-		if (F_ISSET_ATOMIC(page, WT_PAGE_DISK_NOT_ALLOC))
-			__wt_mmap_discard(
-			    session, page->dsk, page->dsk->mem_size);
-		else
-			__wt_overwrite_and_free_len(
-			    session, page->dsk, page->dsk->mem_size);
-	}
+	/* Discard any disk image. */
+	if (F_ISSET_ATOMIC(page, WT_PAGE_DISK_ALLOC))
+		__wt_overwrite_and_free_len(
+		    session, page->dsk, page->dsk->mem_size);
+	if (F_ISSET_ATOMIC(page, WT_PAGE_DISK_MAPPED))
+		__wt_mmap_discard(session, page->dsk, page->dsk->mem_size);
 
 	__wt_overwrite_and_free(session, page);
 }
diff --git a/src/btree/bt_handle.c b/src/btree/bt_handle.c
index 6830bc83c3c..9f4e167b773 100644
--- a/src/btree/bt_handle.c
+++ b/src/btree/bt_handle.c
@@ -342,8 +342,9 @@ __wt_btree_tree_open(
 
 	/* Read the page, then build the in-memory version of the page. */
 	WT_ERR(__wt_bt_read(session, &dsk, addr, addr_size));
-	WT_ERR(__wt_page_inmem(session,
-	    NULL, NULL, dsk.mem, F_ISSET(&dsk, WT_ITEM_MAPPED) ? 1 : 0, &page));
+	WT_ERR(__wt_page_inmem(session, NULL, NULL, dsk.mem,
+	    F_ISSET(&dsk, WT_ITEM_MAPPED) ?
+	    WT_PAGE_DISK_MAPPED : WT_PAGE_DISK_ALLOC, &page));
 	btree->root_page = page;
 
 	if (0) {
diff --git a/src/btree/bt_page.c b/src/btree/bt_page.c
index 7577d23c088..8789411b883 100644
--- a/src/btree/bt_page.c
+++ b/src/btree/bt_page.c
@@ -198,7 +198,7 @@ __wt_page_alloc(WT_SESSION_IMPL *session,
 int
 __wt_page_inmem(
     WT_SESSION_IMPL *session, WT_PAGE *parent, WT_REF *parent_ref,
-    WT_PAGE_HEADER *dsk, int disk_not_alloc, WT_PAGE **pagep)
+    WT_PAGE_HEADER *dsk, uint32_t flags, WT_PAGE **pagep)
 {
 	WT_DECL_RET;
 	WT_PAGE *page;
@@ -254,14 +254,13 @@ __wt_page_inmem(
 	WT_RET(__wt_page_alloc(session, dsk->type, alloc_entries, &page));
 	page->dsk = dsk;
 	page->read_gen = WT_READ_GEN_NOTSET;
-	if (disk_not_alloc)
-		F_SET_ATOMIC(page, WT_PAGE_DISK_NOT_ALLOC);
+	F_SET_ATOMIC(page, flags);
 
 	/*
 	 * Track the memory allocated to build this page so we can update the
 	 * cache statistics in a single call.
 	 */
-	size = disk_not_alloc ? 0 : dsk->mem_size;
+	size = LF_ISSET(WT_PAGE_DISK_ALLOC) ? dsk->mem_size : 0;
 
 	switch (page->type) {
 	case WT_PAGE_COL_FIX:
diff --git a/src/btree/bt_read.c b/src/btree/bt_read.c
index 3a9cb7f8221..85906414999 100644
--- a/src/btree/bt_read.c
+++ b/src/btree/bt_read.c
@@ -103,8 +103,9 @@ __wt_cache_read(WT_SESSION_IMPL *session, WT_PAGE *parent, WT_REF *ref)
 		WT_ERR(__wt_bt_read(session, &tmp, addr, size));
 
 		/* Build the in-memory version of the page. */
-		WT_ERR(__wt_page_inmem(session, parent, ref,
-		    tmp.mem, F_ISSET(&tmp, WT_ITEM_MAPPED) ? 1 : 0, &page));
+		WT_ERR(__wt_page_inmem(session, parent, ref, tmp.mem,
+		    F_ISSET(&tmp, WT_ITEM_MAPPED) ?
+		    WT_PAGE_DISK_MAPPED : WT_PAGE_DISK_ALLOC, &page));
 
 		/* If the page was deleted, instantiate that information. */
 		if (previous_state == WT_REF_DELETED)
diff --git a/src/btree/bt_slvg.c b/src/btree/bt_slvg.c
index 3bad6b84622..6fd26d1f5af 100644
--- a/src/btree/bt_slvg.c
+++ b/src/btree/bt_slvg.c
@@ -533,7 +533,7 @@ __slvg_trk_leaf(WT_SESSION_IMPL *session,
 		 * on every leaf page, and if you need to speed up the salvage,
 		 * it's probably a great place to start.
 		 */
-		WT_ERR(__wt_page_inmem(session, NULL, NULL, dsk, 1, &page));
+		WT_ERR(__wt_page_inmem(session, NULL, NULL, dsk, 0, &page));
 		WT_ERR(__wt_row_leaf_key_copy(session,
 		    page, &page->u.row.d[0], &trk->row_start));
 		WT_ERR(__wt_row_leaf_key_copy(session,
@@ -1591,7 +1591,7 @@ __slvg_row_trk_update_start(
 	 */
 	WT_RET(__wt_scr_alloc(session, trk->size, &dsk));
 	WT_ERR(__wt_bt_read(session, dsk, trk->addr.addr, trk->addr.size));
-	WT_ERR(__wt_page_inmem(session, NULL, NULL, dsk->mem, 1, &page));
+	WT_ERR(__wt_page_inmem(session, NULL, NULL, dsk->mem, 0, &page));
 
 	/*
 	 * Walk the page, looking for a key sorting greater than the specified
diff --git a/src/btree/rec_write.c b/src/btree/rec_write.c
index 3aeca87a2fa..6e1c1245b21 100644
--- a/src/btree/rec_write.c
+++ b/src/btree/rec_write.c
@@ -4007,7 +4007,6 @@ __rec_split_merge_new(WT_SESSION_IMPL *session,
 		page->u.intl.recno = r->bnd[0].recno;
 	page->read_gen = WT_READ_GEN_NOTSET;
 	page->entries = r->bnd_next;
-	page->flags_atomic = WT_PAGE_DISK_NOT_ALLOC;
 
 	/*
 	 * We don't re-write parent pages when child pages split, which means
diff --git a/src/include/btmem.h b/src/include/btmem.h
index 087f5079fb3..cefd4316972 100644
--- a/src/include/btmem.h
+++ b/src/include/btmem.h
@@ -324,8 +324,9 @@ struct __wt_page {
 	uint8_t type;			/* Page type */
 
 #define	WT_PAGE_BUILD_KEYS	0x01	/* Keys have been built in memory */
-#define	WT_PAGE_DISK_NOT_ALLOC	0x02	/* Ignore disk image on page discard */
-#define	WT_PAGE_EVICT_LRU	0x04	/* Page is on the LRU queue */
+#define	WT_PAGE_DISK_ALLOC	0x02	/* Disk image in allocated memory */
+#define	WT_PAGE_DISK_MAPPED	0x04	/* Disk image in mapped memory */
+#define	WT_PAGE_EVICT_LRU	0x08	/* Page is on the LRU queue */
 	uint8_t flags_atomic;		/* Atomic flags, use F_*_ATOMIC */
 };
 
diff --git a/src/include/extern.h b/src/include/extern.h
index ec0fa310de7..f7a5f21fa81 100644
--- a/src/include/extern.h
+++ b/src/include/extern.h
@@ -338,7 +338,7 @@ extern int __wt_page_inmem( WT_SESSION_IMPL *session,
     WT_PAGE *parent,
     WT_REF *parent_ref,
     WT_PAGE_HEADER *dsk,
-    int disk_not_alloc,
+    uint32_t flags,
     WT_PAGE **pagep);
 extern int __wt_cache_read(WT_SESSION_IMPL *session,
     WT_PAGE *parent,