svn commit: r355612 - head/sys/vm

[Doug Moore]

Author: dougm
Date: Wed Dec 11 16:09:57 2019
New Revision: 355612
URL: https://svnweb.freebsd.org/changeset/base/355612

Log:
  Extract code common to _vm_map_clip_start and _vm_map_clip_end into a
  function, vm_map_entry_clone, that can be invoked by each.
  
  Reviewed by: kib, markj
  Differential Revision: https://reviews.freebsd.org/D22760

Modified:
  head/sys/vm/vm_map.c

Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c	Wed Dec 11 15:52:29 2019	(r355611)
+++ head/sys/vm/vm_map.c	Wed Dec 11 16:09:57 2019	(r355612)
@@ -2291,6 +2291,42 @@ vm_map_entry_charge_object(vm_map_t map, vm_map_entry_
 }
 
 /*
+ *	vm_map_entry_clone
+ *
+ *	Create a duplicate map entry for clipping.
+ */
+static vm_map_entry_t
+vm_map_entry_clone(vm_map_t map, vm_map_entry_t entry)
+{
+	vm_map_entry_t new_entry;
+
+	VM_MAP_ASSERT_LOCKED(map);
+
+	/*
+	 * Create a backing object now, if none exists, so that more individual
+	 * objects won't be created after the map entry is split.
+	 */
+	vm_map_entry_charge_object(map, entry);
+
+	/* Clone the entry. */
+	new_entry = vm_map_entry_create(map);
+	*new_entry = *entry;
+	if (new_entry->cred != NULL)
+		crhold(entry->cred);
+	if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
+		vm_object_reference(new_entry->object.vm_object);
+		vm_map_entry_set_vnode_text(new_entry, true);
+		/*
+		 * The object->un_pager.vnp.writemappings for the object of
+		 * MAP_ENTRY_WRITECNT type entry shall be kept as is here.  The
+		 * virtual pages are re-distributed among the clipped entries,
+		 * so the sum is left the same.
+		 */
+	}
+	return (new_entry);
+}
+
+/*
  *	vm_map_clip_start:	[ internal use only ]
  *
  *	Asserts that the given entry begins at or after
@@ -2316,16 +2352,8 @@ _vm_map_clip_start(vm_map_t map, vm_map_entry_t entry,
 	KASSERT(entry->end > start && entry->start < start,
 	    ("_vm_map_clip_start: invalid clip of entry %p", entry));
 
-	/*
-	 * Create a backing object now, if none exists, so that more individual
-	 * objects won't be created after the map entry is split.
-	 */
-	vm_map_entry_charge_object(map, entry);
+	new_entry = vm_map_entry_clone(map, entry);
 
-	/* Clone the entry. */
-	new_entry = vm_map_entry_create(map);
-	*new_entry = *entry;
-
 	/*
 	 * Split off the front portion.  Insert the new entry BEFORE this one,
 	 * so that this entry has the specified starting address.
@@ -2333,22 +2361,7 @@ _vm_map_clip_start(vm_map_t map, vm_map_entry_t entry,
 	new_entry->end = start;
 	entry->offset += (start - entry->start);
 	entry->start = start;
-	if (new_entry->cred != NULL)
-		crhold(entry->cred);
-
 	vm_map_entry_link(map, new_entry);
-
-	if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
-		vm_object_reference(new_entry->object.vm_object);
-		vm_map_entry_set_vnode_text(new_entry, true);
-		/*
-		 * The object->un_pager.vnp.writemappings for the
-		 * object of MAP_ENTRY_WRITECNT type entry shall be
-		 * kept as is here.  The virtual pages are
-		 * re-distributed among the clipped entries, so the sum is
-		 * left the same.
-		 */
-	}
 }
 
 /*
@@ -2377,31 +2390,15 @@ _vm_map_clip_end(vm_map_t map, vm_map_entry_t entry, v
 	KASSERT(entry->start < end && entry->end > end,
 	    ("_vm_map_clip_end: invalid clip of entry %p", entry));
 
-	/*
-	 * Create a backing object now, if none exists, so that more individual
-	 * objects won't be created after the map entry is split.
-	 */
-	vm_map_entry_charge_object(map, entry);
+	new_entry = vm_map_entry_clone(map, entry);
 
-	/* Clone the entry. */
-	new_entry = vm_map_entry_create(map);
-	*new_entry = *entry;
-
 	/*
 	 * Split off the back portion.  Insert the new entry AFTER this one,
 	 * so that this entry has the specified ending address.
 	 */
 	new_entry->start = entry->end = end;
 	new_entry->offset += (end - entry->start);
-	if (new_entry->cred != NULL)
-		crhold(entry->cred);
-
 	vm_map_entry_link(map, new_entry);
-
-	if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
-		vm_object_reference(new_entry->object.vm_object);
-		vm_map_entry_set_vnode_text(new_entry, true);
-	}
 }
 
 /*