svn commit: r189024 - head/sys/vm

[Alan Cox]

Author: alc
Date: Wed Feb 25 07:52:53 2009
New Revision: 189024
URL: http://svn.freebsd.org/changeset/base/189024

Log:
  Prior to r188331 a map entry's last read offset was only updated by a hard
  fault.  In r188331 this update was relocated because of synchronization
  changes to a place where it would occur on both hard and soft faults.  This
  change again restricts the update to hard faults.

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Wed Feb 25 01:49:01 2009	(r189023)
+++ head/sys/vm/vm_fault.c	Wed Feb 25 07:52:53 2009	(r189024)
@@ -868,13 +868,17 @@ vnode_locked:
 		}
 	}
 	/*
-	 * update lastr imperfectly (we do not know how much
-	 * getpages will actually read), but good enough.
+	 * If the page was filled by a pager, update the map entry's
+	 * last read offset.  Since the pager does not return the
+	 * actual set of pages that it read, this update is based on
+	 * the requested set.  Typically, the requested and actual
+	 * sets are the same.
 	 *
 	 * XXX The following assignment modifies the map
 	 * without holding a write lock on it.
 	 */
-	fs.entry->lastr = fs.pindex + faultcount - behind;
+	if (hardfault)
+		fs.entry->lastr = fs.pindex + faultcount - behind;
 
 	if (prot & VM_PROT_WRITE) {
 		vm_object_set_writeable_dirty(fs.object);