svn commit: r207539 - head/sys/vm

[Alan Cox]

Author: alc
Date: Sun May  2 20:24:25 2010
New Revision: 207539
URL: http://svn.freebsd.org/changeset/base/207539

Log:
  Simplify vm_fault().  The introduction of the new page lock renders a bit of
  cleverness by vm_fault() to avoid repeatedly releasing and reacquiring the
  page queues lock pointless.
  
  Reviewed by:	kib, kmacy

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c	Sun May  2 20:12:20 2010	(r207538)
+++ head/sys/vm/vm_fault.c	Sun May  2 20:24:25 2010	(r207539)
@@ -215,7 +215,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr
 {
 	vm_prot_t prot;
 	int is_first_object_locked, result;
-	boolean_t are_queues_locked, growstack, wired;
+	boolean_t growstack, wired;
 	int map_generation;
 	vm_object_t next_object;
 	vm_page_t marray[VM_FAULT_READ];
@@ -478,7 +478,6 @@ readrest:
 				else
 					firstpindex = fs.first_pindex - 2 * VM_FAULT_READ;
 
-				are_queues_locked = FALSE;
 				/*
 				 * note: partially valid pages cannot be 
 				 * included in the lookahead - NFS piecemeal
@@ -495,17 +494,11 @@ readrest:
 					if (mt->busy ||
 					    (mt->oflags & VPO_BUSY))
 						continue;
-					if (!are_queues_locked) {
-						are_queues_locked = TRUE;
-						vm_page_lock(mt);
-						vm_page_lock_queues();
-					} else {
-						vm_page_unlock_queues();
-						vm_page_lock(mt);
-						vm_page_lock_queues();
-					}
+					vm_page_lock(mt);
+					vm_page_lock_queues();
 					if (mt->hold_count ||
 					    mt->wire_count) {
+						vm_page_unlock_queues();
 						vm_page_unlock(mt);
 						continue;
 					}
@@ -515,10 +508,9 @@ readrest:
 					} else {
 						vm_page_cache(mt);
 					}
+					vm_page_unlock_queues();
 					vm_page_unlock(mt);
 				}
-				if (are_queues_locked)
-					vm_page_unlock_queues();
 				ahead += behind;
 				behind = 0;
 			}