Complete r251452:

Avoid to busy/unbusy a page in cases where there is no need to drop the
vm_obj lock, more nominally when the page is full valid after
vm_page_grab().

Sponsored by:	EMC / Isilon storage division
Reviewed by:	alc

2 files changed, 7 insertions, 4 deletions

diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index 5041276..d5e942e 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -1706,18 +1706,19 @@ swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
 	vm_page_t m;
 
 	vm_object_pip_add(object, 1);
-	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL|VM_ALLOC_RETRY);
+	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY |
+	    VM_ALLOC_NOBUSY);
 	if (m->valid == VM_PAGE_BITS_ALL) {
 		vm_object_pip_subtract(object, 1);
 		vm_page_dirty(m);
 		vm_page_lock(m);
 		vm_page_activate(m);
 		vm_page_unlock(m);
-		vm_page_wakeup(m);
 		vm_pager_page_unswapped(m);
 		return;
 	}
 
+	vm_page_busy(m);
 	if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK)
 		panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
 	vm_object_pip_subtract(object, 1);
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index e0a8bf7..6183518 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -241,8 +241,10 @@ vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
 
 	VM_OBJECT_WLOCK(object);
 	pindex = OFF_TO_IDX(offset);
-	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
+	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY |
+	    VM_ALLOC_NOBUSY);
 	if (m->valid != VM_PAGE_BITS_ALL) {
+		vm_page_busy(m);
 		ma[0] = m;
 		rv = vm_pager_get_pages(object, ma, 1, 0);
 		m = vm_page_lookup(object, pindex);
@@ -255,11 +257,11 @@ vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
 			m = NULL;
 			goto out;
 		}
+		vm_page_wakeup(m);
 	}
 	vm_page_lock(m);
 	vm_page_hold(m);
 	vm_page_unlock(m);
-	vm_page_wakeup(m);
 out:
 	VM_OBJECT_WUNLOCK(object);
 	return (m);