- Synchronize access to a vm page's valid field using the containing

   vm object's lock.
 - Reduce the scope of the vm page queues lock in two places.

1 files changed, 45 insertions, 43 deletions

diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index 70b8987..5faad5c 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -324,49 +324,48 @@ vnode_pager_setsize(vp, nsize)
 		 * it can screw up NFS reads, so we don't allow the case.
 		 */
 		if ((nsize & PAGE_MASK) &&
-		    (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL) {
+		    (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL &&
+		    m->valid != 0) {
+			int base = (int)nsize & PAGE_MASK;
+			int size = PAGE_SIZE - base;
+
+			/*
+			 * Clear out partial-page garbage in case
+			 * the page has been mapped.
+			 */
+			pmap_zero_page_area(m, base, size);
+
+			/*
+			 * XXX work around SMP data integrity race
+			 * by unmapping the page from user processes.
+			 * The garbage we just cleared may be mapped
+			 * to a user process running on another cpu
+			 * and this code is not running through normal
+			 * I/O channels which handle SMP issues for
+			 * us, so unmap page to synchronize all cpus.
+			 *
+			 * XXX should vm_pager_unmap_page() have
+			 * dealt with this?
+			 */
 			vm_page_lock_queues();
-			if (m->valid) {
-				int base = (int)nsize & PAGE_MASK;
-				int size = PAGE_SIZE - base;
-
-				/*
-				 * Clear out partial-page garbage in case
-				 * the page has been mapped.
-				 */
-				pmap_zero_page_area(m, base, size);
-
-				/*
-				 * XXX work around SMP data integrity race
-				 * by unmapping the page from user processes.
-				 * The garbage we just cleared may be mapped
-				 * to a user process running on another cpu
-				 * and this code is not running through normal
-				 * I/O channels which handle SMP issues for
-				 * us, so unmap page to synchronize all cpus.
-				 *
-				 * XXX should vm_pager_unmap_page() have
-				 * dealt with this?
-				 */
-				pmap_remove_all(m);
-
-				/*
-				 * Clear out partial-page dirty bits.  This
-				 * has the side effect of setting the valid
-				 * bits, but that is ok.  There are a bunch
-				 * of places in the VM system where we expected
-				 * m->dirty == VM_PAGE_BITS_ALL.  The file EOF
-				 * case is one of them.  If the page is still
-				 * partially dirty, make it fully dirty.
-				 *
-				 * note that we do not clear out the valid
-				 * bits.  This would prevent bogus_page
-				 * replacement from working properly.
-				 */
-				vm_page_set_validclean(m, base, size);
-				if (m->dirty != 0)
-					m->dirty = VM_PAGE_BITS_ALL;
-			}
+			pmap_remove_all(m);
+
+			/*
+			 * Clear out partial-page dirty bits.  This
+			 * has the side effect of setting the valid
+			 * bits, but that is ok.  There are a bunch
+			 * of places in the VM system where we expected
+			 * m->dirty == VM_PAGE_BITS_ALL.  The file EOF
+			 * case is one of them.  If the page is still
+			 * partially dirty, make it fully dirty.
+			 *
+			 * note that we do not clear out the valid
+			 * bits.  This would prevent bogus_page
+			 * replacement from working properly.
+			 */
+			vm_page_set_validclean(m, base, size);
+			if (m->dirty != 0)
+				m->dirty = VM_PAGE_BITS_ALL;
 			vm_page_unlock_queues();
 		}
 	}
@@ -573,14 +572,17 @@ vnode_pager_input_old(object, m)
 				bzero((caddr_t) kva + count, PAGE_SIZE - count);
 		}
 		vm_pager_unmap_page(kva);
+
+		VM_OBJECT_LOCK(object);
 	}
 	vm_page_lock_queues();
 	pmap_clear_modify(m);
 	vm_page_undirty(m);
 	vm_page_flag_clear(m, PG_ZERO);
+	vm_page_unlock_queues();
 	if (!error)
 		m->valid = VM_PAGE_BITS_ALL;
-	vm_page_unlock_queues();
+	VM_OBJECT_UNLOCK(object);
 	return error ? VM_PAGER_ERROR : VM_PAGER_OK;
 }