Make vm_page's PG_ZERO flag immutable between the time of the page's

allocation and deallocation.  This flag's principal use is shortly after
allocation.  For such cases, clearing the flag is pointless.  The only
unusual use of PG_ZERO is in vfs_bio_clrbuf().  However, allocbuf() never
requests a prezeroed page.  So, vfs_bio_clrbuf() never sees a prezeroed
page.

Reviewed by:	tegge@

1 files changed, 1 insertions, 14 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 3b1f0d2..e4924c9 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -1336,9 +1336,6 @@ brelse(struct buf * bp)
 			int had_bogus = 0;
 
 			m = bp->b_pages[i];
-			vm_page_lock_queues();
-			vm_page_flag_clear(m, PG_ZERO);
-			vm_page_unlock_queues();
 
 			/*
 			 * If we hit a bogus page, fixup *all* the bogus pages
@@ -1582,7 +1579,6 @@ vfs_vmio_release(bp)
 			continue;
 			
 		if (m->wire_count == 0) {
-			vm_page_flag_clear(m, PG_ZERO);
 			/*
 			 * Might as well free the page if we can and it has
 			 * no valid data.  We also free the page if the
@@ -2326,10 +2322,8 @@ vfs_setdirty(struct buf *bp)
 		 * test the pages to see if they have been modified directly
 		 * by users through the VM system.
 		 */
-		for (i = 0; i < bp->b_npages; i++) {
-			vm_page_flag_clear(bp->b_pages[i], PG_ZERO);
+		for (i = 0; i < bp->b_npages; i++)
 			vm_page_test_dirty(bp->b_pages[i]);
-		}
 
 		/*
 		 * Calculate the encompassing dirty range, boffset and eoffset,
@@ -2919,7 +2913,6 @@ allocbuf(struct buf *bp, int size)
 					(cnt.v_free_min + cnt.v_cache_min))) {
 					pagedaemon_wakeup();
 				}
-				vm_page_flag_clear(m, PG_ZERO);
 				vm_page_wire(m);
 				vm_page_unlock_queues();
 				bp->b_pages[bp->b_npages] = m;
@@ -3233,7 +3226,6 @@ bufdone(struct buf *bp)
 			if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
 				vfs_page_set_valid(bp, foff, i, m);
 			}
-			vm_page_flag_clear(m, PG_ZERO);
 
 			/*
 			 * when debugging new filesystems or buffer I/O methods, this
@@ -3316,7 +3308,6 @@ vfs_unbusy_pages(struct buf * bp)
 				pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
 			}
 			vm_object_pip_subtract(obj, 1);
-			vm_page_flag_clear(m, PG_ZERO);
 			vm_page_io_finish(m);
 		}
 		vm_page_unlock_queues();
@@ -3402,7 +3393,6 @@ retry:
 		for (i = 0; i < bp->b_npages; i++) {
 			vm_page_t m = bp->b_pages[i];
 
-			vm_page_flag_clear(m, PG_ZERO);
 			if ((bp->b_flags & B_CLUSTER) == 0) {
 				vm_object_pip_add(obj, 1);
 				vm_page_io_start(m);
@@ -3579,9 +3569,6 @@ vfs_bio_clrbuf(struct buf *bp)
 				}
 			}
 			bp->b_pages[i]->valid |= mask;
-			vm_page_lock_queues();
-			vm_page_flag_clear(bp->b_pages[i], PG_ZERO);
-			vm_page_unlock_queues();
 		}
 unlock:
 		VM_OBJECT_UNLOCK(bp->b_object);