Introduce a field to struct vm_page for storing flags that are

synchronized by the lock on the object containing the page.

Transition PG_WANTED and PG_SWAPINPROG to use the new field,
eliminating the need for holding the page queues lock when setting
or clearing these flags.  Rename PG_WANTED and PG_SWAPINPROG to
VPO_WANTED and VPO_SWAPINPROG, respectively.

Eliminate the assertion that the page queues lock is held in
vm_page_io_finish().

Eliminate the acquisition and release of the page queues lock
around calls to vm_page_io_finish() in kern_sendfile() and
vfs_unbusy_pages().

5 files changed, 32 insertions, 24 deletions

diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index 23281e3..4e4e4db 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -1056,16 +1056,14 @@ swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	bp->b_pager.pg_reqpage = reqpage - i;
 
 	VM_OBJECT_LOCK(object);
-	vm_page_lock_queues();
 	{
 		int k;
 
 		for (k = i; k < j; ++k) {
 			bp->b_pages[k - i] = m[k];
-			vm_page_flag_set(m[k], PG_SWAPINPROG);
+			m[k]->oflags |= VPO_SWAPINPROG;
 		}
 	}
-	vm_page_unlock_queues();
 	bp->b_npages = j - i;
 
 	cnt.v_swapin++;
@@ -1093,14 +1091,15 @@ swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 	swp_pager_strategy(bp);
 
 	/*
-	 * wait for the page we want to complete.  PG_SWAPINPROG is always
+	 * wait for the page we want to complete.  VPO_SWAPINPROG is always
 	 * cleared on completion.  If an I/O error occurs, SWAPBLK_NONE
 	 * is set in the meta-data.
 	 */
 	VM_OBJECT_LOCK(object);
-	while ((mreq->flags & PG_SWAPINPROG) != 0) {
+	while ((mreq->oflags & VPO_SWAPINPROG) != 0) {
+		mreq->oflags |= VPO_WANTED;
 		vm_page_lock_queues();
-		vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED);
+		vm_page_flag_set(mreq, PG_REFERENCED);
 		vm_page_unlock_queues();
 		cnt.v_intrans++;
 		if (msleep(mreq, VM_OBJECT_MTX(object), PSWP, "swread", hz*20)) {
@@ -1282,9 +1281,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 			vm_page_dirty(mreq);
 			rtvals[i+j] = VM_PAGER_OK;
 
-			vm_page_lock_queues();
-			vm_page_flag_set(mreq, PG_SWAPINPROG);
-			vm_page_unlock_queues();
+			mreq->oflags |= VPO_SWAPINPROG;
 			bp->b_pages[j] = mreq;
 		}
 		VM_OBJECT_UNLOCK(object);
@@ -1399,7 +1396,7 @@ swp_pager_async_iodone(struct buf *bp)
 	for (i = 0; i < bp->b_npages; ++i) {
 		vm_page_t m = bp->b_pages[i];
 
-		vm_page_flag_clear(m, PG_SWAPINPROG);
+		m->oflags &= ~VPO_SWAPINPROG;
 
 		if (bp->b_ioflags & BIO_ERROR) {
 			/*
@@ -1418,7 +1415,7 @@ swp_pager_async_iodone(struct buf *bp)
 				 * not match anything ).
 				 *
 				 * We have to wake specifically requested pages
-				 * up too because we cleared PG_SWAPINPROG and
+				 * up too because we cleared VPO_SWAPINPROG and
 				 * someone may be waiting for that.
 				 *
 				 * NOTE: for reads, m->dirty will probably
@@ -1472,7 +1469,7 @@ swp_pager_async_iodone(struct buf *bp)
 
 			/*
 			 * We have to wake specifically requested pages
-			 * up too because we cleared PG_SWAPINPROG and
+			 * up too because we cleared VPO_SWAPINPROG and
 			 * could be waiting for it in getpages.  However,
 			 * be sure to not unbusy getpages specifically
 			 * requested page - getpages expects it to be 
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 57a6c49..fd34f40 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1153,10 +1153,11 @@ shadowlookup:
 			goto unlock_tobject;
 		}
 		if ((m->flags & PG_BUSY) || m->busy) {
-			vm_page_flag_set(m, PG_WANTED | PG_REFERENCED);
+			vm_page_flag_set(m, PG_REFERENCED);
 			vm_page_unlock_queues();
 			if (object != tobject)
 				VM_OBJECT_UNLOCK(object);
+			m->oflags |= VPO_WANTED;
 			msleep(m, VM_OBJECT_MTX(tobject), PDROP | PVM, "madvpo", 0);
 			VM_OBJECT_LOCK(object);
   			goto relookup;
@@ -1341,9 +1342,10 @@ vm_object_split(vm_map_entry_t entry)
 		 * not be changed by this operation.
 		 */
 		if ((m->flags & PG_BUSY) || m->busy) {
-			vm_page_flag_set(m, PG_WANTED | PG_REFERENCED);
+			vm_page_flag_set(m, PG_REFERENCED);
 			vm_page_unlock_queues();
 			VM_OBJECT_UNLOCK(new_object);
+			m->oflags |= VPO_WANTED;
 			msleep(m, VM_OBJECT_MTX(orig_object), PDROP | PVM, "spltwt", 0);
 			VM_OBJECT_LOCK(new_object);
 			VM_OBJECT_LOCK(orig_object);
@@ -1476,10 +1478,10 @@ vm_object_backing_scan(vm_object_t object, int op)
 			} else if (op & OBSC_COLLAPSE_WAIT) {
 				if ((p->flags & PG_BUSY) || p->busy) {
 					vm_page_lock_queues();
-					vm_page_flag_set(p,
-					    PG_WANTED | PG_REFERENCED);
+					vm_page_flag_set(p, PG_REFERENCED);
 					vm_page_unlock_queues();
 					VM_OBJECT_UNLOCK(object);
+					p->oflags |= VPO_WANTED;
 					msleep(p, VM_OBJECT_MTX(backing_object),
 					    PDROP | PVM, "vmocol", 0);
 					VM_OBJECT_LOCK(object);
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 0031493..c34b6f2 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -387,8 +387,8 @@ vm_page_flash(vm_page_t m)
 {
 
 	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
-	if (m->flags & PG_WANTED) {
-		vm_page_flag_clear(m, PG_WANTED);
+	if (m->oflags & VPO_WANTED) {
+		m->oflags &= ~VPO_WANTED;
 		wakeup(m);
 	}
 }
@@ -423,7 +423,6 @@ vm_page_io_finish(vm_page_t m)
 {
 
 	VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
-	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
 	m->busy--;
 	if (m->busy == 0)
 		vm_page_flash(m);
@@ -500,7 +499,7 @@ vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg)
 	if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) {
 		if (!mtx_owned(&vm_page_queue_mtx))
 			vm_page_lock_queues();
-		vm_page_flag_set(m, PG_WANTED | PG_REFERENCED);
+		vm_page_flag_set(m, PG_REFERENCED);
 		vm_page_unlock_queues();
 
 		/*
@@ -510,6 +509,7 @@ vm_page_sleep_if_busy(vm_page_t m, int also_m_busy, const char *msg)
 		 * such that even if m->object changes, we can re-lock
 		 * it.
 		 */
+		m->oflags |= VPO_WANTED;
 		msleep(m, VM_OBJECT_MTX(m->object), PVM, msg, 0);
 		return (TRUE);
 	}
@@ -1480,8 +1480,9 @@ retrylookup:
 	if ((m = vm_page_lookup(object, pindex)) != NULL) {
 		vm_page_lock_queues();
 		if (m->busy || (m->flags & PG_BUSY)) {
-			vm_page_flag_set(m, PG_WANTED | PG_REFERENCED);
+			vm_page_flag_set(m, PG_REFERENCED);
 			vm_page_unlock_queues();
+			m->oflags |= VPO_WANTED;
 			msleep(m, VM_OBJECT_MTX(m->object), PVM, "pgrbwt", 0);
 			if ((allocflags & VM_ALLOC_RETRY) == 0)
 				return (NULL);
diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index 2a30f3a..428aee5 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -116,6 +116,7 @@ struct vm_page {
 	u_short wire_count;		/* wired down maps refs (P) */
 	u_int cow;			/* page cow mapping count */
 	short hold_count;		/* page hold count */
+	u_short oflags;			/* page flags (O) */
 	u_char	act_count;		/* page usage count */
 	u_char	busy;			/* page busy count (O) */
 	/* NOTE that these must support one bit per DEV_BSIZE in a page!!! */
@@ -135,6 +136,15 @@ struct vm_page {
 #endif
 };
 
+/*
+ * Page flags stored in oflags:
+ *
+ * Access to these page flags is synchronized by the lock on the object
+ * containing the page (O).
+ */
+#define	VPO_WANTED	0x0002	/* someone is waiting for page */
+#define	VPO_SWAPINPROG	0x0200	/* swap I/O in progress on page */
+
 /* Make sure that u_long is at least 64 bits when PAGE_SIZE is 32K. */
 #if PAGE_SIZE == 32768
 #ifdef CTASSERT
@@ -210,14 +220,12 @@ extern struct pq_coloring page_queue_coloring;
  *	 the object, and such pages are also not on any PQ queue.
  */
 #define	PG_BUSY		0x0001		/* page is in transit (O) */
-#define	PG_WANTED	0x0002		/* someone is waiting for page (O) */
 #define PG_WINATCFLS	0x0004		/* flush dirty page on inactive q */
 #define	PG_FICTITIOUS	0x0008		/* physical page doesn't exist (O) */
 #define	PG_WRITEABLE	0x0010		/* page is mapped writeable */
 #define	PG_ZERO		0x0040		/* page is zeroed */
 #define PG_REFERENCED	0x0080		/* page has been referenced */
 #define PG_CLEANCHK	0x0100		/* page will be checked for cleaning */
-#define PG_SWAPINPROG	0x0200		/* swap I/O in progress on page	     */
 #define PG_NOSYNC	0x0400		/* do not collect for syncer */
 #define PG_UNMANAGED	0x0800		/* No PV management for page */
 #define PG_MARKER	0x1000		/* special queue marker page */
diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index 8532bbf..a8f9912 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -956,7 +956,7 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
 			 * now tell them that it is ok to use
 			 */
 			if (!error) {
-				if (mt->flags & PG_WANTED)
+				if (mt->oflags & VPO_WANTED)
 					vm_page_activate(mt);
 				else
 					vm_page_deactivate(mt);