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Date:      Mon, 27 May 2013 16:12:39 +0000 (UTC)
From:      Attilio Rao <attilio@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-user@freebsd.org
Subject:   svn commit: r251029 - in user/attilio/vmobj-readlock/sys: kern vm
Message-ID:  <201305271612.r4RGCdIv061099@svn.freebsd.org>
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Author: attilio
Date: Mon May 27 16:12:39 2013
New Revision: 251029
URL: http://svnweb.freebsd.org/changeset/base/251029

Log:
  Rework vm_page_sleep_if_busy() in order to acquire the page lock iff
  it requires to sleep.
  This saves some further page_lock acquisitions that were added during
  the development.
  
  Sponsored by:	EMC / Isilon storage division

Modified:
  user/attilio/vmobj-readlock/sys/kern/subr_uio.c
  user/attilio/vmobj-readlock/sys/kern/vfs_bio.c
  user/attilio/vmobj-readlock/sys/vm/vm_fault.c
  user/attilio/vmobj-readlock/sys/vm/vm_object.c
  user/attilio/vmobj-readlock/sys/vm/vm_page.c

Modified: user/attilio/vmobj-readlock/sys/kern/subr_uio.c
==============================================================================
--- user/attilio/vmobj-readlock/sys/kern/subr_uio.c	Mon May 27 15:51:03 2013	(r251028)
+++ user/attilio/vmobj-readlock/sys/kern/subr_uio.c	Mon May 27 16:12:39 2013	(r251029)
@@ -107,9 +107,9 @@ vm_pgmoveco(vm_map_t mapa, vm_offset_t k
 	VM_OBJECT_WLOCK(uobject);
 retry:
 	if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
-		vm_page_lock(user_pg);
 		if (vm_page_sleep_if_busy(user_pg, "vm_pgmoveco"))
 			goto retry;
+		vm_page_lock(user_pg);
 		pmap_remove_all(user_pg);
 		vm_page_free(user_pg);
 		vm_page_unlock(user_pg);

Modified: user/attilio/vmobj-readlock/sys/kern/vfs_bio.c
==============================================================================
--- user/attilio/vmobj-readlock/sys/kern/vfs_bio.c	Mon May 27 15:51:03 2013	(r251028)
+++ user/attilio/vmobj-readlock/sys/kern/vfs_bio.c	Mon May 27 16:12:39 2013	(r251029)
@@ -3459,10 +3459,9 @@ allocbuf(struct buf *bp, int size)
 					m = bp->b_pages[i];
 					KASSERT(m != bogus_page,
 					    ("allocbuf: bogus page found"));
-					do {
-						vm_page_lock(m);
-					} while (vm_page_sleep_if_busy(m,
-					    "biodep"));
+					while (vm_page_sleep_if_busy(m,
+					    "biodep"))
+						continue;
 
 					bp->b_pages[i] = NULL;
 					vm_page_unwire(m, 0);

Modified: user/attilio/vmobj-readlock/sys/vm/vm_fault.c
==============================================================================
--- user/attilio/vmobj-readlock/sys/vm/vm_fault.c	Mon May 27 15:51:03 2013	(r251028)
+++ user/attilio/vmobj-readlock/sys/vm/vm_fault.c	Mon May 27 16:12:39 2013	(r251029)
@@ -379,10 +379,7 @@ RetryFault:;
 				unlock_map(&fs);
 				if (fs.m == vm_page_lookup(fs.object,
 				    fs.pindex)) {
-					vm_page_lock(fs.m);
-					if (!vm_page_sleep_if_busy(fs.m,
-					    "vmpfw"))
-						vm_page_unlock(fs.m);
+					vm_page_sleep_if_busy(fs.m, "vmpfw");
 				}
 				vm_object_pip_wakeup(fs.object);
 				VM_OBJECT_WUNLOCK(fs.object);

Modified: user/attilio/vmobj-readlock/sys/vm/vm_object.c
==============================================================================
--- user/attilio/vmobj-readlock/sys/vm/vm_object.c	Mon May 27 15:51:03 2013	(r251028)
+++ user/attilio/vmobj-readlock/sys/vm/vm_object.c	Mon May 27 16:12:39 2013	(r251029)
@@ -871,7 +871,6 @@ rescan:
 		np = TAILQ_NEXT(p, listq);
 		if (p->valid == 0)
 			continue;
-		vm_page_lock(p);
 		if (vm_page_sleep_if_busy(p, "vpcwai")) {
 			if (object->generation != curgeneration) {
 				if ((flags & OBJPC_SYNC) != 0)
@@ -882,7 +881,6 @@ rescan:
 			np = vm_page_find_least(object, pi);
 			continue;
 		}
-		vm_page_unlock(p);
 		if (!vm_object_page_remove_write(p, flags, &clearobjflags))
 			continue;
 
@@ -1927,8 +1925,12 @@ again:
 			vm_page_unlock(p);
 			continue;
 		}
-		if (vm_page_sleep_if_busy(p, "vmopar"))
+		if ((p->oflags & VPO_BUSY) != 0 || p->busy != 0) {
+			VM_OBJECT_WUNLOCK(object);
+			vm_page_sleep(p, "vmopar");
+			VM_OBJECT_WLOCK(object);
 			goto again;
+		}
 		KASSERT((p->flags & PG_FICTITIOUS) == 0,
 		    ("vm_object_page_remove: page %p is fictitious", p));
 		if ((options & OBJPR_CLEANONLY) != 0 && p->valid != 0) {

Modified: user/attilio/vmobj-readlock/sys/vm/vm_page.c
==============================================================================
--- user/attilio/vmobj-readlock/sys/vm/vm_page.c	Mon May 27 15:51:03 2013	(r251028)
+++ user/attilio/vmobj-readlock/sys/vm/vm_page.c	Mon May 27 16:12:39 2013	(r251029)
@@ -784,17 +784,19 @@ _vm_page_sleep_onpage(vm_page_t m, int p
  *
  *	Sleep and release the page queues lock if VPO_BUSY is set or,
  *	if also_m_busy is TRUE, busy is non-zero.  Returns TRUE if the
- *	thread slept and the page queues lock was released.
- *	Otherwise, retains the page queues lock and returns FALSE.
+ *	thread slept.
  *
- *	The given page and object containing it must be locked.
+ *	The given page must be unlocked and object containing it must
+ *	be locked.
  */
 int
 vm_page_sleep_if_busy(vm_page_t m, const char *msg)
 {
 	vm_object_t obj;
 
+	vm_page_lock_assert(m, MA_NOTOWNED);
 	VM_OBJECT_ASSERT_WLOCKED(m->object);
+
 	if ((m->oflags & VPO_BUSY) != 0 || m->busy != 0) {
 		/*
 		 * The page-specific object must be cached because page
@@ -804,6 +806,7 @@ vm_page_sleep_if_busy(vm_page_t m, const
 		 * held by the callers.
 		 */
 		obj = m->object;
+		vm_page_lock(m);
 		VM_OBJECT_WUNLOCK(obj);
 		_vm_page_sleep_onpage(m, PVM, msg, 0);
 		VM_OBJECT_WLOCK(obj);

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