svn commit: r216799 - head/sys/vm
Konstantin Belousov
kib at FreeBSD.org
Wed Dec 29 12:53:54 UTC 2010
Author: kib
Date: Wed Dec 29 12:53:53 2010
New Revision: 216799
URL: http://svn.freebsd.org/changeset/base/216799
Log:
Move the increment of vm object generation count into
vm_object_set_writeable_dirty().
Fix an issue where restart of the scan in vm_object_page_clean() did
not removed write permissions for newly added pages or, if the mapping
for some already scanned page changed to writeable due to fault.
Merge the two loops in vm_object_page_clean(), doing the remove of
write permission and cleaning in the same loop. The restart of the
loop then correctly downgrade writeable mappings.
Fix an issue where a second caller to msync() might actually return
before the first caller had actually completed flushing the
pages. Clear the OBJ_MIGHTBEDIRTY flag after the cleaning loop, not
before.
Calls to pmap_is_modified() are not needed after pmap_remove_write()
there.
Proposed, reviewed and tested by: alc
MFC after: 1 week
Modified:
head/sys/vm/vm_object.c
head/sys/vm/vm_page.c
Modified: head/sys/vm/vm_object.c
==============================================================================
--- head/sys/vm/vm_object.c Wed Dec 29 12:31:18 2010 (r216798)
+++ head/sys/vm/vm_object.c Wed Dec 29 12:53:53 2010 (r216799)
@@ -101,7 +101,9 @@ SYSCTL_INT(_vm, OID_AUTO, old_msync, CTL
"Use old (insecure) msync behavior");
static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
- int pagerflags);
+ int pagerflags, int flags, int *clearobjflags);
+static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
+ int *clearobjflags);
static void vm_object_qcollapse(vm_object_t object);
static void vm_object_vndeallocate(vm_object_t object);
@@ -753,6 +755,24 @@ vm_object_terminate(vm_object_t object)
vm_object_destroy(object);
}
+static boolean_t
+vm_object_page_remove_write(vm_page_t p, int flags, int *clearobjflags)
+{
+
+ /*
+ * If we have been asked to skip nosync pages and this is a
+ * nosync page, skip it. Note that the object flags were not
+ * cleared in this case so we do not have to set them.
+ */
+ if ((flags & OBJPC_NOSYNC) != 0 && (p->oflags & VPO_NOSYNC) != 0) {
+ *clearobjflags = 0;
+ return (FALSE);
+ } else {
+ pmap_remove_write(p);
+ return (p->dirty != 0);
+ }
+}
+
/*
* vm_object_page_clean
*
@@ -799,17 +819,6 @@ vm_object_page_clean(vm_object_t object,
* object flags.
*/
clearobjflags = 1;
- for (p = vm_page_find_least(object, start);
- p != NULL && p->pindex < tend; p = TAILQ_NEXT(p, listq)) {
- if ((flags & OBJPC_NOSYNC) != 0 &&
- (p->oflags & VPO_NOSYNC) != 0)
- clearobjflags = 0;
- else
- pmap_remove_write(p);
- }
-
- if (clearobjflags && (start == 0) && (tend == object->size))
- vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
rescan:
curgeneration = object->generation;
@@ -827,20 +836,11 @@ rescan:
np = vm_page_find_least(object, pi);
continue;
}
- vm_page_test_dirty(p);
- if (p->dirty == 0)
+ if (!vm_object_page_remove_write(p, flags, &clearobjflags))
continue;
- /*
- * If we have been asked to skip nosync pages and this is a
- * nosync page, skip it. Note that the object flags were
- * not cleared in this case so we do not have to set them.
- */
- if ((flags & OBJPC_NOSYNC) != 0 &&
- (p->oflags & VPO_NOSYNC) != 0)
- continue;
-
- n = vm_object_page_collect_flush(object, p, pagerflags);
+ n = vm_object_page_collect_flush(object, p, pagerflags,
+ flags, &clearobjflags);
if (object->generation != curgeneration)
goto rescan;
np = vm_page_find_least(object, pi + n);
@@ -850,10 +850,13 @@ rescan:
#endif
vm_object_clear_flag(object, OBJ_CLEANING);
+ if (clearobjflags && start == 0 && tend == object->size)
+ vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
}
static int
-vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags)
+vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
+ int flags, int *clearobjflags)
{
vm_page_t ma[vm_pageout_page_count], p_first, tp;
int count, i, mreq, runlen;
@@ -869,8 +872,7 @@ vm_object_page_collect_flush(vm_object_t
tp = vm_page_next(tp);
if (tp == NULL || tp->busy != 0 || (tp->oflags & VPO_BUSY) != 0)
break;
- vm_page_test_dirty(tp);
- if (tp->dirty == 0)
+ if (!vm_object_page_remove_write(tp, flags, clearobjflags))
break;
}
@@ -878,8 +880,7 @@ vm_object_page_collect_flush(vm_object_t
tp = vm_page_prev(p_first);
if (tp == NULL || tp->busy != 0 || (tp->oflags & VPO_BUSY) != 0)
break;
- vm_page_test_dirty(tp);
- if (tp->dirty == 0)
+ if (!vm_object_page_remove_write(tp, flags, clearobjflags))
break;
p_first = tp;
mreq++;
@@ -1985,8 +1986,10 @@ vm_object_set_writeable_dirty(vm_object_
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
- if (object->type != OBJT_VNODE ||
- (object->flags & OBJ_MIGHTBEDIRTY) != 0)
+ if (object->type != OBJT_VNODE)
+ return;
+ object->generation++;
+ if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
return;
vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
}
Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c Wed Dec 29 12:31:18 2010 (r216798)
+++ head/sys/vm/vm_page.c Wed Dec 29 12:53:53 2010 (r216799)
@@ -811,7 +811,6 @@ vm_page_insert(vm_page_t m, vm_object_t
}
}
object->root = m;
- object->generation++;
/*
* show that the object has one more resident page.
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