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Fix incorrect double-termination of vm_object. When a vm_object is

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terminated and flushes pending dirty pages it is possible for the
object to be ref'd (0->1) and then deref'd (1->0) during termination.
We do not terminate the object a second time.

Document vop_stdgetvobject() to explicitly allow it to be called without
the vnode interlock held (for upcoming sync_msync() and ffs_sync()
performance optimizations)

MFC after:	3 days
This commit is contained in:
Matthew Dillon 2001-10-23 01:23:41 +00:00
parent c72ccd014d
commit 4f467cb8c1
1 changed files with 12 additions and 1 deletions
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13
sys/kern/vfs_default.c
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@ -590,8 +590,11 @@ vop_stddestroyvobject(ap)
* removes the primary reference to the object,
* the second time goes one further and is a
* special-case to terminate the object.
*
* don't double-terminate the object
*/
vm_object_terminate(obj);
if ((obj->flags & OBJ_DEAD) == 0)
vm_object_terminate(obj);
} else {
/*
* Woe to the process that tries to page now :-).
@ -601,6 +604,14 @@ vop_stddestroyvobject(ap)
return (0);
}
/*
* Return the underlying VM object. This routine may be called with or
* without the vnode interlock held. If called without, the returned
* object is not guarenteed to be valid. The syncer typically gets the
* object without holding the interlock in order to quickly test whether
* it might be dirty before going heavy-weight. vm_object's use zalloc
* and thus stable-storage, so this is safe.
*/
int
vop_stdgetvobject(ap)
struct vop_getvobject_args /* {