svn commit: r315318 - in head/sys: kern vm
Alan Cox
alc at rice.edu
Wed Mar 15 18:06:34 UTC 2017
On 03/15/2017 12:59, Benjamin Kaduk wrote:
> Should __FreeBSD_version be bumped, e.g., for out-of-tree filesystems
> that have custom vop_advise?
No, I don't think so.
> On Wed, Mar 15, 2017 at 12:43 PM, Alan Cox <alc at freebsd.org
> <mailto:alc at freebsd.org>> wrote:
>
> Author: alc
> Date: Wed Mar 15 17:43:45 2017
> New Revision: 315318
> URL: https://svnweb.freebsd.org/changeset/base/315318
> <https://svnweb.freebsd.org/changeset/base/315318>
>
> Log:
> Relax the locking requirements for vm_object_page_noreuse(). While
> reviewing all uses of OFF_TO_IDX(), I observed that
> vm_object_page_noreuse() is requiring an exclusive lock on the
> object
> when, in fact, a shared lock suffices.
>
> Reviewed by: kib, markj
> MFC after: 3 days
> Differential Revision: https://reviews.freebsd.org/D10011
> <https://reviews.freebsd.org/D10011>
>
> Modified:
> head/sys/kern/vfs_default.c
> head/sys/vm/vm_object.c
>
> Modified: head/sys/kern/vfs_default.c
> ==============================================================================
> --- head/sys/kern/vfs_default.c Wed Mar 15 17:26:19 2017
> (r315317)
> +++ head/sys/kern/vfs_default.c Wed Mar 15 17:43:45 2017
> (r315318)
> @@ -1100,10 +1100,10 @@ vop_stdadvise(struct vop_advise_args *ap
> if (vp->v_object != NULL) {
> start = trunc_page(ap->a_start);
> end = round_page(ap->a_end);
> - VM_OBJECT_WLOCK(vp->v_object);
> + VM_OBJECT_RLOCK(vp->v_object);
> vm_object_page_noreuse(vp->v_object,
> OFF_TO_IDX(start),
> OFF_TO_IDX(end));
> - VM_OBJECT_WUNLOCK(vp->v_object);
> + VM_OBJECT_RUNLOCK(vp->v_object);
> }
>
> bo = &vp->v_bufobj;
>
> Modified: head/sys/vm/vm_object.c
> ==============================================================================
> --- head/sys/vm/vm_object.c Wed Mar 15 17:26:19 2017
> (r315317)
> +++ head/sys/vm/vm_object.c Wed Mar 15 17:43:45 2017
> (r315318)
> @@ -1978,7 +1978,7 @@ vm_object_page_noreuse(vm_object_t objec
> struct mtx *mtx, *new_mtx;
> vm_page_t p, next;
>
> - VM_OBJECT_ASSERT_WLOCKED(object);
> + VM_OBJECT_ASSERT_LOCKED(object);
> KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED))
> == 0,
> ("vm_object_page_noreuse: illegal object %p", object));
> if (object->resident_page_count == 0)
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