svn commit: r351622 - head/sys/kern

[Konstantin Belousov]

On Fri, Aug 30, 2019 at 12:45:54AM +0000, Mateusz Guzik wrote:
> Author: mjg
> Date: Fri Aug 30 00:45:53 2019
> New Revision: 351622
> URL: https://svnweb.freebsd.org/changeset/base/351622
> 
> Log:
>   vfs: tidy up assertions in vfs_subr
>   
>   - assert unlocked vnode interlock in vref
>   - assert right counts in vputx
>   - print debug info for panic in vdrop
>   
>   Sponsored by:	The FreeBSD Foundation
> 
> Modified:
>   head/sys/kern/vfs_subr.c
> 
> Modified: head/sys/kern/vfs_subr.c
> ==============================================================================
> --- head/sys/kern/vfs_subr.c	Fri Aug 30 00:40:08 2019	(r351621)
> +++ head/sys/kern/vfs_subr.c	Fri Aug 30 00:45:53 2019	(r351622)
> @@ -2778,6 +2778,7 @@ void
>  vref(struct vnode *vp)
>  {
>  
> +	ASSERT_VI_UNLOCKED(vp, __func__);
>  	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
>  	_vhold(vp, false);
>  	v_incr_usecount(vp);
> @@ -2853,6 +2854,9 @@ vputx(struct vnode *vp, int func)
>  	else
>  		KASSERT(func == VPUTX_VRELE, ("vputx: wrong func"));
>  	ASSERT_VI_UNLOCKED(vp, __func__);
> +	VNASSERT(vp->v_holdcnt > 0 && vp->v_usecount > 0, vp,
A more precise assert condition would also include
	vp->v_holdcont >= vp->v_usecount

> +	    ("%s: wrong ref counts", __func__));
> +
>  	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
>  
>  	if (vp->v_type != VCHR &&
> @@ -3069,8 +3073,10 @@ _vdrop(struct vnode *vp, bool locked)
>  	else
>  		ASSERT_VI_UNLOCKED(vp, __func__);
>  	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
> -	if ((int)vp->v_holdcnt <= 0)
> -		panic("vdrop: holdcnt %d", vp->v_holdcnt);
> +	if (__predict_false((int)vp->v_holdcnt <= 0)) {
> +		vn_printf(vp, "vdrop: holdcnt %d", vp->v_holdcnt);
> +		panic("vdrop: wrong holdcnt");
> +	}
>  	if (!locked) {
>  		if (refcount_release_if_not_last(&vp->v_holdcnt))
>  			return;