vfs: stop taking the interlock in vnode reclaim

It no longer protects any of tested fields, keeping all the checks racy.

While here make vtryrecycle drop the vnode on its own. Avoids an additional
lock trip.

1 files changed, 7 insertions, 20 deletions

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 22b6ef3f0800..bb338933b371 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1121,24 +1121,12 @@ restart:
 		if (vp->v_type == VBAD || vp->v_type == VNON)
 			goto next_iter;
 
-		if (!VI_TRYLOCK(vp))
-			goto next_iter;
-
-		if (vp->v_usecount > 0 || vp->v_holdcnt == 0 ||
-		    (!reclaim_nc_src && !LIST_EMPTY(&vp->v_cache_src)) ||
-		    VN_IS_DOOMED(vp) || vp->v_type == VNON) {
-			VI_UNLOCK(vp);
-			goto next_iter;
-		}
-
 		object = atomic_load_ptr(&vp->v_object);
 		if (object == NULL || object->resident_page_count > trigger) {
-			VI_UNLOCK(vp);
 			goto next_iter;
 		}
 
-		vholdl(vp);
-		VI_UNLOCK(vp);
+		vhold(vp);
 		TAILQ_REMOVE(&vnode_list, mvp, v_vnodelist);
 		TAILQ_INSERT_AFTER(&vnode_list, vp, mvp, v_vnodelist);
 		mtx_unlock(&vnode_list_mtx);
@@ -1235,21 +1223,18 @@ restart:
 		 * blocking.
 		 */
 		if (vp->v_holdcnt > 0 || (mnt_op != NULL && (mp = vp->v_mount) != NULL &&
-		    mp->mnt_op != mnt_op) || !VI_TRYLOCK(vp)) {
+		    mp->mnt_op != mnt_op)) {
 			continue;
 		}
 		TAILQ_REMOVE(&vnode_list, mvp, v_vnodelist);
 		TAILQ_INSERT_AFTER(&vnode_list, vp, mvp, v_vnodelist);
 		if (__predict_false(vp->v_type == VBAD || vp->v_type == VNON)) {
-			VI_UNLOCK(vp);
 			continue;
 		}
-		vholdl(vp);
+		vhold(vp);
 		count--;
 		mtx_unlock(&vnode_list_mtx);
-		VI_UNLOCK(vp);
 		vtryrecycle(vp);
-		vdrop(vp);
 		mtx_lock(&vnode_list_mtx);
 		goto restart;
 	}
@@ -1520,6 +1505,7 @@ vtryrecycle(struct vnode *vp)
 		CTR2(KTR_VFS,
 		    "%s: impossible to recycle, vp %p lock is already held",
 		    __func__, vp);
+		vdrop(vp);
 		return (EWOULDBLOCK);
 	}
 	/*
@@ -1530,6 +1516,7 @@ vtryrecycle(struct vnode *vp)
 		CTR2(KTR_VFS,
 		    "%s: impossible to recycle, cannot start the write for %p",
 		    __func__, vp);
+		vdrop(vp);
 		return (EBUSY);
 	}
 	/*
@@ -1541,7 +1528,7 @@ vtryrecycle(struct vnode *vp)
 	VI_LOCK(vp);
 	if (vp->v_usecount) {
 		VOP_UNLOCK(vp);
-		VI_UNLOCK(vp);
+		vdropl(vp);
 		vn_finished_write(vnmp);
 		CTR2(KTR_VFS,
 		    "%s: impossible to recycle, %p is already referenced",
@@ -1553,7 +1540,7 @@ vtryrecycle(struct vnode *vp)
 		vgonel(vp);
 	}
 	VOP_UNLOCK(vp);
-	VI_UNLOCK(vp);
+	vdropl(vp);
 	vn_finished_write(vnmp);
 	return (0);
 }