If a file has been completely unlinked, stop automatically syncing the

file.  ffs will discard any pending dirty pages when it is closed,
so we may as well not waste time trying to clean them.  This doesn't
stop other things from writing it out, eg: pageout, fsync(2) etc.

3 files changed, 6 insertions, 1 deletions

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index b421902..b38bc16 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -2378,6 +2378,9 @@ loop:
 		if (vp->v_flag & VXLOCK)	/* XXX: what if MNT_WAIT? */
 			continue;
 
+		if (vp->v_flag & VNOSYNC)	/* unlinked, skip it */
+			continue;
+
 		if (flags != MNT_WAIT) {
 			if (VOP_GETVOBJECT(vp, &obj) != 0 ||
 			    (obj->flags & OBJ_MIGHTBEDIRTY) == 0)
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index f00bc03..9ee79d1 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -163,7 +163,7 @@ struct vnode {
 #define	VXLOCK		0x00100	/* vnode is locked to change underlying type */
 #define	VXWANT		0x00200	/* process is waiting for vnode */
 #define	VBWAIT		0x00400	/* waiting for output to complete */
-/* open for business    0x00800 */
+#define	VNOSYNC		0x01000	/* unlinked, stop syncing */
 /* open for business    0x01000 */
 #define	VOBJBUF		0x02000	/* Allocate buffers in VM object */
 #define	VCOPYONWRITE    0x04000 /* vnode is doing copy-on-write */
diff --git a/sys/ufs/ufs/ufs_vnops.c b/sys/ufs/ufs/ufs_vnops.c
index c0826cf..e52bf93 100644
--- a/sys/ufs/ufs/ufs_vnops.c
+++ b/sys/ufs/ufs/ufs_vnops.c
@@ -758,6 +758,8 @@ ufs_remove(ap)
 		goto out;
 	}
 	error = ufs_dirremove(dvp, ip, ap->a_cnp->cn_flags, 0);
+	if (ip->i_nlink <= 0)
+		vp->v_flag |= VNOSYNC;
 	VN_KNOTE(vp, NOTE_DELETE);
 	VN_KNOTE(dvp, NOTE_WRITE);
 out: