FreeBSD: Lock vnode in zfs_ioctl()

Previously vnode was not locked there, unlike Linux.  It required
locking it in vn_flush_cached_data(), which recursed on the lock
if called from zfs_clone_range(), having the vnode locked.

Reviewed-by: Alan Somers <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#16789
Closes openzfs#16796

Author: amotin

include/os/freebsd/spl/sys/vnode.h

@@ -91,20 +91,16 @@ vn_is_readonly(vnode_t *vp)
 	((vp)->v_object != NULL && \
 	(vp)->v_object->resident_page_count > 0)
 
-#ifndef IN_BASE
 static __inline void
 vn_flush_cached_data(vnode_t *vp, boolean_t sync)
 {
 	if (vm_object_mightbedirty(vp->v_object)) {
 		int flags = sync ? OBJPC_SYNC : 0;
-		vn_lock(vp, LK_SHARED | LK_RETRY);
 		zfs_vmobject_wlock(vp->v_object);
 		vm_object_page_clean(vp->v_object, 0, 0, flags);
 		zfs_vmobject_wunlock(vp->v_object);
-		VOP_UNLOCK(vp);
 	}
 }
-#endif
 
 #define	vn_exists(vp)		do { } while (0)
 #define	vn_invalid(vp)		do { } while (0)

module/os/freebsd/zfs/zfs_vnops_os.c

@@ -291,8 +291,12 @@ zfs_ioctl(vnode_t *vp, ulong_t com, intptr_t data, int flag, cred_t *cred,
 	case F_SEEK_HOLE:
 	{
 		off = *(offset_t *)data;
+		error = vn_lock(vp, LK_SHARED);
+		if (error)
+			return (error);
 		/* offset parameter is in/out */
 		error = zfs_holey(VTOZ(vp), com, &off);
+		VOP_UNLOCK(vp);
 		if (error)
 			return (error);
 		*(offset_t *)data = off;