Author: mjg
Date: Sat Jan 21 18:38:16 2017
New Revision: 312600
URL: https://svnweb.freebsd.org/changeset/base/312600

Log:
  vfs: refactor _vn_lock
  
  Stop testing for LK_RETRY and error multiple times. Also postpone the
  VI_DOOMED until after LK_RETRY was seen as it reads from the vnode.
  
  No functional changes.

Modified:
  head/sys/kern/vfs_vnops.c

Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c   Sat Jan 21 17:39:10 2017        (r312599)
+++ head/sys/kern/vfs_vnops.c   Sat Jan 21 18:38:16 2017        (r312600)
@@ -1539,27 +1539,24 @@ _vn_lock(struct vnode *vp, int flags, ch
 
        VNASSERT((flags & LK_TYPE_MASK) != 0, vp,
            ("vn_lock called with no locktype."));
-       do {
 #ifdef DEBUG_VFS_LOCKS
-               KASSERT(vp->v_holdcnt != 0,
-                   ("vn_lock %p: zero hold count", vp));
+       KASSERT(vp->v_holdcnt != 0,
+                       ("vn_lock %p: zero hold count", vp));
 #endif
-               error = VOP_LOCK1(vp, flags, file, line);
-               flags &= ~LK_INTERLOCK; /* Interlock is always dropped. */
-               KASSERT((flags & LK_RETRY) == 0 || error == 0,
-                   ("LK_RETRY set with incompatible flags (0x%x) or an error 
occurred (%d)",
-                   flags, error));
-               /*
-                * Callers specify LK_RETRY if they wish to get dead vnodes.
-                * If RETRY is not set, we return ENOENT instead.
-                */
-               if (error == 0 && vp->v_iflag & VI_DOOMED &&
-                   (flags & LK_RETRY) == 0) {
+retry:
+       error = VOP_LOCK1(vp, flags, file, line);
+       flags &= ~LK_INTERLOCK; /* Interlock is always dropped. */
+       KASSERT((flags & LK_RETRY) == 0 || error == 0,
+                       ("LK_RETRY set with incompatible flags (0x%x) or an 
error occurred (%d)",
+                        flags, error));
+       if (flags & LK_RETRY) {
+               if ((error != 0))
+                       goto retry;
+               if ((vp->v_iflag & VI_DOOMED)) {
                        VOP_UNLOCK(vp, 0);
                        error = ENOENT;
-                       break;
                }
-       } while (flags & LK_RETRY && error != 0);
+       }
        return (error);
 }
 
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