MFC r279401:

Some fixes for fdescfs lookup code Do not ever return doomed vnode from.
lookup. Reuse the vn_vget_ino_gen() helper to handle parallel unmounts .

1 files changed, 32 insertions, 10 deletions

diff --git a/sys/fs/fdescfs/fdesc_vnops.c b/sys/fs/fdescfs/fdesc_vnops.c
index b976504..1ed531b 100644
--- a/sys/fs/fdescfs/fdesc_vnops.c
+++ b/sys/fs/fdescfs/fdesc_vnops.c
@@ -247,6 +247,28 @@ loop:
 	return (0);
 }
 
+struct fdesc_get_ino_args {
+	fdntype ftype;
+	unsigned fd_fd;
+	int ix;
+	struct file *fp;
+	struct thread *td;
+};
+
+static int
+fdesc_get_ino_alloc(struct mount *mp, void *arg, int lkflags,
+    struct vnode **rvp)
+{
+	struct fdesc_get_ino_args *a;
+	int error;
+
+	a = arg;
+	error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp);
+	fdrop(a->fp, a->td);
+	return (error);
+}
+
+
 /*
  * vp is the current namei directory
  * ndp is the name to locate in that directory...
@@ -265,6 +287,7 @@ fdesc_lookup(ap)
 	char *pname = cnp->cn_nameptr;
 	struct thread *td = cnp->cn_thread;
 	struct file *fp;
+	struct fdesc_get_ino_args arg;
 	int nlen = cnp->cn_namelen;
 	u_int fd, fd1;
 	int error;
@@ -326,6 +349,8 @@ fdesc_lookup(ap)
 		vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
 		vdrop(dvp);
 		fvp = dvp;
+		if ((dvp->v_iflag & VI_DOOMED) != 0)
+			error = ENOENT;
 	} else {
 		/*
 		 * Unlock our root node (dvp) when doing this, since we might
@@ -335,16 +360,13 @@ fdesc_lookup(ap)
 		 * opposite lock order. Vhold the root vnode first so we don't
 		 * lose it.
 		 */
-		vhold(dvp);
-		VOP_UNLOCK(dvp, 0);
-		error = fdesc_allocvp(Fdesc, fd, FD_DESC + fd, dvp->v_mount,
-		    &fvp);
-		fdrop(fp, td);
-		/*
-		 * The root vnode must be locked last to prevent deadlock condition.
-		 */
-		vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
-		vdrop(dvp);
+		arg.ftype = Fdesc;
+		arg.fd_fd = fd;
+		arg.ix = FD_DESC + fd;
+		arg.fp = fp;
+		arg.td = td;
+		error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg,
+		    LK_EXCLUSIVE, &fvp);
 	}
 	
 	if (error)