PERFORCE change 85318 for review

[soc-chenk]

http://perforce.freebsd.org/chv.cgi?CH=85318

Change 85318 by soc-chenk at soc-chenk_leavemealone on 2005/10/14 23:40:32

	Attempt to fix some known non-privilegedly accessible crash schemes
	- tried to fix:
	  - forced unmount when being busy
	  - deadlocks by null mounts
	Submitted by:	soc-chenk

Affected files ...

.. //depot/projects/soc2005/fuse4bsd2/fuse_module/fuse.c#17 edit

Differences ...

==== //depot/projects/soc2005/fuse4bsd2/fuse_module/fuse.c#17 (text+ko) ====

@@ -333,8 +333,18 @@
 out:	
 	mtx_unlock(&caliban->answer_mtx);
 
-	KASSERT(err || fuse_callbn_answered(caliban),
-	        ("fuse requester was woken up but still no answer"));
+	if (! (err || fuse_callbn_answered(caliban))) {
+		/*
+		 * Some deadlocky scenarios can get us here, like SIGKILLing
+		 * the fusexmp daemon after a fuse dir has been null mounted
+		 * over its original copy in the "normal" fs
+		 *
+		 * (I guess there is no need of kicking the daemon at this
+		 * point...)
+		 */
+	        DEBUG2G("fuse requester was woken up but still no answer");
+		err = ENXIO;
+	}
 
 	return (err);
 }
@@ -3520,6 +3530,16 @@
 		panic("non-fat file passed to read routine");
 
 	vn_lock(fp->f_vnode, LK_EXCLUSIVE | LK_RETRY, td);
+
+	if (fp->f_vnode->v_type == VBAD) {
+#if _DEBUG2G
+		DEBUG2G("bad file\n");
+		vn_printf(fp->f_vnode, " * ");
+#endif
+		VOP_UNLOCK(fp->f_vnode, 0, td);
+		return (EBADF);
+	}
+
 	if ((flags & FOF_OFFSET) == 0)
 		uio->uio_offset = fp->f_offset;
 
@@ -4845,6 +4865,16 @@
 		return (0);
 
 	vn_lock(fp->f_vnode, LK_EXCLUSIVE | LK_RETRY, td);
+
+	if (fp->f_vnode->v_type == VBAD) {
+#if _DEBUG2G
+		DEBUG2G("bad file\n");
+		vn_printf(fp->f_vnode, " * ");
+#endif
+		VOP_UNLOCK(fp->f_vnode, 0, td);
+		return (EBADF);
+	}
+
 	if (fp->f_flag & O_APPEND) {
 		VOP_GETATTR(fp->f_vnode, &va, cred, td);
 		uio->uio_offset = va.va_size;