From: David van Moolenbroek <david@minix3.org>
Date: Fri, 17 Jun 2016 18:02:29 +0000 (+0000)
Subject: VFS: fix aborting queued requests after FS crash
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/zpipe.c?a=commitdiff_plain;h=7d0647db6a1e46e7289a13effb6163d41a717cf5;p=minix.git

VFS: fix aborting queued requests after FS crash

The new asserts from git-29e004d exposed an issue in how VFS handles
aborting file system (FS) requests that are queued for a FS (as
opposed to sent to it) when that FS crashes.  In that scenario, the
queued worker has its w_task set to NONE, because there is no ongoing
communication.  However, worker_stop() is called on it regardless,
which used to abort the request only if w_task was not set to NONE,
leading to an improperly aborted request, a warning, and a VFS crash a
bit later.  This patch changes worker_stop() so that w_task need not
be set to a valid endpoint for FS requests to be properly aborted.

Change-Id: Ib73db285e689ae4742b15cba26137bf340bc303b
---

diff --git a/minix/servers/vfs/worker.c b/minix/servers/vfs/worker.c
index 5cc35faed..117a93bad 100644
--- a/minix/servers/vfs/worker.c
+++ b/minix/servers/vfs/worker.c
@@ -535,22 +535,17 @@ void worker_signal(struct worker_thread *worker)
 void worker_stop(struct worker_thread *worker)
 {
   ASSERTW(worker);		/* Make sure we have a valid thread */
-  if (worker->w_task != NONE) {
-	/* This thread is communicating with a driver or file server */
-	if (worker->w_drv_sendrec != NULL) {			/* Driver */
-		worker->w_drv_sendrec->m_type = EIO;
-		worker->w_drv_sendrec = NULL;
-	} else if (worker->w_sendrec != NULL) {		/* FS */
-		worker->w_sendrec->m_type = EIO;
-		worker->w_sendrec = NULL;
-	} else {
-		panic("reply storage consistency error");	/* Oh dear */
-	}
-  } else {
-	/* This shouldn't happen at all... */
-	printf("VFS: stopping worker not blocked on any task?\n");
-	util_stacktrace();
-  }
+  /* This thread is communicating with a driver or file server */
+  if (worker->w_drv_sendrec != NULL) {			/* Driver */
+	assert(worker->w_task != NONE);
+	worker->w_drv_sendrec->m_type = EIO;
+	worker->w_drv_sendrec = NULL;
+  } else if (worker->w_sendrec != NULL) {		/* FS */
+	/* worker->w_task may be NONE if the FS message was still queued */
+	worker->w_sendrec->m_type = EIO;
+	worker->w_sendrec = NULL;
+  } else
+	panic("reply storage consistency error");	/* Oh dear */
   worker_wake(worker);
 }