net/9p: handle flushed Tclunk/Tremove

When a Tclunk or Tremove request is flushed, the fid is not freed on the
server.

p9_client_clunk() should retry once on interrupt, then if interrupted
again, leak the fid for the duration of the connection.

p9_client_remove() should call p9_client_clunk() on interrupt
instead of unconditionally destroying the fid.
Signed-off-by: Jim Garlick <garlick@llnl.gov>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

net/9p/client.c

@@ -1428,6 +1428,7 @@ int p9_client_clunk(struct p9_fid *fid)
 	int err;
 	struct p9_client *clnt;
 	struct p9_req_t *req;
+	int retries = 0;
 
 	if (!fid) {
 		pr_warn("%s (%d): Trying to clunk with NULL fid\n",
@@ -1436,7 +1437,9 @@ int p9_client_clunk(struct p9_fid *fid)
 		return 0;
 	}
 
-	p9_debug(P9_DEBUG_9P, ">>> TCLUNK fid %d\n", fid->fid);
+again:
+	p9_debug(P9_DEBUG_9P, ">>> TCLUNK fid %d (try %d)\n", fid->fid,
+								retries);
 	err = 0;
 	clnt = fid->clnt;
 
@@ -1452,8 +1455,14 @@ int p9_client_clunk(struct p9_fid *fid)
 error:
 	/*
 	 * Fid is not valid even after a failed clunk
+	 * If interrupted, retry once then give up and
+	 * leak fid until umount.
 	 */
-	p9_fid_destroy(fid);
+	if (err == -ERESTARTSYS) {
+		if (retries++ == 0)
+			goto again;
+	} else
+		p9_fid_destroy(fid);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_clunk);
@@ -1478,7 +1487,10 @@ int p9_client_remove(struct p9_fid *fid)
 
 	p9_free_req(clnt, req);
 error:
-	p9_fid_destroy(fid);
+	if (err == -ERESTARTSYS)
+		p9_client_clunk(fid);
+	else
+		p9_fid_destroy(fid);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_remove);