3514 Spurious errors setting up new SMB client sessions

Reviewed by: Bayard Bell <bayard.bell@nexenta.com>
Reviewed by: Dan McDonald <danmcd@nexenta.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

1 files changed, 23 insertions, 10 deletions

diff --git a/usr/src/cmd/fs.d/smbclnt/smbiod/smbiod.c b/usr/src/cmd/fs.d/smbclnt/smbiod/smbiod.c
index 5296cb2be9..32fda8d5fb 100644
--- a/usr/src/cmd/fs.d/smbclnt/smbiod/smbiod.c
+++ b/usr/src/cmd/fs.d/smbclnt/smbiod/smbiod.c
@@ -21,6 +21,7 @@
 
 /*
  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2012 Nexenta Systems, Inc.  All rights reserved.
  */
 
 /*
@@ -281,24 +282,36 @@ iod_newvc(smb_iod_ssn_t *clnt_ssn)
 	bcopy(clnt_ssn, &ctx->ct_iod_ssn, sizeof (ctx->ct_iod_ssn));
 
 	/*
-	 * Do the initial connection setup here, so we can
-	 * report the outcome to the door client.
-	 */
-	err = smb_iod_connect(ctx);
-	if (err != 0)
-		goto out;
-
-	/*
-	 * Create the driver session now, so we don't
-	 * race with the door client findvc call.
+	 * Create the driver session first, so that any subsequent
+	 * requests for the same session will find this one and
+	 * wait, the same as when a reconnect is triggered.
+	 *
+	 * There is still an inherent race here, where two callers
+	 * both find no VC in the driver, and both come here trying
+	 * to create the VC.  In this case, we want the first one
+	 * to actually do the VC setup, and the second to proceed
+	 * as if the VC had been found in the driver.  The second
+	 * caller gets an EEXIST error from the ioctl in this case,
+	 * which we therefore ignore here so that the caller will
+	 * go ahead and look again in the driver for the new VC.
 	 */
 	if ((err = smb_ctx_gethandle(ctx)) != 0)
 		goto out;
 	if (ioctl(ctx->ct_dev_fd, SMBIOC_SSN_CREATE, &ctx->ct_ssn) < 0) {
 		err = errno;
+		if (err == EEXIST)
+			err = 0; /* see above */
 		goto out;
 	}
 
+	/*
+	 * Do the initial connection setup here, so we can
+	 * report the outcome to the door client.
+	 */
+	err = smb_iod_connect(ctx);
+	if (err != 0)
+		goto out;
+
 	/* The rest happens in the iod_work thread. */
 	err = thr_create(NULL, 0, iod_work, ctx, THR_DETACHED, &tid);
 	if (err == 0) {