linux-kernel - [PATCH v3] cifs: Silently ignore unknown oplock break handle

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Message-ID: <20210319135711.11802-1-vincent.whitchurch@axis.com>
Date:   Fri, 19 Mar 2021 14:57:11 +0100
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     Steve French <sfrench@...ba.org>
CC:     <kernel@...s.com>, <tom@...pey.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <linux-cifs@...r.kernel.org>, <samba-technical@...ts.samba.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] cifs: Silently ignore unknown oplock break handle

Make SMB2 not print out an error when an oplock break is received for an
unknown handle, similar to SMB1.  The debug message which is printed for
these unknown handles may also be misleading, so fix that too.

The SMB2 lease break path is not affected by this patch.

Without this, a program which writes to a file from one thread, and
opens, reads, and writes the same file from another thread triggers the
below errors several times a minute when run against a Samba server
configured with "smb2 leases = no".

 CIFS: VFS: \\192.168.0.1 No task to wake, unknown frame received! NumMids 2
 00000000: 424d53fe 00000040 00000000 00000012  .SMB@...........
 00000010: 00000001 00000000 ffffffff ffffffff  ................
 00000020: 00000000 00000000 00000000 00000000  ................
 00000030: 00000000 00000000 00000000 00000000  ................

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---

Notes:
    v3:
    - Change debug print to Tom Talpey's suggestion
    
    v2:
    - Drop change to lease break
    - Rewrite commit message

 fs/cifs/smb2misc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index 60d4bd1eae2b..76cd05b8d53b 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -754,8 +754,8 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
 		}
 	}
 	spin_unlock(&cifs_tcp_ses_lock);
-	cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
-	return false;
+	cifs_dbg(FYI, "No file id matched, oplock break ignored\n");
+	return true;
 }
 
 void
-- 
2.28.0