cifs-respect-o_sync-and-o_direct-flags-during-reconnect.patch

From 44805b0e62f15e90d233485420e1847133716bdc Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <pshilov@microsoft.com>
Date: Tue, 12 Nov 2019 17:16:35 -0800
Subject: CIFS: Respect O_SYNC and O_DIRECT flags during reconnect

From: Pavel Shilovsky <pshilov@microsoft.com>

commit 44805b0e62f15e90d233485420e1847133716bdc upstream.

Currently the client translates O_SYNC and O_DIRECT flags
into corresponding SMB create options when openning a file.
The problem is that on reconnect when the file is being
re-opened the client doesn't set those flags and it causes
a server to reject re-open requests because create options
don't match. The latter means that any subsequent system
call against that open file fail until a share is re-mounted.

Fix this by properly setting SMB create options when
re-openning files after reconnects.

Fixes: 1013e760d10e6: ("SMB3: Don't ignore O_SYNC/O_DSYNC and O_DIRECT flags")
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/cifs/file.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -696,6 +696,13 @@ cifs_reopen_file(struct cifsFileInfo *cf
 	if (backup_cred(cifs_sb))
 		create_options |= CREATE_OPEN_BACKUP_INTENT;
 
+	/* O_SYNC also has bit for O_DSYNC so following check picks up either */
+	if (cfile->f_flags & O_SYNC)
+		create_options |= CREATE_WRITE_THROUGH;
+
+	if (cfile->f_flags & O_DIRECT)
+		create_options |= CREATE_NO_BUFFER;
+
 	if (server->ops->get_lease_key)
 		server->ops->get_lease_key(inode, &cfile->fid);