linux-kernel - [PATCH 3.16 119/148] CIFS: Respect O_SYNC and O

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Message-ID: <lsq.1581185941.660520030@decadent.org.uk>
Date:   Sat, 08 Feb 2020 18:20:58 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Pavel Shilovsky" <pshilov@...rosoft.com>,
        "Steve French" <stfrench@...rosoft.com>
Subject: [PATCH 3.16 119/148] CIFS: Respect O_SYNC and O_DIRECT flags
 during reconnect

3.16.82-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Pavel Shilovsky <pshilov@...rosoft.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")
Signed-off-by: Pavel Shilovsky <pshilov@...rosoft.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/cifs/file.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -711,6 +711,13 @@ 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);