[PATCH 5.10.y] smb: client: fix atomic open with O_DIRECT & O_SYNC

[Sasha Levin <sashal@kernel.org>]

From: Paulo Alcantara <pc@manguebit.org>

[ Upstream commit 4a7d2729dc99437dbb880a64c47828c0d191b308 ]

When user application requests O_DIRECT|O_SYNC along with O_CREAT on
open(2), CREATE_NO_BUFFER and CREATE_WRITE_THROUGH bits were missed in
CREATE request when performing an atomic open, thus leading to
potentially data integrity issues.

Fix this by setting those missing bits in CREATE request when
O_DIRECT|O_SYNC has been specified in cifs_do_create().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Henrique Carvalho <henrique.carvalho@suse.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
[ adapted file paths from fs/smb/client/ to fs/cifs/ ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/cifsglob.h | 11 +++++++++++
 fs/cifs/dir.c      |  1 +
 fs/cifs/file.c     | 17 +++--------------
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index fab543bb0eaf1..a1a27a11dd950 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -26,6 +26,7 @@
 #include <linux/mm.h>
 #include <linux/mempool.h>
 #include <linux/workqueue.h>
+#include <linux/fcntl.h>
 #include "cifs_fs_sb.h"
 #include "cifsacl.h"
 #include <crypto/internal/hash.h>
@@ -2124,4 +2125,14 @@ static inline bool cifs_ses_exiting(struct cifs_ses *ses)
 	return ret;
 }
 
+static inline int cifs_open_create_options(unsigned int oflags, int opts)
+{
+	/* O_SYNC also has bit for O_DSYNC so following check picks up either */
+	if (oflags & O_SYNC)
+		opts |= CREATE_WRITE_THROUGH;
+	if (oflags & O_DIRECT)
+		opts |= CREATE_NO_BUFFER;
+	return opts;
+}
+
 #endif	/* _CIFS_GLOB_H */
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 0d7238cb45b56..73d43d8911aa5 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -348,6 +348,7 @@ cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
 		goto out;
 	}
 
+	create_options |= cifs_open_create_options(oflags, create_options);
 	/*
 	 * if we're not using unix extensions, see if we need to set
 	 * ATTR_READONLY on the create call
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index a56738244f3a9..0191ae0ff8c13 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -216,19 +216,13 @@ cifs_nt_open(char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
  *********************************************************************/
 
 	disposition = cifs_get_disposition(f_flags);
-
 	/* BB pass O_SYNC flag through on file attributes .. BB */
 
 	buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	/* O_SYNC also has bit for O_DSYNC so following check picks up either */
-	if (f_flags & O_SYNC)
-		create_options |= CREATE_WRITE_THROUGH;
-
-	if (f_flags & O_DIRECT)
-		create_options |= CREATE_NO_BUFFER;
+	create_options |= cifs_open_create_options(f_flags, create_options);
 
 	oparms.tcon = tcon;
 	oparms.cifs_sb = cifs_sb;
@@ -750,13 +744,8 @@ cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush)
 	}
 
 	desired_access = cifs_convert_flags(cfile->f_flags);
-
-	/* 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;
+	create_options |= cifs_open_create_options(cfile->f_flags,
+						   create_options);
 
 	if (server->ops->get_lease_key)
 		server->ops->get_lease_key(inode, &cfile->fid);
-- 
2.51.0