[PATCH] cifs: do not attempt unlink-and-retry-rename for SMB2+ mounts

[Ronnie Sahlberg <lsahlber@redhat.com>]

Normally in smb you can not rename ontop of a destination that is held open
except in SMB1 where this is allowed IFF the delete-on-close flag is also set.
This special case is not supported in SMB2 so should not attempt the unlink-and-try-again
since the rename will still fail but we now also delete the destination file.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/inode.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 56ca4b8ccaba..fdea45267a39 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -1777,6 +1777,7 @@ cifs_rename2(struct inode *source_dir, struct dentry *source_dentry,
 	FILE_UNIX_BASIC_INFO *info_buf_target;
 	unsigned int xid;
 	int rc, tmprc;
+	struct TCP_Server_Info *server;
 
 	if (flags & ~RENAME_NOREPLACE)
 		return -EINVAL;
@@ -1786,6 +1787,7 @@ cifs_rename2(struct inode *source_dir, struct dentry *source_dentry,
 	if (IS_ERR(tlink))
 		return PTR_ERR(tlink);
 	tcon = tlink_tcon(tlink);
+	server = tcon->ses->server;
 
 	xid = get_xid();
 
@@ -1809,6 +1811,14 @@ cifs_rename2(struct inode *source_dir, struct dentry *source_dentry,
 			    to_name);
 
 	/*
+	 * Do not attempt unlink-then-try-rename-again for SMB2+.
+	 * Renaming ontop of an existing open file IF the delete-on-close
+	 * flag is set is only supported for SMB1.
+	 */
+	if (rc == -EACCES && server->vals->protocol_id != 0)
+		goto cifs_rename_exit;
+
+	/*
 	 * No-replace is the natural behavior for CIFS, so skip unlink hacks.
 	 */
 	if (flags & RENAME_NOREPLACE)
-- 
2.13.6