cifs: support RENAME_NOREPLACE

This flag gives CIFS the ability to support its native rename semantics.

Implementation is simple: just bail out before trying to hack around the
noreplace semantics.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Steve French <smfrench@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/cifs/cifsfs.c

@@ -848,7 +848,7 @@ const struct inode_operations cifs_dir_inode_ops = {
 	.link = cifs_hardlink,
 	.mkdir = cifs_mkdir,
 	.rmdir = cifs_rmdir,
-	.rename = cifs_rename,
+	.rename2 = cifs_rename2,
 	.permission = cifs_permission,
 /*	revalidate:cifs_revalidate,   */
 	.setattr = cifs_setattr,

fs/cifs/cifsfs.h

@@ -68,8 +68,8 @@ extern int cifs_hardlink(struct dentry *, struct inode *, struct dentry *);
 extern int cifs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
 extern int cifs_mkdir(struct inode *, struct dentry *, umode_t);
 extern int cifs_rmdir(struct inode *, struct dentry *);
-extern int cifs_rename(struct inode *, struct dentry *, struct inode *,
-		       struct dentry *);
+extern int cifs_rename2(struct inode *, struct dentry *, struct inode *,
+			struct dentry *, unsigned int);
 extern int cifs_revalidate_file_attr(struct file *filp);
 extern int cifs_revalidate_dentry_attr(struct dentry *);
 extern int cifs_revalidate_file(struct file *filp);

fs/cifs/inode.c

@@ -1627,8 +1627,9 @@ cifs_do_rename(const unsigned int xid, struct dentry *from_dentry,
 }
 
 int
-cifs_rename(struct inode *source_dir, struct dentry *source_dentry,
-	    struct inode *target_dir, struct dentry *target_dentry)
+cifs_rename2(struct inode *source_dir, struct dentry *source_dentry,
+	     struct inode *target_dir, struct dentry *target_dentry,
+	     unsigned int flags)
 {
 	char *from_name = NULL;
 	char *to_name = NULL;
@@ -1640,6 +1641,9 @@ cifs_rename(struct inode *source_dir, struct dentry *source_dentry,
 	unsigned int xid;
 	int rc, tmprc;
 
+	if (flags & ~RENAME_NOREPLACE)
+		return -EINVAL;
+
 	cifs_sb = CIFS_SB(source_dir->i_sb);
 	tlink = cifs_sb_tlink(cifs_sb);
 	if (IS_ERR(tlink))
@@ -1667,6 +1671,12 @@ cifs_rename(struct inode *source_dir, struct dentry *source_dentry,
 	rc = cifs_do_rename(xid, source_dentry, from_name, target_dentry,
 			    to_name);
 
+	/*
+	 * No-replace is the natural behavior for CIFS, so skip unlink hacks.
+	 */
+	if (flags & RENAME_NOREPLACE)
+		goto cifs_rename_exit;
+
 	if (rc == -EEXIST && tcon->unix_ext) {
 		/*
 		 * Are src and dst hardlinks of same inode? We can only tell