smb: client: fix warning in cifs_smb3_do_mount()

This fixes the following warning reported by kernel test robot

  fs/smb/client/cifsfs.c:982 cifs_smb3_do_mount() warn: possible
  memory leak of 'cifs_sb'

Link: https://lore.kernel.org/all/202306170124.CtQqzf0I-lkp@intel.com/
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: Paulo Alcantara

fs/smb/client/cifsfs.c

@@ -886,11 +886,11 @@ struct dentry *
 cifs_smb3_do_mount(struct file_system_type *fs_type,
 	      int flags, struct smb3_fs_context *old_ctx)
 {
-	int rc;
-	struct super_block *sb = NULL;
-	struct cifs_sb_info *cifs_sb = NULL;
 	struct cifs_mnt_data mnt_data;
+	struct cifs_sb_info *cifs_sb;
+	struct super_block *sb;
 	struct dentry *root;
+	int rc;
 
 	if (cifsFYI) {
 		cifs_dbg(FYI, "%s: devname=%s flags=0x%x\n", __func__,
@@ -899,11 +899,9 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 		cifs_info("Attempting to mount %s\n", old_ctx->source);
 	}
 
-	cifs_sb = kzalloc(sizeof(struct cifs_sb_info), GFP_KERNEL);
-	if (cifs_sb == NULL) {
-		root = ERR_PTR(-ENOMEM);
-		goto out;
-	}
+	cifs_sb = kzalloc(sizeof(*cifs_sb), GFP_KERNEL);
+	if (!cifs_sb)
+		return ERR_PTR(-ENOMEM);
 
 	cifs_sb->ctx = kzalloc(sizeof(struct smb3_fs_context), GFP_KERNEL);
 	if (!cifs_sb->ctx) {
@@ -940,10 +938,8 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 
 	sb = sget(fs_type, cifs_match_super, cifs_set_super, flags, &mnt_data);
 	if (IS_ERR(sb)) {
-		root = ERR_CAST(sb);
 		cifs_umount(cifs_sb);
-		cifs_sb = NULL;
-		goto out;
+		return ERR_CAST(sb);
 	}
 
 	if (sb->s_root) {
@@ -974,13 +970,9 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 	deactivate_locked_super(sb);
 	return root;
 out:
-	if (cifs_sb) {
-		if (!sb || IS_ERR(sb)) {  /* otherwise kill_sb will handle */
-			kfree(cifs_sb->prepath);
-			smb3_cleanup_fs_context(cifs_sb->ctx);
-			kfree(cifs_sb);
-		}
-	}
+	kfree(cifs_sb->prepath);
+	smb3_cleanup_fs_context(cifs_sb->ctx);
+	kfree(cifs_sb);
 	return root;
 }