fsck.ubifs: Check and create the lost+found

This is the 16/18 step of fsck. Check whether the lost+found is existed,
create a new one if it is not found. This step makes sure that disconnected
file can be recovered under the lost+found.

Signed-off-by: Huang Xiaojia <huangxiaojia2@huawei.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 89 insertions, 0 deletions

diff --git a/ubifs-utils/fsck.ubifs/handle_disconnected.c b/ubifs-utils/fsck.ubifs/handle_disconnected.c
new file mode 100644
index 0000000..b9a380f
--- /dev/null
+++ b/ubifs-utils/fsck.ubifs/handle_disconnected.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024, Huawei Technologies Co, Ltd.
+ *
+ * Authors: Huang Xiaojia <huangxiaojia2@huawei.com>
+ *          Zhihao Cheng <chengzhihao1@huawei.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+
+#include "linux_err.h"
+#include "kmem.h"
+#include "ubifs.h"
+#include "defs.h"
+#include "debug.h"
+#include "key.h"
+#include "fsck.ubifs.h"
+
+#define LOST_FOUND_DIR_NAME "lost+found"
+
+/**
+ * check_and_create_lost_found - Check and create the lost+found directory.
+ * @c: UBIFS file-system description object
+ *
+ * This function checks whether the lost+found directory exists and creates a
+ * new one if no valid lost+found existing. If there is a valid lost+found
+ * directory, inode number is stored in @FSCK(c)->lost_and_found. Returns zero
+ * in case of success, a negative error code in case of failure.
+ */
+int check_and_create_lost_found(struct ubifs_info *c)
+{
+	struct ubifs_inode *root_ui, *lost_found_ui;
+	struct fscrypt_name nm;
+	int err = 0;
+
+	root_ui = ubifs_lookup_by_inum(c, UBIFS_ROOT_INO);
+	if (IS_ERR(root_ui)) {
+		err = PTR_ERR(root_ui);
+		/* Previous step ensures that the root dir is valid. */
+		ubifs_assert(c, err != -ENOENT);
+		return err;
+	}
+
+	if (root_ui->flags & UBIFS_CRYPT_FL) {
+		ubifs_msg(c, "The root dir is encrypted, skip checking lost+found");
+		goto free_root;
+	}
+
+	fname_name(&nm) = LOST_FOUND_DIR_NAME;
+	fname_len(&nm) = strlen(LOST_FOUND_DIR_NAME);
+	lost_found_ui = ubifs_lookup(c, root_ui, &nm);
+	if (IS_ERR(lost_found_ui)) {
+		err = PTR_ERR(lost_found_ui);
+		if (err != -ENOENT)
+			goto free_root;
+
+		/* Not found. Create a new lost+found. */
+		err = ubifs_mkdir(c, root_ui, &nm, S_IRUGO | S_IWUSR | S_IXUSR);
+		if (err < 0) {
+			if (err == -ENOSPC) {
+				ubifs_msg(c, "No free space to create lost+found");
+				err = 0;
+			}
+			goto free_root;
+		}
+		lost_found_ui = ubifs_lookup(c, root_ui, &nm);
+		if (IS_ERR(lost_found_ui)) {
+			err = PTR_ERR(lost_found_ui);
+			ubifs_assert(c, err != -ENOENT);
+			goto free_root;
+		}
+		FSCK(c)->lost_and_found = lost_found_ui->vfs_inode.inum;
+		ubifs_msg(c, "Create the lost+found");
+	} else if (!(lost_found_ui->flags & UBIFS_CRYPT_FL) &&
+		   S_ISDIR(lost_found_ui->vfs_inode.mode)) {
+		FSCK(c)->lost_and_found = lost_found_ui->vfs_inode.inum;
+	} else {
+		ubifs_msg(c, "The type of lost+found is %s%s",
+			  ubifs_get_type_name(ubifs_get_dent_type(lost_found_ui->vfs_inode.mode)),
+			  lost_found_ui->flags & UBIFS_CRYPT_FL ? ", encrypted" : "");
+	}
+
+	kfree(lost_found_ui);
+free_root:
+	kfree(root_ui);
+	return err;
+}