// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (c) International Business Machines Corp., 2006 * Copyright (c) Nokia Corporation, 2006, 2007 * * Author: Artem Bityutskiy (Битюцкий Артём) */ /* * This file includes volume table manipulation code. The volume table is an * on-flash table containing volume meta-data like name, number of reserved * physical eraseblocks, type, etc. The volume table is stored in the so-called * "layout volume". * * The layout volume is an internal volume which is organized as follows. It * consists of two logical eraseblocks - LEB 0 and LEB 1. Each logical * eraseblock stores one volume table copy, i.e. LEB 0 and LEB 1 duplicate each * other. This redundancy guarantees robustness to unclean reboots. The volume * table is basically an array of volume table records. Each record contains * full information about the volume and protected by a CRC checksum. Note, * nowadays we use the atomic LEB change operation when updating the volume * table, so we do not really need 2 LEBs anymore, but we preserve the older * design for the backward compatibility reasons. * * When the volume table is changed, it is first changed in RAM. Then LEB 0 is * erased, and the updated volume table is written back to LEB 0. Then same for * LEB 1. This scheme guarantees recoverability from unclean reboots. * * In this UBI implementation the on-flash volume table does not contain any * information about how much data static volumes contain. * * But it would still be beneficial to store this information in the volume * table. For example, suppose we have a static volume X, and all its physical * eraseblocks became bad for some reasons. Suppose we are attaching the * corresponding MTD device, for some reason we find no logical eraseblocks * corresponding to the volume X. According to the volume table volume X does * exist. So we don't know whether it is just empty or all its physical * eraseblocks went bad. So we cannot alarm the user properly. * * The volume table also stores so-called "update marker", which is used for * volume updates. Before updating the volume, the update marker is set, and * after the update operation is finished, the update marker is cleared. So if * the update operation was interrupted (e.g. by an unclean reboot) - the * update marker is still there and we know that the volume's contents is * damaged. */ #include <linux/crc32.h> #include <linux/err.h> #include <linux/slab.h> #include <asm/div64.h> #include "ubi.h" static void self_vtbl_check(const struct ubi_device *ubi); /* Empty volume table record */ static struct ubi_vtbl_record empty_vtbl_record; /** * ubi_update_layout_vol - helper for updatting layout volumes on flash * @ubi: UBI device description object */ static int ubi_update_layout_vol(struct ubi_device *ubi) { … } /** * ubi_change_vtbl_record - change volume table record. * @ubi: UBI device description object * @idx: table index to change * @vtbl_rec: new volume table record * * This function changes volume table record @idx. If @vtbl_rec is %NULL, empty * volume table record is written. The caller does not have to calculate CRC of * the record as it is done by this function. Returns zero in case of success * and a negative error code in case of failure. */ int ubi_change_vtbl_record(struct ubi_device *ubi, int idx, struct ubi_vtbl_record *vtbl_rec) { … } /** * ubi_vtbl_rename_volumes - rename UBI volumes in the volume table. * @ubi: UBI device description object * @rename_list: list of &struct ubi_rename_entry objects * * This function re-names multiple volumes specified in @req in the volume * table. Returns zero in case of success and a negative error code in case of * failure. */ int ubi_vtbl_rename_volumes(struct ubi_device *ubi, struct list_head *rename_list) { … } /** * vtbl_check - check if volume table is not corrupted and sensible. * @ubi: UBI device description object * @vtbl: volume table * * This function returns zero if @vtbl is all right, %1 if CRC is incorrect, * and %-EINVAL if it contains inconsistent data. */ static int vtbl_check(const struct ubi_device *ubi, const struct ubi_vtbl_record *vtbl) { … } /** * create_vtbl - create a copy of volume table. * @ubi: UBI device description object * @ai: attaching information * @copy: number of the volume table copy * @vtbl: contents of the volume table * * This function returns zero in case of success and a negative error code in * case of failure. */ static int create_vtbl(struct ubi_device *ubi, struct ubi_attach_info *ai, int copy, void *vtbl) { … } /** * process_lvol - process the layout volume. * @ubi: UBI device description object * @ai: attaching information * @av: layout volume attaching information * * This function is responsible for reading the layout volume, ensuring it is * not corrupted, and recovering from corruptions if needed. Returns volume * table in case of success and a negative error code in case of failure. */ static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi, struct ubi_attach_info *ai, struct ubi_ainf_volume *av) { … } /** * create_empty_lvol - create empty layout volume. * @ubi: UBI device description object * @ai: attaching information * * This function returns volume table contents in case of success and a * negative error code in case of failure. */ static struct ubi_vtbl_record *create_empty_lvol(struct ubi_device *ubi, struct ubi_attach_info *ai) { … } /** * init_volumes - initialize volume information for existing volumes. * @ubi: UBI device description object * @ai: scanning information * @vtbl: volume table * * This function allocates volume description objects for existing volumes. * Returns zero in case of success and a negative error code in case of * failure. */ static int init_volumes(struct ubi_device *ubi, const struct ubi_attach_info *ai, const struct ubi_vtbl_record *vtbl) { … } /** * check_av - check volume attaching information. * @vol: UBI volume description object * @av: volume attaching information * * This function returns zero if the volume attaching information is consistent * to the data read from the volume tabla, and %-EINVAL if not. */ static int check_av(const struct ubi_volume *vol, const struct ubi_ainf_volume *av) { … } /** * check_attaching_info - check that attaching information. * @ubi: UBI device description object * @ai: attaching information * * Even though we protect on-flash data by CRC checksums, we still don't trust * the media. This function ensures that attaching information is consistent to * the information read from the volume table. Returns zero if the attaching * information is OK and %-EINVAL if it is not. */ static int check_attaching_info(const struct ubi_device *ubi, struct ubi_attach_info *ai) { … } /** * ubi_read_volume_table - read the volume table. * @ubi: UBI device description object * @ai: attaching information * * This function reads volume table, checks it, recover from errors if needed, * or creates it if needed. Returns zero in case of success and a negative * error code in case of failure. */ int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_attach_info *ai) { … } /** * self_vtbl_check - check volume table. * @ubi: UBI device description object */ static void self_vtbl_check(const struct ubi_device *ubi) { … }
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