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lvm2/lib/device/device_id.h

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device usage based on devices file The LVM devices file lists devices that lvm can use. The default file is /etc/lvm/devices/system.devices, and the lvmdevices(8) command is used to add or remove device entries. If the file does not exist, or if lvm.conf includes use_devicesfile=0, then lvm will not use a devices file. When the devices file is in use, the regex filter is not used, and the filter settings in lvm.conf or on the command line are ignored. LVM records devices in the devices file using hardware-specific IDs, such as the WWID, and attempts to use subsystem-specific IDs for virtual device types. These device IDs are also written in the VG metadata. When no hardware or virtual ID is available, lvm falls back using the unstable device name as the device ID. When devnames are used, lvm performs extra scanning to find devices if their devname changes, e.g. after reboot. When proper device IDs are used, an lvm command will not look at devices outside the devices file, but when devnames are used as a fallback, lvm will scan devices outside the devices file to locate PVs on renamed devices. A config setting search_for_devnames can be used to control the scanning for renamed devname entries. Related to the devices file, the new command option --devices <devnames> allows a list of devices to be specified for the command to use, overriding the devices file. The listed devices act as a sort of devices file in terms of limiting which devices lvm will see and use. Devices that are not listed will appear to be missing to the lvm command. Multiple devices files can be kept in /etc/lvm/devices, which allows lvm to be used with different sets of devices, e.g. system devices do not need to be exposed to a specific application, and the application can use lvm on its own set of devices that are not exposed to the system. The option --devicesfile <filename> is used to select the devices file to use with the command. Without the option set, the default system devices file is used. Setting --devicesfile "" causes lvm to not use a devices file. An existing, empty devices file means lvm will see no devices. The new command vgimportdevices adds PVs from a VG to the devices file and updates the VG metadata to include the device IDs. vgimportdevices -a will import all VGs into the system devices file. LVM commands run by dmeventd not use a devices file by default, and will look at all devices on the system. A devices file can be created for dmeventd (/etc/lvm/devices/dmeventd.devices) If this file exists, lvm commands run by dmeventd will use it. Internal implementaion: - device_ids_read - read the devices file . add struct dev_use (du) to cmd->use_devices for each devices file entry - dev_cache_scan - get /dev entries . add struct device (dev) to dev_cache for each device on the system - device_ids_match - match devices file entries to /dev entries . match each du on cmd->use_devices to a dev in dev_cache, using device ID . on match, set du->dev, dev->id, dev->flags MATCHED_USE_ID - label_scan - read lvm headers and metadata from devices . filters are applied, those that do not need data from the device . filter-deviceid skips devs without MATCHED_USE_ID, i.e. skips /dev entries that are not listed in the devices file . read lvm label from dev . filters are applied, those that use data from the device . read lvm metadata from dev . add info/vginfo structs for PVs/VGs (info is "lvmcache") - device_ids_find_renamed_devs - handle devices with unstable devname ID where devname changed . this step only needed when devs do not have proper device IDs, and their dev names change, e.g. after reboot sdb becomes sdc. . detect incorrect match because PVID in the devices file entry does not match the PVID found when the device was read above . undo incorrect match between du and dev above . search system devices for new location of PVID . update devices file with new devnames for PVIDs on renamed devices . label_scan the renamed devs - continue with command processing
2020-06-23 21:25:41 +03:00
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _LVM_DEVICE_ID_H
#define _LVM_DEVICE_ID_H
void free_du(struct dev_use *du);
void free_dus(struct dm_list *list);
void free_did(struct dev_id *did);
void free_dids(struct dm_list *list);
const char *idtype_to_str(uint16_t idtype);
uint16_t idtype_from_str(const char *str);
const char *dev_idtype_for_metadata(struct cmd_context *cmd, struct device *dev);
const char *dev_idname_for_metadata(struct cmd_context *cmd, struct device *dev);
int device_ids_use_devname(struct cmd_context *cmd);
int device_ids_read(struct cmd_context *cmd);
int device_ids_write(struct cmd_context *cmd);
int device_id_add(struct cmd_context *cmd, struct device *dev, const char *pvid,
const char *idtype_arg, const char *id_arg);
void device_id_pvremove(struct cmd_context *cmd, struct device *dev);
void device_ids_match(struct cmd_context *cmd);
int device_ids_match_dev(struct cmd_context *cmd, struct device *dev);
void device_ids_validate(struct cmd_context *cmd, struct dm_list *scanned_devs, int *device_ids_invalid, int noupdate);
int device_ids_version_unchanged(struct cmd_context *cmd);
void device_ids_find_renamed_devs(struct cmd_context *cmd, struct dm_list *dev_list, int *search_count, int noupdate);
const char *device_id_system_read(struct cmd_context *cmd, struct device *dev, uint16_t idtype);
struct dev_use *get_du_for_dev(struct cmd_context *cmd, struct device *dev);
struct dev_use *get_du_for_pvid(struct cmd_context *cmd, const char *pvid);
char *devices_file_version(void);
int devices_file_exists(struct cmd_context *cmd);
int devices_file_touch(struct cmd_context *cmd);
int lock_devices_file(struct cmd_context *cmd, int mode);
int lock_devices_file_try(struct cmd_context *cmd, int mode, int *held);
void unlock_devices_file(struct cmd_context *cmd);
void devices_file_init(struct cmd_context *cmd);
void devices_file_exit(struct cmd_context *cmd);
void unlink_searched_devnames(struct cmd_context *cmd);
#endif
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