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lvm2/lib/cache/lvmcache.h
David Teigland 83fe6e720f 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
2021-02-23 16:43:32 -06:00

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/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2008 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_CACHE_H
#define _LVM_CACHE_H
#include "lib/device/dev-cache.h"
#include "lib/device/dev-type.h"
#include "lib/uuid/uuid.h"
#include "lib/label/label.h"
#include "lib/locking/locking.h"
#define ORPHAN_PREFIX VG_ORPHANS
#define ORPHAN_VG_NAME(fmt) ORPHAN_PREFIX "_" fmt
/* LVM specific per-volume info */
/* Eventual replacement for struct physical_volume perhaps? */
struct cmd_context;
struct format_type;
struct volume_group;
struct physical_volume;
struct dm_config_tree;
struct format_instance;
struct metadata_area;
struct disk_locn;
struct lvmcache_vginfo;
/*
* vgsummary represents a summary of the VG that is read
* without a lock during label scan. It's used to populate
* basic lvmcache vginfo/info during label scan prior to
* vg_read().
*/
struct lvmcache_vgsummary {
const char *vgname;
struct id vgid;
uint64_t vgstatus;
char *creation_host;
const char *system_id;
const char *lock_type;
uint32_t seqno;
uint32_t mda_checksum;
size_t mda_size;
int mda_num; /* 1 = summary from mda1, 2 = summary from mda2 */
unsigned mda_ignored:1;
unsigned zero_offset:1;
unsigned mismatch:1; /* lvmcache sets if this summary differs from previous values */
struct dm_list pvsummaries;
};
int lvmcache_init(struct cmd_context *cmd);
void lvmcache_destroy(struct cmd_context *cmd, int retain_orphans, int reset);
int lvmcache_label_scan(struct cmd_context *cmd);
int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid);
int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid);
int lvmcache_label_reopen_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid);
/* Add/delete a device */
struct lvmcache_info *lvmcache_add(struct cmd_context *cmd, struct labeller *labeller, const char *pvid,
struct device *dev, uint64_t label_sector,
const char *vgname, const char *vgid,
uint32_t vgstatus, int *is_duplicate);
int lvmcache_add_orphan_vginfo(struct cmd_context *cmd, const char *vgname, struct format_type *fmt);
void lvmcache_del(struct lvmcache_info *info);
void lvmcache_del_dev(struct device *dev);
/* Update things */
int lvmcache_update_vgname_and_id(struct cmd_context *cmd, struct lvmcache_info *info,
struct lvmcache_vgsummary *vgsummary);
int lvmcache_update_vg_from_read(struct volume_group *vg, unsigned precommitted);
int lvmcache_update_vg_from_write(struct volume_group *vg);
void lvmcache_lock_vgname(const char *vgname, int read_only);
void lvmcache_unlock_vgname(const char *vgname);
/* Queries */
int lvmcache_lookup_mda(struct lvmcache_vgsummary *vgsummary);
struct lvmcache_vginfo *lvmcache_vginfo_from_vgname(const char *vgname,
const char *vgid);
struct lvmcache_vginfo *lvmcache_vginfo_from_vgid(const char *vgid);
struct lvmcache_info *lvmcache_info_from_pvid(const char *pvid, struct device *dev, int valid_only);
const char *lvmcache_vgname_from_vgid(struct dm_pool *mem, const char *vgid);
const char *lvmcache_vgid_from_vgname(struct cmd_context *cmd, const char *vgname);
struct device *lvmcache_device_from_pvid(struct cmd_context *cmd, const struct id *pvid, uint64_t *label_sector);
const char *lvmcache_vgname_from_info(struct lvmcache_info *info);
const struct format_type *lvmcache_fmt_from_info(struct lvmcache_info *info);
int lvmcache_get_vgnameids(struct cmd_context *cmd,
struct dm_list *vgnameids,
const char *only_this_vgname,
int include_internal);
void lvmcache_drop_metadata(const char *vgname, int drop_precommitted);
void lvmcache_commit_metadata(const char *vgname);
int lvmcache_fid_add_mdas(struct lvmcache_info *info, struct format_instance *fid,
const char *id, int id_len);
int lvmcache_fid_add_mdas_pv(struct lvmcache_info *info, struct format_instance *fid);
int lvmcache_fid_add_mdas_vg(struct lvmcache_vginfo *vginfo, struct format_instance *fid);
int lvmcache_populate_pv_fields(struct lvmcache_info *info,
struct volume_group *vg,
struct physical_volume *pv);
int lvmcache_check_format(struct lvmcache_info *info, const struct format_type *fmt);
void lvmcache_del_mdas(struct lvmcache_info *info);
void lvmcache_del_das(struct lvmcache_info *info);
void lvmcache_del_bas(struct lvmcache_info *info);
int lvmcache_add_mda(struct lvmcache_info *info, struct device *dev,
uint64_t start, uint64_t size, unsigned ignored,
struct metadata_area **mda_new);
int lvmcache_add_da(struct lvmcache_info *info, uint64_t start, uint64_t size);
int lvmcache_add_ba(struct lvmcache_info *info, uint64_t start, uint64_t size);
void lvmcache_set_ext_version(struct lvmcache_info *info, uint32_t version);
uint32_t lvmcache_ext_version(struct lvmcache_info *info);
void lvmcache_set_ext_flags(struct lvmcache_info *info, uint32_t flags);
uint32_t lvmcache_ext_flags(struct lvmcache_info *info);
const struct format_type *lvmcache_fmt(struct lvmcache_info *info);
struct label *lvmcache_get_label(struct lvmcache_info *info);
struct label *lvmcache_get_dev_label(struct device *dev);
int lvmcache_has_dev_info(struct device *dev);
void lvmcache_update_pv(struct lvmcache_info *info, struct physical_volume *pv,
const struct format_type *fmt);
int lvmcache_update_das(struct lvmcache_info *info, struct physical_volume *pv);
int lvmcache_update_bas(struct lvmcache_info *info, struct physical_volume *pv);
int lvmcache_foreach_mda(struct lvmcache_info *info,
int (*fun)(struct metadata_area *, void *),
void *baton);
int lvmcache_foreach_da(struct lvmcache_info *info,
int (*fun)(struct disk_locn *, void *),
void *baton);
int lvmcache_foreach_ba(struct lvmcache_info *info,
int (*fun)(struct disk_locn *, void *),
void *baton);
int lvmcache_foreach_pv(struct lvmcache_vginfo *vginfo,
int (*fun)(struct lvmcache_info *, void *), void * baton);
uint64_t lvmcache_device_size(struct lvmcache_info *info);
void lvmcache_set_device_size(struct lvmcache_info *info, uint64_t size);
struct device *lvmcache_device(struct lvmcache_info *info);
unsigned lvmcache_mda_count(struct lvmcache_info *info);
uint64_t lvmcache_smallest_mda_size(struct lvmcache_info *info);
bool lvmcache_has_duplicate_devs(void);
void lvmcache_del_dev_from_duplicates(struct device *dev);
bool lvmcache_dev_is_unused_duplicate(struct device *dev);
int lvmcache_pvid_in_unused_duplicates(const char *pvid);
int lvmcache_get_unused_duplicates(struct cmd_context *cmd, struct dm_list *head);
int vg_has_duplicate_pvs(struct volume_group *vg);
int lvmcache_found_duplicate_vgnames(void);
bool lvmcache_has_duplicate_local_vgname(const char *vgid, const char *vgname);
int lvmcache_contains_lock_type_sanlock(struct cmd_context *cmd);
void lvmcache_get_max_name_lengths(struct cmd_context *cmd,
unsigned *pv_max_name_len, unsigned *vg_max_name_len);
int lvmcache_vg_is_foreign(struct cmd_context *cmd, const char *vgname, const char *vgid);
bool lvmcache_scan_mismatch(struct cmd_context *cmd, const char *vgname, const char *vgid);
int lvmcache_vginfo_has_pvid(struct lvmcache_vginfo *vginfo, char *pvid);
uint64_t lvmcache_max_metadata_size(void);
void lvmcache_save_metadata_size(uint64_t val);
int dev_in_device_list(struct device *dev, struct dm_list *head);
bool lvmcache_has_bad_metadata(struct device *dev);
bool lvmcache_has_old_metadata(struct cmd_context *cmd, const char *vgname, const char *vgid, struct device *dev);
void lvmcache_get_outdated_devs(struct cmd_context *cmd,
const char *vgname, const char *vgid,
struct dm_list *devs);
void lvmcache_get_outdated_mdas(struct cmd_context *cmd,
const char *vgname, const char *vgid,
struct device *dev,
struct dm_list **mdas);
bool lvmcache_is_outdated_dev(struct cmd_context *cmd,
const char *vgname, const char *vgid,
struct device *dev);
void lvmcache_del_outdated_devs(struct cmd_context *cmd,
const char *vgname, const char *vgid);
void lvmcache_save_bad_mda(struct lvmcache_info *info, struct metadata_area *mda);
void lvmcache_get_bad_mdas(struct cmd_context *cmd,
const char *vgname, const char *vgid,
struct dm_list *bad_mda_list);
void lvmcache_get_mdas(struct cmd_context *cmd,
const char *vgname, const char *vgid,
struct dm_list *mda_list);
const char *dev_filtered_reason(struct device *dev);
const char *devname_error_reason(const char *devname);
struct metadata_area *lvmcache_get_dev_mda(struct device *dev, int mda_num);
void lvmcache_extra_md_component_checks(struct cmd_context *cmd);
unsigned int lvmcache_vg_info_count(void);
#endif
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