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/*
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* Copyright ( C ) 2001 - 2004 Sistina Software , Inc . All rights reserved .
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* Copyright ( C ) 2004 - 2009 Red Hat , Inc . All rights reserved .
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*
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* This file is part of LVM2 .
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*
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* This copyrighted material is made available to anyone wishing to use ,
* modify , copy , or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v .2 .1 .
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program ; if not , write to the Free Software Foundation ,
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* Inc . , 51 Franklin Street , Fifth Floor , Boston , MA 02110 - 1301 USA
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*/
# include "tools.h"
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struct vgextend_params {
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struct pvcreate_params pp ;
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} ;
static int _restore_pv ( struct volume_group * vg , const char * pv_name )
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{
struct pv_list * pvl = NULL ;
pvl = find_pv_in_vg ( vg , pv_name ) ;
if ( ! pvl ) {
log_warn ( " WARNING: PV %s not found in VG %s " , pv_name , vg - > name ) ;
return 0 ;
}
if ( ! pvl - > pv - > dev ) {
log_warn ( " WARNING: The PV %s is still missing. " , pv_name ) ;
return 0 ;
}
improve reading and repairing vg metadata
The fact that vg repair is implemented as a part of vg read
has led to a messy and complicated implementation of vg_read,
and limited and uncontrolled repair capability. This splits
read and repair apart.
Summary
-------
- take all kinds of various repairs out of vg_read
- vg_read no longer writes anything
- vg_read now simply reads and returns vg metadata
- vg_read ignores bad or old copies of metadata
- vg_read proceeds with a single good copy of metadata
- improve error checks and handling when reading
- keep track of bad (corrupt) copies of metadata in lvmcache
- keep track of old (seqno) copies of metadata in lvmcache
- keep track of outdated PVs in lvmcache
- vg_write will do basic repairs
- new command vgck --updatemetdata will do all repairs
Details
-------
- In scan, do not delete dev from lvmcache if reading/processing fails;
the dev is still present, and removing it makes it look like the dev
is not there. Records are now kept about the problems with each PV
so they be fixed/repaired in the appropriate places.
- In scan, record a bad mda on failure, and delete the mda from
mda in use list so it will not be used by vg_read or vg_write,
only by repair.
- In scan, succeed if any good mda on a device is found, instead of
failing if any is bad. The bad/old copies of metadata should not
interfere with normal usage while good copies can be used.
- In scan, add a record of old mdas in lvmcache for later, do not repair
them while reading, and do not let them prevent us from finding and
using a good copy of metadata from elsewhere. One result is that
"inconsistent metadata" is no longer a read error, but instead a
record in lvmcache that can be addressed separate from the read.
- Treat a dev with no good mdas like a dev with no mdas, which is an
existing case we already handle.
- Don't use a fake vg "handle" for returning an error from vg_read,
or the vg_read_error function for getting that error number;
just return null if the vg cannot be read or used, and an error_flags
arg with flags set for the specific kind of error (which can be used
later for determining the kind of repair.)
- Saving an original copy of the vg metadata, for purposes of reverting
a write, is now done explicitly in vg_read instead of being hidden in
the vg_make_handle function.
- When a vg is not accessible due to "access restrictions" but is
otherwise fine, return the vg through the new error_vg arg so that
process_each_pv can skip the PVs in the VG while processing.
(This is a temporary accomodation for the way process_each_pv
tracks which devs have been looked at, and can be dropped later
when process_each_pv implementation dev tracking is changed.)
- vg_read does not try to fix or recover a vg, but now just reads the
metadata, checks access restrictions and returns it.
(Checking access restrictions might be better done outside of vg_read,
but this is a later improvement.)
- _vg_read now simply makes one attempt to read metadata from
each mda, and uses the most recent copy to return to the caller
in the form of a 'vg' struct.
(bad mdas were excluded during the scan and are not retried)
(old mdas were not excluded during scan and are retried here)
- vg_read uses _vg_read to get the latest copy of metadata from mdas,
and then makes various checks against it to produce warnings,
and to check if VG access is allowed (access restrictions include:
writable, foreign, shared, clustered, missing pvs).
- Things that were previously silently/automatically written by vg_read
that are now done by vg_write, based on the records made in lvmcache
during the scan and read:
. clearing the missing flag
. updating old copies of metadata
. clearing outdated pvs
. updating pv header flags
- Bad/corrupt metadata are now repaired; they were not before.
Test changes
------------
- A read command no longer writes the VG to repair it, so add a write
command to do a repair.
(inconsistent-metadata, unlost-pv)
- When a missing PV is removed from a VG, and then the device is
enabled again, vgck --updatemetadata is needed to clear the
outdated PV before it can be used again, where it wasn't before.
(lvconvert-repair-policy, lvconvert-repair-raid, lvconvert-repair,
mirror-vgreduce-removemissing, pv-ext-flags, unlost-pv)
Reading bad/old metadata
------------------------
- "bad metadata": the mda_header or metadata text has invalid fields
or can't be parsed by lvm. This is a form of corruption that would
not be caused by known failure scenarios. A checksum error is
typically included among the errors reported.
- "old metadata": a valid copy of the metadata that has a smaller seqno
than other copies of the metadata. This can happen if the device
failed, or io failed, or lvm failed while commiting new metadata
to all the metadata areas. Old metadata on a PV that has been
removed from the VG is the "outdated" case below.
When a VG has some PVs with bad/old metadata, lvm can simply ignore
the bad/old copies, and use a good copy. This is why there are
multiple copies of the metadata -- so it's available even when some
of the copies cannot be used. The bad/old copies do not have to be
repaired before the VG can be used (the repair can happen later.)
A PV with no good copies of the metadata simply falls back to being
treated like a PV with no mdas; a common and harmless configuration.
When bad/old metadata exists, lvm warns the user about it, and
suggests repairing it using a new metadata repair command.
Bad metadata in particular is something that users will want to
investigate and repair themselves, since it should not happen and
may indicate some other problem that needs to be fixed.
PVs with bad/old metadata are not the same as missing devices.
Missing devices will block various kinds of VG modification or
activation, but bad/old metadata will not.
Previously, lvm would attempt to repair bad/old metadata whenever
it was read. This was unnecessary since lvm does not require every
copy of the metadata to be used. It would also hide potential
problems that should be investigated by the user. It was also
dangerous in cases where the VG was on shared storage. The user
is now allowed to investigate potential problems and decide how
and when to repair them.
Repairing bad/old metadata
--------------------------
When label scan sees bad metadata in an mda, that mda is removed
from the lvmcache info->mdas list. This means that vg_read will
skip it, and not attempt to read/process it again. If it was
the only in-use mda on a PV, that PV is treated like a PV with
no mdas. It also means that vg_write will also skip the bad mda,
and not attempt to write new metadata to it. The only way to
repair bad metadata is with the metadata repair command.
When label scan sees old metadata in an mda, that mda is kept
in the lvmcache info->mdas list. This means that vg_read will
read/process it again, and likely see the same mismatch with
the other copies of the metadata. Like the label_scan, the
vg_read will simply ignore the old copy of the metadata and
use the latest copy. If the command is modifying the vg
(e.g. lvcreate), then vg_write, which writes new metadata to
every mda on info->mdas, will write the new metadata to the
mda that had the old version. If successful, this will resolve
the old metadata problem (without needing to run a metadata
repair command.)
Outdated PVs
------------
An outdated PV is a PV that has an old copy of VG metadata
that shows it is a member of the VG, but the latest copy of
the VG metadata does not include this PV. This happens if
the PV is disconnected, vgreduce --removemissing is run to
remove the PV from the VG, then the PV is reconnected.
In this case, the outdated PV needs have its outdated metadata
removed and the PV used flag needs to be cleared. This repair
will be done by the subsequent repair command. It is also done
if vgremove is run on the VG.
MISSING PVs
-----------
When a device is missing, most commands will refuse to modify
the VG. This is the simple case. More complicated is when
a command is allowed to modify the VG while it is missing a
device.
When a VG is written while a device is missing for one of it's PVs,
the VG metadata is written to disk with the MISSING flag on the PV
with the missing device. When the VG is next used, it is treated
as if the PV with the MISSING flag still has a missing device, even
if that device has reappeared.
If all LVs that were using a PV with the MISSING flag are removed
or repaired so that the MISSING PV is no longer used, then the
next time the VG metadata is written, the MISSING flag will be
dropped.
Alternative methods of clearing the MISSING flag are:
vgreduce --removemissing will remove PVs with missing devices,
or PVs with the MISSING flag where the device has reappeared.
vgextend --restoremissing will clear the MISSING flag on PVs
where the device has reappeared, allowing the VG to be used
normally. This must be done with caution since the reappeared
device may have old data that is inconsistent with data on other PVs.
Bad mda repair
--------------
The new command:
vgck --updatemetadata VG
first uses vg_write to repair old metadata, and other basic
issues mentioned above (old metadata, outdated PVs, pv_header
flags, MISSING_PV flags). It will also go further and repair
bad metadata:
. text metadata that has a bad checksum
. text metadata that is not parsable
. corrupt mda_header checksum and version fields
(To keep a clean diff, #if 0 is added around functions that
are replaced by new code. These commented functions are
removed by the following commit.)
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if ( pvl - > pv - > status & MISSING_PV )
goto clear_flag ;
/*
* when the PV has no used PE ' s vg_read clears the MISSING_PV flag
* and sets this so we know .
*/
if ( pvl - > pv - > unused_missing_cleared )
goto clear_flag ;
log_warn ( " WARNING: PV %s was not missing in VG %s " , pv_name , vg - > name ) ;
return 0 ;
clear_flag :
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pvl - > pv - > status & = ~ MISSING_PV ;
return 1 ;
}
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static int _vgextend_restoremissing ( struct cmd_context * cmd __attribute__ ( ( unused ) ) ,
const char * vg_name , struct volume_group * vg ,
struct processing_handle * handle )
{
struct vgextend_params * vp = ( struct vgextend_params * ) handle - > custom_handle ;
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struct pvcreate_params * pp = & vp - > pp ;
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int fixed = 0 ;
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unsigned i ;
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if ( ! archive ( vg ) )
return_0 ;
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for ( i = 0 ; i < pp - > pv_count ; i + + )
if ( _restore_pv ( vg , pp - > pv_names [ i ] ) )
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fixed + + ;
if ( ! fixed ) {
log_error ( " No PV has been restored. " ) ;
return ECMD_FAILED ;
}
if ( ! vg_write ( vg ) | | ! vg_commit ( vg ) )
return_ECMD_FAILED ;
backup ( vg ) ;
log_print_unless_silent ( " Volume group \" %s \" successfully extended " , vg_name ) ;
return ECMD_PROCESSED ;
}
static int _vgextend_single ( struct cmd_context * cmd , const char * vg_name ,
struct volume_group * vg , struct processing_handle * handle )
{
struct vgextend_params * vp = ( struct vgextend_params * ) handle - > custom_handle ;
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struct pvcreate_params * pp = & vp - > pp ;
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uint32_t mda_copies ;
uint32_t mda_used ;
int ret = ECMD_FAILED ;
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if ( arg_is_set ( cmd , metadataignore_ARG ) & &
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( pp - > force = = PROMPT ) & & ! pp - > yes & &
( vg_mda_copies ( vg ) ! = VGMETADATACOPIES_UNMANAGED ) & &
( yes_no_prompt ( " Override preferred number of copies of VG %s metadata? [y/n]: " , vg_name ) = = ' n ' ) ) {
log_error ( " Volume group %s not changed " , vg_name ) ;
return ECMD_FAILED ;
}
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if ( ! archive ( vg ) )
return_ECMD_FAILED ;
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if ( ! vg_extend_each_pv ( vg , pp ) )
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goto_out ;
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if ( arg_is_set ( cmd , metadataignore_ARG ) ) {
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mda_copies = vg_mda_copies ( vg ) ;
mda_used = vg_mda_used_count ( vg ) ;
if ( ( mda_copies ! = VGMETADATACOPIES_UNMANAGED ) & &
( mda_copies ! = mda_used ) ) {
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log_warn ( " WARNING: Changing preferred number of copies of VG %s metadata from % " PRIu32 " to % " PRIu32 ,
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vg_name , mda_copies , mda_used ) ;
vg_set_mda_copies ( vg , mda_used ) ;
}
}
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log_verbose ( " Volume group \" %s \" will be extended by %d new physical volumes " , vg_name , pp - > pv_count ) ;
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if ( ! vg_write ( vg ) | | ! vg_commit ( vg ) )
goto_out ;
backup ( vg ) ;
log_print_unless_silent ( " Volume group \" %s \" successfully extended " , vg_name ) ;
ret = ECMD_PROCESSED ;
out :
return ret ;
}
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int vgextend ( struct cmd_context * cmd , int argc , char * * argv )
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{
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struct processing_handle * handle ;
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struct vgextend_params vp ;
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struct pvcreate_params * pp = & vp . pp ;
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unsigned restoremissing = arg_is_set ( cmd , restoremissing_ARG ) ;
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const char * vg_name ;
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int ret ;
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if ( ! argc ) {
log_error ( " Please enter volume group name and "
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" physical volume(s) " ) ;
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return EINVALID_CMD_LINE ;
}
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vg_name = skip_dev_dir ( cmd , argv [ 0 ] , NULL ) ;
argc - - ;
argv + + ;
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pvcreate_params_set_defaults ( pp ) ;
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if ( ! pvcreate_params_from_args ( cmd , pp ) )
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return EINVALID_CMD_LINE ;
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pp - > pv_count = argc ;
pp - > pv_names = argv ;
/* Don't create a new PV on top of an existing PV like pvcreate does. */
pp - > preserve_existing = 1 ;
/* pvcreate within vgextend cannot be forced. */
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pp - > force = PROMPT ;
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locking: unify global lock for flock and lockd
There have been two file locks used to protect lvm
"global state": "ORPHANS" and "GLOBAL".
Commands that used the ORPHAN flock in exclusive mode:
pvcreate, pvremove, vgcreate, vgextend, vgremove,
vgcfgrestore
Commands that used the ORPHAN flock in shared mode:
vgimportclone, pvs, pvscan, pvresize, pvmove,
pvdisplay, pvchange, fullreport
Commands that used the GLOBAL flock in exclusive mode:
pvchange, pvscan, vgimportclone, vgscan
Commands that used the GLOBAL flock in shared mode:
pvscan --cache, pvs
The ORPHAN lock covers the important cases of serializing
the use of orphan PVs. It also partially covers the
reporting of orphan PVs (although not correctly as
explained below.)
The GLOBAL lock doesn't seem to have a clear purpose
(it may have eroded over time.)
Neither lock correctly protects the VG namespace, or
orphan PV properties.
To simplify and correct these issues, the two separate
flocks are combined into the one GLOBAL flock, and this flock
is used from the locking sites that are in place for the
lvmlockd global lock.
The logic behind the lvmlockd (distributed) global lock is
that any command that changes "global state" needs to take
the global lock in ex mode. Global state in lvm is: the list
of VG names, the set of orphan PVs, and any properties of
orphan PVs. Reading this global state can use the global lock
in sh mode to ensure it doesn't change while being reported.
The locking of global state now looks like:
lockd_global()
previously named lockd_gl(), acquires the distributed
global lock through lvmlockd. This is unchanged.
It serializes distributed lvm commands that are changing
global state. This is a no-op when lvmlockd is not in use.
lockf_global()
acquires an flock on a local file. It serializes local lvm
commands that are changing global state.
lock_global()
first calls lockf_global() to acquire the local flock for
global state, and if this succeeds, it calls lockd_global()
to acquire the distributed lock for global state.
Replace instances of lockd_gl() with lock_global(), so that the
existing sites for lvmlockd global state locking are now also
used for local file locking of global state. Remove the previous
file locking calls lock_vol(GLOBAL) and lock_vol(ORPHAN).
The following commands which change global state are now
serialized with the exclusive global flock:
pvchange (of orphan), pvresize (of orphan), pvcreate, pvremove,
vgcreate, vgextend, vgremove, vgreduce, vgrename,
vgcfgrestore, vgimportclone, vgmerge, vgsplit
Commands that use a shared flock to read global state (and will
be serialized against the prior list) are those that use
process_each functions that are based on processing a list of
all VG names, or all PVs. The list of all VGs or all PVs is
global state and the shared lock prevents those lists from
changing while the command is processing them.
The ORPHAN lock previously attempted to produce an accurate
listing of orphan PVs, but it was only acquired at the end of
the command during the fake vg_read of the fake orphan vg.
This is not when orphan PVs were determined; they were
determined by elimination beforehand by processing all real
VGs, and subtracting the PVs in the real VGs from the list
of all PVs that had been identified during the initial scan.
This is fixed by holding the single global lock in shared mode
while processing all VGs to determine the list of orphan PVs.
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if ( ! lock_global ( cmd , " ex " ) )
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return_ECMD_FAILED ;
2018-12-07 23:35:22 +03:00
clear_hint_file ( cmd ) ;
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:
- read the devices file
. add struct dev_use (du) struct to cmd->use_devices for each entry
- dev_cache_scan
. add struct device (dev) to dev_cache
- match devices file entries to devices
. match each du on cmd->use_devices to a dev in dev_cache
. sets du->dev, dev->id, dev->flags MATCHED_USE_ID
- label_scan
. filters applied that do not require data from device
. filter-deviceid skips devs without MATCHED_USE_ID, i.e.
devs that are not in the devices file
. read label from dev
. filters applied that require data from device
. read metadata from dev
. lvmcache info/vginfo structs created for PVs/VGs
- 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.
. detect incorrect match because PVID in the devices file entry
does not match the PVID found when the device was read
. undo incorrect device match between du and dev
. 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
man page updates
2020-06-23 21:25:41 +03:00
cmd - > edit_devices_file = 1 ;
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lvmcache_label_scan ( cmd ) ;
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if ( ! ( handle = init_processing_handle ( cmd , NULL ) ) ) {
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log_error ( " Failed to initialize processing handle. " ) ;
return ECMD_FAILED ;
}
if ( ! restoremissing ) {
if ( ! pvcreate_each_device ( cmd , handle , pp ) ) {
destroy_processing_handle ( cmd , handle ) ;
return_ECMD_FAILED ;
}
}
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:
- read the devices file
. add struct dev_use (du) struct to cmd->use_devices for each entry
- dev_cache_scan
. add struct device (dev) to dev_cache
- match devices file entries to devices
. match each du on cmd->use_devices to a dev in dev_cache
. sets du->dev, dev->id, dev->flags MATCHED_USE_ID
- label_scan
. filters applied that do not require data from device
. filter-deviceid skips devs without MATCHED_USE_ID, i.e.
devs that are not in the devices file
. read label from dev
. filters applied that require data from device
. read metadata from dev
. lvmcache info/vginfo structs created for PVs/VGs
- 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.
. detect incorrect match because PVID in the devices file entry
does not match the PVID found when the device was read
. undo incorrect device match between du and dev
. 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
man page updates
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unlock_devices_file ( cmd ) ;
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/*
* It is always ok to add new PVs to a VG - even if there are
* missing PVs . No LVs are affected by this operation , but
* repair processes - particularly for RAID segtypes - can
* be facilitated .
*/
cmd - > handles_missing_pvs = 1 ;
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handle - > custom_handle = & vp ;
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ret = process_each_vg ( cmd , 0 , NULL , vg_name , NULL ,
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READ_FOR_UPDATE | PROCESS_SKIP_SCAN , 0 , handle ,
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restoremissing ? & _vgextend_restoremissing : & _vgextend_single ) ;
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destroy_processing_handle ( cmd , handle ) ;
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return ret ;
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}