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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
The exported VG checking/enforcement was scattered and
inconsistent. This centralizes it and makes it consistent,
following the existing approach for foreign and shared
VGs/PVs, which are very similar to exported VGs/PVs.
The access policy that now applies to foreign/shared/exported
VGs/PVs, is that if a foreign/shared/exported VG/PV is named
on the command line (i.e. explicitly requested by the user),
and the command is not permitted to operate on it because it
is foreign/shared/exported, then an access error is reported
and the command exits with an error. But, if the command is
processing all VGs/PVs, and happens to come across a
foreign/shared/exported VG/PV (that is not explicitly named on
the command line), then the command silently skips it and does
not produce an error.
A command using tags or --select handles inaccessible VGs/PVs
the same way as a command processing all VGs/PVs, and will
not report/return errors if these inaccessible VGs/PVs exist.
The new policy fixes the exit codes on a somewhat random set of
commands that previously exited with an error if they were
looking at all VGs/PVs and an exported VG existed on the system.
There should be no change to which commands are allowed/disallowed
on exported VGs/PVs.
Certain LV commands (lvs/lvdisplay/lvscan) would previously not
display LVs from an exported VG (for unknown reasons). This has
not changed. The lvm fullreport command would previously report
info about an exported VG but not about the LVs in it. This
has changed to include all info from the exported VG.
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.
Save the list of PVs in /run/lvm/hints. These hints
are used to reduce scanning in a number of commands
to only the PVs on the system, or only the PVs in a
requested VG (rather than all devices on the system.)
Previously, a command sent lvmetad new VG metadata in vg_commit().
In vg_commit(), devices are suspended, so any memory allocation
done by the command while sending to lvmetad, or by lvmetad while
updating its cache could deadlock if memory reclaim was triggered.
Now lvmetad is updated in unlock_vg(), after devices are resumed.
The new method for updating VG metadata in lvmetad is in two phases:
1. In vg_write(), before devices are suspended, the command sends
lvmetad a short message ("set_vg_info") telling it what the new
VG seqno will be. lvmetad sees that the seqno is newer than
the seqno of its cached VG, so it sets the INVALID flag for the
cached VG. If sending the message to lvmetad fails, the command
fails before the metadata is committed and the change is not made.
If sending the message succeeds, vg_commit() is called.
2. In unlock_vg(), after devices are resumed, the command sends
lvmetad the standard vg_update message with the new metadata.
lvmetad sees that the seqno in the new metadata matches the
seqno it saved from set_vg_info, and knows it has the latest
copy, so it clears the INVALID flag for the cached VG.
If a command fails between 1 and 2 (after committing the VG on disk,
but before sending lvmetad the new metadata), the cached VG retains
the INVALID flag in lvmetad. A subsequent command will read the
cached VG from lvmetad, see the INVALID flag, ignore the cached
copy, read the VG from disk instead, update the lvmetad copy
with the latest copy from disk, (this clears the INVALID flag
in lvmetad), and use the correct VG metadata for the command.
(This INVALID mechanism already existed for use by lvmlockd.)
If there's parent processing handle, we don't need to create completely
new report group and status report - we'll just reuse the one already
initialized for the parent.
Currently, the situation where this matter is when doing internal report
to do the selection for processing commands where we have parent processing
handle for the command itself and processing handle for the selection
part (that is selection for non-reporting tools).
Previously, duplicate PVs were processed as a side effect
of processing the "chosen" PV in lvmcache. The duplicate
PV would be hacked into lvmcache temporarily in place of
the chosen PV.
In the old way, we had to always process the "chosen" PV
device, even if a duplicate of it was named on the command
line. This meant we were processing a different device than
was asked for. This could be worked around by naming
multiple duplicate devs on the command line in which case
they were swapped in and out of lvmcache for processing.
Now, the duplicate devs are processed directly in their
own processing loop. This means we can remove the old
hacks related to processing dups as a side effect of
processing the chosen device. We can now simply process
the device that was named on the command line.
When the same PVID exists on two or more devices, one device
is preferred and used in the VG, and the others are duplicates
and are not used in the VG. The preferred device exists in
lvmcache as usual. The duplicates exist in a specical list
of unused duplicate devices.
The duplicate devs have the "d" attribute and the "duplicate"
reporting field displays "duplicate" for them.
'pvs' warns about duplicates, but the formal output only
includes the single preferred PV.
'pvs -a' has the same warnings, and the duplicate devs are
included in the output.
'pvs <path>' has the same warnings, and displays the named
device, whether it is preferred or a duplicate.
Allow pvchange and pvresize to process exported VGs,
and have them check for the exported state in their
single function.
Previously, the exported VG state would trigger a
failure in vg_read()/ignore_vg() because the VGs are
being read with READ_FOR_UPDATE. Because these commands
read all VGs to search for the intended PVs, any
exported VG would trigger a failure, even if it was
not related to the intended PV.
When a command modifies a PV or VG, or changes the
activation state of an LV, it will send a dbus
notification when the command is finished. This
can be enabled/disabled with a config setting.
This is common code for handling PV create/remove
that can be shared by pvcreate/vgcreate/vgextend/pvremove.
This does not change any commands to use the new code.
- Pull out the hidden equivalent of process_each_pv
into an actual top level process_each_pv.
- Pull the prompts to the top level, and do not
run any prompts while locks are held.
The orphan lock is reacquired after any prompts are
done, and the devices being created are checked for
any change made while the lock was not held.
Previously, pvcreate_vol() was the shared function for
creating a PV for pvcreate, vgcreate, vgextend.
Now, it will be toollib function pvcreate_each_device().
pvcreate_vol() was called effectively as a helper, from
within vgcreate and vgextend code paths.
pvcreate_each_device() will be called at the same level
as other process_each functions.
One of the main problems with pvcreate_vol() is that
it included a hidden equivalent of process_each_pv for
each device being created:
pvcreate_vol() -> _pvcreate_check() ->
find_pv_by_name() -> get_pvs() ->
get_pvs_internal() -> _get_pvs() -> get_vgids() ->
/* equivalent to process_each_pv */
dm_list_iterate_items(vgids)
vg = vg_read_internal()
dm_list_iterate_items(&vg->pvs)
pvcreate_each_device() reorganizes the code so that
each-VG-each-PV loop is done once, and uses the standard
process_each_pv function at the top level of the function.
Make sure we won't use a PV that is already marked as used. Normally,
VG metadata would stop us from doing that, but we can run into a
situation where such metadata is missing because PVs with MDAs
are missing and the PVs left are the ones with 0 MDAs.
(/dev/sda in this example has 0 MDAs and it belongs to a VG,
but other PVs with MDA are missing)
$ pvs -o pv_name,pv_mda_count /dev/sda
PV #PMda
/dev/sda 0
$ pvcreate /dev/sda
PV '/dev/sda' is marked as belonging to a VG but its metadata is missing.
Can't initialize PV '/dev/sda' without -ff.
$ pvchange -u /dev/sda
PV '/dev/sda' is marked as belonging to a VG but its metadata is missing.
Can't change PV '/dev/sda' without -ff.
Physical volume /dev/sda not changed
0 physical volumes changed / 1 physical volume not changed
$ pvremove /dev/sda
PV '/dev/sda' is marked as belonging to a VG but its metadata is missing.
(If you are certain you need pvremove, then confirm by using --force twice.)
$ vgcreate vg /dev/sda
Physical volume '/dev/sda' is marked as belonging to a VG but its metadata is missing.
Unable to add physical volume '/dev/sda' to volume group 'vg'.
When an orphan PV is changed/resized, the
lvmlockd global lock is converted from sh
to ex. If the command is changing two
orphan PVs, the conversion to ex should
be done only once.
Dop unused value assignments.
Unknown is detected via other combination
(!linear && !striped).
Also change the log_error() message into a warning,
since the function is not really returning error,
but still keep the INTERNAL_ERROR.
Ret value is always set later.
Invalid devices no longer included in the counters printed at the end.
May now need to use --ignoreskippedcluster if relying upon exit status.
If more than one change is requested per-PV, attempt to perform them
all. Note that different arguments still handle exit status
differently.
This is a followup patch for previous patchset that enables selection in
process_each_* fns to fix an issue where field prefixes are not
automatically used for fields in selection criteria.
Use initial report type that matches the intention of each process_each_* functions:
- _process_pvs_in_vg - PVS
- process_each_vg - VGS
- process_each_lv and process_each_lv_in_vg - LVS
This is not normally needed for the selection handle init, BUT we would
miss the field prefix matching, e.g.
lvchange -ay -S 'name=lvol0'
The "name" above would not work if we didn't initialize reporting with
the LVS type at its start. If we pass proper init type, reporting code
can deduce the prefix automatically ("lv_name" in this case).
This report type is then changed further based on what selection criteria we
have. When doing pure selection, not report output, the final report type
is purely based on combination of this initial report type and report types
of the fields used in selection criteria.
pvchange is an exception that does not use toollib yet for iterating
over the list of PVs (process_each_pv) so intialize the
processing_handle and use just like it's used in toollib.
The list of strings is used quite frequently and we'd like to reuse
this simple structure for report selection support too. Make it part
of libdevmapper for general reuse throughout the code.
This also simplifies the LVM code a bit since we don't need to
include and manage lvm-types.h anymore (the string list was the
only structure defined there).
Commit 1a832398a7 moved
some code from _pvchange_single() to main pvchange() and
introduced exit code regression as return codes have not
been properly changed, thus pvchange command exited
with '0' exit code, even though it has reported error.
Also there is a missing vg unlock in error path.
Fix it by counting the total number of expected calls before
checking for pvname and also unlock and relase vg when
pv is not found.
Previously, we have relied on UUIDs alone, and on lvmcache to make getting a
"new copy" of VG metadata fast. If the code which triggers the activation has
the correct VG metadata at hand (the version which is currently on disk), it can
now hand it to the activation code directly.
...to not pollute the common and format-independent code in the
abstraction layer above.
The format1 pv_write has common code for writing metadata and
PV header by calling the "write_disks" fn and when rewriting
the header itself only (e.g. just for the purpose of changing
the PV UUID) during the pvchange operation, we had to tweak
this functionality for the format1 case and we had to assign
the PV the orphan state temporarily.
This patch removes the need for this format1 tweak and it calls
the write_disks with appropriate flag indicating whether this is
a PV write call or a VG write call, allowing for metatada update
for the latter one.
Also, a side effect of the former tweak was that it effectively
invalidated the cache (even for the non-format1 PVs) as we
assigned it the orphan state temporarily just for the format1
PV write to pass.
Also, that tweak made it difficult to directly detect whether
a PV was part of a VG or not because the state was incorrect.
Also, it's not necessary to backup and restore some PV fields
when doing a PV write:
orig_pe_size = pv_pe_size(pv);
orig_pe_start = pv_pe_start(pv);
orig_pe_count = pv_pe_count(pv);
...
pv_write(pv)
...
pv->pe_size = orig_pe_size;
pv->pe_start = orig_pe_start;
pv->pe_count = orig_pe_count;
...this is already done by the layer below itself (the _format1_pv_write fn).
So let's have this cleaned up so we don't need to be bothered
about any 'format1 special case for pv_write' anymore.
Use log_warn to print non-fatal warning messages.
Use of log_error would confuse checker for testing
whether proper error has been reported for some real error.
Accept -q as the short form of --quiet.
Suppress non-essential standard output if -q is given twice.
Treat log/silent in lvm.conf as equivalent to -qq.
Review all log_print messages and change some to
log_print_unless_silent.
When silent, the following commands still produce output:
dumpconfig, lvdisplay, lvmdiskscan, lvs, pvck, pvdisplay,
pvs, version, vgcfgrestore -l, vgdisplay, vgs.
[Needs checking.]
Non-essential messages are shifted from log level 4 to log level 5
for syslog and lvm2_log_fn purposes.
leaving behind the LVM-specific parts of the code (convenience wrappers that
handle `struct device` and `struct cmd_context`, basically). A number of
functions have been renamed (in addition to getting a dm_ prefix) -- namely,
all of the config interface now has a dm_config_ prefix.
Move the free_vg() to vg.c and replace free_vg with release_vg
and make the _free_vg internal.
Patch is needed for sharing VG in vginfo cache so the release_vg function name
is a better fit here.
We allow writing non-orphan PVs only for resize now. The "orphan PV" assert
in pv_write fn uses the "allow_non_orphan" parameter to control this assert.
However, we should find a more elaborate solution so we can remove this
restriction altogether (pv_write together with vg_write is not atomic, we
need to find a safe mechanism so there's an easy revert possible in case of
an error).
When using vgmetadatacopies value other than "umanaged" (0), prompt
the user if the usage of --metadataignore would change the value of
vgmetadatacopies. The main 2 cases are:
1) pvchange --metadataignore
2) vgextend --metadataignore
We leave the prompt check in the tools, and do not change anything
if the user says 'n'.
Examples:
vgextend --metadataignore y vgtest /dev/loop0
Setting metadataignore will override preferred number of copies of VG vgtest metadata.
Are you sure? [y/n]: y
No physical volume label read from /dev/loop0
Physical volume "/dev/loop0" successfully created
Volume group "vgtest" successfully extended
pvchange --metadataignore y /dev/loop3
Setting metadataignore on /dev/loop3 will override preferred number of copies of VG vgtest metadata.
Are you sure? [y/n]: y
WARNING: Changing preferred number of copies of VG vgtest metadata from 3 to 2
Physical volume "/dev/loop3" changed
1 physical volume changed / 0 physical volumes not changed
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
In preparation to call this from both pvcreate as well as pvchange,
move the guts of metadataignore into a library function.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
