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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
There's a bug when lvpoll attempts to write new hints,
related to the fact that lvpoll does not follow the same
scanning process as standard commands.
Fix by disabling the use of hints in lvpoll. We may want
to renable hints in lvpoll in a way that they can be used,
if valid, but not updated if they don't exist or are invalid.
This reverts commit 7474440d3b.
lvs can use the scanning optimization again since it has
been changed in:
"scanning: optimize by checking text offset and checksum"
The scanning optimization can produce warnings from
'lvs' when run concurrently with commands modifying LVs,
so disable the optimization until it can be improved.
Without the scanning optimization, lvs will always
read all PVs twice:
1. read metadata from all PVs, saving it in memory
2. for each VG
3. lock VG
4. reread metadata from all PVs in VG, replacing metadata
saved from step 1
5. run command on VG
6. unlock VG
The optimization would usually cause step 4 to be skipped,
and PVs would be read only once.
Running the command in step 5 using metadata that was not
read under the VG lock is usually fine, except for the
fact that lvs attempts to validate the metadata by comparing
it to current dm state. If other commands are modifying dm
state while lvs is running, lvs may see differences between
metadata from step 1 and dm state checked during step 5,
and print warnings.
(A better fix may be to detect the concurrent change and
fall back to rereading metadata in step 4 only when needed.)
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.
uses vg_write to correct more common or less severe issues,
and also adds the ability to repair some metadata corruption
that couldn't be handled previously.
The new command 'pvck --dump metadata PV' will extract
the current version of VG metadata from a PV for testing
and debugging. --dump metadata_area extracts the entire
text metadata area.
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.)
Native disk scanning is now both reduced and
async/parallel, which makes it comparable in
performance (and often faster) when compared
to lvm using lvmetad.
Autoactivation now uses local temp files to record
online PVs, and no longer requires lvmetad.
There should be no apparent command-level change
in behavior.
For reporting commands (pvs,vgs,lvs,pvdisplay,vgdisplay,lvdisplay)
we do not need to repeat the label scan of devices in vg_read if
they all had matching metadata in the initial label scan. The
data read by label scan can just be reused for the vg_read.
This cuts the amount of device i/o in half, from two reads of
each device to one. We have to be careful to avoid repairing
the VG if we've skipped rescanning. (The VG repair code is very
poor, and will be redone soon.)
The copy of VG metadata stored in lvmcache was not being used
in general. It pretended to be a generic VG metadata cache,
but was not being used except for clvmd activation. There
it was used to avoid reading from disk while devices were
suspended, i.e. in resume.
This removes the code that attempted to make this look
like a generic metadata cache, and replaces with with
something narrowly targetted to what it's actually used for.
This is a way of passing the VG from suspend to resume in
clvmd. Since in the case of clvmd one caller can't simply
pass the same VG to both suspend and resume, suspend needs
to stash the VG somewhere that resume can grab it from.
(resume doesn't want to read it from disk since devices
are suspended.) The lvmcache vginfo struct is used as a
convenient place to stash the VG to pass it from suspend
to resume, even though it isn't related to the lvmcache
or vginfo. These suspended_vg* vginfo fields should
not be used or touched anywhere else, they are only to
be used for passing the VG data from suspend to resume
in clvmd. The VG data being passed between suspend and
resume is never modified, and will only exist in the
brief period between suspend and resume in clvmd.
suspend has both old (current) and new (precommitted)
copies of the VG metadata. It stashes both of these in
the vginfo prior to suspending devices. When vg_commit
is successful, it sets a flag in vginfo as before,
signaling the transition from old to new metadata.
resume grabs the VG stashed by suspend. If the vg_commit
happened, it grabs the new VG, and if the vg_commit didn't
happen it grabs the old VG. The VG is then used to resume
LVs.
This isolates clvmd-specific code and usage from the
normal lvm vg_read code, making the code simpler and
the behavior easier to verify.
Sequence of operations:
- lv_suspend() has both vg_old and vg_new
and stashes a copy of each onto the vginfo:
lvmcache_save_suspended_vg(vg_old);
lvmcache_save_suspended_vg(vg_new);
- vg_commit() happens, which causes all clvmd
instances to call lvmcache_commit_metadata(vg).
A flag is set in the vginfo indicating the
transition from the old to new VG:
vginfo->suspended_vg_committed = 1;
- lv_resume() needs either vg_old or vg_new
to use in resuming LVs. It doesn't want to
read the VG from disk since devices are
suspended, so it gets the VG stashed by
lv_suspend:
vg = lvmcache_get_suspended_vg(vgid);
If the vg_commit did not happen, suspended_vg_committed
will not be set, and in this case, lvmcache_get_suspended_vg()
will return the old VG instead of the new VG, and it will
resume LVs based on the old metadata.
The persistent filter should not be imported by any command that doesn't
use it so take addtional note of REQUIRES_FULL_LABEL_SCAN (for vgrename)
and introduce IGNORE_PERSISTENT_FILTER for vgscan and pvscan.
. Define a prototype for every lvm command.
. Match every user command with one definition.
. Generate help text and man pages from them.
The new file command-lines.in defines a prototype for every
unique lvm command. A unique lvm command is a unique
combination of: command name + required option args +
required positional args. Each of these prototypes also
includes the optional option args and optional positional
args that the command will accept, a description, and a
unique string ID for the definition. Any valid command
will match one of the prototypes.
Here's an example of the lvresize command definitions from
command-lines.in, there are three unique lvresize commands:
lvresize --size SizeMB LV
OO: --alloc Alloc, --autobackup Bool, --force,
--nofsck, --nosync, --noudevsync, --reportformat String, --resizefs,
--stripes Number, --stripesize SizeKB, --poolmetadatasize SizeMB
OP: PV ...
ID: lvresize_by_size
DESC: Resize an LV by a specified size.
lvresize LV PV ...
OO: --alloc Alloc, --autobackup Bool, --force,
--nofsck, --nosync, --noudevsync,
--reportformat String, --resizefs, --stripes Number, --stripesize SizeKB
ID: lvresize_by_pv
DESC: Resize an LV by specified PV extents.
FLAGS: SECONDARY_SYNTAX
lvresize --poolmetadatasize SizeMB LV_thinpool
OO: --alloc Alloc, --autobackup Bool, --force,
--nofsck, --nosync, --noudevsync,
--reportformat String, --stripes Number, --stripesize SizeKB
OP: PV ...
ID: lvresize_pool_metadata_by_size
DESC: Resize a pool metadata SubLV by a specified size.
The three commands have separate definitions because they have
different required parameters. Required parameters are specified
on the first line of the definition. Optional options are
listed after OO, and optional positional args are listed after OP.
This data is used to generate corresponding command definition
structures for lvm in command-lines.h. usage/help output is also
auto generated, so it is always in sync with the definitions.
Every user-entered command is compared against the set of
command structures, and matched with one. An error is
reported if an entered command does not have the required
parameters for any definition. The closest match is printed
as a suggestion, and running lvresize --help will display
the usage for each possible lvresize command.
The prototype syntax used for help/man output includes
required --option and positional args on the first line,
and optional --option and positional args enclosed in [ ]
on subsequent lines.
command_name <required_opt_args> <required_pos_args>
[ <optional_opt_args> ]
[ <optional_pos_args> ]
Command definitions that are not to be advertised/suggested
have the flag SECONDARY_SYNTAX. These commands will not be
printed in the normal help output.
Man page prototypes are also generated from the same original
command definitions, and are always in sync with the code
and help text.
Very early in command execution, a matching command definition
is found. lvm then knows the operation being done, and that
the provided args conform to the definition. This will allow
lots of ad hoc checking/validation to be removed throughout
the code.
Each command definition can also be routed to a specific
function to implement it. The function is associated with
an enum value for the command definition (generated from
the ID string.) These per-command-definition implementation
functions have not yet been created, so all commands
currently fall back to the existing per-command-name
implementation functions.
Using per-command-definition functions will allow lots of
code to be removed which tries to figure out what the
command is meant to do. This is currently based on ad hoc
and complicated option analysis. When using the new
functions, what the command is doing is already known
from the associated command definition.
'lvchange --resync LV' or 'lvchange --syncaction repair LV' request the
RAID layout specific parity blocks in raid4/5/6 to be recreated or the
mirrored blocks to be copied again from the master leg/copy for raid1/10,
thus not allowing a rebuild of a particular PV.
Introduce repeatable option '--[raid]rebuild PV' to allow to request
rebuilds of specific PVs in a RaidLV which are known to contain corrupt
data (e.g. rebuild a raid1 master leg).
Add test lvchange-rebuild-raid.sh to test/shell doing rebuild
variations on raid1/10 and 5; add aux function check_status_chars
to support the new test.
- Resolves rhbz1064592
lvm fullreport executes 5 subreports (vg, pv, lv, pvseg, seg) per each VG
(and so taking one VG lock each time) within one command which makes it
easier to produce full report about LVM entities.
Since all 5 subreports for a VG are done under a VG lock, the output is
more consistent mainly in cases where LVM entities may be changed in
parallel.
pvmove began processing tags unintentionally from commit,
6d7dc87cb pvmove: use toollib
pvmove works on a single PV, but tags can match multiple PVs.
If we allowed tags, but processed only the first matching PV,
then the resulting PV would be unpredictable.
Also, the current processing code does not allow us to simply
report an error and do nothing if more than one PV matches the tag,
because the command starts processing PVs as they are found,
so it's too late to do nothing if a second PV matches.
Add support for active cache LV.
Handle --cachemode args validation during command line processing.
Rework some lvm2 internal to use lvm2 defined CACHE_MODE enums
indepently on libdm defines and use enum around the code instead
of passing and comparing strings.
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.
Move checking the lvmetad state, and the possible rescan,
out of lvmetad_send() to the start of the command.
Previously, the token mismatch and rescan would occur
within lvmetad_send() for some other request. Now,
the token mismatch is detected earlier, so the
rescan can be done before the main command is in
progress. Rescanning deep within the processing of
another command will disturb the lvmcache state of
that other command.
A rescan already exists at the start of the command
for the case where foreign VGs are going to be read.
This same rescan is now also performed when there is
an lvmetad token mismatch (from a changed global_filter).
The commands pvscan/vgscan/lvscan/vgimport are excluded
from this preemptive checking/rescanning for lvmetad
because they want to do rescanning themselves explicitly.
If rescanning devices fails, then lvmetad has not been
correctly repopulated and should not be used, so make
the command revert to not using lvmetad.
Use <> around user entered option parameters to make it visually
different (just like we use Italic style in man page).
TODO:
In the future we should consistently provide such notation and
possibly generate it automagically from some internal data structures.
Preferably for man pages as well so we report actual set of supported
options.
This command option can be used to trigger a D-Bus
notification independent of the usual notifications
that are sent from other commands as an effect of
changes to PV/VG/LV state. If lvm is not built with
dbus notification support or if notify_dbus is disabled
in the config, this command will exit with an error.
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.
Use process_each_vg() to lock and read the old VG,
and then call the main vgrename code.
When real VG names are used (not a UUID in place of the
old name), the command still pre-locks the new name
(when strcmp wants it locked first), before calling
process_each_vg on the old name.
In the case where the old name is replaced with a UUID,
process_each_vg now translates that UUID into the real
VG name, which it locks and reads. In this case, we
cannot do pre-locking to maintain lock ordering because
the old name is unknown. So, in this case the strcmp
based lock ordering is suppressed and the old name is
always locked first. This opens a remote chance for
lock ordering conflict between racing vgrenames between
two names where one or both commands use the UUID.
In general, --select should be used to specify a VG by UUID,
but vgrename already allows a uuid to be substituted for
the name, so continue to allow it in that case.
Pass the single vgname as a new process_each_vg arg
instead of setting a cmd flag to tell process_each_vg
to take only the first vgname arg from argv.
Other commands with different argv formats will be
able to use it this way.
Just for convenience to display all new configuration settings
introduced since given version (before, there was only --atversion
to display settings introduced in concrete version).
For example:
$ lvmconfig --type new --sinceversion 2.2.120
allocation {
# cache_mode="writethrough"
# cache_settings {
# }
}
global {
use_lvmlockd=0
# lvmlockd_lock_retries=3
# sanlock_lv_extend=256
use_lvmpolld=1
}
activation {
}
# report {
# compact_output_cols=""
# time_format="%Y-%m-%d %T %z"
# }
local {
# host_id=0
}
The ONE_VGNAME_ARG was being passed and tested as
vg_read() flag but it's a cmd struct flag.
(It affects command arg processing in toollib,
not vg_read behavior. Flags related to command
processing are generally cmd struct flags, while
vg_read arg flags are generally related to vg_read
behavior.)
