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The cmd struct is now required in many more functions, and
it's added as a function arg for most direct dev-cache function
calls. The cmd struct is added to struct device (dev->cmd) so
that it can be accessed in many other cases where dev-cache
functions are being called from places where getting the cmd
struct is too difficult.
The list of dm devs was in the cmd struct and had a
different lifetime than the radix trees referencing
those dm devs. Now the list and radix trees are
created and destroyed together.
An OS installer can create system.devices for the system and
disks, but an OS image cannot create the system-specific
system.devices. The OS image can instead configure the
image so that lvm will create system.devices on first boot.
Image preparation steps to enable auto creation of system.devices:
- create empty file /etc/lvm/devices/auto-import-rootvg
- remove any existing /etc/lvm/devices/system.devices
- enable lvm-devices-import.path
- enable lvm-devices-import.service
On first boot of the prepared image:
- udev triggers vgchange -aay --autoactivation event <rootvg>
- vgchange activates LVs in the root VG
- vgchange finds the file /etc/lvm/devices/auto-import-rootvg,
and no /etc/lvm/devices/system.devices, so it creates
/run/lvm/lvm-devices-import
- lvm-devices-import.path is run when /run/lvm/lvm-devices-import
appears, and triggers lvm-devices-import.service
- lvm-devices-import.service runs vgimportdevices --rootvg --auto
- vgimportdevices finds /etc/lvm/devices/auto-import-rootvg,
and no system.devices, so it creates system.devices containing
PVs in the root VG, and removes /etc/lvm/devices/auto-import-rootvg
and /run/lvm/lvm-devices-import
Run directly, vgimportdevices --rootvg (without --auto), will create
a new system.devices for the root VG, or will add devices for the
root VG to an existing system.devices.
Do not modify flags field from 'strcut command_name' and
instead control this via cmd_context get_vgname_from_options.
Flag GET_VGNAME_FROM_OPTIONS is currently used only by lvconvert.
Create backup copies of system.devices in /etc/lvm/devices/backup
named system.devices-YYYYMMDD.HHMMSS.NNNN. NNNN is the version
counter from the file.
Each time that an lvm command writes a new system.devices file,
it also writes the same file in the backup directory.
A new comment line is added to system.devices with HASH=<num>
where <num> is a crc calculated from the uncommented lines in
system.devices. This lets lvm detect if the file has been
modified outside of lvm itself.
If system.devices is edited directly, the next time a command
reads the file, the crc will not match the HASH value. The
command will then rewrite system.devices with the correct HASH
value, and create a backup reflecting the edits.
A default limit of 50 backup files is kept, configurable by
lvm.conf devicesfile_backup_limit (set to 0 to disable backups.)
Add code to handle creation of thin-pool with VDO data backend
which can be seen as compressed deduplicated thin-pool.
To avoid need of changing to many internal APIs, pass the conversion
parameters for create thin-pool data volume via cmd_context.
Fix commit 847f1dd99c
"device_id: rewrite validation of devname entries"
which began calling device_ids_refresh() in cases where it
was unnecessary, leading to extra PV searches and warnings.
Specifically, a command like "lvs <vg>" would use the hints
file to scan only devices for the named VG. This means that
scanning other PVs would be skipped, and device IDs of those
PVs could not be validated because there are no PVID values
to verify. This missing info would cause messages about
the missing info, and would cause device_ids_refresh to
search for the PVs that had been intentionally skipped.
If the system changes, locate PVs that appear on different devices,
and update the device IDs in the devices file. A system change is
detected by saving the DMI product_uuid or hostname in the devices
file, and comparing it to the current system value. If a root PV
is restored or copied to a new system with different devices, then
the product_uuid or hostname should change, and trigger lvm to
locate PVIDs from system.devices on new devices.
"vgchange -aay --autoactivation event" is called by our udev rule.
When the udev rule runs, symlinks for devices may not all be created
yet. If the regex filter contains symlinks, it won't work correctly.
This command uses devices that already passed through pvscan. Since
pvscan applies the regex filter correctly, this command inherits the
filtering from pvscan and can skip the regex filter itself.
See the previous commit
"pvscan: use alternate device names from DEVLINKS to check filter"
pvscan --cache <dev> is called by our udev rule at a time when all
the symlinks for <dev> may not be created yet (by other udev rules.)
The regex filter in lvm.conf may refer to <dev> using a symlink name
that hasn't yet been created, which would cause <dev> to not match
the filter regex. The DEVLINKS env var, set by udev, contains all
the symlink names for <dev> that have been or will be created.
So, we add all these symlink names to dev->aliases, as if we had
found them in /dev. This allows <dev> to be recognized by a regex
filter containing a symlink for <dev>.
Handle multiple devices using the same serial number as
their device id. After matching devices to devices file
entries, if there is a discrepency between the ondisk PVID
and the devices file PVID, then rematch devices to
devices file entries using PVID, looking at all disks
on the system with the same serial number.
Internally, NUM and BIN fields are marked as DM_REPORT_FIELD_TYPE_NUM_NUMBER
through libdevmapper API. The new 'json_std' format mandates that the report
string representing such a value must be a number, not an arbitrary string.
This is because numeric values in 'json_std' format do not have double quotes
around them. This practically means, we can't use string synonyms
("named reserved values") for such values and the report string must always
represent a proper number.
With 'json' and 'basic' formats, this is not an issue because 'basic' format
doesn't have any structure or typing at all and 'json' format puts all values
in quotes, including numeric ones.
Since we check for present DM devices - cache result for
futher use of checking presence of such device.
lvm2 uses cache result for label scan, but also when
it tries to activate or deactivate LV - however only simple
target 'striped' is reasonably supported.
Use disable_dm_devs to be able to control when lv_info()
get cache or uncached results.
TODO: support more type, however this is getting very complicated.
Port another optimization from pvscan -aay to vgchange -aay:
"pvscan: only add device args to dev cache"
This optimization avoids doing a full dev_cache_scan, and
instead populates dev-cache with only the devices in the
VG being activated.
This involves shifting the use of pvs_online files from
the hints interface up to the higher level label_scan
interface. This specialized label_scan is structured
around creating a list of devices from the pvs_online
files. Previously, a list of all devices was created
first, and then reduced based on the pvs_online files.
The initial step of listing all devices was slow when
thousands of devices are present on the system.
This optimization extends the previous optimization that
used pvs_online files to limit the devices that were
actually scanned (i.e. reading to identify the device):
"vgchange -aay: optimize device scan using pvs_online files"
The information in /run/lvm/pvs_online/<pvid> files can
be used to build a list of devices for a given VG.
The pvscan -aay command has long used this information to
activate a VG while scanning only devices in that VG, which
is an important optimization for autoactivation.
This patch implements the same thing through the existing
device hints interface, so that the optimization can be
applied elsewhere. A future patch will take advantage of
this optimization in vgchange -aay, which is now used in
place of pvscan -aay for event activation.
Resolve event_activation configure option just once.
Do not print debug_devs about 'bad' filtering, when
actually filter already printed reason for skipping
Do not trace more then once about backup being disabled.
No debug when unlinked file does not exists in pvscan.
Configure via lvm.conf log/journal or command line --journal.
Possible values:
"command" records command information.
"output" records default command output.
"debug" records full command debugging.
Multiple values can be set in lvm.conf as an array.
One value can be set in --journal which is added to
values set in lvm.conf
pvscan --cache <dev>
. read only dev
. create online file for dev
pvscan --listvg <dev>
. read only dev
. list VG using dev
pvscan --listlvs <dev>
. read only dev
. list VG using dev
. list LVs using dev
pvscan --cache --listvg [--checkcomplete] <dev>
. read only dev
. create online file for dev
. list VG using dev
. [check online files and report if VG is complete]
pvscan --cache --listlvs [--checkcomplete] <dev>
. read only dev
. create online file for dev
. list VG using dev
. list LVs using dev
. [check online files and report if VG is complete]
. [check online files and report if LVs are complete]
[--vgonline]
can be used with --checkcomplete, to enable use of a vg online
file. This results in only the first pvscan command to see
the complete VG to report 'VG complete', and others will report
'VG finished'. This allows the caller to easily run a single
activation of the VG.
[--udevoutput]
can be used with --cache --listvg --checkcomplete, to enable
an output mode that prints LVM_VG_NAME_COMPLETE='vgname' that
a udev rule can import, and prevents other output from the
command (other output causes udev to ignore the command.)
The list of complete LVs is meant to be passed to lvchange -aay,
or the complete VG used with vgchange -aay.
When --checkcomplete is used, lvm assumes that that the output
will be used to trigger event-based autoactivation, so the pvscan
does nothing if event_activation=0 and --checkcomplete is used.
Example of listlvs
------------------
$ lvs -a vg -olvname,devices
LV Devices
lv_a /dev/loop0(0)
lv_ab /dev/loop0(1),/dev/loop1(1)
lv_abc /dev/loop0(3),/dev/loop1(3),/dev/loop2(1)
lv_b /dev/loop1(0)
lv_c /dev/loop2(0)
$ pvscan --cache --listlvs --checkcomplete /dev/loop0
pvscan[35680] PV /dev/loop0 online, VG vg incomplete (need 2).
VG vg incomplete
LV vg/lv_a complete
LV vg/lv_ab incomplete
LV vg/lv_abc incomplete
$ pvscan --cache --listlvs --checkcomplete /dev/loop1
pvscan[35681] PV /dev/loop1 online, VG vg incomplete (need 1).
VG vg incomplete
LV vg/lv_b complete
LV vg/lv_ab complete
LV vg/lv_abc incomplete
$ pvscan --cache --listlvs --checkcomplete /dev/loop2
pvscan[35682] PV /dev/loop2 online, VG vg is complete.
VG vg complete
LV vg/lv_c complete
LV vg/lv_abc complete
Example of listvg
-----------------
$ pvscan --cache --listvg --checkcomplete /dev/loop0
pvscan[35684] PV /dev/loop0 online, VG vg incomplete (need 2).
VG vg incomplete
$ pvscan --cache --listvg --checkcomplete /dev/loop1
pvscan[35685] PV /dev/loop1 online, VG vg incomplete (need 1).
VG vg incomplete
$ pvscan --cache --listvg --checkcomplete /dev/loop2
pvscan[35686] PV /dev/loop2 online, VG vg is complete.
VG vg complete
dev_cache_index_devs() is taking a large amount of time
when there are many PVs. The index keeps track of
devices that are currently in use by active LVs. This
info is used to print warnings for users in some limited
cases.
The checks/warnings that are enabled by the index are not
needed by pvscan --cache, so disable it in this case.
This may be expanded to other cases in future commits.
dev_cache_index_devs should also be improved in another
commit to avoid the extreme delays with many devices.
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
Since we need to preserve allocated strings across 2 separate
activation calls of '_tree_action()' we need to use other mem
pool them dm->mem - but since cmd->mem is released between
individual lvm2 locking calls, we rather introduce a new separate
mem pool just for pending deletes with easy to see life-span.
(not using 'libmem' as it would basicaly keep allocations over
the whole lifetime of clvmd)
This patch is fixing previous commmit where the memory was
improperly used after pool release.
With previous patch 30a98e4d67 we
started to put devices one pending_delete list instead
of directly scheduling their removal.
However we have operations like 'snapshot merge' where we are
resuming device tree in 2 subsequent activation calls - so
1st such call will still have suspened devices and no chance
to push 'remove' ioctl.
Since we curently cannot easily solve this by doing just single
activation call (which would be preferred solution) - we introduce
a preservation of pending_delete via command structure and
then restore it on next activation call.
This way we keep to remove devices later - although it might be
not the best moment - this may need futher tunning.
Also we don't keep the list of operation in 1 trasaction
(unless we do verify udev symlinks) - this could probably
also make it more correct in terms of which 'remove' can
be combined we already running 'resume'.
Avoid having PVs with different logical block sizes in the same VG.
This prevents LVs from having mixed block sizes, which can produce
file system errors.
The new config setting devices/allow_mixed_block_sizes (default 0)
can be changed to 1 to return to the unrestricted mode.
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.
and implement it based on a device, not based
on a pv struct (which is not available when the
device is not a part of the vg.)
currently only the vgremove command wipes outdated
pvs until more advanced recovery is added in a
subsequent commit
If udev info is missing for a device, (which would indicate
if it's an MD component), then do an end-of-device read to
check if a PV is an MD component. (This is skipped when
using hints since we already know devs in hints are good.)
A new config setting md_component_checks can be used to
disable the additional end-of-device MD checks, or to
always enable end-of-device MD checks.
When both hints and udev info are disabled/unavailable,
the end of PVs will now be scanned by default. If md
devices with end-of-device superblocks are not being
used, the extra I/O overhead can be avoided by setting
md_component_checks="start".
