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Currently, we have two modes of activation, an unnamed nominal mode
(which I will refer to as "complete") and "partial" mode. The
"complete" mode requires that a volume group be 'complete' - that
is, no missing PVs. If there are any missing PVs, no affected LVs
are allowed to activate - even RAID LVs which might be able to
tolerate a failure. The "partial" mode allows anything to be
activated (or at least attempted). If a non-redundant LV is
missing a portion of its addressable space due to a device failure,
it will be replaced with an error target. RAID LVs will either
activate or fail to activate depending on how badly their
redundancy is compromised.
This patch adds a third option, "degraded" mode. This mode can
be selected via the '--activationmode {complete|degraded|partial}'
option to lvchange/vgchange. It can also be set in lvm.conf.
The "degraded" activation mode allows RAID LVs with a sufficient
level of redundancy to activate (e.g. a RAID5 LV with one device
failure, a RAID6 with two device failures, or RAID1 with n-1
failures). RAID LVs with too many device failures are not allowed
to activate - nor are any non-redundant LVs that may have been
affected. This patch also makes the "degraded" mode the default
activation mode.
The degraded activation mode does not yet work in a cluster. A
new cluster lock flag (LCK_DEGRADED_MODE) will need to be created
to make that work. Currently, there is limited space for this
extra flag and I am looking for possible solutions. One possible
solution is to usurp LCK_CONVERT, as it is not used. When the
locking_type is 3, the degraded mode flag simply gets dropped and
the old ("complete") behavior is exhibited.
Accidently it's been commited - but it has also shown,
that on heavy loaded systems (like our test machine could be)
slightly bigger timeouts which waits longer for udev rules
processing does help and avoids occasional refuse of deactivation
because device is still being open.
(i.e. lvcreate...; lvchange -an...)
Unsure how we could now synchronize for this. On very slow(/loaded)
system 5 second timeout is simply not enough.
TODO: introduce at least lvm.conf configurable setting to
allow longer 'retry' loops.
Reindent lv_check_not_in_use to simplify internal loop code.
Also return always '0/1' (drop -1) - since we only
check for failure (0) - and we don't really know
why lv_info() has failed.
Drop unused passed cmd pointer from function.
TODO:
We have two similar functions (though not identical)
lv_manip.c: for_each_sub_lv()
metadata.c: _lv_each_dependency()
They seem to not always match - we should probably convert
to use only a single function.
This function is typically called for cmd context refresh or destroy.
On the non-clustered case we already unlocked all messages,
however when i.e. 'clvmd' gets break signal it may have
still couple messages queued.
For now just report an error.
Building on the new DM function that parses DM cache status, we
introduce the following LVM level functions to aquire information
about cache devices:
- lv_cache_block_info: retrieves information on the cache's block/chunk usage
- lv_cache_policy_info: retrieves information on the cache's policy
If the volume_list filters out volume from activation,
it is still success result for this function.
Change the error message back to verbose level.
Detect if the volume is active localy before zeroing,
so we report error a bit later for cases, where volume
could not be activated because it doesn't pass through volume
list (but user still could create volume when he disables
zeroing)
Add LV_TEMPORARY flag for LVs with limited existence during command
execution. Such LVs are temporary in way that they need to be activated,
some action done and then removed immediately. Such LVs are just like
any normal LV - the only difference is that they are removed during
LVM command execution. This is also the case for LVs representing
future pool metadata spare LVs which we need to initialize by using
the usual LV before they are declared as pool metadata spare.
We can optimize some other parts like udev to do a better job if
it knows that the LV is temporary and any processing on it is just
useless.
This flag is orthogonal to LV_NOSCAN flag introduced recently
as LV_NOSCAN flag is primarily used to mark an LV for the scanning
to be avoided before the zeroing of the device happens. The LV_TEMPORARY
flag makes a difference between a full-fledged LV visible in the system
and the LV just used as a temporary overlay for some action that needs to
be done on underlying PVs.
For example: lvcreate --thinpool POOL --zero n -L 1G vg
- first, the usual LV is created to do a clean up for pool metadata
spare. The LV is activated, zeroed, deactivated.
- between "activated" and "zeroed" stage, the LV_NOSCAN flag is used
to avoid any scanning in udev
- betwen "zeroed" and "deactivated" stage, we need to avoid the WATCH
udev rule, but since the LV is just a usual LV, we can't make a
difference. The LV_TEMPORARY internal LV flag helps here. If we
create the LV with this flag, the DM_UDEV_DISABLE_DISK_RULES
and DM_UDEV_DISABLE_OTHER_RULES flag are set (just like as it is
with "invisible" and non-top-level LVs) - udev is directed to
skip WATCH rule use.
- if the LV_TEMPORARY flag was not used, there would normally be
a WATCH event generated once the LV is closed after "zeroed"
stage. This will make problems with immediated deactivation that
follows.
This patch reinstates the lv_info call to check for open count of
the LV we're removing/deactivating - this was changed with commit 125712b
some time ago and we relied on the ioctl retry logic deeper in the libdm
while calling the exact 'remove' ioctl.
However, there are still some situations in which it's still required to
check for open count before we do any 'remove' actions - this mainly
applies to LVs which consist of several sub LVs, like it is for
virtual snapshot devices.
The commit 1146691 fixed the issue with ordering of actions during
virtual snapshot removal while the snapshot is still open. But
the check for the open status of the snapshot is still prone to
marking the snapshot as in use with an immediate exit even though
this could be a temporary asynchronous open only, most notably
because of udev and its WATCH udev rule with accompanying scans
for the event which is asynchronous. The situation where this crops
up most often is when we're closing the LV that was open for read-write
and then calling lvremove immediately.
This patch reinstates the original lv_info call for the open status
of the LV in the lv_check_not_in_use fn that gets called before
we do any LV removal/deactivation. In addition to original logic,
this patch adds its own retry loop with a delay (25x0.2 seconds)
besides the existing ioctl retry loop.
Component LVs of a thinpool can be RAID LVs. Users who attempt a
scrubbing operation directly on a thinpool will be prompted to
specify the sub-LV they wish the operation to be performed on. If
neither of the sub-LVs are RAID, then a message telling them that
the operation can only be performed on a RAID LV will be given.
Since the virtual snapshot has no reason to stay alive once we
detach related snapshot - deactivate whole thing in front of
snapshot removal - otherwice the code would get tricky for
support in cluster.
The correct full solution would require to have transactions
for libdm operations.
Also enable to the check for snapshot being opened prior
the origin deactivation, otherwise we could easily end
with the origin being deactivate, but snapshot still kept
active, desynchronizing locking state in cluster.
A common scenario is during new LV creation when we need to wipe the
newly created LV and avoid any udev scanning before this stage otherwise
it could cause the device (the LV) to be claimed by some other subsystem
for which there were stale metadata within LV data.
This patch adds possibility to mark the LV we're just about to wipe with
a flag that gets passed to udev via DM_COOKIE as a subsystem specific
flag - DM_SUBSYSTEM_UDEV_FLAG0 (in this case the subsystem is "LVM")
so LVM udev rules will take care of handling that.
Some code has been added recently which makes it impossible to compile
when "configure --disable-devmapper" is used. This patch just shuffles
the code around so it's under proper #ifdef DEVMAPPER_SUPPORT.
When NULL info struct is passed in - function is usable
as a quick query for lv_is_active_locally() - with a bonus
we may query for layered device.
So it could be seen as a more efficient lv_is_active_locally().
Properly skip unmonitoring of thin pool volume in deactivation code
path. Code makes sure if there is just any thin pool user
it stays monitored with all its resources.
The status printed for dm-raid targets on older kernels does not include
the syncaction field. This is handled by dev_manager_raid_status() just
fine by populating the raid status structure with NULL for that field.
However, lv_raid_sync_action() does not properly handle that field being
NULL. So, check for it and return 0 if it is NULL.
Revert commit 37ffe6a. If static variables are to be used then we
will put them elsewhere and limit the optimization to reporting
code, rather that have it be used in the general case.
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.
There are places where 'lv_is_active' was being used where it was
more correct to use 'lv_is_active_locally'. For example, when checking
for the existance of a kernel instance before asking for its status.
Most of the time these would work correctly. (RAID is only allowed on
non-clustered VGs at the moment, which means that 'lv_is_active' and
'lv_is_active_locally' would give the same result.) However, it is
more correct to use the proper variant and it helps with future
scenarios where targets might be allowed exclusively (or clustered) in
a cluster VG.
New options to 'lvchange' allow users to scrub their RAID LVs.
Synopsis:
lvchange --syncaction {check|repair} vg/raid_lv
RAID scrubbing is the process of reading all the data and parity blocks in
an array and checking to see whether they are coherent. 'lvchange' can
now initaite the two scrubbing operations: "check" and "repair". "check"
will go over the array and recored the number of discrepancies but not
repair them. "repair" will correct the discrepancies as it finds them.
'lvchange --syncaction repair vg/raid_lv' is not to be confused with
'lvconvert --repair vg/raid_lv'. The former initiates a background
synchronization operation on the array, while the latter is designed to
repair/replace failed devices in a mirror or RAID logical volume.
Additional reporting has been added for 'lvs' to support the new
operations. Two new printable fields (which are not printed by
default) have been added: "syncaction" and "mismatches". These
can be accessed using the '-o' option to 'lvs', like:
lvs -o +syncaction,mismatches vg/lv
"syncaction" will print the current synchronization operation that the
RAID volume is performing. It can be one of the following:
- idle: All sync operations complete (doing nothing)
- resync: Initializing an array or recovering after a machine failure
- recover: Replacing a device in the array
- check: Looking for array inconsistencies
- repair: Looking for and repairing inconsistencies
The "mismatches" field with print the number of descrepancies found during
a check or repair operation.
The 'Cpy%Sync' field already available to 'lvs' will print the progress
of any of the above syncactions, including check and repair.
Finally, the lv_attr field has changed to accomadate the scrubbing operations
as well. The role of the 'p'artial character in the lv_attr report field
as expanded. "Partial" is really an indicator for the health of a
logical volume and it makes sense to extend this include other health
indicators as well, specifically:
'm'ismatches: Indicates that there are discrepancies in a RAID
LV. This character is shown after a scrubbing
operation has detected that portions of the RAID
are not coherent.
'r'efresh : Indicates that a device in a RAID array has suffered
a failure and the kernel regards it as failed -
even though LVM can read the device label and
considers the device to be ok. The LV should be
'r'efreshed to notify the kernel that the device is
now available, or the device should be 'r'eplaced
if it is suspected of failing.
I've updated the dm_status_raid structure and dm_get_status_raid()
function to make it handle the new kernel status fields that will
be coming in dm-raid v1.5.0. It is backwards compatible with the
old status line - initializing the new fields to '0'. The new
structure is also more amenable to future changes. It includes a
'reserved' field that is currently initialized to zero but could
be used to hold flags describing new features. It also now uses
pointers for the character strings instead of attempting to allocate
their space along with the structure (causing the size of the
structure to be variable). This allows future fields to be appended.
The new fields that are available are:
- sync_action : shows what the sync thread in the kernel is doing
(idle, frozen, resync, recover, check, repair, or
reshape)
- mismatch_count: shows the number of discrepancies which were
found or repaired by a "check" or "repair"
process, respectively.
For example, the old call and reference:
find_config_tree_str(cmd, "devices/dir", DEFAULT_DEV_DIR)
...now becomes:
find_config_tree_str(cmd, devices_dir_CFG)
So we're referring to the named configuration ID instead
of passing the configuration path and the default value
is taken from central config definition in config_settings.h
automatically.
Add basic support for converting LV into an external origin volume.
Syntax:
lvconvert --thinpool vg/pool --originname renamed_origin -T origin
It will convert volume 'origin' into a thin volume, which will
use 'renamed_origin' as an external read-only origin.
All read/write into origin will go via 'pool'.
renamed_origin volume is read-only volume, that could be activated
only in read-only mode, and cannot be modified.
We can avoid many dev_manager (ioctl) calls by caching the results of
previous calls to lv_raid_dev_health. Just considering the case where
'lvs -a' is called to get the attributes of a RAID LV and its sub-lvs,
this function would be called many times. (It would be called at least
7 times for a 3-way RAID1 - once for the health of each sub-LV and once
for the health of the top-level LV.) This is a good idea because the
sub-LVs are processed in groups along with their parent RAID LV and in
each case, it is the parent LV whose status will be queried. Therefore,
there only needs to be one trip through dev_manager for each time the
group is processed.
Similar to the way thin* accesses its kernel status, we add a method
for RAID to grab the various values in its status output without the
higher levels (LVM) having to understand how to parse the output.
Added functions include:
- lib/activate/dev_manager.c:dev_manager_raid_status()
Pulls the status line from the kernel
- libdm/libdm-deptree.c:dm_get_status_raid()
Parses status line and puts components into dm_status_raid struct
- lib/activate/activate.c:lv_raid_dev_health()
Accesses dm_status_raid to deliver raid dev_health string
The new structure and functions can provide a more unified way to access
status information. ('lv_raid_percent' could switch to using these
functions, for example.)
In case we don't want to activate, autoactivate or have the
VG/LV read-only. Primarily targeted for the auto_activation_volume_list,
but it makes no harm for other settings (the part of the code
that reads these three settings is shared, but there's no
reason to separate it only for this change).
Change 'lv_passes_volumes_filter' fn back to static as it's not
actually needed in the other code (a remnant from devel version).
Fix lvm.conf comment referencing '--autoactivate' which was finally
decided to be '--activate ay'.
Define an 'activation_handler' that gets called automatically on
PV appearance/disappearance while processing the lvmetad_pv_found
and lvmetad_pv_gone functions that are supposed to update the
lvmetad state based on PV availability state. For now, the actual
support is for PV appearance only, leaving room for PV disappearance
support as well (which is a more complex problem to solve as this
needs to count with possible device stack).
Add a new activation change mode - CHANGE_AAY exposed as
'--activate ay/-aay' argument ('activate automatically').
Factor out the vgchange activation functionality for use in other
tools (like pvscan...).
Code adds better support for monitoring of thin pool devices.
update_pool_lv uses DMEVENTD_MONITOR_IGNORE to not manipulate with monitoring.
vgchange & lvchange are checking real thin pool device for existance
as we are using _tpool real device and visible LV pool device might not
be even active (_tpool is activated implicitely for any thin volume).
monitor_dev_for_events is another _lv_postorder like code it might be worth
to think about reusing it here - for now update the code to properly
monitory thin volume deps.
For unmonitoring add extra code to check the usage of thin pool - in case it's in use
unmonitoring of thin volume is skipped.
Extend the usage of origin_only flag to allow resume of thin pool LV
(when it's active) to pass only the messages.
origin_only flag will skip detection of already resumed tree for thin_pool,
so we do not need to suspend the tree and we just send messages.
Pass in the origin_only flag also for thin volumes - but curently the flag
is not used to its best.
FIXME: achieve the state where only thin volume snapshot origin is
suspended without its childrens - let's explore whether this may
happen automatically inside libdm (might be generic for other targets).
So the code would not need to annotate the node for this.
This patch to the suspend code - like the similar change for resume -
queries the lock mode of a cluster volume and records whether it is active
exclusively. This is necessary for suspend due to the possibility of
preloading targets. Failure to check to exclusivity causes the cluster target
of an exclusively activated mirror to be used when converting - rather than
the single machine target.
This value returns percentage of 'mapped' size compared with total LV size.
(Without passed seg pointer it return highest mapped size - but it's
not used yet.)
Use static buffer instead of stack allocated buffer.
This reduces stack size usage of lvm tool and the
change is very simple.
Since the whole library is not thread safe - it should not
add any new problems - and if there will be some conversion
it's easy to convert this to use some preallocated buffer.
Add filter which tries to check if scanned device is part
of active multipath.
Firstly, only SCSI major number devices are handled in filter.
Then it checks if device has exactly one holder (in sysfs) and
if it is device-mapper device and DM-UUID is prefixed by "MPATH-".
If so, this device is filtered out.
The whole filter can be switched off by setting
mpath_component_detection in lvm.conf.
https://bugzilla.redhat.com/show_bug.cgi?id=597010
Signed-off-by: Milan Broz <mbroz@redhat.com>
To ensure we properly handle LV cluster locking - explicitely do
not allow to change the availability of the thin pool that is in use
for some thin LV.
As soon as the thin volume is created the only way to activate pool
is via implicit dependency.
Ignore thinpool open count for lv/vgchange operations.
This patch also does some clean-up of the splitmirrors code.
I've attempted to clean-up the splitmirrors code to make it easier to
understand with fewer operations. I've tried to reduce the number of
metadata operations without compromising the intermediate stages which
are necessary for easy clean-up in the even of failure.
These changes now correctly handle cluster situations - including exclusive
cluster mirrors. Whereas before, a splitmirror operation would result in
remote nodes having LVM commands report the newly split LV with a proper
name while DM commands would report the old (pre-split) names of the device.
IOW, there was a kernel/userspace mismatch.
Before, we used to display "Can't remove open logical volume" which was
generic. There 3 possibilities of how a device could be opened:
- used by another device
- having a filesystem on that device which is mounted
- opened directly by an application
With the help of sysfs info, we can distinguish the first two situations.
The third one will be subject to "remove retry" logic - if it's opened
quickly (e.g. a parallel scan from within a udev rule run), this will
finish quickly and we can remove it once it has finished. If it's a
legitimate application that keeps the device opened, we'll do our best
to remove the device, but we will fail finally after a few retries.
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.
teardown sequence. (Previously the snapshot was deactivated while its
origin was active and before its removal was committed to disk, so
restarting after a crash at the point would leave corruption.)
