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Since code is using -cdata and -cmeta UUID suffixes, it does not need
any new 'extra' ID to be generated and stored in metadata.
Since introduce of new 'segtype' cache+CACHE_USES_CACHEVOL we can
safely assume 'new' cache with cachevol will now be created
without extra metadata_id and data_id in metadata.
For backward compatibility, code still reads them in case older
version of metadata have them - so it still should be able
to activate such volumes.
Bonus is lowered size of lv structure used to store info about LV
(noticable with big volume groups).
Enhance activation of cached devices using cachevol.
Correctly instatiace cachevol -cdata & -cmeta devices with
'-' in name (as they are only layered devices).
Code is also a bit more compacted (although still not ideal,
as the usage of extra UUIDs stored in metadata is troublesome
and will be repaired later).
NOTE: this patch my brink potentially minor incompatiblity for 'runtime' upgrade
Enhance 'activation' experience for VDO pool to more closely match
what happens for thin-pools where we do use a 'fake' LV to keep pool
running even when no thinLVs are active. This gives user a choice
whether he want to keep thin-pool running (wihout possibly lenghty
activation/deactivation process)
As we do plan to support multple VDO LVs to be mapped into a single VDO,
we want to give user same experience and 'use-patter' as with thin-pools.
This patch gives option to activate VDO pool only without activating
VDO LV.
Also due to 'fake' layering LV we can protect usage of VDO pool from
command like 'mkfs' which do require exlusive access to the volume,
which is no longer possible.
Note: VDO pool contains 1024 initial sectors as 'empty' header - such
header is also exposed in layered LV (as read-only LV).
For blkid we are indentified as LV with UUID suffix - thus private DM
device of lvm2 - so we do not need to store any extra info in this
header space (aka zero is good enough).
When lvm2 is activating layered pool LV (to basically keep pool opened,
the other function used to be 'locking' be in sync with DM table)
use this LV in read-only mode - this prevents 'write' access into
data volume content of thin-pool.
Note: since EMPTY/unused thin-pool is created as 'public LV' for generic
use by any user who i.e. wish to maintain thin-pool and thins himself.
At this moment, thin-pool appears as writable LV. As soon as the 1st.
thinLV is created, layer volume will appear is 'read-only' LV from this moment.
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'.
Resuming of 'error' table entry followed with it's dirrect removal
is now troublesame with latest udev as it may skip processing of
udev rules for already 'dropped' device nodes.
As we cannot 'synchronize' with udev while we know we have devices
in suspended state - rework 'cleanup' so it collects nodes
for removal into pending_delete list and process the list with
synchronization once we are without any suspended nodes.
When pvmove is finished, we do a tricky operation since we try to
resume multiple different device that were all joined into 1 big tree.
Currently we use the infromation from existing live DM table,
where we can get list of all holders of pvmove device.
We look for these nodes (by uuid) in new metadata, and we do now a full
regular device add into dm tree structure. All devices should be
already PRELOAD with correct table before entering suspend state,
however for correctly working readahead we need to put correct info
also into RESUME tree. Since table are preloaded, the same table
is skip and resume, but correct read ahead is now set.
Udev is running udev-rule action upon 'resume'.
However lvm2 in special case is doing replacement of
'soon-to-be-removed' device with 'error' target for resuming
and then follows actual removal - the sequence is usually quick,
so when udev start action - it can result in 'strange' error
message in kernel log like:
Process '/usr/sbin/dmsetup info -j 253 -m 17 -c --nameprefixes --noheadings --rows -o name,uuid,suspended' failed with exit code 1.
To avoid this - we need to ensure there is synchronization wait for udev
between 'resume' and 'remove' part of this process.
However existing code put strict requirement to avoid synchronizing with
udev inside critical section - but this originally came from requirement
to not do anything special while there could be devices in
suspend-state. Now we are able to see differnce between critical section
with or without suspended devices. For udev synchronization only
suspended devices are prohibited to be there - so slightly relax
condition and allow calling and using 'fs_sync()' even inside critical
section - but there must not be any suspended device.
Move DM usage into dev_manager.c source file.
Also convert STATUS to INFO ioctl - as that's enough
to obtain UUID - this also avoid issuing unwanted flush on checked DM
device for being mpath.
and "cachepool" to refer to a cache on a cache pool object.
The problem was that the --cachepool option was being used
to refer to both a cache pool object, and to a standard LV
used for caching. This could be somewhat confusing, and it
made it less clear when each kind would be used. By
separating them, it's clear when a cachepool or a cachevol
should be used.
Previously:
- lvm would use the cache pool approach when the user passed
a cache-pool LV to the --cachepool option.
- lvm would use the cache vol approach when the user passed
a standard LV in the --cachepool option.
Now:
- lvm will always use the cache pool approach when the user
uses the --cachepool option.
- lvm will always use the cache vol approach when the user
uses the --cachevol option.
Since the parse_vdo_pool_status() become vdo_manip API part,
and there will be no 'dm' matching status parser,
the API can be simplified and closely match thin API here.
Commit 813347cf84 added extra validation,
however in this particular we do want to trim suffix out so rather ignore
resulting error code here intentionaly.
If a single, standard LV is specified as the cache, use
it directly instead of converting it into a cache-pool
object with two separate LVs (for data and metadata).
With a single LV as the cache, lvm will use blocks at the
beginning for metadata, and the rest for data. Separate
dm linear devices are set up to point at the metadata and
data areas of the LV. These dm devs are given to the
dm-cache target to use.
The single LV cache cannot be resized without recreating it.
If the --poolmetadata option is used to specify an LV for
metadata, then a cache pool will be created (with separate
LVs for data and metadata.)
Usage:
$ lvcreate -n main -L 128M vg /dev/loop0
$ lvcreate -n fast -L 64M vg /dev/loop1
$ lvs -a vg
LV VG Attr LSize Type Devices
main vg -wi-a----- 128.00m linear /dev/loop0(0)
fast vg -wi-a----- 64.00m linear /dev/loop1(0)
$ lvconvert --type cache --cachepool fast vg/main
$ lvs -a vg
LV VG Attr LSize Origin Pool Type Devices
[fast] vg Cwi---C--- 64.00m linear /dev/loop1(0)
main vg Cwi---C--- 128.00m [main_corig] [fast] cache main_corig(0)
[main_corig] vg owi---C--- 128.00m linear /dev/loop0(0)
$ lvchange -ay vg/main
$ dmsetup ls
vg-fast_cdata (253:4)
vg-fast_cmeta (253:5)
vg-main_corig (253:6)
vg-main (253:24)
vg-fast (253:3)
$ dmsetup table
vg-fast_cdata: 0 98304 linear 253:3 32768
vg-fast_cmeta: 0 32768 linear 253:3 0
vg-main_corig: 0 262144 linear 7:0 2048
vg-main: 0 262144 cache 253:5 253:4 253:6 128 2 metadata2 writethrough mq 0
vg-fast: 0 131072 linear 7:1 2048
$ lvchange -an vg/min
$ lvconvert --splitcache vg/main
$ lvs -a vg
LV VG Attr LSize Type Devices
fast vg -wi------- 64.00m linear /dev/loop1(0)
main vg -wi------- 128.00m linear /dev/loop0(0)
devices/scan_lvs (default 1) determines whether lvm
will scan LVs for layered PVs. The lvm behavior has
always been to scan LVs, but it's rare for LVs to have
layered PVs, and much more common for there to be many
LVs that substantially slow down scanning with no benefit.
This is implemented in the usable filter, and has the
same effect as listing all LVs in the global_filter.
When pvmoving LV - the target for LV is a mirror so the validation
that checked the type is matching was incorrect.
While we need a more generic enhancment of LVS output for pvmoved LVs,
for now at least stop showing internal errors and 'X' symbols in attrs.
As we start refactoring the code to break dependencies (see doc/refactoring.txt),
I want us to use full paths in the includes (eg, #include "base/data-struct/list.h").
This makes it more obvious when we're breaking abstraction boundaries, eg, including a file in
metadata/ from base/
If the tools for checking thin_pool or cache metadata are missing,
issue rather just a WARNING, but let the operation of activation
continue.
This has the advantage, the if user is missing those tools,
but he already started to use thinpool or cacheing, he can
access these volumes with a WARNING.
Also if the user is using too old tools i.e. for CacheV2 format
dmpd tool 0.7 is required - provide informative WARNING and
skip failure from older tool version which can't understand
new format V2.
Just like lvm2 has internal devices like _tdata which is using UUID with
suffix, there is similar private type of device for crypto device where
they are using CRYPT-TEMP uuid prefix.
Also ignore stratis.
Some kernel version suffer from bad state transition where a device
steps into 'frozen' mode. Any application that tries to read such
raid gets unfortunatelly bloked.
As some sort of protection try to skip such raid device from being
scanned to minimize chances to block lvm2 command on such scan.
When such device is found, warning gets printed.
RaidLVs on read_only_volume_list have their SubLVs
activated readonly thus disabling metadata updates
or image resynchronization/recovery. Bug also causes
automatic repairs to fail.
Fix by always activating the RAID SubLVs readwrite.
Resolves: rhbz1208269
When snapshot is created in read-only mode with 'lvcreate -s -pr...',
lvm2 still needs to be able to write to layered -cow volume
to store metadata and exceptions blocks.
TODO: in some case we might be able to do full tree with read-only
volume but this probably needs futher validation:
1. checking snapshot header already exist
2. origin & snapshot are both in read-only mode.
Introduce:
lv_is_component() check is LV is actually a component device.
lv_component_is_active() checking if any component device is active.
lv_holder_is_active() is any component holding device is active.
Use new 3rd. state of trace_pvmove_deps == 2.
In this state we know, we have already seen the node and can skip futher
testing. Remainging value 1 signals we want to track, and value 0
is for ignoring tracking, but node is still checking in this case.
Reduces large amount of duplicate ioctl queries.
Use code which detectes handlers in a way, which is more
backward-compatible friendly.
Replace read of 'sysfs' uuid entry with dm ioctl call.
Use /sys/block/dm-X/holders path instead of
new path /sys/dev/block/major:minor/holders.
TODO:
There are few more occurencies of this logic around the code
so some abstract interface should be considered.
When pvmove is finished and does 'suspend/resume' on PVMOVE LV,
on resume path committed metadata are already showing 'standalone'
pvmove LV prepared just for removal.
However code should be able to 'resume' preloaded LV there were
participating in pvmove operation.
Previously this was all done in the 'tools' part of lvm2 code.
So the lvconvert upon pvmove finish had to explicitely call 'resume' on every such LV.
Now 'smarted' activation code is able to deduce and combine all information from
the active dm table and committed metadata so single call resolves
it all in one go.
Internally holders are detected by reading sysfs directory to capture
all needed UUID which are then looked in lvm2 metadata and all such
LVs are automatically collected into dmtree.
When metadata LV size was over DM_THIN_MAX_METADATA_SIZE sectors,
the info() routine was incorrectly trying to match bigger size,
while we do never pass any bigger device.
Fixing a case, where lvs should be displaying status for metadata
LV with 16GB size.
In order to support striped raid5/6/10 LV reshaping (change
of LV type, stripesize or number of legs), this patch
introduces infrastructure prerequisites to be used
by raid_manip.c extensions in followup patches.
This base is needed for allocation of out-of-place
reshape space required by the MD raid personalities to
avoid writing over data in-place when reading off the
current RAID layout or number of legs and writing out
the new layout or to a different number of legs
(i.e. restripe)
Changes:
- add members reshape_len to 'struct lv_segment' to store
out-of-place reshape length per component rimage
- add member data_copies to struct lv_segment
to support more than 2 raid10 data copies
- make alloc_lv_segment() aware of both reshape_len and data_copies
- adjust all alloc_lv_segment() callers to the new API
- add functions to retrieve the current data offset (needed for
out-of-place reshaping space allocation) and the devices count
from the kernel
- make libdm deptree code aware of reshape_len
- add LV flags for disk add/remove reshaping
- support import/export of the new 'struct lv_segment' members
- enhance lv_extend/_lv_reduce to cope with reshape_len
- add seg_is_*/segtype_is_* macros related to reshaping
- add target version check for reshaping
- grow rebuilds/writemostly bitmaps to 246 bit to support kernel maximal
- enhance libdm deptree code to support data_offset (out-of-place reshaping)
and delta_disk (legs add/remove reshaping) target arguments
Related: rhbz834579
Related: rhbz1191935
Related: rhbz1191978
When cache volume may be converted from normal to -real layer LV
we need to improve logic for call cache_check.
With this patch, we register call for cache_check only when metadata LV
is not yet present in active table slot (should match initial table
load).
This avoids unwanted checking when cache would become layer device
online.
Activation of raid has brough up also splitted image with tracing
(without taking lock for this).
So when raid is now activate - such image is not put into
table (with _rmeta). When user needs such device, just active it.
Simplify info run for use only for INFO & STATUS.
Drop handling MKNODES within _info_run() call
and use more advanced _setup_task_run() directly.
This allows to further simplify _info_run().
Integrate also query for inactive table and
handle dm_task_run() and dm_task_get_info()
(thus switching to setup_task_run)
Add one exception case for DM_DEVICE_TARGET_MSG.
This allows further shortening and simplification of all
other users of this function.
Start moving selection of status taken for a LV into a single place.
The logic for showing info & status has been spread over multiple
places and were doing too complex decision going agains each other.
Unify selection of status of origin & cow scanned device.
TODO: in future we want to grab status for LV and layered LV and have
both statuses present for display - i.e. when 'old snapshot'
of thinLV is takes and there is ongoing merge - at some moment
we are not capable to show all needed info.
When lvm2 wants to see a status, it needs to validate,
segment for status reading is matching whan lvm2 expects in
metadata.
Also ensure status failure will not cause '0' from info reading
when actual info was collected properly.
Failure in 'status' reading is considered to be
a 'log_warn()' event only.
When we can't parse status, switch to warning as this is not
considered an errornous case. LVS is not supposed to return
error status code when device is not what it's been expected to
be - but it should be WARNING a user there is something unexpected.
Make it easier to replace missing segments with 'zero' returning
target - otherwise user would have to create some extra target
to provide zeros as /dev/zero can't be used (not a block device).
Also break code loop when segment is found and make it an INTERNAL_ERROR
where it's missing.
This patch fixes link validation for used thin-pool.
Udev rules correctly creates symlinks only for unused new thin-pool.
Such thin-pool can be used by foreing apps (like Docker) thus
has /dev/vg/lv link.
However when thin-pool becomes used by thinLV - this link is no
longer exposed to user - but internal verfication missed this
and caused messages like this to be printed upon 'vgchange -ay':
The link /dev/vg/pool should have been created by udev but it was not
found. Falling back to direct link creation.
And same with 'vgchange -an':
The link /dev/vg/pool should have been removed by udev but it is still
present. Falling back to direct link removal.
This patch ensures only unused thin-pool has this link.
Add more code to properly store status for snapshot segment
maintaining lvm2 fiction of COW and snapshot internal volumes.
The key issue here is however not though-through reporting
logic - as there is no single answer for whole line state.
It not counting with layer and we may need few more ioctl to
cover all reporting needs depending upon what is actually
needed.
In reality we need to 'cache' more ioctl status queries for
individual LVs and their segments (so they checked at most once).
The other 'hard' topic for conversion is mirror segment handling.
Also we definitelly need to relocate some logic into segment's methods,
yet it might be complex as we have not clear border between targets.
TODO: define more clearly how are reporting fields defined in case
we 'stack' volumes like - cache of stacked thin LV snapshot origin.
To get better control when flushing is used add extra arg when
setting up dm task.
By default now check dm device status without flush.
(At this moment this should effect only thin and cache volumes).
Also switch dev_manager_thin_pool_status() to use more
readable 'flush' parameter instead of 'no_flush'.
Improve code for snapshot merge for readabilty
and also reduce number of tests needed to decide
if merging can or cannot be started.
(Further improving 9cccf5245a)
To recognize in runtime if we are merging or not
to make consistent decision between suspend and resume
add function to parse thin table line when add
merging thin device to the table.
A snapshot merge into its origin cannot be initiated while the devices
are in use. If there is outside interference (such as from udev),
the suspend (preload) and resume stages can reach conflicting decisions
about whether or not to proceed.
Try to make the logic more robust by checking the inactive or live
table during resume. (This is still not perfect.)
When scanning if device is being usable as PV,
we call STATUS - but this status should not cause
any flushing.
Skip also open_count information as it's not needed.
Devices without "LVM-" uuid prefix have been generated by very old
version of lvm2 2.00 and 2.01.
Since version 2.02 all lvm2 devices are using prefix "LVM-".
However checking for present of ancient non prefixed devices does
take extra IOCTL per every call and for majority of todays user
it will not find anything new.
So use the assumption that users with kernel 3.X and newer are not
really using such old versions of lvm2 (year <2005) and with their
new kernel they are also using new version of lvm2 and skip
checking for them.
This change also makes trace logs more readable.
When leaving preload routine it should not altet state of flush required
when it's been already set to 1 and drop it to 0.
The API here is unclean, but current usage expects the same
variable pointer is for all preload calls and combines 'flush_required'
across all of them.
Commit 844b009584 tried to move
limit for usage of noflush to 'preload' however this was not
correctly processed.
Intead explicitly check for which types we do not want noflush
and also add debug message in this case.
Fix regression caused by commit ba41ee1dc9.
The idea was to use no_flush for changed device only for thin volumes
and thin pools but also to merge this with change made in commit
844b009584.
However the resulting condition has caused misbehavior for the mirror
suspend - as that has been before the ONLY allowed target type
that could have been suspended with noflush.
Result was badly working repair for --type mirror that has been
passing 'flush' to the repaired mirror target whenever preload
wrongly set flush_required.
The origin code has required the flush_required to be set whenever
deivce size is changed.
Now it first detects if device size got smaller
'dm_tree_node_size_changed(root) < 0' - this requires flush.
Otherwise it checks device is not thin volume nor thin pool and its
size has changed (got bigger) and requires flush.
This mean upsize of thin-pool or thin volume will not require flush.
