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To avoid the chance of freeing a saved vg while another
code path is using it, defer freeing saved vgs until
all the lvmcache content is dropped for the vg.
There are likely more bits of code that can be removed,
e.g. lvm1/pool-specific bits of code that were identified
using FMT flags.
The vgconvert command can likely be reduced further.
The lvm1-specific config settings should probably have
some other fields set for proper deprecation.
Shift refresh of mirror table right into monitor_dev_for_events().
Use !vg_write_lock_held() to recognize use of lvchange/vgchange.
(this shall change if this would no longer work, but requires
futher some API changes).
With this patch dm mirror table is only refreshed when necassary.
Also update WARNING message about mirror usage without monitoring
and display LV name.
In some pvmove tests, clvmd uses the new (precommitted)
saved_vg, but then requests the old saved_vg, and
expects that the new saved_vg be returned instead of
the old. So, when returning the new saved_vg, forget
the old one so we don't return it again.
After reading a VG, stash it in lvmcache as "saved_vg".
Before reading the VG again, try to use the saved_vg.
The saved_vg is dropped on VG lock operations.
The copy of the VG which clvmd stashes in lvmcache should
not only be used between suspend and resume, but between
sequential LV operations in clvmd, so that clvmd does not
need to reread the VG for each one. Prepare for that by
renaming the stashed VG as "saved_vg".
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.
Whenever we make visible LV out of previously invisible one,
reload it's table - the is mandator for proper udev rule
processing as well as ensure content of dm table is correct.
TODO: this new generic rule probably make extra raid rules unnecessary.
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.
Detect we are in prioritezed section instead of critical one,
since these operation were supposed to NOT be happining during
whole set of operation.
This patch fixes verification of udev operations.
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.
Occasionaly users may need to peek into 'component devices.
Normally lvm2 does not let users activation component.
This patch adds special mode where user can activate
component LV in a 'read-only' mode i.e.:
lvchange -ay vg/pool_tdata
All devices can be deactivated with:
lvchange -an vg | vgchange -an....
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.
So this is a bit more complex and possibly worth futher checking.
ATM clvmd drops cmd->mem mempool AFTER refresh of cmd.
So anything allocating from cmd->mem during toolcontext init
will likely die at some point in time.
As a quick fix - just use regular malloc/free for 'dso' alloction.
It's worth to note - cmd->libmem seems to be often misused
causing hidden memleaking for clvmd.
Build dso plugin name during segtype initialisation and just
use the string during command life-time.
Also slightlt update message verbosity and make it very_verbose
when operation is going to be made and 'verbose' when it's done.
Avoid using same return code for reporting 2 different things
and stricly report error code by return value and add new
parameter for reporting monitoring status.
This makes easier to recognize which error we got from dm_event
and continue only with ENOENT.
In fact pvmove does support 'clustered-core' target for clustered
pvmove of LVs activated on multiple nodes.
This patch restores support for activation of pvmove on all nodes
for LVs that are also activate on all nodes.
Add protectional internall error whenever we spot activation
of 'exclusive' only segments in 'non-exclusive' mode.
TODO: possibly the activation locking could be enhanced to handle
this fully behind the scene - as for now this works purely for
lvchange/vgchange activation.
In case of failed legs, raid replaces those with
e.g. "vg-lv_rimage_0-missing_0_0" mapped to an error target.
Those errouneously remain on deactivation.
Fix by removing them on deactivation/removal of the RaidLV.
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.
Check also all snapshosts when resume is requested,
the origin volume is already resume, but possibly
some subLV or snapshot LV could be suspended if
we are still in critical_section.
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.
Only thin-pool with origin_only suspend is allowed to be not suspending anything.
In such case pairing resume will 'decrement' critical section counter.
Just like suspend handles preload for pvmove finish,
in similar way handle suspend of starting pvmove.
In this case the precommited metadata are checked for list of PVMOVEed
LVs and those are suspended in with committed metadata.
Whenever pvmove tree is going to be generated for suspend
and such LV has a user - use this 'using LV' to generate
correct dm tree holding all components.
LV is asked for resume, and its already resume and tool
is inside 'critical_section()' check if there is any suspended sub LV.
In that case 'resume' operation will not be skipped.
When old snapshot is merged, lvm2 still can report some data about
merged 'snapshot' - i.e. it occupied space in VG.
This patch fixes regression from commit:
6fd20be629
and resolved RHBZ: 1460161
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
Add to commits 87117c2b25 and 0b8bf73a63 to avoid refreshing two
times altogether, thus avoiding issues related to clustered, remotely
activated RaidLV. Avoid need to repeat "lvchange --refresh RaidLV"
two times as a workaround to refresh a RaidLV. Fix handles removal
of temporary *-missing-* devices created for any missing segments
in RAID SubLVs during activation.
Because the kernel dm-raid target isn't able to handle transiently
failing devices properly we need
"[dm-devel][PATCH] dm raid: fix transient device failure processing"
as well.
test: add lvchange-raid-transient-failures.sh
and enhance lvconvert-raid.sh
Resolves: rhbz1025322
Related: rhbz1265191
Related: rhbz1399844
Related: rhbz1404425
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.
To be ready to show status of cache volume, call the status
with layer. Layer is automatically detected in this case when
cache volume is used in 'layered' form (needs -real suffix).
When LV is external origin, show info for LV but
status for -layer. So we expose more info to a user
as otherwise active external origin is only linear
mapping of -real layer.
We do the same for i.e. old snaphost origin.
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.
It's actually not needed to call extra lv_has_target_type() to detect
snapshot merge is in progress - decode this right during status
capturing and save even few extra ioctl calls.
Drop LV from passed API arg - it's always segment being checked.
Also use_layer is now in full control of lv_info_with_seg_status().
It decides which device needs to be checked to get 'the most info'.
TODO: future version should be able to expose status from
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.
Translate log_info() into log_very_verbose() which is macro
supposed to be used by our code.
log_info() is internal macro with eventually some 'symbolic' meaning
in syslogging daemons.
Check for dm-raid target version with non-standard raid4 mapping expecting the dedicated
parity device in the last rather than the first slot and prohibit to create, activate or
convert to such LVs from striped/raid0* or vice-versa in order to avoid data corruption.
Add related tests to lvconvert-raid-takeover.sh
Resolves: rhbz1388962
Avoid monitoring of activated cache-pool - where the only purpose ATM
is to clear metadata volume which is actually activate in place
of cache-pool name (using public LV name).
Since VG lock is held across whole clear operation, dmeventd cannot
be used anyway - however in case of appliction crash we may
leave unmonitored device.
In future we may provide better mechanism as the current name
replacemnet is creating 'uncommon' table setups in case the metadata
LV is more complex type like raid (needs some futher thinking about
error path results).
Another point to think about is the fact we should not clear device
while holding lock (i.e. dmeventd mirror repair cannot work in cases
like this).
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.
We have only 2 users of _lv_active() - one was already checking for ==1
while the other use (_lv_is_active()) could have take '-1' as a sign of having
an LV active. So return 0 and log_debug also the reason while detection
has failed (i.e. in case --driverload n - it's kind of expectable,
but might have confused user seeing just <backtrace>).
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'.
Before executing modprobe for given module name, just check
if the module is not already present in /sys/module.
Useful when checking dm-cache-policy modules as we do not
having matching interface like for targets.
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.
Use meta% to expose highest mapped sector in thinLV.
so showing there 100.00% means thinLV maps latest sector.
Currently using a 'trick' with total_numerator to pass-in
device size when 'seg==NULL'
TODO: Improve device status API per target - current 'percentage'
is not really extensible.
Previous fix missed the fact the we do query for 'percent' with
seg value either set or unset (API overload...)
When 'seg' was unset, we still issue flush with status.
Fix it by cheking segtype by target_type.
As we check for segtype - we could also skip whole percentage
if the 'segtype' is unknown by code directly.
Reported-by: Ming-Hung Tsai <mingnus gmail com
dmeventd daemon may call further code itself that looks at /dev, e.g.
via dmeventd_lvm2_command call. We need to have a consistent view of
the /dev content at that time. Therefore, sync /dev content before
calling monitoring hook which contacts dmeventd.
This problem was quite hidden before, but now it has manifested itself
because of recent additions to dev-cache code where we started looking
at device holders as seen in sysfs. What happened here was that the
device was already in sysfs, but not yet under /dev and this triggered
the new error message sometimes:
log_error("%s: failed to find associated device structure for holder %s.", devname, devpath);
This problem has manifested recently in our api/pytest.sh test from
testsuite where we create thin pool LVs and thin LVs and hence it also
causes dmeventd to be used as well and these error messages were
visible there.
Currently it's been checked for 'zero' header for thin-pool,
but lets use it always for cache as well - since it's relatively 'cheap'
detection of read 'error' problems as thin/cache tools
currently do not work fast enough in this case.
Fix reporting of Fail thin-pool target status
as attr[8] letter 'F'.
Report 'needs_check' status from thin-pool target via
attr field [4] (letter 'c'/'C'), and also via CheckNeeded field.
TODO: think about better name here?
TODO: lots of prop_not_implemented_set
Remove long outstand unused code lines, which were already
been obsoleted by other code.
Statuses and snapshot tree creation is already handled differently.
Also drop some 'extra' log_error() and use only stack;
since error has already been reported.
Since we do not use dev_manager in a way we would have destroyed VG
content while in-use - we could safely keep just pointer.
So dropping strdup.
Also it seems we actually no longer use vg_name for anything
so it may possibly go away completely unless it would be useful
for debugging...
lv preload for detached LVs started to be used also
for various other types which just happens to pass through
weak if() condition.
TODO: find here better solution to rather explicitly check
for types we really need to preload.
We do not won't to 'expose' internals of VG struct.
ATM we use lists to keep all LVs - we may want to switch
to better struct for quicker 'search'.
Since we do not need 'lists' but always actual LV,
switch find_lv_in_vg_by_lvid() to return LV,
and replaces some use case of find_lv_in_vg()
with 'better' working find_lv() which already
returns LV.
When 'lvextend -L+XX vg/thinpool' do not leave inactive table
loaded for 'wrapping' LV on top of resized thin-pool
(ATM we use linear LV for this with same size as thin-pool).
Coverity noticed this condition is always false and the error
path could never be visited.
So check for all mismatches of supported messages
and actually mark log_error as internal error.
Recognize the target only 'extends' and do not enforce
'flush' in this case. Only the size reduction
still requires flush (so disables usage of no_flush flag).
If some other targets do require flush before suspend,
they have to explicitly ask for it.
While the activation code tries to evaluate which target
really needs flush with suspend and which may go without flush,
it has stayed effectively disabled by original commit:
33f732c5e9 since here
it only allows to pass non-pvmoving 'mirrors'.
So remove check for mirror LV type and only disable
no_flush for 'pvmove'..
TODO: Looking into history - it also seemed like raid target
would have always required flushing but it's been later
removed without clean explanation.
If some more targets really do need 'no_flush' it should
been handle at their 'level' - since we now stack multiple
targets over itself.
Since we may easily get blocked when checking for percentage
of thin-pool - do not flush and just show current values.
This avoids holding VG locked when pool is overfilled.
Try to detect thin-pool which my block lvm2 command from furher
processing (i.e. lvextend).
Check if pool is read-only or out-of-space and in this case thins
will skipped from being scanned (so user may miss some PVs located
on thin volumes).
Require global/{thin,cache}_{check,repair}_options to be always defined.
If not defined directly by user in the configuration and if there's no
concrete default option to use, make "" (empty string) the default one -
it's then clearly visible in the "lvmconfig --type default" (and
generated lvm.conf) and also it makes its handling in the code more
straightforward so we don't need to handle undefined values.
This means, if there are no default values for these settings defined,
we end up with this generated now:
{thin,cache}_{check,repair}_options = [ "" ]
So the value is never undefined and if it is, it's an error.
(The cache_repair_options is actually not used in the code at the moment,
but once the code using this setting is in, it will follow the same logic
as used for thin_repair_options.)
Existing messaging intarface for thin-pool has a few 'weak' points:
* Message were posted with each 'resume' operation, thus not allowing
activation of thin-pool with the existing state.
* Acceleration skipped suspend step has not worked in cluster,
since clvmd resumes only nodes which are suspended (have proper lock
state).
* Resume may fail and code is not really designed to 'fail' in this
phase (generic rule here is resume DOES NOT fail unless something serious
is wrong and lvm2 tool usually doesn't handle recovery path in this case.)
* Full thin-pool suspend happened, when taken a thin-volume snapshot.
With this patch the new method relocates message passing into suspend
state.
This has a few drawbacks with current API, but overal it performs
better and gives are more posibilities to deal with errors.
Patch introduces a new logic for 'origin-only' suspend of thin-pool and
this also relates to thin-volume when taking snapshot.
When suspend_origin_only operation is invoked on a pool with
queued messages then only those messages are posted to thin-pool and
actual suspend of thin pool and data and metadata volume is skipped.
This makes taking a snapshot of thin-volume lighter operation and
avoids blocking of other unrelated active thin volumes.
Also fail now happens in 'suspend' state where the 'Fail' is more expected
and it is better handled through error paths.
Activation of thin-pool is now not sending any message and leaves upto a tool
to decided later how to finish unfinished double-commit transaction.
Problem which needs some API improvements relates to the lvm2 tree
construction. For the suspend tree we do not add target table line
into the tree, but only a device is inserted into a tree.
Current mechanism to attach messages for thin-pool requires the libdm
to know about thin-pool target, so lvm2 currently takes assumption, node
is really a thin-pool and fills in the table line for this node (which
should be ensured by the PRELOAD phase, but it's a misuse of internal API)
we would possibly need to be able to attach message to 'any' node.
Other thing to notice - current messaging interface in thin-pool
target requires to suspend thin volume origin first and then send
a create message, but this could not have any 'nice' solution on lvm2
side and IMHO we should introduce something like 'create_after_resume'
message.
Patch also changes the moment, where lvm2 transaction id is increased.
Now it happens only after successful finish of kernel transaction id
change. This change was needed to handle properly activation of pool,
which is in the middle of unfinished transaction, and also this corrects
usage of thin-pool by external apps like Docker.
Note that this is just a quick fix and it needs more robust fix to
encompass any combination, not just the (old) snapshot one!
This started with this report:
https://bugzilla.redhat.com/show_bug.cgi?id=1219222
If we have devices/ignore_suspended_devices=1 set based on which we
filter out suspended devices as unusable (or if we ignore suspended
devices by force, e.g. during lvconvert called from dmeventd) and
when we have snapshot and snapshot origin devices in the play, we
need to look at their components unerneath (*-real and *-cow) to
check if they're not suspended. If they are, the snapshot/snapshot
origin is not usable as well and hence it needs to be filtered out
by filter-usable.c code which does suspended device filtering.
Not going into much details here, more details are in the bugzilla
mentioned above. However, this is a quick fix since snapshot
and this exact situation is not the only one. So this is
something that needs to be revisited and fixed properly
with full dm tree and checking the whole stack to state
whether the device at the very top is usable or not.
Older lvm2 tools where always providing linear mapping for thin pool.
Recent lvm2 version however support external usage of thin pool and
empty/unused pools are loaded without such external linear mapping.
So this patch covers 'upgrade' problem, where older tool has activated
thin-pool with 'linear' layer mapping, and newer tools didn't expected
such mapping to exist and were not able to deactivate such table.
So before checking for new layout in dm-table, check if there is not
an old one already there.
Check splitted leg is active before preload.
(Since splitmirrors currently only does work active raid volumes
it's not a change for current code flow).
Minor optimization included - when already positively checked
for raid image don't check again for raid metadata.
for_each_sub_lv() normally does not put pool_lv into deps.
So for now go around it in 'lv_preload()' and add explicit
call with pool.
TODO: think about a better way, we want pool_lv deps only in certain
moments, so maybe for_each_sub_lv() needs new arg for this.
When raid is being splitted, extracted leg & metadata
is still floating in the table - and thus we need to
detect this case and properly preload their matching
table so consequent activation of extracted LVs properly
renames (and FREES) existing raid images, so ongoing
image name shifting will work.
