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Internal _alloc_init() is only called from allocate_extents(),
which already does prevent usage of virtual segments.
So mark as internal error early and do not process it any further.
Since we mark cache-pool as 'hidden/private' while it is in-use,
we may still allow user to change it's name.
It should not cause any harm and user may prefer better naming
for a cache-pool in use.
Currently the code creates the log separately after allocating space for
the data and as no data allocation is needed this second time,
total_extents ends up holding zero so use new_extents directly instead.
This option could never have been printed in lvm2 metadata, so it could
be safely removed as it could have been set only as 0.
These configurable setting is supported via metadata profile.
Use single code to evaluate if the percentage value has
crossed threshold.
Recalculate amount value to always fit bellow
threshold so there are not need any extra reiterations
to reach this state in case policy amount is too small.
Before this patch:
$ lvs -a -o name,layout,role test/lvmlock
LV Layout Role
[lvmlock] linear public
With this patch applied:
$ lvs -a -o name,layout,role test/lvmlock
LV Layout Role
[lvmlock] linear private,lockd,sanlock
Certain stacks of cached LVs may have unexpected consequences.
So add a warning function called when LV is cached to detect
such caces and WARN user about them - the best we could do ATM.
When we insert layer we also move status flag-bits for certain LV types,
so internal volume_group structure remains consistent.
(Perhaps it's misuse of 'insert_layer' function and we should have
another similar function for this.)
Basically we aim to maintain the same state as after reading fresh
metadata out of volume group.
Currently we when i.e. cache 'raid' LV - this should transfer 'raidLV' flag
to _corigin LV and cache is no longer a raid.
TODO: bits for stacked devices needs more exact rules.
Change logic and naming of some internal API functions.
cache_set_mode() and cache_set_policy() both take segment.
cache mode is now correctly 'masked-in'.
If the passed segment is 'cache' segment - it will automatically
try to find 'defaults' according to profiles if the are NOT
specified on command line or they are NOT already set for cache-pool.
These defaults are never set for cache-pool.
lvrename should not be done if the LV is active on another host.
This check was mistakenly removed when the code was changed to
use LV uuids in locks rather than LV names.
A segfault was reported when extending an LV with a smaller number of
stripes than originally used. Under unusual circumstances, the cling
detection code could successfully find a match against the excess
stripe positions and think it had finished prematurely leading to an
allocation being pursued with a length of zero.
Rename ix_offset to num_positional_areas and move it to struct
alloc_state so that _is_condition() can obtain access to it.
In _is_condition(), areas_size can no longer be assumed to match the
number of positional slots being filled so check this newly-exposed
num_positional_areas directly instead. If the slot is outside the
range we are trying to fill, just ignore the match for now.
(Also note that the code still only performs cling detection against
the first segment of the LV.)
Keep policy name separate from policy settings and avoid
to mangling and demangling this string from same config tree.
Ensure policy_name is always defined.
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.
Synchronize with udev logic before reusing device as snapshot.
This patch tries to fix the problem with udev, where we manage
to 'active' LV for clearing, then we deactivate such device and
active again as member of 'origin&snapshot' tree all in 1 step.
There needs to be a sync point where udev has time to remove all links,
otherwise we race with scans and we may end-up with mysterious 'free'
links in the system pointing to wrong dm names.
This patch tries to fix failing topology cluster tests..
When performing initial allocation (so there is nothing yet to
cling to), use the list of tags in allocation/cling_tag_list to
partition the PVs. We implement this by maintaining a list of
tags that have been "used up" as we proceed and ignoring further
devices that have a tag on the list.
https://bugzilla.redhat.com/983600
Add A_PARTITION_BY_TAGS set when allocated areas should not share tags
with each other and allow _match_pv_tags to accept an alternative list
of tags. (Not used yet.)
Do not keep dangling LVs if they're removed from the vg->lvs list and
move them to vg->removed_lvs instead (this is actually similar to already
existing vg->removed_pvs list, just it's for LVs now).
Once we have this vg->removed_lvs list indexed so it's possible to
do lookups for LVs quickly, we can remove the LV_REMOVED flag as
that one won't be needed anymore - instead of checking the flag,
we can directly check the vg->removed_lvs list if the LV is present
there or not and to say if the LV is removed or not then. For now,
we don't have this index, but it may be implemented in the future.
This avoids a problem in which we're using selection on LV list - we
need to do the selection on initial state and not on any intermediary
state as we process LVs one by one - some of the relations among LVs
can be gone during this processing.
For example, processing one LV can cause the other LVs to lose the
relation to this LV and hence they're not selectable anymore with
the original selection criteria as it would be if we did selection
on inital state. A perfect example is with thin snapshots:
$ lvs -o lv_name,origin,layout,role vg
LV Origin Layout Role
lvol1 thin,sparse public,origin,thinorigin,multithinorigin
lvol2 lvol1 thin,sparse public,snapshot,thinsnapshot
lvol3 lvol1 thin,sparse public,snapshot,thinsnapshot
pool thin,pool private
$ lvremove -ff -S 'lv_name=lvol1 || origin=lvol1'
Logical volume "lvol1" successfully removed
The lvremove command above was supposed to remove lvol1 as well as
all its snapshots which have origin=lvol1. It failed to do so, because
once we removed the origin lvol1, the lvol2 and lvol3 which were
snapshots before are not snapshots anymore - the relations change
as we're processing these LVs one by one.
If we do the selection first and then execute any concrete actions on
these LVs (which is what this patch does), the behaviour is correct
then - the selection is done on the *initial state*:
$ lvremove -ff -S 'lv_name=lvol1 || origin=lvol1'
Logical volume "lvol1" successfully removed
Logical volume "lvol2" successfully removed
Logical volume "lvol3" successfully removed
Similarly for all the other situations in which relations among
LVs are being changed by processing the LVs one by one.
This patch also introduces LV_REMOVED internal LV status flag
to mark removed LVs so they're not processed further when we
iterate over collected list of LVs to be processed.
Previously, when we iterated directly over vg->lvs list to
process the LVs, we relied on the fact that once the LV is removed,
it is also removed from the vg->lvs list we're iterating over.
But that was incorrect as we shouldn't remove LVs from the list
during one iteration while we're iterating over that exact list
(dm_list_iterate_items safe can handle only one removal at
one iteration anyway, so it can't be used here).
cmirror uses the CPG library to pass messages around the cluster and maintain
its bitmaps. When a cluster mirror starts-up, it must send the current state
to any joining members - a checkpoint. When mirrors are large (or the region
size is small), the bitmap size can exceed the message limit of the CPG
library. When this happens, the CPG library returns CPG_ERR_TRY_AGAIN.
(This is also a bug in CPG, since the message will never be successfully sent.)
There is an outstanding bug (bug 682771) that is meant to lift this message
length restriction in CPG, but for now we work around the issue by increasing
the mirror region size. This limits the size of the bitmap and avoids any
issues we would otherwise have around checkpointing.
Since this issue only affects cluster mirrors, the region size adjustments
are only made on cluster mirrors. This patch handles cluster mirror issues
involving pvmove, lvconvert (from linear to mirror), and lvcreate. It also
ensures that when users convert a VG from single-machine to clustered, any
mirrors with too many regions (i.e. a bitmap that would be too large to
properly checkpoint) are trapped.
Dop unused value assignments.
Unknown is detected via other combination
(!linear && !striped).
Also change the log_error() message into a warning,
since the function is not really returning error,
but still keep the INTERNAL_ERROR.
Ret value is always set later.
Before, we refreshed filters and we did full rescan of devices if
we passed through wiping (wipe_known_signatures fn call). However,
this fn returns success even if no signatures were found and so
nothing was wiped. In this case, it's not necessary to do the
filter refresh/rescan of devices as nothing changed clearly.
This patch exports number of wiped signatures from all the
wiping functions below. The caller (_pvcreate_check) then checks
whether any wiping was done at all and if not, no refresh/rescan
is done, saving some time and resources.
for_each_sub_lv() now scans in depth also pools, however for
rename we actually do want to skip pools.
So add a new for_each_sub_lv_except_pools() to be used by rename,
every other user of for_each_sub_lv() scans every sub LV with pools
included.
This is i.e. necessary for properly working preload of pools
that are using raid arrays.
Support error_if_no_space feature for thin pools.
Report more info about thinpool status:
(out_of_data (D), metadata_read_only (M), failed (F) also as health
attribute.)
When creating cluster mirrors while they're not supposed to be activated
immediately after creation, we don't need to check for cmirrord availability.
We can just create these mirrors and let the check to be done on activation
later on. This is addendum for commit cba6186325.
When creating/activating clustered mirrors, we should have cmirrord
available and running. If it's not, we ended up with rather cryptic
errors like:
$ lvcreate -l1 -m1 --type mirror vg
Error locking on node 1: device-mapper: reload ioctl on failed: Invalid argument
Failed to activate new LV.
$ vgchange -ay vg
Error locking on node node 1: device-mapper: reload ioctl on failed: Invalid argument
This patch adds check for cmirror availability and it errors out
properly, also giving a more precise error messge so users are able
to identify the source of the problem easily:
$ lvcreate -l1 -m1 --type mirror vg
Shared cluster mirrors are not available.
$ vgchange -ay vg
Error locking on node 1: Shared cluster mirrors are not available.
Exclusively activated cluster mirror LVs are OK even without cmirrord:
$ vgchange -aey vg
1 logical volume(s) in volume group "vg" now active
Since we support device stack of pools over pool
(thin-pool with cache data volume) the existing code
is no longer able to detect orphan _pmspare.
So instead do a _pmspare check after volume removal,
and remove spare afterwards.
More efficient spare volume creation. Save 1 extra commit
and properly activate this volume according to our cluster
activation rules (using lv_active_change() for this).
Since we 'layer' for cache origin which and we support dropping
cache layer - we need to restore origin name in case
the origin LV is more complex target - i.e. raid.
Drop _corig from name
Cleanup and rename parent -> parent_lv.
Revert part of commit 51a29e6056,
it's probably bad idea to continue with any recovery, when
vg_write() or vg_commit() fail - so it's better to leave it as it is.
Let's use this function for more activations in the code.
'needs_exlusive' will enforce exlusive type for any given LV.
We may want to activate LV in exlusive mode, even when we know
the LV (as is) supports non-exlusive activation as well.
lvcreate -ay -> exclusive & local
lvcreate -aay -> exclusive & local
lvcreate -aly -> exclusive & local
lvcreate -aey -> exclusive (might be on any node).
Call check_new_thin_pool() to detect in-use thin-pool.
Save extra reactivation of thin-pool when thin pool is not active.
(it's now a bit more expensive to invoke thin_check for new pools.)
For new pools:
We now active locally exclusively thin-pool as 'public' LV.
Validate transaction_id is till 0.
Deactive.
Prepare create message for thin-pool and exclusively active pool.
Active new thin LV.
And deactivate thin pool if it used to be inactive.
Unlike with thin-pool - with cache we support all args also
directly when create cache volume.
So the result of 'separate' cache-pool creation and setting its
options should give same result as specifying those args
during cache creation.
Cache-pool values are used as defaults if the params are
not specified with cache creation.
Move code for creation of thin volume into a single place
out of lv_extend(). This allows to drop extra pool arg
for alloc_lv_segment() && lv_extend() and makes code
more easier to read and follow.
When we create volumes with chunk size bigger then extent size
we try to round up to some nearest chunk boundary.
Until now we did this for thins - use same logic for
cache volumes.
Refactor lvcreate code.
Prefer to use arg_outside_list_is_set() so we get automatic 'white-list'
validation of supported options with different segment types.
Drop used lp->cache, lp->cache and use seg_is_cache(), seg_is_thin()
Draw clear border where is the last moment we could change create
segment type.
When segment type is given with --type - do not allow it to be changed
later.
Put together tests related to individual segment types.
Finish cache conversion at proper part of lv_manip code after
the vg_metadata are written - so we could correcly clean-up created
stripe LV for cache volume.
We want to print smarter warning message only when
the zeroing was not provided on the first zeroable segment
of newly created LV.
Put warning within _should_wipe_lv function to avoid reevaluation
of same conditions twice.
Hide creation of temporary LVs and print them only in verbose mode.
e.g. hides confusing message about creation of _pmspare
device during creation of pool.
Instead of segtype->ops->name() introduce lvseg_name().
This also allows us to leave name() function 'empty' for default
return of segtype->name.
TODO: add functions for rest of ops->
When we are given an existing LV name - it needs to be allowed
to pass in even restricted name as the LV could have existed
long before we introduced some new restriction on prefix/suffix.i
Fix the regression on name limits and drop restriction to be applied
on any existing LVs - only the new created LV names have to be
complient with current name restrictions.
FIXME: we are currently using restricted names incorrectly in few
other places - device_is_usable() skips restricted names,
and udev flags are also incorrectly set for restricted names
so these LVs are not getting links properly.
Move code to better locations.
Improve test and remove invalid ones
(i.e. no reason to require cache size to be >= then origin).
Correctly comment where the code is doing actual conversion
of other existing volume - we do already a similar thing with
external origins.
Lots of new command line options and combinations is now supported.
Hopefully older syntax still works as well.
lvcreate --cache --cachepool vg/pool -l1
lvcreate --type cache --cachepool vg/pool -l1
lvcreate --type cache-pool vg/pool -l1
lvcreate --type cache-pool --name pool vg -l1
... and many many more ...
Since _pmspare is internal volume move it to
lv_remove_single - so it's automatically removed with
last remove thin-pool.
lv_remove_with_dependencies() is not always used for pool removal.
We are not using already defined segement type names where we could.
There is a lot of other places in device-mapper and LVM2 we have those
hardcoded so we should better finally have a common interface in
libdevmapper to avoid this.
Use of lv_info() internally in lv_check_not_in_use(),
so it always could use with_open_count properly.
Skip sysfs() testing in open_count == 0 case.
Accept just 'lv' pointer like other functions.
The function has 'built-in' lv_is_active_locally check,
which however is not what we need to check in many place.
For now at least remotely active snapshot merge is
detected and for this case merge on next activation is scheduled.
We use adjusted_mirror_region_size() in two different contexts.
Either on command line -
here we do want to inform user about reduction of size.
Or in pvmove activation context -
here we should only use 'verbose' info.
When requesting to reload an LV imrove this API to
automatically reload its lock holding LV as in cluster
only top-level LVs are addressable with lock.
Try to enforce consistent macro usage along these lines:
lv_is_mirror - mirror that uses the original dm-raid1 implementation
(segment type "mirror")
lv_is_mirror_type - also includes internal mirror image and log LVs
lv_is_raid - raid volume that uses the new dm-raid implementation
(segment type "raid")
lv_is_raid_type - also includes internal raid image / log / metadata LVs
lv_is_mirrored - LV is mirrored using either kernel implementation
(excludes non-mirror modes like raid5 etc.)
lv_is_pvmove - internal pvmove volume
Use lv_is_* macros throughout the code base, introducing
lv_is_pvmove, lv_is_locked, lv_is_converting and lv_is_merging.
lv_is_mirror_type no longer includes pvmove.
Use lv_update_and_reload() and lv_update_and_reload_origin()
to handle write/suspend/commit/resume sequence.
In few places this properly handle vg_revert() after suspend failure,
and also ensures there is metadata backup after successful vg_commit().
Fix rename operation for snapshot (cow) LV.
Only the snapshot's origin has the lock and by mistake suspend
and resume has been called for the snapshot LV.
This further made volumes unusable in cluster.
So instead of suspend and resuming list of LVs,
we need to just suspend and resume origin.
As the sequence write/suspend/commit/resume
is widely used in lvm2 code base - move it to
new lv_update_and_reload function.
Fixing problem, when user sets volume_list and excludes thin pools
from activation. In this case pool return 'success' for skipped activation.
We need to really check the volume it is actually active to properly
to remove queued pool messages. Otherwise the lvm2 and kernel
metadata started to go async since lvm2 believed, messages were submitted.
Add also better check for threshold when create a new thin volume.
In this case we require local activation of thin pool so we are able
to check pool fullness.
This patch makes the keyword combinations found in "lv_layout" and
"lv_role" much more understandable - there were some ambiguities
for some of the combinations which lead to confusion before.
Now, the scheme used is:
LAYOUTS ("how the LV is laid out"):
===================================
[linear] (all segments have number of stripes = 1)
[striped] (all segments have number of stripes > 1)
[linear,striped] (mixed linear and striped)
raid (raid layout always reported together with raid level, raid layout == image + metadata LVs underneath that make up raid LV)
[raid,raid1]
[raid,raid10]
[raid,raid4]
[raid,raid5] (exact sublayout not specified during creation - default one used - raid5_ls)
[raid,raid5,raid5_ls]
[raid,raid5,raid6_rs]
[raid,raid5,raid5_la]
[raid,raid5,raid5_ra]
[raid6,raid] (exact sublayout not specified during creation - default one used - raid6_zr)
[raid,raid6,raid6_zr]
[raid,raid6,raid6_nc]
[raid,raid6,raid6_ns]
[mirror] (mirror layout == log + image LVs underneath that make up mirror LV)
thin (thin layout always reported together with sublayout)
[thin,sparse] (thin layout == allocated out of thin pool)
[thin,pool] (thin pool layout == data + metadata volumes underneath that make up thin pool LV, not supposed to be used for direct use!!!)
[cache] (cache layout == allocated out of cache pool in conjunction with cache origin)
[cache,pool] (cache pool layout == data + metadata volumes underneath that make up cache pool LV, not supposed to be used for direct use!!!)
[virtual] (virtual layout == not hitting disk underneath, currently this layout denotes only 'zero' device used for origin,thickorigin role)
[unknown] (either error state or missing recognition for such layout)
ROLES ("what's the purpose or use of the LV - what is its role"):
=================================================================
- each LV has either of these two roles at least: [public] (public LV that users may use freely to write their data to)
[public] (public LV that users may use freely to write their data to)
[private] (private LV that LVM maintains; not supposed to be directly used by user to write his data to)
- and then some special-purpose roles in addition to that:
[origin,thickorigin] (origin for thick-style snapshot; "thick" as opposed to "thin")
[origin,multithickorigin] (there are more than 2 thick-style snapshots for this origin)
[origin,thinorigin] (origin for thin snapshot)
[origin,multithinorigin] (there are more than 2 thin snapshots for this origin)
[origin,extorigin] (external origin for thin snapshot)
[origin,multiextoriginl (there are more than 2 thin snapshots using this external origin)
[origin,cacheorigin] (cache origin)
[snapshot,thicksnapshot] (thick-style snapshot; "thick" as opposed to "thin")
[snapshot,thinsnapshot] (thin-style snapshot)
[raid,metadata] (raid metadata LV)
[raid,image] (raid image LV)
[mirror,image] (mirror image LV)
[mirror,log] (mirror log LV)
[pvmove] (pvmove LV)
[thin,pool,data] (thin pool data LV)
[thin,pool,metadata] (thin pool metadata LV)
[cache,pool,data] (cache pool data LV)
[cache,pool,metadata] (cache pool metadata LV)
[pool,spare] (pool spare LV - common role of LV that makes it used for both thin and cache repairs)
The 'lv_type' field name was a bit misleading. Better one is 'lv_role'
since this fields describes what's the actual use of the LV currently -
its 'role'.
Sort out the lvresize calculation code to handle size changes
specified as physical extents as well as logical extents
and to process mirror resizing and raid extensions correctly.
The 'approx alloc' option was masking the underlying problem.
The lv_type_name function is remnant from old code that reported
only single string for the LV type. LV types are now reported
in a more extended way as keyword list that describe the type
precisely (using lv_layout_and_type fn).
The lv_type_name was used in some error messages to display the
type of the LV so just reinstate the old messages back referencing
the type directly with a string - this is enough for error messages.
They don't need to display the LV type as precisely as it's used
on lvs output (which is optimized for selection anyway).
$ lvs -a -o name,vg_name,attr,layout,type
LV VG Attr Layout Type
lvol0 vg -wI-a----- linear linear
[pvmove0] vg p-C-aom--- mirror mirror,pvmove
(added "mirror" for pvmove LV)
$ lvs -a -o name,vg_name,attr,layout,type
LV VG Attr Layout Type
lvol0 vg ori------- linear external,multiple,origin,thin
[lvol1_pmspare] vg ewi------- linear metadata,pool,spare
lvol2 vg Vwi-a-tz-- thin snapshot,thin
lvol3 vg Vwi-a-tz-- thin snapshot,thin
pool vg twi-a-tz-- pool,thin pool,thin
[pool_tdata] vg Twi-ao---- linear data,pool,thin
[pool_tmeta] vg ewi-ao---- linear metadata,pool,thin
(added "multiple" for external origin used for more than one
thin snapshot - lvol0 in the example above)
Thin snapshots having external origins missed the "snapshot" keyword for
lv_type field. Also, thin external origins which are thin devices (from
another pool) were not recognized properly.
For example, external origin itself can be either non-thin volume (lvol0
below) or it can be a thin volume from another pool (lvol3 below):
Before this patch:
$ lvs -o name,vg_name,attr,pool_lv,origin,layout,type
Internal error: Failed to properly detect layout and type for for LV vg/lvol3
Internal error: Failed to properly detect layout and type for for LV vg/lvol3
LV VG Attr Pool Origin Layout Type
lvol0 vg ori------- linear external,origin,thin
lvol2 vg Vwi-a-tz-- pool lvol0 thin thin
lvol3 vg ori---tz-- pool unknown external,origin,thin,thin
lvol4 vg Vwi-a-tz-- pool1 lvol3 thin thin
pool vg twi-a-tz-- pool,thin pool,thin
pool1 vg twi-a-tz-- pool,thin pool,thin
- lvol2 as well as lvol4 have missing "snapshot" in type field
- lvol3 has unrecognized layout (should be "thin"), but has double
"thin" in lv_type which is incorrect
- (also there's double "for" in the internal error message)
With this patch applied:
$ lvs -o name,vg_name,attr,pool_lv,origin,layout,type
LV VG Attr Pool Origin Layout Type
lvol0 vg ori------- linear external,origin,thin
lvol2 vg Vwi-a-tz-- pool lvol0 thin snapshot,thin
lvol3 vg ori---tz-- pool thin external,origin,thin
lvol4 vg Vwi-a-tz-- pool1 lvol3 thin snapshot,thin
pool vg twi-a-tz-- pool,thin pool,thin
pool1 vg twi-a-tz-- pool,thin pool,thin
The maximum stripe size is equal to the volume group PE size. If that
size falls below the STRIPE_SIZE_MIN, the creation of RAID 4/5/6 volumes
becomes impossible. (The kernel will fail to load a RAID 4/5/6 mapping
table with a stripe size less than STRIPE_SIZE_MIN.) So, we report an
error if it is attempted.
This is very rare because reducing the PE size down that far limits the
size of the PV below that of modern devices.
metadata/lv_manip.c:269: warning: declaration of "snapshot_count" shadows a global declaration
There's existing function called "snapshot_count" so rename the
variable to "snap_count".
The lv_layout and lv_type fields together help with LV identification.
We can do basic identification using the lv_attr field which provides
very condensed view. In contrast to that, the new lv_layout and lv_type
fields provide more detialed information on exact layout and type used
for LVs.
For top-level LVs which are pure types not combined with any
other LV types, the lv_layout value is equal to lv_type value.
For non-top-level LVs which may be combined with other types,
the lv_layout describes the underlying layout used, while the
lv_type describes the use/type/usage of the LV.
These two new fields are both string lists so selection (-S/--select)
criteria can be defined using the list operators easily:
[] for strict matching
{} for subset matching.
For example, let's consider this:
$ lvs -a -o name,vg_name,lv_attr,layout,type
LV VG Attr Layout Type
[lvol1_pmspare] vg ewi------- linear metadata,pool,spare
pool vg twi-a-tz-- pool,thin pool,thin
[pool_tdata] vg rwi-aor--- level10,raid data,pool,thin
[pool_tdata_rimage_0] vg iwi-aor--- linear image,raid
[pool_tdata_rimage_1] vg iwi-aor--- linear image,raid
[pool_tdata_rimage_2] vg iwi-aor--- linear image,raid
[pool_tdata_rimage_3] vg iwi-aor--- linear image,raid
[pool_tdata_rmeta_0] vg ewi-aor--- linear metadata,raid
[pool_tdata_rmeta_1] vg ewi-aor--- linear metadata,raid
[pool_tdata_rmeta_2] vg ewi-aor--- linear metadata,raid
[pool_tdata_rmeta_3] vg ewi-aor--- linear metadata,raid
[pool_tmeta] vg ewi-aor--- level1,raid metadata,pool,thin
[pool_tmeta_rimage_0] vg iwi-aor--- linear image,raid
[pool_tmeta_rimage_1] vg iwi-aor--- linear image,raid
[pool_tmeta_rmeta_0] vg ewi-aor--- linear metadata,raid
[pool_tmeta_rmeta_1] vg ewi-aor--- linear metadata,raid
thin_snap1 vg Vwi---tz-k thin snapshot,thin
thin_snap2 vg Vwi---tz-k thin snapshot,thin
thin_vol1 vg Vwi-a-tz-- thin thin
thin_vol2 vg Vwi-a-tz-- thin multiple,origin,thin
Which is a situation with thin pool, thin volumes and thin snapshots.
We can see internal 'pool_tdata' volume that makes up thin pool has
actually a level10 raid layout and the internal 'pool_tmeta' has
level1 raid layout. Also, we can see that 'thin_snap1' and 'thin_snap2'
are both thin snapshots while 'thin_vol1' is thin origin (having
multiple snapshots).
Such reporting scheme provides much better base for selection criteria
in addition to providing more detailed information, for example:
$ lvs -a -o name,vg_name,lv_attr,layout,type -S 'type=metadata'
LV VG Attr Layout Type
[lvol1_pmspare] vg ewi------- linear metadata,pool,spare
[pool_tdata_rmeta_0] vg ewi-aor--- linear metadata,raid
[pool_tdata_rmeta_1] vg ewi-aor--- linear metadata,raid
[pool_tdata_rmeta_2] vg ewi-aor--- linear metadata,raid
[pool_tdata_rmeta_3] vg ewi-aor--- linear metadata,raid
[pool_tmeta] vg ewi-aor--- level1,raid metadata,pool,thin
[pool_tmeta_rmeta_0] vg ewi-aor--- linear metadata,raid
[pool_tmeta_rmeta_1] vg ewi-aor--- linear metadata,raid
(selected all LVs which are related to metadata of any type)
lvs -a -o name,vg_name,lv_attr,layout,type -S 'type={metadata,thin}'
LV VG Attr Layout Type
[pool_tmeta] vg ewi-aor--- level1,raid metadata,pool,thin
(selected all LVs which hold metadata related to thin)
lvs -a -o name,vg_name,lv_attr,layout,type -S 'type={thin,snapshot}'
LV VG Attr Layout Type
thin_snap1 vg Vwi---tz-k thin snapshot,thin
thin_snap2 vg Vwi---tz-k thin snapshot,thin
(selected all LVs which are thin snapshots)
lvs -a -o name,vg_name,lv_attr,layout,type -S 'layout=raid'
LV VG Attr Layout Type
[pool_tdata] vg rwi-aor--- level10,raid data,pool,thin
[pool_tmeta] vg ewi-aor--- level1,raid metadata,pool,thin
(selected all LVs with raid layout, any raid layout)
lvs -a -o name,vg_name,lv_attr,layout,type -S 'layout={raid,level1}'
LV VG Attr Layout Type
[pool_tmeta] vg ewi-aor--- level1,raid metadata,pool,thin
(selected all LVs with raid level1 layout exactly)
And so on...
Make lvresize -l+%FREE support approximate allocation.
Move existing "Reducing/Extending' message to verbose level
and change it to say 'up to' if approximate allocation is being used.
Replace it with a new message that gives the actual old and new size or
says 'unchanged'.
Fix get_pool_params to only read params.
Add poolmetadataspare option to get_pool_params.
Move all profile code into update_pool_params.
Move recalculate code into pool_manip.c
The get_lv_type_name helps with translating volume type
to human readable form (can be used in reports or
various messages if needed).
The lv_is_linear and lv_is_striped complete the set of
lv_is_* functions that identify exact volume types.
Support remove of thin volumes With --force --force
when thin pools is damaged.
This way it's possible to remove thin pool with
unrepairable metadata without requiring to
manually edit lvm2 metadata.
lvremove -ff vg/pool
removes all thin volumes and pool even when
thin pool cannot be activated (to accept
removal of thin volumes in kernel metadata)
Since vg_name inside /lib function has already been ignored mostly
except for a few debug prints - make it and official internal API
feature.
vg_name is used only in /tools while the VG is not yet openned,
and when lvresize/lvcreate /lib function is called with VG pointer
already being used, then vg_name becomes irrelevant (it's not been
validated anyway).
So any internal user of lvcreate_params and lvresize_params does not
need to set vg_name pointer and may leave it NULL.
I've changed build_parallel_areas_from_lv to take a new parameter
that allows the caller to build parallel areas by LV vs by segment.
Previously, the function created a list of parallel areas for each
segment in the given LV. When it came time for allocation, the
parallel areas were honored on a segment basis. This was problematic
for RAID because any new RAID image must avoid being placed on any
PVs used by other images in the RAID. For example, if we have a
linear LV that has half its space on one PV and half on another, we
do not want an up-convert to use either of those PVs. It should
especially not wind up with the following, where the first portion
of one LV is paired up with the second portion of the other:
------PV1------- ------PV2-------
[ 2of2 image_1 ] [ 1of2 image_1 ]
[ 1of2 image_0 ] [ 2of2 image_0 ]
---------------- ----------------
Previously, it was possible for this to happen. The change makes
it so that the returned parallel areas list contains one "super"
segment (seg_pvs) with a list of all the PVs from every actual
segment in the given LV and covering the entire logical extent range.
This change allows RAID conversions to function properly when there
are existing images that contain multiple segments that span more
than one PV.
pvmove can be used to move single LVs by name or multiple LVs that
lie within the specified PV range (e.g. /dev/sdb1:0-1000). When
moving more than one LV, the portions of those LVs that are in the
range to be moved are added to a new temporary pvmove LV. The LVs
then point to the range in the pvmove LV, rather than the PV
range.
Example 1:
We have two LVs in this example. After they were
created, the first LV was grown, yeilding two segments
in LV1. So, there are two LVs with a total of three
segments.
Before pvmove:
--------- --------- ---------
| LV1s0 | | LV2s0 | | LV1s1 |
--------- --------- ---------
| | |
-------------------------------------
PV | 000 - 255 | 256 - 511 | 512 - 767 |
-------------------------------------
After pvmove inserts the temporary pvmove LV:
--------- --------- ---------
| LV1s0 | | LV2s0 | | LV1s1 |
--------- --------- ---------
| | |
-------------------------------------
pvmove0 | seg 0 | seg 1 | seg 2 |
-------------------------------------
| | |
-------------------------------------
PV | 000 - 255 | 256 - 511 | 512 - 767 |
-------------------------------------
Each of the affected LV segments now point to a
range of blocks in the pvmove LV, which purposefully
corresponds to the segments moved from the original
LVs into the temporary pvmove LV.
The current implementation goes on from here to mirror the temporary
pvmove LV by segment. Further, as the pvmove LV is activated, only
one of its segments is actually mirrored (i.e. "moving") at a time.
The rest are either complete or not addressed yet. If the pvmove
is aborted, those segments that are completed will remain on the
destination and those that are not yet addressed or in the process
of moving will stay on the source PV. Thus, it is possible to have
a partially completed move - some LVs (or certain segments of LVs)
on the source PV and some on the destination.
Example 2:
What 'example 1' might look if it was half-way
through the move.
--------- --------- ---------
| LV1s0 | | LV2s0 | | LV1s1 |
--------- --------- ---------
| | |
-------------------------------------
pvmove0 | seg 0 | seg 1 | seg 2 |
-------------------------------------
| | |
| -------------------------
source PV | | 256 - 511 | 512 - 767 |
| -------------------------
| ||
-------------------------
dest PV | 000 - 255 | 256 - 511 |
-------------------------
This update allows the user to specify that they would like the
pvmove mirror created "by LV" rather than "by segment". That is,
the pvmove LV becomes an image in an encapsulating mirror along
with the allocated copy image.
Example 3:
A pvmove that is performed "by LV" rather than "by segment".
--------- ---------
| LV1s0 | | LV2s0 |
--------- ---------
| |
-------------------------
pvmove0 | * LV-level mirror * |
-------------------------
/ \
pvmove_mimage0 / pvmove_mimage1
------------------------- -------------------------
| seg 0 | seg 1 | | seg 0 | seg 1 |
------------------------- -------------------------
| | | |
------------------------- -------------------------
| 000 - 255 | 256 - 511 | | 000 - 255 | 256 - 511 |
------------------------- -------------------------
source PV dest PV
The thing that differentiates a pvmove done in this way and a simple
"up-convert" from linear to mirror is the preservation of the
distinct segments. A normal up-convert would simply allocate the
necessary space with no regard for segment boundaries. The pvmove
operation must preserve the segments because they are the critical
boundary between the segments of the LVs being moved. So, when the
pvmove copy image is allocated, all corresponding segments must be
allocated. The code that merges ajoining segments that are part of
the same LV when the metadata is written must also be avoided in
this case. This method of mirroring is unique enough to warrant its
own definitional macro, MIRROR_BY_SEGMENTED_LV. This joins the two
existing macros: MIRROR_BY_SEG (for original pvmove) and MIRROR_BY_LV
(for user created mirrors).
The advantages of performing pvmove in this way is that all of the
LVs affected can be moved together. It is an all-or-nothing approach
that leaves all LV segments on the source PV if the move is aborted.
Additionally, a mirror log can be used (in the future) to provide tracking
of progress; allowing the copy to continue where it left off in the event
there is a deactivation.
The list of strings is used quite frequently and we'd like to reuse
this simple structure for report selection support too. Make it part
of libdevmapper for general reuse throughout the code.
This also simplifies the LVM code a bit since we don't need to
include and manage lvm-types.h anymore (the string list was the
only structure defined there).
- When defining configuration source, the code now uses separate
CONFIG_PROFILE_COMMAND and CONFIG_PROFILE_METADATA markers
(before, it was just CONFIG_PROFILE that did not make the
difference between the two). This helps when checking the
configuration if it contains correct set of options which
are all in either command-profilable or metadata-profilable
group without mixing these groups together - so it's a firm
distinction. The "command profile" can't contain
"metadata profile" and vice versa! This is strictly checked
and if the settings are mixed, such profile is rejected and
it's not used. So in the end, the CONFIG_PROFILE_COMMAND
set of options and CONFIG_PROFILE_METADATA are mutually exclusive
sets.
- Marking configuration with one or the other marker will also
determine the way these configuration sources are positioned
in the configuration cascade which is now:
CONFIG_STRING -> CONFIG_PROFILE_COMMAND -> CONFIG_PROFILE_METADATA -> CONFIG_FILE/CONFIG_MERGED_FILES
- Marking configuration with one or the other marker will also make
it possible to issue a command context refresh (will be probably
a part of a future patch) if needed for settings in global profile
set. For settings in metadata profile set this is impossible since
we can't refresh cmd context in the middle of reading VG/LV metadata
and for each VG/LV separately because each VG/LV can have a different
metadata profile assinged and it's not possible to change these
settings at this level.
- When command profile is incorrect, it's rejected *and also* the
command exits immediately - the profile *must* be correct for the
command that was run with a profile to be executed. Before this
patch, when the profile was found incorrect, there was just the
warning message and the command continued without profile applied.
But it's more correct to exit immediately in this case.
- When metadata profile is incorrect, we reject it during command
runtime (as we know the profile name from metadata and not early
from command line as it is in case of command profiles) and we
*do continue* with the command as we're in the middle of operation.
Also, the metadata profile is applied directly and on the fly on
find_config_tree_* fn call and even if the metadata profile is
found incorrect, we still need to return the non-profiled value
as found in the other configuration provided or default value.
To exit immediately even in this case, we'd need to refactor
existing find_config_tree_* fns so they can return error. Currently,
these fns return only config values (which end up with default
values in the end if the config is not found).
- To check the profile validity before use to be sure it's correct,
one can use :
lvm dumpconfig --commandprofile/--metadataprofile ProfileName --validate
(the --commandprofile/--metadataprofile for dumpconfig will come
as part of the subsequent patch)
- This patch also adds a reference to --commandprofile and
--metadataprofile in the cmd help string (which was missing before
for the --profile for some commands). We do not mention --profile
now as people should use --commandprofile or --metadataprofile
directly. However, the --profile is still supported for backward
compatibility and it's translated as:
--profile == --metadataprofile for lvcreate, vgcreate, lvchange and vgchange
(as these commands are able to attach profile to metadata)
--profile == --commandprofile for all the other commands
(--metadataprofile is not allowed there as it makes no sense)
- This patch also contains some cleanups to make the code handling
the profiles more readable...
Perform two allocation attempts with cling if maximise_cling is set,
first with then without positional fill.
Avoid segfaults from confusion between positional and sorted sequential
allocation when number of stripes varies as reported here:
https://www.redhat.com/archives/linux-lvm/2014-March/msg00001.html
Set A_POSITIONAL_FILL if the array of areas is being filled
positionally (with a slot corresponding to each 'leg') rather
than sequentially (with all suitable areas found, to be sorted
and selected from).
When pvmove0 is finished, it replaces temporarily pvmove0
with error segment, however in this case, pvmove0 remains
unremovable in case pvmove --abort is interrupted in this
moment - since it's not a pvmove anymore and normal
lvremove can't be used to remove LOCKED lv.
Since the usability problem were fixed, we can use this function.
Cleanup orphan LVs with TEMPORARY flags
(reduces couple blkid error reports, but couple of them
is still left...)
Since cache segment is purely virtual mapping, it has nothing for
discard. Discardable is cache origin here which is now
properly removed on 'delete' phase.
Plain lv_empty() call needs to only detach cache origin and leave
origin unchanged.
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.
Use proper vgmem memory pool for allocation of LV name in the vg
and check if new renamed LV is a valid name.
TODO: validation should really use also VG name, othewise we are not
able to tell "vgname-lvname" will be valid.
Create a separate function to validation snapshot min chunk value
and relocate code into snapshot_manip file.
This function will be shared with lvconvert then.
When we create thin-pool we have used trick to keep
volume active, but since we now support TEMPORARY flag,
we could just localy active & deactive metadata LV,
and let the thinpool through normal activation process.
The same as for allocation/thin_pool_chunk_size - the default value
used is just a starting point. The calculation continues using the
properties of the devices actually used.
The allocation/thin_pool_chunk_size is a bit more complex. It's default
value is evaluated in runtime based on selected thin_pool_chunk_size_policy.
But the value is just a starting point. The calculation then continues
with dependency on the properties of the devices used. Which means for
such a default value, we know only the starting value.
While stripe size is twice the physical extent size,
the original code will not reduce stripe size to maximum
(physical extent size).
Signed-off-by: Zhiqing Zhang <zhangzq.fnst@cn.fujitsu.com>
Start to convert percentage size handling in lvresize to the new
standard. Note in the man pages that this code is incomplete.
Fix a regression in non-percentage allocation in my last check in.
This is what I am aiming for:
-l<extents>
-l<percent> LV/ORIGIN
sets or changes the LV size based on the specified quantity
of logical logical extents (that might be backed by
a higher number of physical extents)
-l<percent> PVS/VG/FREE
sets or changes the LV size so as to allocate or free the
desired quantity of physical extents (that might amount to a
lower number of logical extents for the LV concerned)
-l+50%FREE - Use up half the remaining free space in the VG when
carrying out this operation.
-l50%VG - After this operation, this LV should be using up half the
space in the VG.
-l200%LV - Double the logical size of this LV.
-l+100%LV - Double the logical size of this LV.
-l-50%LV - Reduce the logical size of this LV by half.
Several fixes for the recent changes that treat allocation percentages
as upper limits.
Improve messages to make it easier to see what is happening.
Fix some cases that failed with errors when they didn't need to.
Fix crashes when first_seg() returns NULL.
Remove a couple of log_errors that were actually debugging messages.
Remove 'skip' argument passed into the function.
We always used '0' - as this is the only supported
option (-K) and there is no complementary option.
Also add some testing for behaviour of skipping.
When an origin exists and the 'lvcreate' command is used to create
a cache pool + cache LV, the table is loaded into the kernel but
never instantiated (suspend/resume was never called). A user running
LVM commands would never know that the kernel did not have the
proper state unless they also ran the dmsetup 'table/status' command.
The solution is to suspend/resume the cache LV to make the loaded
tables become active.
Introduce a new parameter called "approx_alloc" that is set when the
desired size of a new LV is specified in percentage terms. If set,
the allocation code tries to get as much space as it can but does not
fail if can at least get some.
One of the practical implications is that users can now specify 100%FREE
when creating RAID LVs, like this:
~> lvcreate --type raid5 -i 2 -l 100%FREE -n lv vg
lv_active_change will enforce proper activation.
Modification of activation was wrong and lead to misuse of
autoactivation. Fix allows to use proper local exclusive activation,
while the removed code turned this into just exclusive
activation (losing required local property).
The libblkid can detect DM_snapshot_cow signature and when creating
new LVs with blkid wiping used (allocation/use_blkid_wiping=1 lvm.conf
setting and --wipe y used at the same time - which it is by default).
Do not issue any prompts about this signature when new LV is created
and just wipe it right away without asking questions. Still keep the
log in verbose mode though.
This patch allows users to create cache LVs with 'lvcreate'. An origin
or a cache pool LV must be created first. Then, while supplying the
origin or cache pool to the lvcreate command, the cache can be created.
Ex1:
Here the cache pool is created first, followed by the origin which will
be cached.
~> lvcreate --type cache_pool -L 500M -n cachepool vg /dev/small_n_fast
~> lvcreate --type cache -L 1G -n lv vg/cachepool /dev/large_n_slow
Ex2:
Here the origin is created first, followed by the cache pool - allowing
a cache LV to be created covering the origin.
~> lvcreate -L 1G -n lv vg /dev/large_n_slow
~> lvcreate --type cache -L 500M -n cachepool vg/lv /dev/small_n_fast
The code determines which type of LV was supplied (cache pool or origin)
by checking its type. It ensures the right argument was given by ensuring
that the origin is larger than the cache pool.
If the user wants to remove just the cache for an LV. They specify
the LV's associated cache pool when removing:
~> lvremove vg/cachepool
If the user wishes to remove the origin, but leave the cachepool to be
used for another LV, they specify the cache LV.
~> lvremove vg/lv
In order to remove it all, specify both LVs.
This patch also includes tests to create and remove cache pools and
cache LVs.
This patch allows the creation and removal of cache pools. Users are not
yet able to create cache LVs. They are only able to define the space used
for the cache and its characteristics (chunk_size and cache mode ATM) by
creating the cache pool.
Cache pools require a data and metadata area (like thin pools). Unlike
thin pool, if 'cache_pool_metadata_require_separate_pvs' is not set to
'1', the metadata and data area will be allocated from the same device.
It is also done in a manner similar to RAID, where a single chunk of
space is allocated and then split to form the metadata and data device -
ensuring that they are together.
Avoid use of external origin with size unaligned/incompatible with
thin pool chunk size, since the last chunk is not correctly provisioned
when it is overwritten.
Since we are currently incapable of providing zeroes for
reextended thin volume area, let's disable extension of
such already reduce thin volumes.
(in-release change)
When thin volume is using external origin, current thin target
is not able to supply 'extended' size with empty pages.
lvm2 detects version and disables extension of LV past the external
origin size in this case.
Thin LV could be however still reduced and extended freely bellow
this size.
In preparation for other segment types that create and use "pools", we
s/create_thin_pool/create_pool/. This way it is not awkward when creating
a cachepool, for example, to use "create_thin_pool".
Only flag thin LV for no scanning in udev if this LV is about
to be wiped. This happens only in case the thin LV's pool was not
created with zeroing of the new blocks enabled.
If we're calling pvcreate on a device that already has a PV label,
the blkid detects the existing PV and then we consider it for wiping
before we continue creating the new PV label and we issue a warning
with a prompt whether such old PV label should be removed. We don't
do this with native signature detection code. Let's make it consistent
with old behaviour.
But still keep this "PV" (identified as "LVM1_member" or "LVM2_member"
by blkid) detection when creating new LVs to avoid unexpected PV label
appeareance inside LV.
Optimize and cleanup recently introduced new function wipe_lv.
Use compound literals to get nicely initialized wipe_params struct.
Pass in lv as explicit argument for wipe_lv.
Use cmd from lv structure.
Initialize only non-null members so it's easy to see what
is the special arg.
This is actually the wipefs functionailty as a matter of fact
(wipefs uses the same libblkid calls).
libblkid is more rich when it comes to detecting various
signatures, including filesystems and users can better
decide what to erase and what should be kept.
The code is shared for both pvcreate (where wiping is necessary
to complete the pvcreate operation) and lvcreate where it's up
to the user to decide.
The verbose output contains a bit more information about the
signature like LABEL and UUID.
For example:
raw/~ # lvcreate -L16m vg
WARNING: linux_raid_member signature detected on /dev/vg/lvol0 at offset 4096. Wipe it? [y/n]
or more verbose one:
raw/~ # lvcreate -L16m vg -v
...
Found existing signature on /dev/vg/lvol0 at offset 4096: LABEL="raw.virt:0" UUID="da6af139-8403-5d06-b8c4-13f6f24b73b1" TYPE="linux_raid_member" USAGE="raid"
WARNING: linux_raid_member signature detected on /dev/vg/lvol0 at offset 4096. Wipe it? [y/n]
The verbose output is the same output as found in blkid.
Use common wipe_lv (former set_lv) fn to do zeroing as well as signature
wiping if needed. Provide new struct wipe_lv_params to define the
functionality.
Bind "lvcreate -W/--wipesignatures y" with proper wipe_lv call.
Also, add "yes" and "force" to lvcreate_params so it's possible
to apply them for the prompt: "WARNING: %s detected on %s. Wipe it? [y/n]".
This patch fixes mostly cluster behavior but also updates
non-cluster reaction where calls like 'lvchange -aln'
lead to incorrect errors for some segment types.
Fix the implicit activation rules where some segment types could
be activated only in exclusive mode in cluster.
lvm2 command was not preserver 'local' property and incorrectly
converted local activations in to plain exclusive, so the local
activation could have activate volumes exclusively, but remotely.
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.
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.
