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The lvmetad connection is created within the
init_connections() path during command startup,
rather than via the old lvmetad_active() check.
The old lvmetad_active() checks are replaced
with lvmetad_used() which is a simple check that
tests if the command is using/connected to lvmetad.
The old lvmetad_set_active(cmd, 0) calls, which
stopped the command from using lvmetad (to revert to
disk scanning), are replaced with lvmetad_make_unused(cmd).
The code in _print_historical_lv function works with temporary
"descendants_buffer" that is allocated and freed within this
function.
When printing text out, we used "outf" macro which called
"out_text" fn and it checked return value and if failed,
the macro called "return_0" automatically. But since we
use the temporary buffer, if any of the out_text calls
fails, we need to deallocate this buffer properly - that's
the "goto_out", otherwise we'll be leaking memory.
So add new "outfgo" helper macro which does the same as "outf",
but it calls "goto_out" instead of "return_0" so we can jump
to a cleanup hook at the end.
Also export historical LVs when exporting LVM2 metadata.
This is list of all historical LVs listed in
"historical_logical_volumes" metadata section with all
the properties exported for each historical LV.
For example, we have this thin snapshot sequence:
lvol1 --> lvol2 --> lvol3
\
--> lvol4
We end up with these metadata:
logical_volume {
...
(lvol1, lvol3 and lvol4 listed here as usual - no change here)
...
}
historical_logical_volumes {
lvol2 {
id = "S0Dw1U-v5sF-LwAb-W9SI-pNOF-Madd-5dxSv5"
creation_time = 1456919613 # 2016-03-02 12:53:33 +0100
removal_time = 1456919620 # 2016-03-02 12:53:40 +0100
origin = "lvol1"
descendants = ["lvol3", "lvol4"]
}
}
By removing lvol1 further, we end up with:
historical_logical_volumes {
lvol2 {
id = "S0Dw1U-v5sF-LwAb-W9SI-pNOF-Madd-5dxSv5"
creation_time = 1456919613 # 2016-03-02 12:53:33 +0100
removal_time = 1456919620 # 2016-03-02 12:53:40 +0100
origin = "-lvol1"
descendants = ["lvol3", "lvol4"]
}
lvol1 {
id = "me0mes-aYnK-nRfT-vNlV-UiR1-GP7r-ojbROr"
creation_time = 1456919608 # 2016-03-02 12:53:28 +0100
removal_time = 1456919767 # 2016-03-02 12:56:07 +0100
}
}
This uses the vg->pv_write_list in place of the
vg->pvs_to_write list, and eliminates the use of
pvcreate_params. The label remove and zeroing
steps are shifted out of vg_write() to the higher
level like pvcreate will do.
The backup_restore_vg is used directly for restoring the VG from backup.
It's also used to do the VG conversions from one metadata format to
another which means vgconvert calls backup_restore_vg too.
When restoring VG from backup, we need to rewrite/write PV headers as
PVs may have been orphans before and now they're becoming part of some
VG - we need to write the PV_EXT_USED flag at least.
When using the backup_restore_vg for vgconvert, we need to write
completely new PV header in different format.
Avoid the special "pv_write" call and handling that was used before
this patch in vgconvert (vgconvert_single function to be more precise)
and reuse existing internal interface to register PV header for writing
(or rewriting) via vg->pvs_to_write list instead like we do it elsewhere
in the code.
This patch also resolves a problem in which PV headers with target
format were written in the vgconvert_single fn as orphans and VG
metadata were added later on - this was a tiny hack actually.
We can't do this now - we need to write the PV as belonging
to a VG because otherwise the PV_EXT_USED flag won't be written
properly (if the PV header is written as orphan, the PV_EXT_USED
is set to 0, of course, even though metadata are attached later).
So this patch removes this tiny inconsistency which was passing
just fine before because we didn't have any relation to the VG
in PV header before. Now we have the PV_EXT_USED flag which says
the "PV is used in some VG".
Use process_each_vg() to lock and read the old VG,
and then call the main vgrename code.
When real VG names are used (not a UUID in place of the
old name), the command still pre-locks the new name
(when strcmp wants it locked first), before calling
process_each_vg on the old name.
In the case where the old name is replaced with a UUID,
process_each_vg now translates that UUID into the real
VG name, which it locks and reads. In this case, we
cannot do pre-locking to maintain lock ordering because
the old name is unknown. So, in this case the strcmp
based lock ordering is suppressed and the old name is
always locked first. This opens a remote chance for
lock ordering conflict between racing vgrenames between
two names where one or both commands use the UUID.
It's getting a bit more complex here.
Basic idea behind is - check_current_backup() should not
log error when a user is using a read-only filesystem,
so e.g. vgscan will not report any error when it tries
to take missing backup.
We still have cases when error could be reported though,
e.g. the backup this would be a symbolic link, but these
are rather misconfiguration and unexpected case.
We have to modes of 'archive()' usage -
1. compulsory - fail stops command and user may try '-An' option
to do a command.
2. non-compulsory - some fails in archiving are ignorable (i.e.
read-only filesystem where archive dir is located).
Those 2 cases needs to be properly handle - i.e. the non-compulsory
logging should not be tampering error logging message production.
So more work here is needed
When checking minimum mda size, make sure the mda_size after alignment
and calculation is more than 0 - if there's no place for an MDA at the
end of the disk, the _text_pv_add_metadata_area does not try to add it
there and it returns (because we already have the MDA at the start of
the disk at least).
Actually, we don't need extra condition as introduced in commit
00348c0a63. We should fix the last
condition:
(mdac->rlocn.size >= mdah->size)
...which should be:
(MDA_HEADER_SIZE + (rlocn ? rlocn->size : 0) + mdac->rlocn.size >= mdah->size))
Where the "mdac" is new metadata, the "rlocn" is old metadata.
So the main problem with the previous condition was that it
didn't count in MDA_HEADER_SIZE properly (and possible existing
metadata - the "rlocn"). This could have caused the error state
where metadata in ring buffer overlap to not be hit.
Replace the new condition introduced in 00348c0a63
with the improved one for the condition that existed there
already but it was just incomplete.
We're already checking whether old and new meta do not overlap in
ring buffer (as we need to keep both old and new meta during vg_write
up until vg_commit).
We also need to check whether the new metadata do not overlap
themselves in case we don't have old metadata yet (...because
we're in vgcreate). This could happen if we're creating a VG so
that the very first metadata written are long enough that it wraps
themselves in metadata ring buffer.
Although we limited the minimum metadata area size better with the
previous commit ccb8da404d which
makes the initial VG metadata overlap in ring buffer to be less
probable, the risk of hitting this overlap condition is still there
if we still manage to generate big enough metadata somehow.
For example, users can provide many and/or long VG tags during vgcreate
so that the VG metadata is long enough to start to wrap in the ring
buffer again...
Also, leave out the note about "circular buffer" which is
an internal imeplementation detail anyway and not quite
informational for users:
Before this patch:
$ vgcreate vg1 /dev/sda
VG vg1 metadata too large for circular buffer
Failed to write VG vg1.
With this patch applied:
$ vgcreate vg1 /dev/sda
VG vg1 metadata too large: size of metadata to write is 691 bytes while PV metadata area size on /dev/sda is 512 bytes.
Failed to write VG vg1.
When using lvm shell, some structures which are cached in memory may be
reused. This happens for the struct label (a part of lvmcache_info
structure) when lvmetad is used in which case the PV scan is not
done that would normally overwrite these label structures in memory
and making them up-to-date.
This is all consequence of the fact that struct lvmcache_info and
struct label are not always assigned in the same part of the code.
For example, if lvmetad *is not* used, parts of the struct label are
reassigned in label_read fn while struct lvmcache_info is created
elsewhere. No part of the code reused struct label (and its "dev"
field) before calling label_read fn. That's why the real bug is
hidden when using lvm shell without lvmetad.
However, with lvmetad and lvm shell, the situation is a bit different.
The label_read fn is not called if lvmetad *is* used, hence the
struct label may have ended up not initialized properly.
There was missing assignment for the dev field in struct label
in _text_pv_write fn which caused this problem to appear in
lvm shell with lvmetad, for example:
Before this patch:
lvm> pvcreate /dev/sda
Physical volume "/dev/sda" successfully created
lvm> pvs /dev/sda
PV VG Fmt Attr PSize PFree
unknown device lvm2 --- 128.00m 128.00m
With this patch applied:
lvm> pvcreate /dev/sda
Physical volume "/dev/sda" successfully created
lvm> pvs /dev/sda
PV VG Fmt Attr PSize PFree
/dev/sda lvm2 --- 128.00m 128.00m
Also, this problem had not appeared before changes introduced
by commits e1a63905d1 through
3a6f91d713 which, among other
things, added proper label field type reporting. Before, label
reporting was the same as using struct physical_volume which
has its own dev field assigned and so this problem was not exposed.
This reverts commit 70db1d523d.
Since we use 'strncpy' even for case where it exactly matches
the buffer size and \0 is not expected to be added there.
vgsummary information contains provisional VG information
that is obtained without holding the VG lock. This info
can be used to lock the VG, and then read it with vg_read().
After the VG is read properly, the vgsummary info should
be verified.
Add the VG lock_type to the vgsummary. It needs to be
known before the VG can be locked and read.
Use 64bit arithmentic for PV size calculation (Coverity).
Also remove sector shift for compared PV size, since all
values are already held in sectors.
This fixes validatio of PV size when restoring PV
from vg metadata backup file.
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
pv_write is called both to write orphans and to rewrite PV headers
of PVs in VGs. It needs to select the correct VG id so that the
internal cache state gets updated correctly.
It only affected commands that involved further steps after
the pv_write and was often masked because the metadata would
be re-read off disk and correct itself.
"Incorrect metadata area header checksum" warnings appeared.
Example:
Create vg1 containing dev1, dev2 and dev3.
Hide dev1 and dev2 from the system.
Fix up vg1 with vgreduce --removemissing.
Bring back dev1 and dev2.
In a single operation reinstate dev1 and dev2 into vg1 (vgextend).
Done as separate operations (automatically fix-up dev1 and dev2 as orphans,
then vgextend) it worked, but done all in one go the internal cache got
corrupted and warnings about checksum errors appeared.
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).
The code never mixes reads of committed and precommitted metadata,
so there's no need to attempt to set PRECOMMITTED when
*use_previous_vg is being set.
Refactor the recent metadata-reading optimisation patches.
Remove the recently-added cache fields from struct labeller
and struct format_instance.
Instead, introduce struct lvmcache_vgsummary to wrap the VG information
that lvmcache holds and add the metadata size and checksum to it.
Allow this VG summary information to be looked up by metadata size +
checksum. Adjust the debug log messages to make it clear when this
shortcut has been successful.
(This changes the optimisation slightly, and might be extendable
further.)
Add struct cached_vg_fmtdata to format-specific vg_read calls to
preserve state alongside the VG across separate calls and indicate
if the details supplied match, avoiding the need to read and
process the VG metadata again.
Detect an lvm1 system id by looking at the WRITE_LOCKED flag.
Don't copy this lvm1 system id into vg->system_id so that the
restrictions associated with the new system id are not applied
to the old VG with the inherited lvm1 system id.
Use similar logic as with text_vg_import_fd() and avoid repeated
parsing of same mda and its config tree for vgname_from_mda().
Remember last parsed vgname, vgid and creation_host in labeller
structure and if the metadata have the same size and checksum,
return this stored info.
TODO: The reuse of labeller struct is not ideal, some lvmcache API for
this functionality would be nicer.
When reading VG mda from multiple PVs - do all the validation only
when mda is seen for the first time and when mda checksum and length
is same just return already existing VG pointer.
(i.e. using 300PVs for a VG would lead to create and destroy 300 config trees....)
Previous versions of lvm will not obey the restrictions
imposed by the new system_id, and would allow such a VG
to be written. So, a VG with a new system_id is further
changed to force previous lvm versions to treat it as
read-only. This is done by removing the WRITE flag from
the metadata status line of these VGs, and putting a new
WRITE_LOCKED flag in the flags line of the metadata.
Versions of lvm that recognize WRITE_LOCKED, also obey the
new system_id. For these lvm versions, WRITE_LOCKED is
identical to WRITE, and the rules associated with matching
system_id's are imposed.
A new VG lock_type field is also added that causes the same
WRITE/WRITE_LOCKED transformation when set. A previous
version of lvm will also see a VG with lock_type as read-only.
Versions of lvm that recognize WRITE_LOCKED, must also obey
the lock_type setting. Until the lock_type feature is added,
lvm will fail to read any VG with lock_type set and report an
error about an unsupported lock_type. Once the lock_type
feature is added, lvm will allow VGs with lock_type to be
used according to the rules imposed by the lock_type.
When both system_id and lock_type settings are removed, a VG
is written with the old WRITE status flag, and without the
new WRITE_LOCKED flag. This allows old versions of lvm to
use the VG as before.
Set ACCESS_NEEDS_SYSTEM_ID VG status flag whenever there is
a non-lvm1 system_id set. Prevents concurrent access from
older LVM2 versions.
Not set on VGs that bear a system_id only due to conversion
from lvm1 metadata.
format_text processes both lvm2 on-disk metadata and metadata read
from other sources such as backup files. Add original_fmt field
to retain the format type of the original metadata.
Before this patch, /etc/lvm/archives would contain backups of
lvm1 metadata with format = "lvm2" unless the source was lvm1 on-disk
metadata.
When checking whether the system ID permits access to a VG, check for
each permitted situation first, and only then issue the appropriate
error message. Always issue a message for now. (We'll try to
suppress some of those later when the VG concerned wasn't explicitly
requested.)
Add more messages to try to ensure every return code is checked and
every error path (and only an error path) contains a log_error().
Add self-correction to vgchange -c to deal with situations where
the cluster state and system ID state are out-of-sync (e.g. if
old tools were used).
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.)
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.
The warnings arg was used to enable logging of warnings
when reading a PV. This arg is turned into a set of flags
with the WARN_PV_READ flag matching the existing behavior.
A new flag WARN_INCONSISTENT is added that will cause
vg_read_internal() to log the "VG is not consistent"
warning so the various callers do not need to log
this warning themselves.
A new vg_read flag READ_WARN_INCONSISTENT is used from
reporting to enable the WARN_INCONSISTENT flag in
vg_read_internal.
[Committed by agk with cosmetic changes and tweaks.]
Do not let fly metadata with just 'minor' set
(since they would not be readable on older version)
Be permissive with invalid major/minor number and
just report them as problem, but allow to use
such metadata with default major:minor.
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.
Few unecessary comments were written to on-disc metadata.
Use outfc() to have comments only in archived files.
(may also save couple bytes in ringbuffer).
TODO: needed validation against newline char...
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...
Add CONFIG_FILE_SPECIAL config source id to make a difference between
real configuration tree (like lvm.conf and tag configs) and special purpose
configuration tree (like LVM metadata, persistent filter).
This makes it easier to attach correct customized data to the config
tree that is created out of the source then.
When the backup is disabled, avoid testing backup presence.
This only leads to errors being logged in debug trace and the missing
backup can't be fixed, since it's disabled.
This is probably not optimal, but makes the lvmetad case mimic non-lvmetad code
more closely. It also fixes vgremove of a partially corrupt VG with lvmetad, as
_vg_write_raw (and consequently, entire vg_write) currently panics when it
encounters a corrupt MDA. Ideally, we'd be able to explicitly control when it is
safe to ignore them.
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.
The size of any metadata must be ignored when calculating the size of an
orphan PV.
Bug introduced by 603b45e0ed ("pvresize: Do
not use pv_read (get the PV from orphan VG).")
Block creations of archive and backup files for internal orphan VGs.
Bug introduced by 603b45e0ed ("pvresize: Do
not use pv_read (get the PV from orphan VG).")
The metadata/disk_areas setting was incorrectly registered as
"string" configuration option but it's a section where each area
is defined in its own subsection with "start_sector", "size" and "id"
setting.
This setting is not officialy supported, it's undocumented and it's
used solely for debugging.
Note: At this moment, it does not seem to be working with lvmetad!
It will likely not fail to duplicate empty string, but
just keep the test of result of this function consistent.
Also on error path restore extent_size if in some
case someone would still use that variable.
All labellers always use the "private" (void *) field as the fmt pointer. Making
this fact explicit in the type of the labeller simplifies the label reporting
code which needs to extract the format. Moreover, it removes a number of
error-prone casts from the code.
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.
Addendum to commit ce7489e which introduced a new *internal* LV_NOSCAN
flag and so it needs to be marked that way properly otherwise it
ends up unrecognized and improperly handled during metadata export.
When reading an info about MDAs from lvmetad, we need to use 64 bit
int to read the value of the offset/size, otherwise the value is
overflows and then it's used throughout!
This is dangerous if we're trying to write such metadata area then,
mostly visible if we're using 2 mdas where the 2nd one is at the end
of the underlying device and hence the value of the mda offset is
high enough to cause problems:
(the offset trimmed to value of 0 instead of 4096m, so we write
at the very start of the disk (or elsewhere if the offset has
some other value!)
[1] raw/~ # lvcreate -s -l 100%FREE vg --virtualsize 4097m
Logical volume "lvol0" created
[1] raw/~ # pvcreate --metadatacopies 2 /dev/vg/lvol0
Physical volume "/dev/vg/lvol0" successfully created
[1] raw/~ # hexdump -n 512 /dev/vg/lvol0
0000000 0000 0000 0000 0000 0000 0000 0000 0000
*
0000200
[1] raw/~ # pvchange -u /dev/vg/lvol0
Physical volume "/dev/vg/lvol0" changed
1 physical volume changed / 0 physical volumes not changed
[1] raw/~ # hexdump -n 512 /dev/vg/lvol0
0000000 d43e d2a5 4c20 4d56 2032 5b78 4135 7225
0000010 4e30 3e2a 0001 0000 0000 0000 0000 0000
0000020 0000 0010 0000 0000 0000 0000 0000 0000
0000030 0000 0000 0000 0000 0000 0000 0000 0000
*
0000200
=======
(the offset overflows to undefined values which is far behind
the end of the disk)
[1] raw/~ # lvcreate -s -l 100%FREE vg --virtualsize 100g
Logical volume "lvol0" created
[1] raw/~ # pvcreate --metadatacopies 2 /dev/vg/lvol0
Physical volume "/dev/vg/lvol0" successfully created
[1] raw/~ # pvchange -u /dev/vg/lvol0
/dev/vg/lvol0: lseek 18446744073708503040 failed: Invalid argument
/dev/vg/lvol0: lseek 18446744073708503040 failed: Invalid argument
Failed to store physical volume "/dev/vg/lvol0"
0 physical volumes changed / 1 physical volume not changed
Also add -k/--setactivationskip y/n and -K/--ignoreactivationskip
options to lvcreate.
The --setactivationskip y sets the flag in metadata for an LV to
skip the LV during activation. Also, the newly created LV is not
activated.
Thin snapsots have this flag set automatically if not specified
directly by the --setactivationskip y/n option.
The --ignoreactivationskip overrides the activation skip flag set
in metadata for an LV (just for the run of the command - the flag
is not changed in metadata!)
A few examples for the lvcreate with the new options:
(non-thin snap LV => skip flag not set in MDA + LV activated)
raw/~ $ lvcreate -l1 vg
Logical volume "lvol0" created
raw/~ $ lvs -o lv_name,attr vg/lvol0
LV Attr
lvol0 -wi-a----
(non-thin snap LV + -ky => skip flag set in MDA + LV not activated)
raw/~ $ lvcreate -l1 -ky vg
Logical volume "lvol1" created
raw/~ $ lvs -o lv_name,attr vg/lvol1
LV Attr
lvol1 -wi------
(non-thin snap LV + -ky + -K => skip flag set in MDA + LV activated)
raw/~ $ lvcreate -l1 -ky -K vg
Logical volume "lvol2" created
raw/~ $ lvs -o lv_name,attr vg/lvol2
LV Attr
lvol2 -wi-a----
(thin snap LV => skip flag set in MDA (default behaviour) + LV not activated)
raw/~ $ lvcreate -L100M -T vg/pool -V 1T -n thin_lv
Logical volume "thin_lv" created
raw/~ $ lvcreate -s vg/thin_lv -n thin_snap
Logical volume "thin_snap" created
raw/~ $ lvs -o name,attr vg
LV Attr
pool twi-a-tz-
thin_lv Vwi-a-tz-
thin_snap Vwi---tz-
(thin snap LV + -K => skip flag set in MDA (default behaviour) + LV activated)
raw/~ $ lvcreate -s vg/thin_lv -n thin_snap -K
Logical volume "thin_snap" created
raw/~ $ lvs -o name,attr vg/thin_lv
LV Attr
thin_lv Vwi-a-tz-
(thins snap LV + -kn => no skip flag in MDA (default behaviour overridden) + LV activated)
[0] raw/~ # lvcreate -s vg/thin_lv -n thin_snap -kn
Logical volume "thin_snap" created
[0] raw/~ # lvs -o name,attr vg/thin_snap
LV Attr
thin_snap Vwi-a-tz-
If "vgcreate/lvcreate --profile <profile_name>" is used, the profile
name is automatically stored in metadata for making it possible to
load it automatically next time the VG/LV is used.
This is per VG/LV profile loading on demand. The profile itself is saved
in struct volume_group/logical_volume as "profile" field so we can
reference it whenever needed.
A helper type that helps with identification of the configuration source
which makes handling the configuration cascade a bit easier, mainly
removing and adding configuration trees to cascade dynamically.
Currently, the possible types are:
CONFIG_UNDEFINED - configuration is not defined yet (not initialized)
CONFIG_FILE - one file configuration
CONFIG_MERGED_FILES - configuration that is a result of merging more files into one
CONFIG_STRING - configuration string typed on cmd line directly
CONFIG_PROFILE - profile configuration (the new type of configuration, patches will follow...)
Also, generalize existing "remove_overridden_config_tree" to work with
configuration type identification in a cascade. Before, it was just
the CONFIG_STRING we used. Now, we need some more to add in a
cascade (like the CONFIG_PROFILE). So, we have:
struct dm_config_tree *remove_config_tree_by_source(struct cmd_context *cmd, config_source_t source);
config_source_t config_get_source_type(struct dm_config_tree *cft);
... for removing the tree by its source type from the cascade and
simply getting the source type.
In the last update not all code paths have set the archived flag.
If we run in test mode or without archiving enabled - set the bit
as well - so test whether archiving has been called succesfully
will be ok. (in relase fix).
Do not keep multiple archives for the executed command.
Reuse the ALLOCATABLE_PV from pv status for
ARCHIVED_VG vg status. Mark VG with the bit with the
first archivation.
...not the other way round as it was before. This way it makes
more sense as BA use is exceptional and it's useless to
contaminate the log with messages about BA not being found
in metadata.
When vgname has not existed in metadata, it has crashed on double free
in format_instance destroy() - since VG was created, used FID and was
released - which also released FID, so further use was accessing bad
memory.
Fix it for this code path before release_vg() so FID will exists
when _vg_read_file_name() returns NULL.
'lvchange' is used to alter a RAID 1 logical volume's write-mostly and
write-behind characteristics. The '--writemostly' parameter takes a
PV as an argument with an optional trailing character to specify whether
to set ('y'), unset ('n'), or toggle ('t') the value. If no trailing
character is given, it will set the flag.
Synopsis:
lvchange [--writemostly <PV>:{t|y|n}] [--writebehind <count>] vg/lv
Example:
lvchange --writemostly /dev/sdb1:y --writebehind 512 vg/raid1_lv
The last character in the 'lv_attr' field is used to show whether a device
has the WriteMostly flag set. It is signified with a 'w'. If the device
has failed, the 'p'artial flag has priority.
Example ("nosync" raid1 with mismatch_cnt and writemostly):
[~]# lvs -a --segment vg
LV VG Attr #Str Type SSize
raid1 vg Rwi---r-m 2 raid1 500.00m
[raid1_rimage_0] vg Iwi---r-- 1 linear 500.00m
[raid1_rimage_1] vg Iwi---r-w 1 linear 500.00m
[raid1_rmeta_0] vg ewi---r-- 1 linear 4.00m
[raid1_rmeta_1] vg ewi---r-- 1 linear 4.00m
Example (raid1 with mismatch_cnt, writemostly - but failed drive):
[~]# lvs -a --segment vg
LV VG Attr #Str Type SSize
raid1 vg rwi---r-p 2 raid1 500.00m
[raid1_rimage_0] vg Iwi---r-- 1 linear 500.00m
[raid1_rimage_1] vg Iwi---r-p 1 linear 500.00m
[raid1_rmeta_0] vg ewi---r-- 1 linear 4.00m
[raid1_rmeta_1] vg ewi---r-p 1 linear 4.00m
A new reportable field has been added for writebehind as well. If
write-behind has not been set or the LV is not RAID1, the field will
be blank.
Example (writebehind is set):
[~]# lvs -a -o name,attr,writebehind vg
LV Attr WBehind
lv rwi-a-r-- 512
[lv_rimage_0] iwi-aor-w
[lv_rimage_1] iwi-aor--
[lv_rmeta_0] ewi-aor--
[lv_rmeta_1] ewi-aor--
Example (writebehind is not set):
[~]# lvs -a -o name,attr,writebehind vg
LV Attr WBehind
lv rwi-a-r--
[lv_rimage_0] iwi-aor-w
[lv_rimage_1] iwi-aor--
[lv_rmeta_0] ewi-aor--
[lv_rmeta_1] ewi-aor--
For example, the old call and reference:
find_config_tree_str(cmd, "devices/dir", DEFAULT_DEV_DIR)
...now becomes:
find_config_tree_str(cmd, devices_dir_CFG)
So we're referring to the named configuration ID instead
of passing the configuration path and the default value
is taken from central config definition in config_settings.h
automatically.
Just to prevent accidental and improper use when reading the layout
from disk because of the already existing disk_areas_xl[0] lists
that are variable in size. We can read pv_header_extension only
after we know exactly where the lists end...
The PV header extension information (PV header extension version, flags
and list of Embedding Area locations) is stored just beyond the PV header base.
When calculating the Embedding Area start value (ea_start), the same logic is
used as when calculating the pe_start value for Data Area - the value must
follow exactly the same alignment restrictions for its start value
(the alignment detected automatically or provided via command line using
the --dataalignment and --dataalignmentoffset arguments).
The Embedding Area is placed at the very start of the PV, starting at
ea_start. The Data Area starting at pe_start is placed next. The pe_start is
still properly aligned. Due to the pe_start alignment, it's possible that the
resulting Embedding Area size (ea_size) ends up bigger in size than requested
(but never less than requested).
New tools with PV header extension support will read the extension
if it exists and it's not an error if it does not exist (so old PVs
will still work seamlessly with new tools).
Old tools without PV header extension support will just ignore any
extension.
As for the Embedding Area location information (its start and size),
there are actually two places where this is stored:
- PV header extension
- VG metadata
The VG metadata contains a copy of what's written in the PV header
extension about the Embedding Area location (NULL value is not copied):
physical_volumes {
pv0 {
id = "AkSSRf-difg-fCCZ-NjAN-qP49-1zzg-S0Fd4T"
device = "/dev/sda" # Hint only
status = ["ALLOCATABLE"]
flags = []
dev_size = 262144 # 128 Megabytes
pe_start = 67584
pe_count = 23 # 92 Megabytes
ea_start = 2048
ea_size = 65536 # 32 Megabytes
}
}
The new metadata fields are "ea_start" and "ea_size".
This is mostly useful when restoring the PV by using existing
metadata backups (e.g. pvcreate --restorefile ...).
New tools does not require these two fields to exist in VG metadata,
they're not compulsory. Therefore, reading old VG metadata which doesn't
contain any Embedding Area information will not end up with any kind
of error but only a debug message that the ea_start and ea_size values
were not found.
Old tools just ignore these extra fields in VG metadata.
PV header extension comes just beyond the existing PV header base:
PV header base (existing):
- uuid
- device size
- null-terminated list of Data Areas
- null-terminater list of MetaData Areas
PV header extension:
- extension version
- flags
- null-terminated list of Embedding Areas
This patch also adds "eas" (Embedding Areas) list to lvmcache (lvmcache_info)
and it also adds support for common operations on the list (just like for
already existing "das" - Data Areas list):
- lvmcache_add_ea
- lvmcache_update_eas
- lvmcache_foreach_ea
- lvmcache_del_eas
Also, add ea_start and ea_size to struct physical_volume for processing
PV Embedding Area location throughout the code (currently only one
Embedding Area is supported, though the definition on disk allows for
more if needed in the future...).
Also, define FMT_EAS format flag to mark that the format actually
supports Embedding Areas (currently format-text only).
If zero metadata copies are used, there's no further recalculation of
PV alignment that happens when adding metadata areas to the PV and
which actually calculates the alignment correctly as a matter of fact.
So fix this for "PV without MDA" case as well.
Before this patch:
[1] raw/~ # pvcreate --dataalignment 8m --dataalignmentoffset 4m
--metadatacopies 1 /dev/sda
Physical volume "/dev/sda" successfully created
[1] raw/~ # pvs -o pv_name,pe_start
PV 1st PE
/dev/sda 12.00m
[1] raw/~ # pvcreate --dataalignment 8m --dataalignmentoffset 4m
--metadatacopies 0 /dev/sda
Physical volume "/dev/sda" successfully created
[1] raw/~ # pvs -o pv_name,pe_start
PV 1st PE
/dev/sda 8.00m
After this patch:
[1] raw/~ # pvcreate --dataalignment 8m --dataalignmentoffset 4m
--metadatacopies 1 /dev/sda
Physical volume "/dev/sda" successfully created
[1] raw/~ # pvs -o pv_name,pe_start
PV 1st PE
/dev/sda 12.00m
[1] raw/~ # pvcreate --dataalignment 8m --dataalignmentoffset 4m
--metadatacopies 0 /dev/sda
Physical volume "/dev/sda" successfully created
[1] raw/~ # pvs -o pv_name,pe_start
PV 1st PE
/dev/sda 12.00m
Also, remove a superfluous condition "pv->pe_start < pv->pe_align" in:
if (pe_start == PV_PE_START_CALC && pv->pe_start < pv->pe_align)
pv->pe_start = pv->pe_align ...
This part of the condition is not reachable as with the PV_PE_START_CALC,
we always have pv->pe_start set to 0 from the PV struct initialisation
(...the pv->pe_start value is just being calculated).
Allow restoring metadata with thin pool volumes.
No validation is done for this case within vgcfgrestore tool -
thus incorrect metadata may lead to destruction of pool content.
Use log_warn to print non-fatal warning messages.
Use of log_error would confuse checker for testing
whether proper error has been reported for some real error.
We were using daemon_send_simple until now, but it is no longer adequate, since
we need to manipulate requests in a generic way (adding a validity token to each
request), and the tree-based request interface is much more suitable for this.
Add 3rd daemon return state "unknown" for lookups that are carried out
successfully but don't find the item requested.
Avoid issuing error messages when it's expected that a device that's
being looked up in lvmetad might not be there.
Make sure both hash tables are initialized before _read_sections() call.
Presents no functional change (since PV scan phase was not adding LV hashes),
but makes the code easier to handle mem failing case, and static analyzer is
hapier as well.
Adding at least stack traces with some FIXMEs for cases,
where we might want to do something cleaver - maybe fail command
or give user hints something is not going well ?
For remote_backup is stack probably 'good' enough for now.
Move commod code to destroy orphan VG into free_orphan_vg() function.
Use orphan vgmem for creation of PV lists.
Remove some free_pv_fid() calls (FIXME: check all of them)
FIXME: Check whether we could merge release_vg back again for all VGs.
Basic support to keep info when the LV was created.
Host and time is stored into LV mda section.
FIXME: Current version doesn't support configurable string via lvm.conf
and used fixed version strftime "%Y-%m-%d %T %z".
RAID is not like traditional LVM mirroring. LVM mirroring required failed
devices to be removed or the logical volume would simply hang. RAID arrays can
keep on running with failed devices. In fact, for RAID types other than RAID1,
removing a device would mean substituting an error target or converting to a
lower level RAID (e.g. RAID6 -> RAID5, or RAID4/5 to RAID0). Therefore, rather
than removing a failed device unconditionally and potentially allocating a
replacement, RAID allows the user to "replace" a device with a new one. This
approach is a 1-step solution vs the current 2-step solution.
example> lvconvert --replace <dev_to_remove> vg/lv [possible_replacement_PVs]
'--replace' can be specified more than once.
example> lvconvert --replace /dev/sdb1 --replace /dev/sdc1 vg/lv
Use static buffer instead of stack allocated buffer.
This reduces stack size usage of lvm tool and the
change is very simple.
Since the whole library is not thread safe - it should not
add any new problems - and if there will be some conversion
it's easy to convert this to use some preallocated buffer.
When a PV label write is deferred to a vg_write call (as introduced by a patch
in 2.02.86), the PV is flagged with the internal UNLABELLED_PV flag. However,
when calling vg_archive before vg_write, we still have the PV labelled with the
UNLABELLED_PV flag which was not recognised as a proper flag while exporting
VG metadata:
# vgcreate vg /dev/sda
No physical volume label read from /dev/sda
Metadata inconsistency: Not all flags successfully exported.
Metadata inconsistency: Not all flags successfully exported.
Writing physical volume data to disk "/dev/sda"
Physical volume "/dev/sda" successfully created
Volume group "vg" successfully created
functionality. A number of bugs (copied and pasted all over the code) should
disappear:
- most string lookup based on dm_config_find_node would segfault when
encountering a non-zero integer (the intention there was to print an
error message instead)
- check for required sections in metadata would have been satisfied by
values as well (i.e. not sections)
- encountering a section in place of expected flag value would have
segfaulted (due to assumed but unchecked cn->v != NULL)
leaving behind the LVM-specific parts of the code (convenience wrappers that
handle `struct device` and `struct cmd_context`, basically). A number of
functions have been renamed (in addition to getting a dm_ prefix) -- namely,
all of the config interface now has a dm_config_ prefix.
There's a very high memory usage when calling _pv_analyse_mda_raw (e.g. while
executing pvck) that can end up with "out of memory".
_pv_analyse_mda_raw scans for metadata in the MDA, iteratively increasing the
size to scan with SECTOR_SIZE until we find a probable config section or we're
at the edge of the metadata area. However, when using a memory pool, we're also
iteratively chasing for bigger and bigger mempool chunk which can't be found
and so we're always allocating a new one, consuming more and more memory...
This patch just changes the mempool to direct memory allocation in this
problematic part of the code.
Move the free_vg() to vg.c and replace free_vg with release_vg
and make the _free_vg internal.
Patch is needed for sharing VG in vginfo cache so the release_vg function name
is a better fit here.
Implementation described in doc/lvm2-raid.txt.
Basic support includes:
- ability to create RAID 1/4/5/6 arrays
- ability to delete RAID arrays
- ability to display RAID arrays
Notable missing features (not included in this patch):
- ability to clean-up/repair failures
- ability to convert RAID segment types
- ability to monitor RAID segment types
It's useful to keep the partial flag cached - so just move the call
for vg_mark_partil_lvs() into import_vg_from_config_tree() so it gets
evaluated before it goes through the lvmcache.
This patch should not present any functional change.
Note: It is rather temporal solution - proper place is probably inside the
'read' call back - but needs some more discussion.
For now using this minor hack.
transient error), stemming from the following sequence of events:
1) devices fail IO, triggering repair
2) dmeventd starts fixing up the mirror
3) during the downconversion, a new metadata version is written
--> the devices come back online here
4) the mirror device suspend/resume is called to update DM tables
5) during the suspend/resume cycle, *pre*-commit metadata is read;
however, since the failed devices are now back online, we get back
inconsistent set of precommit metadata and the whole operation fails
The patch relaxes the check that fails in step 5 above, namely by ignoring
inconsistencies coming from PVs that are marked MISSING.
Before, we used vg_write_lock_held call to determnine the way a device is
opened. Unfortunately, this opened many devices in RW mode when it was not
really necessary. With the OPTIONS+="watch" rule used in the udev rules,
this could fire numerous events while closing such devices (and it caused
useless scans from within udev rules in return).
A common bug we hit with this was with the lvremove command which was unable
to remove the LV since it was being opened from within the udev rules. This
patch should minimize such situations (at least with respect to LVM handling
of devices).
Though there's still a possibility someone will open a device 'outside' in
parallel and fire the event based on the watch rule when closing a device
once opened for RW.
Avoid using of already released memory when duplicated MDA is found.
As get_pv_from_vg_by_id() may call lvmcache_label_scan() use the local copy
of the vgname and vgid on the stack as vginfo may dissapear and code was
then accessing garbage in memory.
i.e. pvs /dev/loop0
(when /dev/loop0 and /dev/loop1 has same MDA content)
Invalid read of size 1
at 0x523C986: dm_hash_lookup (hash.c:325)
by 0x440C8C: vginfo_from_vgname (lvmcache.c:399)
by 0x4605C0: _create_vg_text_instance (format-text.c:1882)
by 0x46140D: _text_create_text_instance (format-text.c:2243)
by 0x47EB49: _vg_read (metadata.c:2887)
by 0x47FBD8: vg_read_internal (metadata.c:3231)
by 0x477594: get_pv_from_vg_by_id (metadata.c:344)
by 0x45F07A: _get_pv_if_in_vg (format-text.c:1400)
by 0x45F0B9: _populate_pv_fields (format-text.c:1414)
by 0x45F40F: _text_pv_read (format-text.c:1493)
by 0x480431: _pv_read (metadata.c:3500)
by 0x4802B2: pv_read (metadata.c:3462)
Address 0x652ab80 is 0 bytes inside a block of size 4 free'd
at 0x4C2756E: free (vg_replace_malloc.c:366)
by 0x442277: _free_vginfo (lvmcache.c:963)
by 0x44235E: _drop_vginfo (lvmcache.c:992)
by 0x442B23: _lvmcache_update_vgname (lvmcache.c:1165)
by 0x443449: lvmcache_update_vgname_and_id (lvmcache.c:1358)
by 0x443C07: lvmcache_add (lvmcache.c:1492)
by 0x46588C: _text_read (text_label.c:271)
by 0x466A65: label_read (label.c:289)
by 0x4413FC: lvmcache_label_scan (lvmcache.c:635)
by 0x4605AD: _create_vg_text_instance (format-text.c:1881)
by 0x46140D: _text_create_text_instance (format-text.c:2243)
by 0x47EB49: _vg_read (metadata.c:2887)
Add testing script
As code uses strncpy(system_id, NAME_LEN) and doesn't set '\0'
Fix it by always allocating NAME_LEN + 1 buffer size and with zalloc
we always get '\0' as the last byte.
This bug may trigger some unexpected behavior of the string operation
code - depends on the pool allocator.
FIXME: refactor this code to alloc_vg.
Missing free_vg on error_path in lvmcache_get_vg fn. Call destroy_instance
only if the fid is not part of the vg in backup_read_vg fn (otherwise it's
part of the VG we're returning and we definitely don't want to destroy it!).
This is essential for proper format instance ref_count support. We must
use these functions to set the fid everywhere from now on, even the NULL
value!
We'd like to use the fid mempool for text_context that is stored
in the instance (we used cmd mempool before, so the order of
initialisation was not a matter, but now it is since we need to
create the fid mempool first which happens in create_instance fn).
The text_context initialisation is not needed anywhere outside the
create_instance fn so move it there.
Format instances can be created anytime on demand and it contains
metadata area information mostly (at least for now, but in the future,
we may store more things here to update/edit in a PV/VG). In case we
have lots of metadata areas, memory consumption will rise. Using cmd
context mempool is not quite optimal here because it is destroyed too
late. So let's use a separate mempool for format instances.
Reference counting is used because fids could be shared, e.g. each PV
has either a PV-based fid or VG-based fid. If it's VG-based, each PV has
a shared fid with the VG - a reference to VG's fid.
Create new function alloc_vg() to allocate VG structure.
It takes pool_name (for easier debugging).
and also take vg_name to futher simplify code.
Move remainder of _build_vg_from_pds to _pool_vg_read
and use vg memory pool for import functions.
(it's been using smem -> fid mempool -> cmd mempool)
(FIXME: remove mempool parameter for import functions and use vg).
Move remainder of the _build_vg to _format1_vg_read
We allow writing non-orphan PVs only for resize now. The "orphan PV" assert
in pv_write fn uses the "allow_non_orphan" parameter to control this assert.
However, we should find a more elaborate solution so we can remove this
restriction altogether (pv_write together with vg_write is not atomic, we
need to find a safe mechanism so there's an easy revert possible in case of
an error).
Add a small fix that preserves pe_start for lvm1 PVs when being converted.
(this fix needs to be replaced with something more clever, but let's have this working now)
If the PV is already part of the VG (so the pv->fid == vg->fid), it makes no
sense to attach the mdas information from PV to a VG. Instead, we read new
PV metadata information from cache and attach it to the VG fid.
This function also sets a reference to a new VG format instance for all PVs
that are part of the VG so the PV-VG interconnection is consistent after the
change.
Add supporting functions to work with the format instance and metadata area
structures stored within the format instance. Add support for simple indexing
of metadata areas using PV id and mda order (for on-disk PV only for now, we
can extend the indexing even for other mdas if needed - we only need to define
a proper key for the index).
New strategy for memory locking to decrease the number of call to
to un/lock memory when processing critical lvm functions.
Introducing functions for critical section.
Inside the critical section - memory is always locked.
When leaving the critical section, the memory stays locked
until memlock_unlock() is called - this happens with
sync_local_dev_names() and sync_dev_names() function call.
memlock_reset() is needed to reset locking numbers after fork
(polldaemon).
The patch itself is mostly rename:
memlock_inc -> critical_section_inc
memlock_dec -> critical_section_dec
memlock -> critical_section
Daemons (clmvd, dmevent) are using memlock_daemon_inc&dec
(mlockall()) thus they will never release or relock memory they've
already locked memory.
Macros sync_local_dev_names() and sync_dev_names() are functions.
It's better for debugging - and also we do not need to add memlock.h
to locking.h header (for memlock_unlock() prototyp).
Change function import_vg_from_buffer() to import_vg_from_config_tree().
Instead of creating config tree inside the function allow config tree to
be passed as parameter - usable later for caching.
