David Teigland [Tue, 8 Jun 2021 22:12:09 +0000 (17:12 -0500)]
devices: rework libudev usage
related to config settings:
obtain_device_info_from_udev (controls if lvm gets
a list of devices from readdir /dev or from libudev)
external_device_info_source (controls if lvm asks
libudev for device information)
. Make the obtain_device_list_from_udev setting
affect only the choice of readdir /dev vs libudev.
The setting no longer controls if udev is used for
device type checks.
. Change obtain_device_list_from_udev default to 0.
This helps avoid boot timeouts due to slow libudev
queries, avoids reported failures from
udev_enumerate_scan_devices, and avoids delays from
"device not initialized in udev database" errors.
Even without errors, for a system booting with 1024 PVs,
lvm2-pvscan times improve from about 100 sec to 15 sec,
and the pvscan command from about 64 sec to about 4 sec.
. For external_device_info_source="none", remove all
libudev device info queries, and use only lvm
native device info.
. For external_device_info_source="udev", first check
lvm native device info, then check libudev info.
. Remove sleep/retry loop when attempting libudev
queries for device info. udev info will simply
be skipped if it's not immediately available.
. Only set up a libdev connection if it will be used by
obtain_device_list_from_udev/external_device_info_source.
. For native multipath component detection, use
/etc/multipath/wwids. If a device has a wwid
matching an entry in the wwids file, then it's
considered a multipath component. This is
necessary to natively detect multipath
components when the mpath device is not set up.
The dev cache index is expensive and slow, so limit it
to commands that are used to observe the state of lvm.
The index is only used to print warnings about incorrect
device use by active LVs, e.g. if an LV is using a
multipath component device instead of the multipath
device. Commands that continue to use the index and
print the warnings:
A couple other commands were borrowing the DEV_USED_FOR_LV
flag to just check if a device was actively in use by LVs.
These are converted to the new dev_is_used_by_active_lv().
Add tool 'vdoimport' to support easy conversion of an existing VDO manager managed
VDO volumes into lvm2 managed VDO LV.
When physical converted volume is already a logical volume, conversion
happens with the VG itself, just with validation for extent_size, so
the virtually sized logical VDO volume size can be expressed in extents.
David Teigland [Thu, 1 Jul 2021 22:25:43 +0000 (17:25 -0500)]
pvscan: skip indexing devices used by LVs
dev_cache_index_devs() is taking a large amount of time
when there are many PVs. The index keeps track of
devices that are currently in use by active LVs. This
info is used to print warnings for users in some limited
cases.
The checks/warnings that are enabled by the index are not
needed by pvscan --cache, so disable it in this case.
This may be expanded to other cases in future commits.
dev_cache_index_devs should also be improved in another
commit to avoid the extreme delays with many devices.
David Teigland [Tue, 29 Jun 2021 17:40:03 +0000 (12:40 -0500)]
scan: move metadata vgname check
There have been two separate checks for metadata
validity: first that the metadata text begins with
a valid VG name, and second the checksum of the
metadata text. These happen in different places,
which means there have been two separate error paths
for invalid metadata. This also causes large metadata
to be read in multiple parts, the first part is read
just to check the vgname, and then remaining parts are
read later when the full metadata is needed.
This patch moves the vg name verification so it's
done just before the checksum verification, which
results in a single error path for invalid metadata,
and causes the entire metadata to be read together
rather that in parts from different parts of the code.
David Teigland [Mon, 28 Jun 2021 23:10:47 +0000 (18:10 -0500)]
scan: retry reading metadata on error
If label_scan encounters bad vg metadata, invalidate
bcache data for the device and reread the mda_header
and metadata text back to back. With concurrent commands
modifying large metadata, it's possible that the entire
metadata area can be rewritten in the time between a
command reading the mda_header and reading the metadata
text that the header points to. Since the label_scan
is just assembling an initial overview of devices, it
doesn't use locking to serialize with other commands
that may be modifying the vg metadata at the same time.
changed the default writecache block size from 512 to 4096
when no file system is detected. The fs block size detection
requires the libblkid BLOCK_SIZE feature, so skip tests on
systems without this. Otherwise, 4096 writecache added to
512 xfs leads fs io or mount failures.
Zdenek Kabelac [Mon, 28 Jun 2021 15:53:08 +0000 (17:53 +0200)]
vdo: support vdo_pool_header_size
Add profilable configurable setting for vdo pool header size, that is
used as 'extra' empty space at the front and end of vdo-pool device
to avoid having a disk in the system the may have same data is real
vdo LV.
For some conversion cases however we may need to allow using '0' header size.
TODO: in this case we may eventually avoid adding 'linear' mapping layer
in future - but this requires further modification over lvm code base.
Tony Asleson [Tue, 15 Jun 2021 03:04:09 +0000 (22:04 -0500)]
lvmdbusd: Wrap json.load in try/except
In testing where we inject large amounts of additional output in stderr
we can occassionally get truncated stdout from lvm. Catching and dumping
the json for debug before we re-raise the exception. As this doesn't
happen without the error injecting wrapper around lvm, the error seems to
be with the wrapper.
When exec'ing lvm, it's possible to get large amounts of both stdout
and stderr depending on the state of lvm and the size of the lvm
configuration. If we allow any of the buffers to fill we can end
up deadlocking the process. Ensure we are handling stdout & stderr
during lvm execution.
Tony Asleson [Thu, 10 Jun 2021 18:38:38 +0000 (13:38 -0500)]
lvmdbusd: Defer dbus object removal
When we are walking the new lvm state comparing it to the old state we can
run into an issue where we remove a VG that is no longer present from the
object manager, but is still needed by LVs that are left to be processed.
When we try to process existing LVs to see if their state needs to be
updated, or if they need to be removed, we need to be able to reference the
VG that was associated with it. However, if it's been removed from the
object manager we fail to find it which results in:
Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/lvmdbusd/utils.py", line 666, in _run
self.rc = self.f(*self.args)
File "/usr/lib/python3.6/site-packages/lvmdbusd/fetch.py", line 36, in _main_thread_load
cache_refresh=False)[1]
File "/usr/lib/python3.6/site-packages/lvmdbusd/lv.py", line 146, in load_lvs
lv_name, object_path, refresh, emit_signal, cache_refresh)
File "/usr/lib/python3.6/site-packages/lvmdbusd/loader.py", line 68, in common
num_changes += dbus_object.refresh(object_state=o)
File "/usr/lib/python3.6/site-packages/lvmdbusd/automatedproperties.py", line 160, in refresh
search = self.lvm_id
File "/usr/lib/python3.6/site-packages/lvmdbusd/lv.py", line 483, in lvm_id
return self.state.lvm_id
File "/usr/lib/python3.6/site-packages/lvmdbusd/lv.py", line 173, in lvm_id
return "%s/%s" % (self.vg_name_lookup(), self.Name)
File "/usr/lib/python3.6/site-packages/lvmdbusd/lv.py", line 169, in vg_name_lookup
return cfg.om.get_object_by_path(self.Vg).Name
Instead of removing objects from the object manager immediately, we will
keep them in a list and remove them once we have processed all of the state.
Leo Yan [Wed, 16 Jun 2021 13:44:27 +0000 (21:44 +0800)]
tests: Fix building for IDM program
When execute IDM testing, the command reports error:
/usr/bin/install: cannot stat ‘lib/idm_inject_failure’: No such file
or directory
Since there have a stale program in my local environment, thus Makefile
always uses the stale program and doesn't report any issue. In the
brand new repository, it doesn't contain an idm_inject_failure program,
and Makefile doesn't build it without specifying the dependency, thus
the test command complaints the file 'idm_inject_failure' is not found.
This patch adds the dependency 'lib/idm_inject_failure' for IDM testing,
so it can firstly build the injection program and dismiss the error.
David Teigland [Tue, 8 Jun 2021 19:49:34 +0000 (14:49 -0500)]
lvmdevices: add deviceidtype option
When adding a device to the devices file with --adddev, lvm
by default chooses the best device ID type for the new device.
The new --deviceidtype option allows the user to override the
built in preference. This is useful if there's a problem with
the default type, or if a secondary type is preferrable.
If the specified deviceidtype does not produce a device ID,
then lvm falls back to the preference it would otherwise use.
Zdenek Kabelac [Tue, 8 Jun 2021 17:39:15 +0000 (19:39 +0200)]
backup: automatically store data on vg_unlock
Previously there have been necessary explicit call of backup (often
either forgotten or over-used). With this patch the necessity to
store backup is remember at vg_commit and once the VG is unlocked,
the committed metadata are automatically store in backup file.
This may possibly alter some printed messages from command when the
backup is now taken later.
Zdenek Kabelac [Tue, 8 Jun 2021 17:02:07 +0000 (19:02 +0200)]
archiving: take archive automatically
Instead of calling explicit archive with command processing logic,
move this step towards 1st. vg_write() call, which will automatically
store archive of committed metadata.
This slightly changes some error path where the error in archiving
was detected earlier in the command, while now some on going command
'actions' might have been, but will be simply scratched in case
of error (since even new metadata would not have been even written).
So general effect should be only some command message ordering.
Leo Yan [Tue, 8 Jun 2021 06:45:09 +0000 (14:45 +0800)]
lvmlockd: Fix the compilation warning
As SUSE build tool reports the warning:
lvmlockd-core.c: In function 'client_thread_main':
lvmlockd-core.c:4959:37: warning: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 6 [-Wformat-truncation=]
snprintf(buf, sizeof(buf), "path[%d]", i);
^~
lvmlockd-core.c:4959:31: note: directive argument in the range [0, 2147483647]
snprintf(buf, sizeof(buf), "path[%d]", i);
^~~~~~~~~~
To dismiss the compilation warning, enlarge the array "buf" to 17
bytes to support the max signed integer: string format 6 bytes + signed
integer 10 bytes + terminal char "\0".
Reported-by: Heming Zhao <heming.zhao@suse.com> Signed-off-by: Leo Yan <leo.yan@linaro.org>
Leo Yan [Thu, 3 Jun 2021 09:59:25 +0000 (17:59 +0800)]
tests: multi-hosts: Test lease timeout with LV shareable mode
This patch is to test timeout handling after activate LV with shareable
mode. It has the same logic with the testing for LV exclusive mode,
except it verifies the locking with shareable mode.
On the host A:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_lv_sh_timeout_hosta.sh
On the host B:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_lv_sh_timeout_hostb.sh
Leo Yan [Thu, 3 Jun 2021 09:59:24 +0000 (17:59 +0800)]
tests: multi-hosts: Test lease timeout with LV exclusive mode
This patch is to test timeout handling after activate LV with exclusive
mode. It contains two scripts for host A and host B separately.
The script on host A firstly creates VGs and LVs based on the passed
back devices, every back device is for a dedicated VG and a LV is
created as well in the VG. Afterwards, all LVs are activated by host A,
so host A acquires the lease for these LVs. Then the test is designed
to fail on host A.
After the host A fails, host B starts to run the paired testing script,
it firstly fails to activate the LVs since the locks are leased by
host A; after lease expiration (after 70s), host B can achieve the lease
for LVs and it can operate LVs and VGs.
On the host A:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_lv_ex_timeout_hosta.sh
On the host B:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_lv_ex_timeout_hostb.sh
Leo Yan [Thu, 3 Jun 2021 09:59:23 +0000 (17:59 +0800)]
tests: multi-hosts: Add LV testing
This patch is to add LV testing on multi hosts. There have two scripts,
the script multi_hosts_lv_hosta.sh is used to create LVs on one host,
and the second script multi_hosts_lv_hostb.sh will acquire
global lock and VG lock, and remove VGs. The testing flow verifies the
locking operations between two hosts with lvmlockd and the backend
locking manager.
On the host A:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_lv_hosta.sh
On the host B:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_lv_hostb.sh
Leo Yan [Thu, 3 Jun 2021 09:59:22 +0000 (17:59 +0800)]
tests: multi-hosts: Add VG testing
This patch is to add VG testing on multi hosts. There have two scripts,
the script multi_hosts_vg_hosta.sh is used to create VGs on one host,
and the second script multi_hosts_vg_hostb.sh afterwards will acquire
global lock and VG lock, and remove VGs. The testing flow verifies the
locking operations between two hosts with lvmlockd and the backend
locking manager.
On the host A:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_vg_hosta.sh
On the host B:
make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3,/dev/sdl3 \
LVM_TEST_MULTI_HOST=1 T=multi_hosts_vg_hostb.sh
Leo Yan [Thu, 3 Jun 2021 09:59:21 +0000 (17:59 +0800)]
tests: idm: Add testing for IDM lock manager failure
If the IDM lock manager fails to access drives, might partially fail to
access drives (e.g. it fails to access one of three drives), or totally
fail to access drives, the lock manager should handle properly for these
cases. When the drives are partially failure, if the lock manager still
can renew the lease for the locking, then it doesn't need to take any
action for the drive failure; otherwise, if it detects it cannot renew
the locking majority, it needs ti immediately kill the VG from the
lvmlockd.
This patch adds the test for verification the IDM lock manager failure;
the command can be used as below:
# make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdp3,/dev/sdl3,/dev/sdq3 \
LVM_TEST_FAILURE=1 T=idm_ilm_failure.sh
Leo Yan [Thu, 3 Jun 2021 09:59:20 +0000 (17:59 +0800)]
tests: idm: Add testing for the fabric's half brain failure
If the fabric is broken instantly and the partial drives connected on
the fabric disappear from the system. For this case, according to the
locking algorithm in idm, the lease will not lose since the half drives
are still alive so can renew the lease for the half drives. On the
other hand, since the VG lock requires to acquire the majority of drive
number, but half drives failure cannot achieve the majority, so it
cannot acquire the lock for VG and thus cannot change metadata for VG.
This patch is to add half brain failure for idm; the test command is as
below:
# make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdp3,/dev/sdo3 LVM_TEST_FAILURE=1 \
T=idm_fabric_failure_half_brain.sh
Leo Yan [Thu, 3 Jun 2021 09:59:19 +0000 (17:59 +0800)]
tests: idm: Add testing for the fabric failure and timeout
If the fabric is broken instantly, the drives connected on the fabric
will disappear from the system. For worst case, the lease is timeout
and the drives cannot recovery back. So a new test is added to emulate
this scenario, it uses a drive for LVM operations and this drive is also
used for locking scheme; if the drive and all its associated paths (if
the drive supports multiple paths) are disconnected, the lock manager
should stop the lockspace for the VG/LVs.
And afterwards, if the drive recovers back, the VG/LV resident in the
drive should be operated properly. The test command is as below:
# make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdp3 LVM_TEST_FAILURE=1 \
T=idm_fabric_failure_timeout.sh
Leo Yan [Thu, 3 Jun 2021 09:59:18 +0000 (17:59 +0800)]
tests: idm: Add testing for the fabric failure
When the fabric failure occurs, it will lose the connection with hosts
instantly, and after a while it can recovery back so that the hosts can
continue to access the drives.
For this case, the locking manager should be reliable for this case and
can dynamically handle this case and allows user to continue to use the
VG/LV with associated locking scheme.
This patch adds a testing to emulate the fabric faliure, verify LVM
commands for this case. The testing usage is:
# make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdo3,/dev/sdp3,/dev/sdp4 \
LVM_TEST_FAILURE=1 T=idm_fabric_failure.sh
Leo Yan [Thu, 3 Jun 2021 09:59:17 +0000 (17:59 +0800)]
tests: Add testing for lvmlockd failure
After the lvmlockd abnormally exits and relaunch the daemon, if LVM
commands continue to run, lvmlockd and the backend lock manager (e.g.
sanlock lock manager or IDM lock manager) should can continue to serve
the requests from LVM commands.
This patch adds a test to emulate lvmlockd failure, and verify the LVM
commands after lvmlockd recovers back. Below is an example for testing
the case:
# make check_lvmlockd_idm \
LVM_TEST_BACKING_DEVICE=/dev/sdo3,/dev/sdp3,/dev/sdp4 \
LVM_TEST_FAILURE=1 T=lvmlockd_failure.sh
Leo Yan [Thu, 3 Jun 2021 09:59:16 +0000 (17:59 +0800)]
tests: Support idm failure injection
When the drive failure occurs, the IDM lock manager and lvmlockd should
handle this case properly. E.g. when the IDM lock manager detects the
lease renewal failure caused by I/O errors, it should invoke the kill
path which is predefined by lvmlockd, so that the kill path program
(like lvmlockctl) can send requests to lvmlockd to stop and drop lock
for the relevant VG/LVs.
To verify the failure handling flow, this patch introduces an idm
failure injection program, it can input the "percentage" for drive
failures so that can emulate different failure cases.
Leo Yan [Thu, 3 Jun 2021 09:59:15 +0000 (17:59 +0800)]
tests: stress: Add multi-threads stress testing for PV/VG/LV
This patch is to add the stress testing, which launches three threads,
one thread is for creating/removing PV, one thread is for
creating/removing VG, and the last one thread is for LV operations.
Leo Yan [Thu, 3 Jun 2021 09:59:14 +0000 (17:59 +0800)]
tests: stress: Add multi-threads stress testing for VG/LV
This patch is to add the stress testing, which launches two threads,
each thread creates LV, activate and deactivate LV in the loop; so this
can test for multi-threading in lvmlockd and its backend lock manager.
Leo Yan [Thu, 3 Jun 2021 09:59:10 +0000 (17:59 +0800)]
tests: Support multiple backing devices
In current implementation, the option "LVM_TEST_BACKING_DEVICE" only
supports to specify one backing device; this patch is to extend the
option to support multiple backing devices by using comma as separator,
e.g. below command specifies two backing devices:
make check_lvmlockd_idm LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3
This can allow the testing works on multiple drives and verify the
locking scheme if can work as expected for multiple drives case. For
example, for Seagate IDM locking scheme, if a VG uses two PVs, every PV
is resident on a drive, thus the locking operations will be sent to two
drives respectively; so the extension for "LVM_TEST_BACKING_DEVICE" can
help to verify different drive configurations for locking.
Leo Yan [Thu, 3 Jun 2021 09:59:09 +0000 (17:59 +0800)]
tests: Enable the testing for IDM locking scheme
This patch is to introduce testing option LVM_TEST_LOCK_TYPE_IDM, with
specifying this option, the Seagate IDM lock manager will be launched as
backend for testing. Also add the prepare and remove shell scripts for
IDM.
David Teigland [Wed, 2 Jun 2021 21:29:54 +0000 (16:29 -0500)]
pvchange: fix file locking deadlock
Calling clear_hint_file() to invalidate hints would acquire
the hints flock before the global flock which could cause deadlock.
The lock order requires the global lock to be taken first.
pvchange was always invalidating hints, which was unnecessary;
only invalidate hints when changing a PV uuid. Because of the
lock ordering, take the global lock before clear_hint_file which
locks the hints file.
Leo Yan [Fri, 21 May 2021 02:56:37 +0000 (10:56 +0800)]
configure: Add macro LOCKDIDM_SUPPORT
The macro LOCKDIDM_SUPPORT is missed in configure.h.in file, thus when
execute "configure" command, it has no chance to add this macro in the
automatic generated header include/configure.h.
This patch adds macro LOCKDIDM_SUPPORT into configure.h.in.
Leo Yan [Fri, 7 May 2021 02:25:15 +0000 (10:25 +0800)]
lib: locking: Parse PV list for IDM locking
For shared VG or LV locking, IDM locking scheme needs to use the PV
list assocated with VG or LV for sending SCSI commands, thus it requires
to use some places to generate PV list.
In reviewing the flow for LVM commands, the best place to generate PV
list is in the locking lib. So this is why this patch parses PV list as
shown. It iterates over all the PV nodes one by one, and compare with
the VG name or LV prefix string. If any PV matches, then the PV is
added into the PV list. Finally the PV list is sent to lvmlockd daemon.
Here as mentioned, it compares LV prefix string with the format
"lv_name_", the reason is it needs to find out all relevant PVs, e.g.
for the thin pool, it has LVs for metadata, pool, error, and raw LV, so
we can use the prefix string to find out all PVs belonging to the thin
pool.
For the global lock, it's not covered in this patch. To avoid the egg
and chicken issue, we need to prepare the global lock ahead before any
locking can be used. So the global lock's PV list is established in
lvmlockd daemon by iterating all drives with partition labeled with
"propeller".
Leo Yan [Fri, 7 May 2021 02:25:14 +0000 (10:25 +0800)]
lib: locking: Add new type "idm"
We can consider the drive firmware a server to handle the locking
request from nodes, this essentially is a client-server model.
DLM uses the kernel as a central place to manage locks, so it also
complies with client-server model for locking operations. This is
why IDM and DLM are similar with each other for their wrappers.
This patch largely works by generalizing the DLM code paths and then
providing degeneralized functions as wrappers for both IDM and DLM.
Leo Yan [Fri, 7 May 2021 02:25:13 +0000 (10:25 +0800)]
lvmlockd: idm: Hook Seagate IDM wrapper APIs
To allow the IDM locking scheme be used by users, this patch hooks the
IDM wrapper; it also introducs a new locking type "idm" and we can use
it for global lock with option '-g idm'.
To support IDM locking type, the main change in the data structure is to
add pvs path arrary. The pvs list is transferred from the lvm commands,
when lvmlockd core layer receives message, it extracts the message with
the keyword "path[idx]". Finally, the pv list will pass to IDM lock
manager as the target drives for sending IDM SCSI commands.
Leo Yan [Fri, 7 May 2021 02:25:12 +0000 (10:25 +0800)]
lvmlockd: idm: Introduce new locking scheme
Alongside the existed locking schemes of DLM and sanlock, this patch is
to introduce new locking scheme: In-Drive-Mutex (IDM).
With the IDM support in the drive, the locks are resident in the drive,
thus, the locking lease is maintained in a central place: the drive
firmware. We can consider this is a typical client-server model,
every host (or node) in the server cluster launches the request for
leasing mutex to a drive firmware, the drive firmware works as an
arbitrator to grant the mutex to a requester and it can reject other
applicants if the mutex has been acquired. To satisfy the LVM
activation for different modes, IDM supports two locking modes:
exclusive and shareable.
Every IDM is identified with two IDs, one is the host ID and another is
the resource ID. The resource ID is a unique identifier for what the
resource it's protected, in the integration with lvmlockd, the resource
ID is combined with VG's UUID and LV's UUID; for the global locking,
the bytes in resource ID are all zeros, and for the VG locking, the
LV's UUID is set as zero. Every host can generate a random UUID and
use it as the host ID for the SCSI command, this ID is used to clarify
the ownership for mutex.
For easily invoking the IDM commands to drive, like other locking
scheme (e.g. sanlock), a daemon program named IDM lock manager is
created, so the detailed IDM SCSI commands are encapsulated in the
daemon, and lvmlockd uses the wrapper APIs to communicate with the
daemon program.
This patch introduces the IDM locking wrapper layer, it forwards the
locking requests from lvmlockd to the IDM lock manager, and returns the
result from drives' responding.
One thing should be mentioned is the IDM's LVB. IDM supports LVB to max
7 bytes when stores into the drive, the most significant byte of 8 bytes
is reserved for control bits. For this reason, the patch maps the
timestamp in macrosecond unit with its cached LVB, essentially, if any
timestamp was updated by other nodes, that means the local LVB is
invalidate. When the timestamp is stored into drive's LVB, it's
possbile to cause time-going-backwards issue, which is introduced by the
time precision or missing synchronization acrossing over multiple nodes.
So the IDM wrapper fixes up the timestamp by increment 1 to the latest
value and write back into drive.
Currently LVB is used to track VG changes and its purpose is to notify
lvmetad cache invalidation when detects any metadata has been altered;
but lvmetad is not used anymore for caching metadata, LVB doesn't
really work. It's possible that the LVB functionality could be useful
again in the future, so let's enable it for IDM in the first place.
While we heavily try to spot arrays that are not yet in-sync,
some kernels tends to block our lvm2 command in kernel,
while we resume these smaller raid arrays even for 5 seconds.
But since the result is not really wrong - report these
check failures only as TEST WARNING.
Missed -l option in man page, although users should prefer
lvresize -r when the also want to do a volume management,
as there they can specify i.e. extents for allocation.
Also mention dm-crypt support in command description.
If the 'act' has been already processed by add_client_result()
it could have been possibly release - so avoid accessin 'act->'
afterward and go for next item directly.