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When using caches with BIG pool size (>TB) there is required
to use relatively huge chunk size. Once the chunksize has
got over 1MiB - kernel cache target stopped writing such chunks
back on this if the migration_threshold remained on default 1MiB
(2048 sectors) size.
This patch ensure, DM layer will not let pass table line which
has not big enough migration threshold that can let pass
at least 8 chunks (independently of lvm2 metadata).
Since configure.h is a generated header and it's missing traditional
ifdefs preambule - it can be included & parsed multiple times.
Normally compiler is fine when defines have same value and there is
no warning - yet we don't need to parse this several times
and by adding -include directive we can ensure every file
in the package is rightly compile with configure.h as the
first header file.
Drop very old original format of VDO target and focus on V2 version.
So some variables were renamed or replaced.
There is no compatibility preserved (with assumption so far this is
experimental feature and there is no real user).
Note - version currently VDO calls this version 6.2.
A bit of chicken & egg problem - dmeventd needs to use old libdm library.
VDO is only part of new device_mapper internal library.
So include directly source file for parsing status - this fixes usability
problem of VDO plugin introduced with previous Makefile reshaping
patchset.
NOTE: source file needs to be keep then compilable in both environments.
Also add missing copyright header.
Ensure configure.h is always 1st. included header.
Maybe we could eventually introduce gcc -include option, but for now
this better uses dependency tracking.
Also move _REENTRANT and _GNU_SOURCE into configure.h so it
doesn't need to be present in various source files.
This ensures consistent compilation of headers like stdio.h since
it may produce different declaration.
Patch 668c9d0762 introduced regression,
since the code here would actually always return failing result.
Replace it with more simple call to strndup().
For some targets we do not want to generate dependencies.
Also add note about usage of such Makefile - it might be
possibly better to rename it to different filename to avoid
any confusion.
Just for case ensure compiler is not able to optimize
memset() away for resources that are released.
This idea of using memory barrier is taken from openssl.
Other options would be to check for 'explicit_bzero' function.
When preparing ioctl buffer and flatting all parameters,
add table parameters only to ioctl that do process them.
Note: list of ioctl should be kept in sync with kernel code.
DM_DEVICE_CREATE with table is doing several ioctl operations,
however only some of then takes parameters.
Since _create_and_load_v4() reused already existing dm task from
DM_DEVICE_RELOAD it has also kept passing its table parameters
to DM_DEVICE_RESUME ioctl - but this ioctl is supposed to not take
any argument and thus there is no wiping of passed data - and
since kernel returns buffer and shortens dmi->data_size accordingly,
anything past returned data size remained uncleared in zfree()
function.
This has problem if the user used dm_task_secure_data (i.e. cryptsetup),
as in this case binary expact secured data are erased from main memory
after use, but they may have been left in place.
This patch is also closing the possible hole for error path,
which also reuse same dm task structure for DM_DEVICE_REMOVE.
This could be seen as continuation of
6cee8f1b06.
Some test maching with old udev system shows problem,
where udev 'jumps on' leg device after mirror target
releases its legs - since udev does not (in this old case) skips
such device from scanning - it opens device - and this prevent
leg device to be deactivated - effectively such device stays
'leaked' in DM table invisibly to lvm2 command.
So to 'combat' this issue - if the device has '_mimage' in its name,
the retry of deactivation is automatically assumed.
NOTE: wider impact is unexpected - as it's touching only old mirror
target which is nowadays replaced with 'raid'.
In case there will be some problem identified - probably both patches
should be reverted.
With older systems and udevs we don't have control over scanning of lvm2
internal devices - so far we set retry-removal only for top-level LVs,
but in occasional cases udev can be 'fast enough' to open device for
scanning and prevent removal of such device from DM table.
So to combat this case - try to pass 'retry' flag also for removal of
internal device so see how many races can go away with this simple
patch.
Note: patch is applied only to internal version of libdm so the external
API remains working in the old way for now.
If a single, standard LV is specified as the cache, use
it directly instead of converting it into a cache-pool
object with two separate LVs (for data and metadata).
With a single LV as the cache, lvm will use blocks at the
beginning for metadata, and the rest for data. Separate
dm linear devices are set up to point at the metadata and
data areas of the LV. These dm devs are given to the
dm-cache target to use.
The single LV cache cannot be resized without recreating it.
If the --poolmetadata option is used to specify an LV for
metadata, then a cache pool will be created (with separate
LVs for data and metadata.)
Usage:
$ lvcreate -n main -L 128M vg /dev/loop0
$ lvcreate -n fast -L 64M vg /dev/loop1
$ lvs -a vg
LV VG Attr LSize Type Devices
main vg -wi-a----- 128.00m linear /dev/loop0(0)
fast vg -wi-a----- 64.00m linear /dev/loop1(0)
$ lvconvert --type cache --cachepool fast vg/main
$ lvs -a vg
LV VG Attr LSize Origin Pool Type Devices
[fast] vg Cwi---C--- 64.00m linear /dev/loop1(0)
main vg Cwi---C--- 128.00m [main_corig] [fast] cache main_corig(0)
[main_corig] vg owi---C--- 128.00m linear /dev/loop0(0)
$ lvchange -ay vg/main
$ dmsetup ls
vg-fast_cdata (253:4)
vg-fast_cmeta (253:5)
vg-main_corig (253:6)
vg-main (253:24)
vg-fast (253:3)
$ dmsetup table
vg-fast_cdata: 0 98304 linear 253:3 32768
vg-fast_cmeta: 0 32768 linear 253:3 0
vg-main_corig: 0 262144 linear 7:0 2048
vg-main: 0 262144 cache 253:5 253:4 253:6 128 2 metadata2 writethrough mq 0
vg-fast: 0 131072 linear 7:1 2048
$ lvchange -an vg/min
$ lvconvert --splitcache vg/main
$ lvs -a vg
LV VG Attr LSize Type Devices
fast vg -wi------- 64.00m linear /dev/loop1(0)
main vg -wi------- 128.00m linear /dev/loop0(0)
Checks whether VDO support is enabled.
Detects presence of 'vdoformat' tool which is required for to format VDO pool.
ATM build of VDO is NOT automatically enabled (None is default).
To enable build of LVM with VDO support use:
configure --with-vdo=internal
TODO: Maybe future version may switch to link some small VDO library for formating
(would require linking and package dependency).
When node loading fails, there is not much the caller can do,
since there is 'unknown' set of devices preloaded.
Only suspend during preload knows future precommitted 'metadata',
so it's non-trivial to drop 'preloaded' entries with any later call.
However dm tree tracks newly loaded entries - so in this case it
may simplify the recovery path by dropping preloaded entries so
they are not leaked in the DM table.
For better code reuse split _node_send_messages into commont
messaging part and separate _thin_pool_node_send_messages.
Patch makes it possible to better reuse common code for messaging
other targets.
The device-mapper directory now holds a copy of libdm source. At
the moment this code is identical to libdm. Over time code will
migrate out to appropriate places (see doc/refactoring.txt).
The libdm directory still exists, and contains the source for the
libdevmapper shared library, which we will continue to ship (though
not neccessarily update).
All code using libdm should now use the version in device-mapper.
