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When creating VDO pool based of % values, lvm2 is now more clever
and avoids to create 'unsupportable' sizes of physical backend
volumes as 16TiB is maximum size supported by VDO target
(and also limited by maximum supportable slabs (8192) based on slab
size.
If the requested virtual size is approaching max supported size 4PiB,
switch header size to 0.
Newer VDO kernel target require to have matching virtual size - this
however cause incompatiblity when lvcreate is let to format VDO data
device and read the usable size from vdoformat.
Altough this is a kernel regression and will likely get fixed,
lvm2 can actually reformat VDO device to use properly aligned VDO LV
size to make this problem disappear.
Add function to check for avaialble memory for particular VDO
configuration - to avoid unnecessary machine swapping for configs
that will not fit into memory (possibly in locked section).
Formula tries to estimate RAM size machine can use also with
swapping for kernel target - but still leaving some amount of
usable RAM.
Estimation is based on documented RAM usage of VDO target.
If the /proc/meminfo would be theoretically unavailable, try to use
'sysinfo()' function, however this is giving only free RAM without
the knowledge about how much RAM could be eventually swapped.
TODO: move _get_memory_info() into generic lvm2 API function used
by other targets with non-trivial memory requirements.
When thin-pool had queued some delete message on extension operation
such message has been 'lost' and thin-pool kernel metadata has been
left with a thin volume that no longer existed for lvm2 metadata.
dev_name(dev) returns "[unknown]" if there are no names
on dev->aliases. It's meant mainly for log messages.
Many places assume a valid path name is returned, and
use it directly. A caller that wants to use the path
from dev_name() must first check if the dev has any
paths with dm_list_empty(&dev->aliases).
When compiled and used with:
CFLAGS="-fsanitize=address -g -O0"
ASAN_OPTIONS=strict_string_checks=1:detect_stack_use_after_return=1:check_initialization_order=1:strict_init_order=1
we have few reported issue - they where not normally spotted, since
we were still accessing our own memory - but ouf of buffer-range.
TODO: there is still something to enhance with handling of #orphan vgids
After a vg_write, this function was used to attempt to
make lvmcache data match the new state written to disk.
It was not updated correctly in a many or most cases,
and the resulting lvmcache is not actually used after
vg_write, making the update unnecessary.
pvscan --cache <dev>
. read only dev
. create online file for dev
pvscan --listvg <dev>
. read only dev
. list VG using dev
pvscan --listlvs <dev>
. read only dev
. list VG using dev
. list LVs using dev
pvscan --cache --listvg [--checkcomplete] <dev>
. read only dev
. create online file for dev
. list VG using dev
. [check online files and report if VG is complete]
pvscan --cache --listlvs [--checkcomplete] <dev>
. read only dev
. create online file for dev
. list VG using dev
. list LVs using dev
. [check online files and report if VG is complete]
. [check online files and report if LVs are complete]
[--vgonline]
can be used with --checkcomplete, to enable use of a vg online
file. This results in only the first pvscan command to see
the complete VG to report 'VG complete', and others will report
'VG finished'. This allows the caller to easily run a single
activation of the VG.
[--udevoutput]
can be used with --cache --listvg --checkcomplete, to enable
an output mode that prints LVM_VG_NAME_COMPLETE='vgname' that
a udev rule can import, and prevents other output from the
command (other output causes udev to ignore the command.)
The list of complete LVs is meant to be passed to lvchange -aay,
or the complete VG used with vgchange -aay.
When --checkcomplete is used, lvm assumes that that the output
will be used to trigger event-based autoactivation, so the pvscan
does nothing if event_activation=0 and --checkcomplete is used.
Example of listlvs
------------------
$ lvs -a vg -olvname,devices
LV Devices
lv_a /dev/loop0(0)
lv_ab /dev/loop0(1),/dev/loop1(1)
lv_abc /dev/loop0(3),/dev/loop1(3),/dev/loop2(1)
lv_b /dev/loop1(0)
lv_c /dev/loop2(0)
$ pvscan --cache --listlvs --checkcomplete /dev/loop0
pvscan[35680] PV /dev/loop0 online, VG vg incomplete (need 2).
VG vg incomplete
LV vg/lv_a complete
LV vg/lv_ab incomplete
LV vg/lv_abc incomplete
$ pvscan --cache --listlvs --checkcomplete /dev/loop1
pvscan[35681] PV /dev/loop1 online, VG vg incomplete (need 1).
VG vg incomplete
LV vg/lv_b complete
LV vg/lv_ab complete
LV vg/lv_abc incomplete
$ pvscan --cache --listlvs --checkcomplete /dev/loop2
pvscan[35682] PV /dev/loop2 online, VG vg is complete.
VG vg complete
LV vg/lv_c complete
LV vg/lv_abc complete
Example of listvg
-----------------
$ pvscan --cache --listvg --checkcomplete /dev/loop0
pvscan[35684] PV /dev/loop0 online, VG vg incomplete (need 2).
VG vg incomplete
$ pvscan --cache --listvg --checkcomplete /dev/loop1
pvscan[35685] PV /dev/loop1 online, VG vg incomplete (need 1).
VG vg incomplete
$ pvscan --cache --listvg --checkcomplete /dev/loop2
pvscan[35686] PV /dev/loop2 online, VG vg is complete.
VG vg complete
Consider missing config tree from vg read to be an internal error
since we do not want to 'regenerate' this one in expesive parsing way.
Also if there is any failure on recreating committed VG, make it also
a 'vg_write' error.
Corrupt metadata text (with good mda header) was being handled
in the label_scan phase, but not in the vg_read phase. This
was sufficient because metadata areas would always be read and
checksummed during label_scan (metadata parsing was skipped
previously as an optimization.)
This changed with the optimization in
commit 61a6f9905e
"metadata: optimize reading metadata copies in scan"
Now, some metadata areas will not be read and checksummed
at all during the label_scan phase, only during the vg_read
phase. This means that bad metadata text may first be detected
in the vg_read phase. So, add equivalent bad metadata handling
to the vg_read path to match the label_scan path.
When creating lvm2 metadata for VG, lvm2 allocate some buffer,
and if buffer is not big enough, the buffer is 'reallocated' bigger,
and whole metadata creation is repeated until metadata fits.
We can try to use 'previous' metadata size as hint to reduce looping
here.
When cache creation fails on table reload path, implemen more
advanced revert solution, that tries to restore state of LVM
metadata into is look before actual caching started.
New versions of kvdo module exposes statistics at new location:
/sys/block/dm-XXX/vdo/statistics/...
Enhance lvm2 to access this location first.
Also if the statistic info is missing - make it 'debug' level info,
so it is not failing 'lvs' command.
Since VDO is always returns 'zero' on unprovisioned read
and every provisioned block is always 'zeroed' on partial writes,
we can avoid 'zeroing' of such LVs.
pvid and vgid are sometimes a null-terminated string, and
other times a 'struct id', and the two types were often
cast between each other. When a struct id was cast to a char
pointer, the resulting string would not necessarily be null
terminated. Casting a null-terminated string id to a
struct id is fine, but is still avoided when possible.
A struct id is: int8_t uuid[ID_LEN]
A string id is: char pvid[ID_LEN + 1]
A convention is introduced to help distinguish them:
- variables and struct fields named "pvid" or "vgid"
should be null-terminated strings.
- variables and struct fields named "pv_id" or "vg_id"
should be struct id's.
- examples:
char pvid[ID_LEN + 1];
char vgid[ID_LEN + 1];
struct id pv_id;
struct id vg_id;
Function names also attempt to follow this convention.
Avoid casting between the two types as much as possible,
with limited exceptions when known to be safe and clearly
commented.
Avoid using variations of strcpy and strcmp, and instead
use memcpy/memcmp with ID_LEN (with similar limited
exceptions possible.)
When splitting VG with thin/cache pool volume, handle pmspare during
such split and allocate new pmspare in new VG or extend existing pmspare
there and eventually drop pmspare in original VG if is no longer needed
there.
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.
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.
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.
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.
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.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
