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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.
A cache LV - from LVM's perpective - is a user accessible device that
links the cachepool LV and the origin LV. The following functions
were added to facilitate the creation and removal of this top-level
LV:
1) 'lv_cache_create' - takes a cachepool and an origin device and links
them into a new top-level LV of 'cache' segment type. No allocation
is necessary in this function, as the sub-LVs contain all of the
necessary allocated space. Only the top-level layer needs to be
created.
2) 'lv_cache_remove' - this function removes the top-level LV of a
cache LV - promoting the cachepool and origin sub-LVs to top-level
devices and leaving them exposed to the user. That is, the
cachepool is unlinked and free to be used with another origin to
form a new cache LV; and the origin is no longer cached.
(Currently, if the cache needs to be flushed, it is done in this
function and the function waits for it to complete before proceeding.
This will be taken out in a future patch in favor of polling.)
Building on the new DM function that parses DM cache status, we
introduce the following LVM level functions to aquire information
about cache devices:
- lv_cache_block_info: retrieves information on the cache's block/chunk usage
- lv_cache_policy_info: retrieves information on the cache's policy
Avoid use of external origin with size unaligned/incompatible with
thin pool chunk size, since the last chunk is not correctly provisioned
when it is overwritten.
This patch adds the new cachepool segment type - the first of two
necessary to eventually create 'cache' logical volumes. In addition
to the new segment type, updates to makefiles, configure files, the
lv_segment struct, and some necessary libdevmapper flags.
The cachepool is the LV and corresponding segment type that will hold
all information pertinent to the cache itself - it's size, cachemode,
cache policy, core arguments (like migration_threshold), etc.
In preparation for other segment types that create and use "pools", we
s/create_thin_pool/create_pool/. This way it is not awkward when creating
a cachepool, for example, to use "create_thin_pool".
Introduce FMT_OBSOLETE to identify pool metadata and use it and FMT_MDAS
instead of hard-coded format names.
Explain device accesses on pvscan --cache man page.
Replacement of pv_read by find_pv_by_name in commit
651d5093ed caused spurious
error messages when running pvcreate or vgextend against an
unformatted device.
Physical volume /dev/loop4 not found
Physical volume "/dev/loop4" successfully created
Physical volume /dev/loop4 not found
Physical volume /dev/loop4 not found
Physical volume "/dev/loop4" successfully created
Volume group "vg1" successfully extended
Optimize and cleanup recently introduced new function wipe_lv.
Use compound literals to get nicely initialized wipe_params struct.
Pass in lv as explicit argument for wipe_lv.
Use cmd from lv structure.
Initialize only non-null members so it's easy to see what
is the special arg.
Drop find_merging_snapshot() function. Use find_snapshot()
called after check for lv_is_merging_origin() which
is the commonly used code path - so we avoid duplicated
tests and potential risk of derefering NULL point
in unhandled error path.
Use common wipe_lv (former set_lv) fn to do zeroing as well as signature
wiping if needed. Provide new struct wipe_lv_params to define the
functionality.
Bind "lvcreate -W/--wipesignatures y" with proper wipe_lv call.
Also, add "yes" and "force" to lvcreate_params so it's possible
to apply them for the prompt: "WARNING: %s detected on %s. Wipe it? [y/n]".
Revert 4777eb6872 which put
target_present check into init_snapshot_merge(). However
this function is also used when parsing metadata. So we would
get this present test performed even when target is not really
needed. So move this target_present test directly into lvconvert.
Replace the code with the refactored vgreduce_single instead
of calling its own implementation.
Corrects bug: https://bugzilla.redhat.com/show_bug.cgi?id=989174
Signed-off-by: Tony Asleson <tasleson@redhat.com>
Moving the core functionality of vgreduce single into
lib/metadata/vg.c so that the command line and lvm2app library
can call the same core functionality. New function is
vgreduce_single.
Signed-off-by: Tony Asleson <tasleson@redhat.com>
Add LV_TEMPORARY flag for LVs with limited existence during command
execution. Such LVs are temporary in way that they need to be activated,
some action done and then removed immediately. Such LVs are just like
any normal LV - the only difference is that they are removed during
LVM command execution. This is also the case for LVs representing
future pool metadata spare LVs which we need to initialize by using
the usual LV before they are declared as pool metadata spare.
We can optimize some other parts like udev to do a better job if
it knows that the LV is temporary and any processing on it is just
useless.
This flag is orthogonal to LV_NOSCAN flag introduced recently
as LV_NOSCAN flag is primarily used to mark an LV for the scanning
to be avoided before the zeroing of the device happens. The LV_TEMPORARY
flag makes a difference between a full-fledged LV visible in the system
and the LV just used as a temporary overlay for some action that needs to
be done on underlying PVs.
For example: lvcreate --thinpool POOL --zero n -L 1G vg
- first, the usual LV is created to do a clean up for pool metadata
spare. The LV is activated, zeroed, deactivated.
- between "activated" and "zeroed" stage, the LV_NOSCAN flag is used
to avoid any scanning in udev
- betwen "zeroed" and "deactivated" stage, we need to avoid the WATCH
udev rule, but since the LV is just a usual LV, we can't make a
difference. The LV_TEMPORARY internal LV flag helps here. If we
create the LV with this flag, the DM_UDEV_DISABLE_DISK_RULES
and DM_UDEV_DISABLE_OTHER_RULES flag are set (just like as it is
with "invisible" and non-top-level LVs) - udev is directed to
skip WATCH rule use.
- if the LV_TEMPORARY flag was not used, there would normally be
a WATCH event generated once the LV is closed after "zeroed"
stage. This will make problems with immediated deactivation that
follows.
A common scenario is during new LV creation when we need to wipe the
newly created LV and avoid any udev scanning before this stage otherwise
it could cause the device (the LV) to be claimed by some other subsystem
for which there were stale metadata within LV data.
This patch adds possibility to mark the LV we're just about to wipe with
a flag that gets passed to udev via DM_COOKIE as a subsystem specific
flag - DM_SUBSYSTEM_UDEV_FLAG0 (in this case the subsystem is "LVM")
so LVM udev rules will take care of handling that.
When the pool is created from non-linear target the more complex rules
have to be used and stacking needs to properly decode args for _tdata
LV. Also proper allocation policies are being used according to those
set in lvm2 metadata for data and metadata LVs.
Also properly check for active pool and extra code to active it
temporarily.
With this fix it's now possible to use:
lvcreate -L20 -m2 -n pool vg --alloc anywhere
lvcreate -L10 -m2 -n poolm vg --alloc anywhere
lvconvert --thinpool vg/pool --poolmetadata vg/poolm
lvresize -L+10 vg/pool
The function 'get_pv_list_for_lv' will assemble all the PVs that are
used by the specified LV. It uses 'for_each_sub_lv' to traverse all
of the sub-lvs which may compose it.
When creating a new thin pool and there's no profile requested
via "lvcreate --profile ...", inherit any VG profile if it's attached.
Currently this applies to these settings:
allocation/thin_pool_chunk_size
allocation/thin_pool_discards
allocation/thin_pool_zero
Add --poolmetadataspare option and creates and handles
pool metadata spare lv when thin pool is created.
With default setting 'y' it tries to ensure, spare has
at least the size of created LV.
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-
Start separating the validation from the action in the basic lvresize
code moved to the library.
Remove incorrect use of command line error codes from lvresize library
functions. Move errors.h to tools directory to reinforce this,
exporting public versions of the error codes in lvm2cmd.h for dmeventd
plugins to use.
The pv resize code required that a lvm_vg_write be done
to commit the change. When the method to add the ability
to list all PVs, including ones that are not assocated with
a VG we had no way for the user to make the change persistent.
Thus additional resize code was move and now liblvm calls into
a resize function that does indeed write the changes out, thus
not requiring the user to explicitly write out he changes.
Signed-off-by: Tony Asleson <tasleson@redhat.com>
As locks are held, you need to call the included function
to release the memory and locks when done transversing the
list of physical volumes.
V2: Rebase fix
V3: Prevent VGs from getting cached and then write protected.
Signed-off-by: Tony Asleson <tasleson@redhat.com>
Simplified version of lv resize.
v3: Rebase changes to make work. Needed to set sizeargs = 1
to indicate to resize that we are asking for a size based
resize.
Signed-off-by: Tony Asleson <tasleson@redhat.com>
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.
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.
This patch adds the ability to set the minimum and maximum I/O rate for
sync operations in RAID LVs. The options are available for 'lvcreate' and
'lvchange' and are as follows:
--minrecoveryrate <Rate> [bBsSkKmMgG]
--maxrecoveryrate <Rate> [bBsSkKmMgG]
The rate is specified in size/sec/device. If a suffix is not given,
kiB/sec/device is assumed. Setting the rate to 0 removes the preference.
'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--
The pv_by_path might be also dangerous to use as it does not
count with any other metadata areas but the ones found on the PV
itself. If metadata was not found on the PV referenced by the path,
it returned no PV though it might have been referenced by metadata
elsewhere (on other PVs...).
Before, the find_pv_by_name call always failed if the PV found was orphan.
However, we might use this function even for a PV that is not part of any VG.
This patch adds 'allow_orphan' arg to find_pv_by_name fn that allows that.
Keep the flag whether given thin pool argument has been given on command
line or it's been 'estimated'
Call of update_pool_params() must not change cmdline given args and
needs to know this info.
Since there is a need to move this update function into /lib, we cannot
use arg_count().
FIXME: we need some generic mechanism here.
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).
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).
Extract restorable PV creation parameters from struct pvcreate_params into
a separate struct pvcreate_restorable_params for clarity and also for better
maintainability when adding any new items later.
Currently it is impossible to remove a failed PV which has a RAID LV
on it. This patch fixes the issue by replacing the failed PV with an
'error' segment within the affected sub-LVs. Once there is no longer
a RAID LV using the PV, it can be removed.
Most often, it is better to replace a failed RAID device with a spare.
(You can use 'lvconvert --repair <vg>/<LV>' to accomplish that.)
However, if there are no spares in the volume group and none will be
added, it is useful to be able to removed the failed device.
Following patches address the ability to perform 'lvconvert' operations
on RAID LVs that contain sub-LVs composed of 'error' segments.
We have been using 'mirror_region_size' in lvm.conf as the default region
size for RAID logical volumes as well as mirror logical volumes. Since,
"raid" is more inclusive and representative than "mirror", I have changed
the name of this setting. We must still check for the old setting and warn
the user if we are overriding it with the new setting if both happen to be
present.
Target tells us its version, and we may allow different set of options
to be supported with different version of driver.
Idea is to provide individual feature flags and later be
able to query for them.
The 'copy_percent' function takes the 'extents_copied' field from each
segment in an LV to create the numerator for the ratio that is to
become the copy_percent. (Otherwise known as the 'sync' percent for
non-pvmove uses, like mirror LVs and RAID LVs.) This function safely
works on RAID - not just mirrors - so it is better to have it in
lv_manip.c rather than mirror.c.
There's a lot of different functions that do a lot of different things
in lv_manip.c, so I placed the function near a function in lv_manip.c
that it was close to in metadata-exported.h. Different placement in the
file or a different name for the function may be useful.
Add arg support for discard.
Add discard ignore, nopassdown, passdown (=default) support.
Flags could be set per pool.
lvcreate [--discard {ignore|no_passdown|passdown}] vg/thinlv
Define an 'activation_handler' that gets called automatically on
PV appearance/disappearance while processing the lvmetad_pv_found
and lvmetad_pv_gone functions that are supposed to update the
lvmetad state based on PV availability state. For now, the actual
support is for PV appearance only, leaving room for PV disappearance
support as well (which is a more complex problem to solve as this
needs to count with possible device stack).
Add a new activation change mode - CHANGE_AAY exposed as
'--activate ay/-aay' argument ('activate automatically').
Factor out the vgchange activation functionality for use in other
tools (like pvscan...).
We're refererring to 'activation' all over the code and we're talking
about 'LVs being activated' all the time so let's use 'activation/activate'
everywhere for clarity and consistency (still providing the old
'available' keyword as a synonym for backward compatibility with
existing environments).
Read lvm.conf setting for monitoring for each command. So we should not
activate monitoring if the default compilation is set to monitor during
lvconvert commnads.
Patch also removes check for clustered VG and allows to disable monitoring
for clustered VG with the assumption, the problem with monitoring and dmeventd
flag passing for INGNORE is already fixed.
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
To ensure we properly handle LV cluster locking - explicitely do
not allow to change the availability of the thin pool that is in use
for some thin LV.
As soon as the thin volume is created the only way to activate pool
is via implicit dependency.
Ignore thinpool open count for lv/vgchange operations.
lvm part of messaging.
Each message is now stored it's own thin pool section:
message1 {
create = lv
}
Messages are queued to thin pool dm target when this target
is going to be resumed or used through some dependency.
Currently 'delete' message are purely queued and processed
with next thin pool resume operation (i.e. create_thin).
WARNING - thin provisioning support is developmental code.
Example:
~> lvconvert --type raid1 vg/mirror_lv
Steps to convert "mirror" to "raid1"
1) Allocate a RAID metadata LV for each mirror image from the same PVs
on which they are located.
2) Clear the metadata LVs. This involves writing LVM metadata, so we don't
change any aspects of the mirror LV before this so that the user can easily
remove LVs from the failed convert attempt while retaining the original
mirror.
3) Remove the mirror log, if it exists.
4) Add metadata LVs to mirror LV
5) Rename mirror sub-lvs (s/mimage/rimage/)
6) Change flags and segtype from mirror to raid1
Revert John patch, which fixed only 1 place where ~LVM_WRITE was in use and
convert ommited LVM_READ/WRITE flags to 64bit constants as well.
(Since both 'status' flags for LV and VG are 64bit.)
~> lvconvert --splitmirrors 1 --trackchanges vg/lv
The '--trackchanges' option allows a user the ability to use an image of
a RAID1 array for the purposes of temporary read-only access. The image
can be merged back into the array at a later time and only the blocks that
have changed in the array since the split will be resync'ed. This
operation can be thought of as a partial split. The image is never completely
extracted from the array, in that the array reserves the position the device
occupied and tracks the differences between the array and the split image via
a bitmap. The image itself is rendered read-only and the name (<LV>_rimage_*)
cannot be changed. The user can complete the split (permanently splitting the
image from the array) by re-issuing the 'lvconvert' command without the
'--trackchanges' argument and specifying the '--name' argument.
~> lvconvert --splitmirrors 1 --name my_split vg/lv
Merging the tracked image back into the array is done with the '--merge'
option (included in a follow-on patch).
~> lvconvert --merge vg/lv_rimage_<n>
The internal mechanics of this are relatively simple. The 'raid' device-
mapper target allows for the specification of an empty slot in an array
via '- -'. This is what will be used if a partial activation of an array
is ever required. (It would also be possible to use 'error' targets in
place of the '- -'.) If a RAID image is found to be both read-only and
visible, then it is considered separate from the array and '- -' is used
to hold it's position in the array. So, all that needs to be done to
temporarily split an image from the array /and/ cause the kernel target's
bitmap to track (aka "mark") changes made is to make the specified image
visible and read-only. To merge the device back into the array, the image
needs to be returned to the read/write state of the top-level LV and made
invisible.
Users already have the ability to split an image from an LV of "mirror"
segtype. This patch extends that ability to LVs of "raid1" segtype.
This patch only allows a single image to be split off, however. (The
"mirror" segtype allows an arbitrary number of images to be split off.
e.g. 4-way => 3-way/linear, 2-way/2-way, linear,3-way)
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
are affected by the move. (Currently it's possible for I/O to become
trapped between suspended devices amongst other problems.
The current fix was selected so as to minimise the testing surface. I
hope eventually to replace it with a cleaner one that extends the
deptree code.
Some lvconvert scenarios still suffer from related problems.
allows us to allocate all images of a mirror (or RAID array) at one
time during create.
The current mirror implementation still requires a separate allocation
for the log, however.
Since format instances will use own memory pool, it's necessary to properly
deallocate it. For now, only fid is deallocated. The PV structure itself
still uses cmd mempool mostly, but anytime we'd like to add a mempool
in the struct physical_volume, we can just rename this fn to free_pv and
add the code (like we have free_vg fn for VGs).
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.
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).
Fixing some const warnings - with API change in:
int vg_extend(struct volume_group *vg, int pv_count, const char *const *pv_names,
Change is needed - as lvm2api expects const behaviour here.
So vg_extend() is doing local strdup for unescaping.
skip_dev_dir return const char* from const char* vg_name.
Rest of the patch is cleanup of related warnings.
Also using dm_report_filed_string() API change to simplify
casting in _string_disp and _lvname_disp.
Add configurable option to define minimal size of
of block device usable as a PV.
pv_min_size() is added to lvm-globals and it's being
initialized through _process_config.
Macro PV_MIN_SIZE is unused and removed.
New define DEFAULT_PV_MIN_SIZE_KB is added to lvm-global
and unlike PV_MIN_SIZE it uses KB units.
Should help users with various slow devices attached to the system,
which cannot be easily filtered out (like FDD on /dev/sdX):
https://bugzilla.redhat.com/show_bug.cgi?id=644578
This patch is similar to the other patches for pv and vg
functionality, and separates lv functionality into separate
files, concentrating on reporting fields and simple functions.
The metadata.[ch] files are very large. This patch makes a first
attempt at separating out pv functions and data, particularly
related to the reporting fields calculations.
More code could be moved here but for now I'm stopping at reporting
functions 'get' / 'set' functions.
The metadata.[ch] files are very large. This patch makes a first
attempt at separating out vg functions and data, particularly
related to the reporting fields calculations.
Pass metadataignore through PV creation / setup paths.
As a result of this cleanup, we can remove the unnecessary setting
of mda_ignore bits inside pvcreate_single(), after call to pv_create.
For now, just set metadataignore to '0' in some places. This is
equivalent to the prior functionality, although the 0 is given
by the caller not hardcoded in _mda_setup() call.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Allow metadataignore flag to be passed in to pvcreate.
Ideally, more refactoring of the mda allocation / initialization
is warranted, but for now, we just add another parameter to 'add_mda'
to take an existing mda ignored flag. We need to do this or pv_write
loses the state of the mda 'ignored' flag before copying and writing
to disk.
In preparation to call this from both pvcreate as well as pvchange,
move the guts of metadataignore into a library function.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Allowing an 'all' and 'unmanaged' value is more intuitive, and
provides a simple way for users to get back to original LVM behavior
of metadata written to all PVs in the volume group.
If the user requests "--vgmetadatacopies unmanaged", this instructs
LVM not to manage the ignore bits to achieve a specific number of
metadata copies in the volume group. The user is free to use
"pvchange --metadataignore" to control the mdas on a per-PV basis.
If the user requests "--vgmetadatacopies all", this instructs LVM
to do 2 things: 1) clear all ignore bits, and 2) set the "unmanaged"
policy going forward.
Internally, we use the special MAX_UINT32 value to indicate 'all'.
This 'just' works since it's the largest value possible for the
field and so all 'ignore' bits on all mdas in the VG will get
cleared inside _vg_metadata_balance(). However, after we've
called the _vg_metadata_balance function, we check for the special
'all' value, and if set, we write the "unmanaged" value into the
metadata. As such, the 'all' value is never written to disk.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
This patch adds the get and partially implemented set function.
The 'set' function should probably ignore or un-ignore metadata areas
based on new values.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Add a field to struct volume_group to later implement metadata
balancing:
- mda_copies: target # of non-ignored mdas in the VG; default 0 (do
not control pv 'ignore mdas' bit.
This patch just adds the parameter to the structures with the default
values but does not modify any commands. Should be no functional change.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Define a new pvs field, pv_mda_used_count, and a new vgs field,
vg_mda_used_count to match the existing pv_mda_count and vg_mda_count.
These new fields count the number of mdas that have the 'ignored' bit
clear (they are in use on the PV / VG). Also define various supporting
functions to implement the counting as well as setting the ignored
flag and determining if an mda is ignored. These high level functions
call into the lower level location independent mda ignore functions
defined by earlier patches.
Note that counting ignored mdas in a vg requires traversing both lists
and checking for the ignored bit on the mda. The count of 'ignored'
mdas then is defined by having the bit set, not by which list the mda
is on. The list does determine whether LVM actually does read/write to
the mda, though we must count the bits in order to return accurate numbers
for the various counts. Also, pv_mda_set_ignored must search both vg
lists for ignored mda. If the state changes and needs to be committed
to disk, the ignored mda will be on the non-ignored list.
Note also in pv_mda_set_ignored(), we must properly manage the mda lists.
If we change the ignored state of an mda, we must change any mdas on
vg->fid->metadata_areas that correspond to this pv. Also, we may
need to allocate a copy of the mda, as is done when fid->metadata_areas
is populated from _vg_read(), if we are un-ignoring an ignored mda.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Add a second mda list, metadata_areas_ignored to fid, and a couple
functions, fid_add_mda() and fid_add_mdas() to help manage the lists.
These functions are needed to properly count the ignored mdas and
manage the lists attached to the 'fid' and ultimately the 'vg'.
Ensure metadata_areas_ignored is initialized in other formats, even
if the list is never used.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Introduce struct cmd_vg to store information about needed
volume group name, vgid, flags and the pointer to opened VG.
Keep VGs list in alphabetical order for locking order.
Introduce functions:
cmd_vg_add() add new cmd_vg entry.
cmd_vg_lookup() search cmd_vgs for vg_name.
cmd_vg_read() open VGs in cmd_vgs list.
cmd_vg_release() close VGs in reversed order.
Add pointer to linked list of opened VGs. List temporarily keeps
the information about needed or locked and opened VGs for replicator target.
Also add cmd_missing_vgs flag information for quick check and
also for possible continuos process_each_lv() usage where we need
to detect whether failure has been caused by missing VG or
some other reason.
Adding configure.in support for Replicators.
Adding basic lib lvm support for Replicators.
Adding flags REPLICATOR and REPLICATOR_LOG.
Adding segments SEG_REPLICATOR and SEG_REPLICATOR_DEV.
Adding basic methods for handling replicator metadata.
Some commands start with a pvname, but we'd like to force users to
start with a vg handle to obtain a pv handle. Our best option seems
to be providing a way to look up the vgname from the pvname, and then
require them to use vg_read/vg_open.
In addition to the pvname lookup function, this patch also provides a
lookup by pvid. The lookup by pvid can be used in conjunction with
lvmcache_get_pvids to process all pvs in the system.
The pvid find function first calls lvmcache_vgname_from_pvid, which may
cause the label to be read if it is not in the cache. If the vgname is
returned is an orphan, we then check to see if there are metadata areas,
and if not, we scan every PV on the system by calling scan_vgs_for_pvs().
In most cases we should not need to do this, and by using the info->mdas
count, we avoid calling pv_read() as prior code did. So this patch is a
bit cleaner and should allow us to refactor more of the pv code.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
are active mirrors or snapshots.
We don't have the mechanisms in place to change the device-mapper
tables for those targets that have behavioral differences between
cluster and single machine instances. Allowing users to change
the attribute but not changing the target's behavior can lead to
data corruption.
The following bugs are fixed/avoided by this patch:
235123 - vgchange -c [ny] do not change target types when necessary
289331 - RFE: switching from cluster domain to local domain needs to deactivate volume somehow
289541 - when changing from local to cluster, volumes can not appear to be deactivated
Allow lv_remove_with_dependencies() to know the top-level LV that was
requested to be removed (otherwise it recurses and we lose context).
A merging snapshot cannot be removed directly but the associated origin
can be. Disallow removal of a merging snapshot unless the associated
origin is also being removed.
We should write metadata into next position in the ring buffer while calling
vgrename and vgcfgrestore. At this code level (_vg_write_raw), we were not able
to determine if this is a rename or not. If yes, then accompanying VG structure
passed here has a new name set, not the old one.
When looking for a location where to put metadata next, we were given a NULL
value because of failed VG name comparison (in _find_vg_rlocn) between the
name in existing metadata and metadata we're just about to write.
This resets the position in the ring buffer, overwriting any existing metadata
(and also incorrectly updates the cache to "orphan" afterwards).
This patch just adds old_name item in struct volume_group that we can check and use
if necessary and detect renames at lower layers as well.
The same applies for vgcfgrestore, but here we're using a special value of
old_name, an empty string, to disable the check with existing metadata totally.
lvm2app needs a link back to the vg in order to use the vg handle for
memory allocations as well as other things. This patch adds the field
to struct physical_volume, and sets pv->vg when reading a vg from disk or
extending a vg by using the helper function previously added,
add_pvl_to_vgs(). Moves and renames are handled with separate code
inside move_pv() and vgmerge(). Add pv->vg check to vg_validate().
A NULL value in pv->vg signifies membership in the orphan VG.
Note though in the case of pv_read() on a device with metadatacopies == 0,
more devices may need to be read for an authoritative answer.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Add a delete function to manage the vg->pvs list.
NOTE: It may be possible to do further cleanup to these add/del functions
by passing a 'pv' as input instead of 'pv_list'. The pv_list is used for
functions which do allocations (lvcreate) while other places in the code
just manage a list of 'pv' (e.g. import functions, vgextend, etc).
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
When moving parts of striped LVs, pvmove wouldn't care about leaving you with
two stripes on the same disk. Now --alloc anywhere is needed for that.
(Tried and gave up on two alternative approaches before the one committed here.)
. Add "monitoring" option to "activation" section of lvm.conf
. Have clvmd consult the lvm.conf "activation/monitoring" too.
. Introduce toollib.c:get_activation_monitoring_mode().
. Error out when both --monitor and --ignoremonitoring are provided.
. Add --monitor and --ignoremonitoring support to lvcreate. Update
lvcreate man page accordingly.
. Clarify that '--monitor' controls the start and stop of monitoring in
the {vg,lv}change man pages.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Similar refactoring to vgchange - pull out common parts and put into
library function for reuse. Should be no functional change.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Pull out common code to be called from tools as well as lvm2app.
Leave archive() at tool level so we can use from vgcreate
as well as vgchange. Should be no functional change.
- add stack macro in vgchange
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Internally we store sizes in sectors, but lvm2app exports sizes
in bytes. We could get fancier and allow units configuration but
this fix should do for now.
Fixes rhbz561422.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
where we should not expose internal VG names/uuids (the ones with "#" prefix )through the
interface. Otherwise, we could end up with library users opening internal VGs which will
initiate locking mechanism that won't be cleaned up properly.
"#orphans_{lvm1, lvm2, pool}" names are treated in a special way, they are truncated first
to "orphans" and this is used as a part of the lock name then (e.g. while calling lvm_vg_open()).
When library user calls lvm_vg_close(), the original name "orphans_{lvm1, lvm2, pool}"
is used directly and therefore no unlock occurs.
We should exclude internal VG names and uuids in the lists provided by lvmcache:
lvmcache_get_vgids() and lvmcache_get_vgnames().
Eliminate 'merging_snapshot' from 'struct logical_volume' and just use
'snapshot' for origin lv's reference to the merging snapshot; also set
MERGING in the origin lv's status.
Make 'merging_snapshot' pointer that points from the origin to the
segment that represents the merging snapshot.
Import/export 'merging_store' metadata.
Do not allow creating snapshots while another snapshot is merging.
Snapshot created in this state would certainly contain invalid data.
NOTE: patches at the end of this series will remove 'merging_snapshot'
and will introduce helpful wrappers and cleanups.
The physical_volume, volume_group, logical_volume and lv_segment
structures' 'status' member is now uint64_t.
The alignment of these structures was also audited to remove holes. The
movement of some members in 'volume_group' and 'lv_segment' eliminates
holes. The 'physical_volume' structure still has one 4-byte hole after
'pe_size'; the other structures no longer have any holes. Each
structures' size has not changed.
Rename fill_default_pvcreate_params to pvcreate_params_set_defaults.
Rename pvcreate_validate_restore_params to pvcreate_restore_params_validate.
Rename pvcreate_validate_params to pvcreate_params_validate.
Similar to other vg_set_* functions, we create a vg_set_clustered() function
which does a few checks and sets a flag. This is where we check for
any limitations of clusters.
We need defaults for pvcreate_params at a higher level - this will
allow us to use a common function from the tools to take defaults,
then fill in any non-defaults from the commandline.
Future patches will refactor vgcreate/vgextend to call this function
if one or more pvcreate parameters are given on the commandline.
Another refactoring for implicit pvcreate support. We need to get
the pvcreate parameters somehow to the vg_extend routine. Options
seemed to be:
1. Attach the parameters to struct volume_group. I personally
did not like this idea in most cases, though one could make an
agrument why it might be ok at least for some of the parameters
(e.g. metadatacopies).
2. Pass them in to the extend routine. This second route seemed
to be the best approach given the constraints.
Future patches will parse the command line and fill in the actual
values for the pvcreate_single call.
Should be no functional change.
Clean up VG_RESIZEABLE flag by creating vg_is_resizeable().
Update comment - we no longer have ALLOW_RESIZEABLE.
Also use vg_is_exported() in one place missed by earlier patch.
Should be no functional change.
Of the vgs field vg_attr, a few of the most likely to be used attributes
are clustered, exported, and partial. This patch adds the following 3
functions:
uint64_t lvm_vg_is_clustered(const vg_t vg)
uint64_t lvm_vg_is_exported(const vg_t vg)
uint64_t lvm_vg_is_partial(const vg_t vg)
Split vg_remove_single into vg_remove_check (mandatory checks before
vgremove) and vg_remove (do actual remove by committing to disk).
In liblvm, we'd like to provide an consistent API that allows multiple
changes in memory, then let lvm_vg_write() control the commit to disk. In
some cases (for example, lvresize calls fsadm) this may not be possible.
However, since we are using an object model and dividing things into small
operations, the most logical model seems to be the lvm_vg_write model, and
handling the special cases as they arrive. So as best as possible
we move towards this end.
A possible optimization would be to consolidate vg_remove (committing)
code with vgreduce code. A second possible optimization is making vgreduce
of the last device equivalent to vgremove. Today, lvm_vg_reduce fails if
vgreduce is called with the last device, but from an object model perspective
we could view this as equivalent to vgremove and allow it. My gut feel is
we do not want to do this though.
Author: Dave Wysochanski <dwysocha@redhat.com>
Later patches should consolidate the vgremove / vgreduce functions but for
now let's clarify what vg_remove actually does by changing the name.
Author: Dave Wysochanski <dwysocha@redhat.com>
Adds pe_align_offset to 'struct physical_volume'; is initialized with
set_pe_align_offset(). After pe_start is established pe_align_offset is
added to it.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
For now, a simple way to enforce the read/write semantics is to just save the
open mode of the VG. If the caller uses lvm_vg_create, the mode is write.
The caller using lvm_vg_open can use either read or write to open the VG.
Once we have this, we enforce the permissions on each API call and don't allow
a caller to modify a VG that has not been opened properly.
This may be better combined with the locking mode, but I view that as future
cleanup, past this initial release. The intial release should enforce the
basic object semantics though, as described in the lvm.h file.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Adding the ability to get the seqno is important for an application to
determine if something has changed in a VG. Otherwise, the only way to
know is to open the VG with write permission and hold the handle.
This function behaves a little bit different than vg_reduce_single, because
it allowes to remove even the latest pv. This has been done to be consistent
to lvm_vg_create, which creates an empty vg.
removed_pvs has been added to the volume_group struct. vg_reduce adds remove
pvs to this list to be able to commit the changes for the pvs in lvm_vg_comm
in liblvm2app.
Initialize removed_pvs list in format-specific volume_group constructors.
Ideally, we should have a base constructor here that initializes the general
non-format specific members of struct volume_group. But until then, there
are multiple places to initialize these members. Maybe a better patch would
be a base constructor patch for struct volume_group. That is more work
though.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Thomas Woerner <twoerner@redhat.com>
Author: Dave Wysochanski <dwysocha@redhat.com>
For liblvm 'get' functions, we should share code with the reporting functions.
This means we need common code to return the values for the fields.
In this patch we refactor a few of the fields needed in liblvm.
Unfortunately, for the simple fields that do derefernces of structure
members (for example, vg_extent_count), we cannot call the common function
from the reporting infrastructure without more refactoring. The reason is
that the dereference of the simple fields is done deep inside the reporting
code (to get the generic "data" pointer), and the display function is a
generic 'size32' function. We can fix these issues later with more
refactoring.
Should be no functional change and the testsuite should cover any possible
regressions. The only fields in the report affected by this patch are:
vg_size, vg_free, and pv_mda_count.
Author: Dave Wysochanski <dwysocha@redhat.com>
After some refactorings, we can now move the bulk of _lvcreate into the
internal library, and we can call from liblvm. In the future, we should
refactor lv_create_single further, probably by segtype, to reduce the
size of struct lvcreate_params. For now this is a reasonable refactor
and allows us to re-use the function from liblvm.
Author: Dave Wysochanski <dwysocha@redhat.com>
In preparation for implicit pvcreate during vgcreate / vgextend,
move bulk of pvcreate logic inside library.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Author: Dave Wysochanski <dwysocha@redhat.com>
Define the 5 main liblvm objects to be the pv, vg, lv, lvseg, and pvseg.
We need handles defined to all these objects in order for liblvm to be
equivalent to the reporting commands pvs, vgs, and lvs.
- move vg_t, lv_t, and pv_t from metadata-exported.h into lvm.h
- move lv_segment and pv_segment forward declarations into lvm.h
- add lvseg_t and pvseg_t to lvm.h
NOTE: We currently have an inconsistency in handle definitions.
lvm_t is defined as a pointer, while these other handles are just
structures. We should pick one scheme and be consistent - perhaps
define all handles as pointers (this is what I've seen elsewhere).
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Acked-by: Alasdair G Kergon <agk@redhat.com>
The checks for RESIZEABLE_VG should now be inside the various functions that
have to do such operations.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Acked-by: Alasdair G Kergon <agk@redhat.com>
In the future we may export these functions or something like them in liblvm
For now this helps in cleaning up the checks for RESIZEABLE since we can
use the internal library function vg_bad_status_bits.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Acked-by: Alasdair G Kergon <agk@redhat.com>
Move check for active LVs outside of library function. The vgremove
liblvm function function will fail if there are active LVs. It will
be the application's responsibility to check this condition and remove
the LVs individually before calling vgremove. Note also that we've
duplicated the EXPORTED_VG check in vgremove_single (tools) and
vg_remove_single (library). Duplication seemed the only option here
since we don't want to do the automatic removal of LVs (in the tools)
if the vg is exported, and we still need to protect the library call
from removal if the vg is exported.
We still need to deal with the ORPHAN lock but vg_remove_single is now
very close to our liblvm function.
TODO: Refactor lvremove in a similar way.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
vg_t *vg_create(struct cmd_context *cmd, const char *vg_name);
This is the first step towards the API called to create a VG.
Call vg_lock_newname() inside this function. Use _vg_make_handle()
where possible.
Now we have 2 ways to construct a volume group:
1) vg_read: Used when constructing an existing VG from disks
2) vg_create: Used when constructing a new VG
Both of these interfaces obtain a lock, and return a vg_t *.
The usage of _vg_make_handle() inside vg_create() doesn't fit
perfectly but it's ok for now. Needs some cleanup though and I've
noted "FIXME" in the code.
Add the new vg_create() plus vg 'set' functions for non-default
VG parameters in the following tools:
- vgcreate: Fairly straightforward refactoring. We just moved
vg_lock_newname inside vg_create so we check the return via
vg_read_error.
- vgsplit: The refactoring here is a bit more tricky. Originally
we called vg_lock_newname and depending on the error code, we either
read the existing vg or created the new one. Now vg_create()
calls vg_lock_newname, so we first try to create the VG. If this
fails with FAILED_EXIST, we can then do the vg_read. If the
create succeeds, we check the input parameters and set any new
values on the VG.
TODO in future patches:
1. The VG_ORPHAN lock needs some thought. We may want to treat
this as any other VG, and require the application to obtain a handle
and pass it to other API calls (for example, vg_extend). Or,
we may find that hiding the VG_ORPHAN lock inside other APIs is
the way to go. I thought of placing the VG_ORPHAN lock inside
vg_create() and tying it to the vg handle, but was not certain
this was the right approach.
2. Cleanup error paths. Integrate vg_read_error() with vg_create and
vg_read* error codes and/or the new error APIs.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
NOTE: vg_set_alloc_policy() returns success if you try to set a value that
is already stored. The behavior of vgchange is the same though - it fails.
There is a fixme noted in the code about this inconsistency, which should
be resolved if possible.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
In liblvm, we will reserve the word 'change' to mean an API that
both sets one or more values, and commits to disk. This will be
consistent with the LVM commandline. The existing vg_change_pesize()
function does not commit to disk, but just changes the extent_size
and ensures all internal structures are updated. This logic should
be contained in a function that sets the value.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Remove unneeded LOCK_NONBLOCKING from vg_read() API and tools that
use it. We no longer need this flag anywhere since we now automatically
set LCK_NONBLOCK inside lock_vol() if vgs_locked().
For further details, see:
commit d52b3fd3fe
Author: Dave Wysochanski <dwysocha@redhat.com>
Date: Wed May 13 13:02:52 2009 +0000
Remove NON_BLOCKING lock flag from tools and set a policy to auto-set.
As a simplification to the tools and further liblvm, this patch pushes
the setting of NON_BLOCKING lock flag inside the lock_vol() call.
The policy we set is if any existing VGs are currently locked, we
set the NON_BLOCKING flag.
At some point it may make sense to add this flag back if we get an
RFE from a liblvm user, but for now let's keep it as simple as
possible.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Remove READ_CHECK_EXISTENCE and vg_might_exist().
This flag and API is no longer used now that we have a separate
API to check for existence.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Remove unneeded LOCK_KEEP from vg_read() interface.
Update comment to clarify cases where _vg_lock_and_read() may return
with an error but the lock held. Would be nice to make the vg_read()
interface consistent with regards to lock held and error behavior.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Sun May 3 12:32:30 CEST 2009 Petr Rockai <me@mornfall.net>
* Rework the toollib interface (process_each_*) on top of new vg_read.
Rebased 6/26/09 by Dave W.
- Add skipping message to process_each_lv
- Remove inconsistent_t.
Various tools need to check for existence of a VG before doing something
(vgsplit, vgrename, vgcreate). Currently we don't have an interface to
check for existence, but the existence check is part of the vg_read* call(s).
This patch is an attempt to pull out some of that functionality into a
separate function, and hopefully simplify our vg_read interface, and
move those patches along.
vg_lock_newname() is only concerned about checking whether a vg exists in
the system. Unfortunately, we cannot just scan the system, but we must first
obtain a lock. Since we are reserving a vgname, we take a WRITE lock on
the vgname. Once obtained, we scan the system to ensure the name does
not exist. The return codes and behavior is in the function header.
You might think of this function as similar to an open() call with
O_CREAT and O_EXCL flags (returns failure with -EEXIST if file already
exists).
NOTE: I think including the word "lock" in the function name is important,
as it clearly states the function obtains a lock and makes the code more
readable, especially when it comes to cleanup / unlocking. The ultimate
function name is somewhat open for debate though so later we may rename.
Several commands calls process_each_vg() and in provided
callback it explicitly recovers VG if inconsistent.
(vgchange, vgconvert, vgscan)
It means that old VG is released and reread but the function
above (process_one_vg) tries to unlock and release old VG.
Patch moves the repair logic into _process_one_vg() function.
It always tries to read vg (even inconsistent) and then decides
what to do according new defined parameter.
Also patch unifies inconsistent error messages.
The only slight change if for vgremove command, where
it now tries to repair VG before it removes if force arg is given.
(It works similar way before, just the order of operation changed).
When mirror convert polling is started (mainly as backgound process,
in lvchange -a y or in lvconvert itself) it tries to read VG
and LV identified by its name.
Unfortunatelly, the VG can have already different LV under the same name,
and various more or less funny things can happen (note that
_finish_lvconvert_mirror suspends the volume for example).
(the typical example is our testing script which continuously recreates
LVs under the same name in the same VG.)
This patch adds optional uuid parameter which helps to properly
select the monitoring object. For lvconvert polling it is set to LV UUID
and both _get_lvconvert_vg and _get_lvconvert_lv uses it to read proper VG/LV.
(In the pvmove case it is NULL, here we poll for physical volume name).
We can temporarily violate max_lv during mirror conversion etc.
(If the operation fails, orphan mirror images are visible to administrator
for manual remove for example. Not that this should ever happen:-)
Force limit only for lvcreate (and vg merge) command.
Patch also adds simple max_lv tests into testsuite
The vg->lv_count parameter now includes always number of visible
logical volumes.
Note that virtual snapshot volume (snapshotX) is never visible,
but it is stored in metadata with visible flag.
link_lv_to_vg and unlink_lv_from_vg are the only functions
for adding/removing logical volume from volume group.
Only these function should manipulate with vg->lvs list.
