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The last commit related to this was incomplete:
"Implement lock-override options without locking type"
This is further reworking and reduction of the locking.[ch]
layer which handled all clustering, but is now only used
for file locking. The "locking types" that this layer
implemented were removed previously, leaving only the
standard file locking. (Some cluster-related artifacts
remain to be cleared out later.)
Command options to override or modify locking behavior
are reimplemented here without using the locking types.
Also, deprecated locking_type values are recognized,
and implemented as if one of the equivalent override
options was set.
Options that override file locking are:
. --nolocking disables all file locking.
. --readonly grants read lock requests without actually
taking a file lock, and refuses write lock requests.
. --ignorelockingfailure tries to set up file locks and
uses them normally if possible. When not possible, it
behaves like --readonly, but allows activation.
. --sysinit is the same as ignorelockingfailure.
. global/metadata_read_only acquires actual read file
locks, and refuses write lock requests.
(Some of these options could probably be deprecated
because they were added as workarounds to various
locking_type behaviors that are now deprecated.)
The locking_type setting now has one valid value: 1 which
refers to standard file locking. Configs that contain
deprecated values are recognized and still work in
largely the same way:
. 0 disabled all locking, now implemented like --nolocking
is set. Allow the nolocking option in all commands.
. 1 is the normal file locking setting and is unchanged.
. 2 was for external locking which was not used, and
reverts to normal file locking.
. 3 was for cluster/clvm. This reverts to normal file
locking, and prints messages about lvmlockd.
. 4 was equivalent to readonly, now implemented like
--readonly is set.
. 5 disabled all locking, now implemented like
--nolocking is set.
The options: --nolocking, --readonly, --sysinit
override, or make exceptions to, the normal file locking
behavior. Implement these by just checking for the
options in the file locking path instead of using
special locking types.
Basic LV functions:
activate_lv(), deactivate_lv(),
suspend_lv(), resume_lv()
were routed through the locking infrastruture on the way to:
lv_activate_with_filter(), lv_deactivate(),
lv_suspend_if_active(), lv_resume_if_active()
This commit removes the locking infrastructure from the
middle and calls the later functions directly from the former.
There were a couple of ancillary steps that the locking
infrastructure added along the way which are still included:
- critical section inc/dec during suspend/resume
- checking for active component LVs during activate
The "activation" file lock (serializing activation) has not
been kept because activation commands have been changed to
take the VG file lock exclusively which makes the activation
lock unused and unnecessary.
Four commands lock two VGs at a time:
- vgsplit and vgmerge already have their own logic to
acquire the locks in the correct order.
- vgimportclone and vgrename disable this ordering check.
Different flavors of activate_lv() and lv_is_active()
which are meaningful in a clustered VG can be eliminated
and replaced with whatever that flavor already falls back
to in a local VG.
e.g. lv_is_active_exclusive_locally() is distinct from
lv_is_active() in a clustered VG, but in a local VG they
are equivalent. So, all instances of the variant are
replaced with the basic local equivalent.
For local VGs, the same behavior remains as before.
For shared VGs, lvmlockd was written with the explicit
requirement of local behavior from these functions
(lvmlockd requires locking_type 1), so the behavior
in shared VGs also remains the same.
In this command, lvcreate creates a new LV and then combines
it with an existing cache pool, producing a cache LV. This
command was previously not allowed in in a shared VG.
It's not an error if a command requests the global lock
when it has already acquired it. It shouldn't happen,
but there could be cases we've not found.
As we start refactoring the code to break dependencies (see doc/refactoring.txt),
I want us to use full paths in the includes (eg, #include "base/data-struct/list.h").
This makes it more obvious when we're breaking abstraction boundaries, eg, including a file in
metadata/ from base/
There are likely more bits of code that can be removed,
e.g. lvm1/pool-specific bits of code that were identified
using FMT flags.
The vgconvert command can likely be reduced further.
The lvm1-specific config settings should probably have
some other fields set for proper deprecation.
Occasionaly users may need to peek into 'component devices.
Normally lvm2 does not let users activation component.
This patch adds special mode where user can activate
component LV in a 'read-only' mode i.e.:
lvchange -ay vg/pool_tdata
All devices can be deactivated with:
lvchange -an vg | vgchange -an....
While 'file-locking' code always dropped cached VG before
lock was taken - other locking types actually missed this.
So while the cache dropping has been implement for i.e. clvmd,
actually running command in cluster keept using cache even
when the lock has been i.e. dropped and taken again.
This rather 'hard-to-hit' error was noticable in some
tests running in cluster where content of PV has been
changed (metadata-balance.sh)
Fix the code by moving cache dropping directly lock_vol() function.
TODO: it's kind of strange we should ever need drop_cached_metadata()
used in several places - this all should happen automatically
this some futher thinking here is likely needed.
In fact pvmove does support 'clustered-core' target for clustered
pvmove of LVs activated on multiple nodes.
This patch restores support for activation of pvmove on all nodes
for LVs that are also activate on all nodes.
Introduce enum dev_io_reason to categorise block device I/O
in debug messages so it's obvious what it is for.
DEV_IO_SIGNATURES /* Scanning device signatures */
DEV_IO_LABEL /* LVM PV disk label */
DEV_IO_MDA_HEADER /* Text format metadata area header */
DEV_IO_MDA_CONTENT /* Text format metadata area content */
DEV_IO_FMT1 /* Original LVM1 metadata format */
DEV_IO_POOL /* Pool metadata format */
DEV_IO_LV /* Content written to an LV */
DEV_IO_LOG /* Logging messages */
There is no need to differentiation between clustered VG and normal VG.
As the activation depends on locking type.
Use unconditionally locally exclusive activation for pvmove.
When activation of LVs fails prior pvmove start, try to deactivate
already activated LVs.
TODO: possibly remember which LVs where already activate and only those
take down - devices which are already in-use will stay active.
Activation lock has a primary purpose to serialize locking of individual
LV in case there is no other protecting mechanism for parallel
execution.
However in the case an activated LV is composed from several other LVs,
noone should be able to manipulate with those LVs as well.
This patch add a very 'naive' global VG activation locking in this case.
In the future we may introduce smarter function detecting minimal closed
graph components if this will appear as bottleneck
Patch checks if the VG Write lock is held - in this case we do not
need any more locking - command has exclusive access to VG.
In case we have clustered VG and we are activating an LV which does not
need other LVs - we also do not need any more locks.
In all other cases take respective lock - for single LV - use lvid,
for complex LVs use vgname.
In a shared VG, lvconvert must be used to create thin pools
and cache pools, not the lvcreate variants of those commands.
Deny these cases early in lvcreate using the new command defs.
Denying these cases deeper in the code was missing some
cleanup of the partially completed command.
Revert the lvmlockd.c changes from:
commit 0bf836aa14
"tidy: prefer not using else after return"
The commit introduced at least one regression, which broke
lvcreate of a thin pool in a shared VG.
After the internal lvmlock LV (holding sanlock leases) is
extended to hold more leases, it needs to be zeroed.
sanlock expects to see either zeroed blocks or blocks
initialized with leases.
Some lvconvert commands can be used directly on the data sublv:
lvconvert ... vg/pool_tdata
The correct LV lock to use in lvmlockd is the one on the pool LV.
If the VG holding the global lock is removed, we can indicate
that as the reason for not being able to acquire the global
lock in subsequent error messages, and can suggest enabling
the global lock in another VG. (This helpful error message
will go away if the global lock is enabled in another VG,
or if lvmlockd is restarted.)
Previously, a command sent lvmetad new VG metadata in vg_commit().
In vg_commit(), devices are suspended, so any memory allocation
done by the command while sending to lvmetad, or by lvmetad while
updating its cache could deadlock if memory reclaim was triggered.
Now lvmetad is updated in unlock_vg(), after devices are resumed.
The new method for updating VG metadata in lvmetad is in two phases:
1. In vg_write(), before devices are suspended, the command sends
lvmetad a short message ("set_vg_info") telling it what the new
VG seqno will be. lvmetad sees that the seqno is newer than
the seqno of its cached VG, so it sets the INVALID flag for the
cached VG. If sending the message to lvmetad fails, the command
fails before the metadata is committed and the change is not made.
If sending the message succeeds, vg_commit() is called.
2. In unlock_vg(), after devices are resumed, the command sends
lvmetad the standard vg_update message with the new metadata.
lvmetad sees that the seqno in the new metadata matches the
seqno it saved from set_vg_info, and knows it has the latest
copy, so it clears the INVALID flag for the cached VG.
If a command fails between 1 and 2 (after committing the VG on disk,
but before sending lvmetad the new metadata), the cached VG retains
the INVALID flag in lvmetad. A subsequent command will read the
cached VG from lvmetad, see the INVALID flag, ignore the cached
copy, read the VG from disk instead, update the lvmetad copy
with the latest copy from disk, (this clears the INVALID flag
in lvmetad), and use the correct VG metadata for the command.
(This INVALID mechanism already existed for use by lvmlockd.)
This reverts commit fa69ed0bc8.
This code sometimes expects to be presented with a read-only filesystem
(during some boot sequences for example) and copes appropriately with
this and it should not lead to expected error messages that might cause
unnecessary alarm.
lv_name arg is only used without known LV for resolving '*lv'.
Once we know *lv, never use lv_name ever again.
So setting it when passing *lv has not needed.
Use common API design and pass just LV pointer to lv_manip.c functions.
Read cmd struct via lv->vg->cmd when needed.
Also do not try to return EINVALID_CMD_LINE error when we
have already openned VG - this error code can only be returned before
locking VG.
If 'vgcreate --shared' finds both sanlock and dlm are running,
print a more accurate error message:
"Found multiple lock managers, select one with --lock-type."
When neither is running, we still print:
"Failed to detect a running lock manager to select lock type."
vgchange --lock-type iterates through LVs to ensure
no LVs are active before changing the lock type of
the VG, but the loop was not checking that an LV
actually has a lock before trying it, so it would
fail if the VG had any LVs that don't use locks,
e.g it would fail on a tmeta LV from a pool.
This applies the same rule/logic to dlm VGs that has always
existed for sanlock VGs. Allowing a dlm VG to be removed
while its lockspace was still running on other hosts largely
worked, but there were difficult problems if another VG with
the same name was recreated. Forcing the VG lockspace to
be stopped, gives both sanlock and dlm VGs the same behavior.
Add a new arg to lockd_start_vg() that indicates
it is being called for a new lockd VG, so that
lvmlockd knows the lockspace being started is new.
(Will be used by a following commit.)
This was only used to return two flags indicating specific
reasons for a lock failure so that a more specific error
message could be printed by the command (lockspace had been
stopped, or lockspace had an error starting.)
Remove the list, given its limited usefulness, the fact it
would easily become inaccurate, and the fact it was causing
misleading error messages. The error conditions it was meant
to help could be reported differently.
Previously, a command would only rescan a lockd VG
when lvmetad returned the "vg_invalid" flag indicating
that the cached copy was invalid (which is done by
lvmlockd.) This is still the only usual reason for
rescanning a lockd VG, but two new special cases are
added where we also do the rescan:
. When the --shared option is used to display lockd VGs
from hosts not using lvmlockd. This is the same case
as using --foreign to display foreign VGs, but --shared
was missing the corresponding bits to rescan the VGs.
. When a lockd VG is allowed to be read for displaying
after failing to acquire the lock from lvmlockd. In
this case, the usual mechanism for validating the
cache is missed, so assume the cache would have been
invalidated. (This had been a previous todo item
that was lost during other cleanup.)
These were long-standing todos that were lost track of.
This makes lvmlockd removal steps for dlm VGs closely match
sanlock VGs. Because dlm lockspaces are not required to be
stopped on all hosts before vgremove, there is an extra bit
for dlm lockspaces, where a flag is set in the VG lock lvb
indicating that the VG was removed. If other hosts happen
to use the VG lock they will see this flag and stop their
lockspace.
Remove the existing lock type using the same functions
used to remove the lockd components during vgremove.
This results in a "clean" VG and lvmlockd state after
the vgchange, i.e. no bits left over from previous
lock type.
When vgremove is used to remove multiple VGs in one command,
e.g. vgremove foo bar, the first VG (foo) that is removed
may have held the sanlock global lock. In this case,
do not continue removing further VGs (bar) without the
global lock.
This adds the infrastructure, code paths, error reporting,
etc. to handle storage errors, or storage loss, under the
sanlock leases in a VG that is being used. The loss of
storage means sanlock cannot renew its leases, which means
that the host needs to stop using the shared VG before its
leases expire.
This still requires manually shutting down a VG that has
lost lease storage, e.g. unmounting file systems,
deactivating LVs in the VG. The next step is to
automatically use a command like blkdeactivate to do that.
When a command is flagged with NO_METADATA_PROCESSING flag, it means
such command does not process any metadata and hence it doens't require
lvmetad, lvmpolld and it can get away with no locking too. These are
mostly simple commands (like lvmconfig/dumpconfig, version, types,
segtypes and other builtin commands that do not process metadata
in any way).
At first, when lvm command is executed, create toolcontext without
initializing connections (lvmetad,lvmpolld) and without initializing
filters (which depend on connections init). Instead, delay this
initialization until we know we need this. That is, until the
lvm_run_command fn is called in which we know what the actual
command to run is and hence we can avoid any connection, filter
or locking initiliazation for commands that would not make use
of it anyway.
For all the other create_toolcontext calls, we keep the original
behaviour - the filters and connections are initialized together
with the toolcontext.
This tries harder to avoid creating duplicate global locks in
sanlock VGs by refusing to create a new sanlock VG with a
global lock if other sanlock VGs exist that may have a gl.
There is no longer an "enable" option for the global lock,
so remove the bit of code that was checking for it. It
was an optional variation anyway, and not one that was likely
to be used.
Also update the corresponding comment describing global lock
creation.
When lvmlockd is compiled without support for one of the
lock managers (sanlock or dlm), and a command tries to use
one of them, explain that in the error message.
