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2016-10-19dlm: audit and remove any unnecessary uses of module.hPaul Gortmaker1-0/+2
Historically a lot of these existed because we did not have a distinction between what was modular code and what was providing support to modules via EXPORT_SYMBOL and friends. That changed when we forked out support for the latter into the export.h file. This means we should be able to reduce the usage of module.h in code that is obj-y Makefile or bool Kconfig. In the case of some code where it is modular, we can extend that to also include files that are building basic support functionality but not related to loading or registering the final module; such files also have no need whatsoever for module.h The advantage in removing such instances is that module.h itself sources about 15 other headers; adding significantly to what we feed cpp, and it can obscure what headers we are effectively using. Since module.h might have been the implicit source for init.h (for __init) and for export.h (for EXPORT_SYMBOL) we consider each instance for the presence of either and replace as needed. In the dlm case, we remove module.h from a global header and only introduce it in the files where it is explicitly required, since there is nothing modular in dlm_internal.h itself. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David Teigland <teigland@redhat.com>
2014-06-06fs/dlm/lockspace.c: convert simple_str to kstrFabian Frederick1-4/+17
Replace obsolete functions. Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Christine Caulfield <ccaulfie@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-02-14dlm: use INFO for recovery messagesDavid Teigland1-4/+4
The log messages relating to the progress of recovery are minimal and very often useful. Change these to the KERN_INFO level so they are always available. Signed-off-by: David Teigland <teigland@redhat.com>
2013-10-16dlm: Avoid that dlm_release_lockspace() incorrectly returns -EBUSYBart Van Assche1-3/+1
When dlm_release_lockspace(ls, 1) is invoked on a busy system immediately after the last dlm_unlock() AST has finished it can occur that lkb_idr_is_local() is invoked for the unlocked LKB since removal from ls_lkbidr only occurs after the AST has returned. If that happens dlm_release_lockspace(ls, 1) will return -EBUSY instead of releasing the lockspace. Fix this race condition by changing lkb_idr_is_local() such that it only returns true for LKB's that have not yet been unlocked. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: David Teigland <teigland@redhat.com>
2013-06-25dlm: log an error for unmanaged lockspacesDavid Teigland1-1/+8
Log an error message if the dlm user daemon exits before all the lockspaces have been removed. Signed-off-by: David Teigland <teigland@redhat.com>
2013-02-27dlm: don't use idr_remove_all()Tejun Heo1-1/+0
idr_destroy() can destroy idr by itself and idr_remove_all() is being deprecated. The conversion isn't completely trivial for recover_idr_clear() as it's the only place in kernel which makes legitimate use of idr_remove_all() w/o idr_destroy(). Replace it with idr_remove() call inside idr_for_each_entry() loop. It goes on top so that it matches the operation order in recover_idr_del(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christine Caulfield <ccaulfie@redhat.com> Cc: David Teigland <teigland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-08-08dlm: fix unlock balance warningsDavid Teigland1-3/+12
The in_recovery rw_semaphore has always been acquired and released by different threads by design. To work around the "BUG: bad unlock balance detected!" messages, adjust things so the dlm_recoverd thread always does both down_write and up_write. Signed-off-by: David Teigland <teigland@redhat.com>
2012-07-16dlm: fix race between remove and lookupDavid Teigland1-2/+19
It was possible for a remove message on an old rsb to be sent after a lookup message on a new rsb, where the rsbs were for the same resource name. This could lead to a missing directory entry for the new rsb. It is fixed by keeping a copy of the resource name being removed until after the remove has been sent. A lookup checks if this in-progress remove matches the name it is looking up. Signed-off-by: David Teigland <teigland@redhat.com>
2012-07-16dlm: use idr instead of list for recovered rsbsDavid Teigland1-0/+3
When a large number of resources are being recovered, a linear search of the recover_list takes a long time. Use an idr in place of a list. Signed-off-by: David Teigland <teigland@redhat.com>
2012-07-16dlm: use rsbtbl as resource directoryDavid Teigland1-22/+1
Remove the dir hash table (dirtbl), and use the rsb hash table (rsbtbl) as the resource directory. It has always been an unnecessary duplication of information. This improves efficiency by using a single rsbtbl lookup in many cases where both rsbtbl and dirtbl lookups were needed previously. This eliminates the need to handle cases of rsbtbl and dirtbl being out of sync. In many cases there will be memory savings because the dir hash table no longer exists. Signed-off-by: David Teigland <teigland@redhat.com>
2012-05-02dlm: fixes for nodir modeDavid Teigland1-0/+20
The "nodir" mode (statically assign master nodes instead of using the resource directory) has always been highly experimental, and never seriously used. This commit fixes a number of problems, making nodir much more usable. - Major change to recovery: recover all locks and restart all in-progress operations after recovery. In some cases it's not possible to know which in-progess locks to recover, so recover all. (Most require recovery in nodir mode anyway since rehashing changes most master nodes.) - Change the way nodir mode is enabled, from a command line mount arg passed through gfs2, into a sysfs file managed by dlm_controld, consistent with the other config settings. - Allow recovering MSTCPY locks on an rsb that has not yet been turned into a master copy. - Ignore RCOM_LOCK and RCOM_LOCK_REPLY recovery messages from a previous, aborted recovery cycle. Base this on the local recovery status not being in the state where any nodes should be sending LOCK messages for the current recovery cycle. - Hold rsb lock around dlm_purge_mstcpy_locks() because it may run concurrently with dlm_recover_master_copy(). - Maintain highbast on process-copy lkb's (in addition to the master as is usual), because the lkb can switch back and forth between being a master and being a process copy as the master node changes in recovery. - When recovering MSTCPY locks, flag rsb's that have non-empty convert or waiting queues for granting at the end of recovery. (Rename flag from LOCKS_PURGED to RECOVER_GRANT and similar for the recovery function, because it's not only resources with purged locks that need grant a grant attempt.) - Replace a couple of unnecessary assertion panics with error messages. Signed-off-by: David Teigland <teigland@redhat.com>
2012-01-04dlm: add recovery callbacksDavid Teigland1-8/+35
These new callbacks notify the dlm user about lock recovery. GFS2, and possibly others, need to be aware of when the dlm will be doing lock recovery for a failed lockspace member. In the past, this coordination has been done between dlm and file system daemons in userspace, which then direct their kernel counterparts. These callbacks allow the same coordination directly, and more simply. Signed-off-by: David Teigland <teigland@redhat.com>
2012-01-04dlm: add node slots and generationDavid Teigland1-0/+5
Slot numbers are assigned to nodes when they join the lockspace. The slot number chosen is the minimum unused value starting at 1. Once a node is assigned a slot, that slot number will not change while the node remains a lockspace member. If the node leaves and rejoins it can be assigned a new slot number. A new generation number is also added to a lockspace. It is set and incremented during each recovery along with the slot collection/assignment. The slot numbers will be passed to gfs2 which will use them as journal id's. Signed-off-by: David Teigland <teigland@redhat.com>
2011-11-18dlm: convert rsb list to rb_treeBob Peterson1-14/+9
Change the linked lists to rb_tree's in the rsb hash table to speed up searches. Slow rsb searches were having a large impact on gfs2 performance due to the large number of dlm locks gfs2 uses. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com>
2011-07-15dlm: use workqueue for callbacksDavid Teigland1-22/+21
Instead of creating our own kthread (dlm_astd) to deliver callbacks for all lockspaces, use a per-lockspace workqueue to deliver the callbacks. This eliminates complications and slowdowns from many lockspaces sharing the same thread. Signed-off-by: David Teigland <teigland@redhat.com>
2011-07-12dlm: improve rsb searchesDavid Teigland1-0/+10
By pre-allocating rsb structs before searching the hash table, they can be inserted immediately. This avoids always having to repeat the search when adding the struct to hash list. This also adds space to the rsb struct for a max resource name, so an rsb allocation can be used by any request. The constant size also allows us to finally use a slab for the rsb structs. Signed-off-by: David Teigland <teigland@redhat.com>
2011-07-11dlm: keep lkbs in idrDavid Teigland1-62/+54
This is simpler and quicker than the hash table, and avoids needing to search the hash list for every new lkid to check if it's used. Signed-off-by: David Teigland <teigland@redhat.com>
2011-07-01dlm: use vmalloc for hash tablesBryn M. Reeves1-9/+9
Allocate dlm hash tables in the vmalloc area to allow a greater maximum size without restructuring of the hash table code. Signed-off-by: Bryn M. Reeves <bmr@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com>
2011-04-01dlm: delayed reply message warningDavid Teigland1-3/+3
Add an option (disabled by default) to print a warning message when a lock has been waiting a configurable amount of time for a reply message from another node. This is mainly for debugging. Signed-off-by: David Teigland <teigland@redhat.com>
2010-03-07Driver core: Constify struct sysfs_ops in struct kobj_typeEmese Revfy1-1/+1
Constify struct sysfs_ops. This is part of the ops structure constification effort started by Arjan van de Ven et al. Benefits of this constification: * prevents modification of data that is shared (referenced) by many other structure instances at runtime * detects/prevents accidental (but not intentional) modification attempts on archs that enforce read-only kernel data at runtime * potentially better optimized code as the compiler can assume that the const data cannot be changed * the compiler/linker move const data into .rodata and therefore exclude them from false sharing Signed-off-by: Emese Revfy <re.emese@gmail.com> Acked-by: David Teigland <teigland@redhat.com> Acked-by: Matt Domsch <Matt_Domsch@dell.com> Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com> Acked-by: Hans J. Koch <hjk@linutronix.de> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by: Jens Axboe <jens.axboe@oracle.com> Acked-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-26dlm: Send lockspace name with ueventsSteven Whitehouse1-1/+13
Although it is possible to get this information from the path, its much easier to provide the lockspace as a seperate env variable. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com>
2009-11-30dlm: always use GFP_NOFSDavid Teigland1-10/+5
Replace all GFP_KERNEL and ls_allocation with GFP_NOFS. ls_allocation would be GFP_KERNEL for userland lockspaces and GFP_NOFS for file system lockspaces. It was discovered that any lockspaces on the system can affect all others by triggering memory reclaim in the file system which could in turn call back into the dlm to acquire locks, deadlocking dlm threads that were shared by all lockspaces, like dlm_recv. Signed-off-by: David Teigland <teigland@redhat.com>
2009-05-07dlm: fix use count with multiple joinsDavid Teigland1-7/+6
When a lockspace was joined multiple times, the global dlm use count was incremented when it should not have been. This caused the global dlm threads to not be stopped when all lockspaces were eventually be removed. Signed-off-by: David Teigland <teigland@redhat.com>
2009-05-07dlm: Make name input parameter of {,dlm_}new_lockspace() constGeert Uytterhoeven1-2/+2
| fs/gfs2/lock_dlm.c:207: warning: passing argument 1 of 'dlm_new_lockspace' discards qualifiers from pointer target type Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: David Teigland <teigland@redhat.com>
2009-01-28dlm: Change rwlock which is only used in write mode to a spinlockSteven Whitehouse1-1/+1
The ls_dirtbl[].lock was an rwlock, but since it was only used in write mode a spinlock will suffice. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com>
2009-01-08dlm: change rsbtbl rwlock to spinlockDavid Teigland1-1/+1
The rwlock is almost always used in write mode, so there's no reason to not use a spinlock instead. Signed-off-by: David Teigland <teigland@redhat.com>
2008-11-13dlm: fix shutdown cleanupDavid Teigland1-1/+1
Fixes a regression from commit 0f8e0d9a317406612700426fad3efab0b7bbc467, "dlm: allow multiple lockspace creates". An extraneous 'else' slipped into a code fragment being moved from release_lockspace() to dlm_release_lockspace(). The result of the unwanted 'else' is that dlm threads and structures are not stopped and cleaned up when the final dlm lockspace is removed. Trying to create a new lockspace again afterward will fail with "kmem_cache_create: duplicate cache dlm_conn" because the cache was not previously destroyed. Signed-off-by: David Teigland <teigland@redhat.com>
2008-08-28dlm: fix locking of lockspace list in dlm_scandDavid Teigland1-2/+25
The dlm_scand thread needs to lock the list of lockspaces when going through it. Signed-off-by: David Teigland <teigland@redhat.com>
2008-08-28dlm: detect available userspace daemonDavid Teigland1-1/+23
If dlm_controld (the userspace daemon that controls the setup and recovery of the dlm) fails, the kernel should shut down the lockspaces in the kernel rather than leaving them running. This is detected by having dlm_controld hold a misc device open while running, and if the kernel detects a close while the daemon is still needed, it stops the lockspaces in the kernel. Knowing that the userspace daemon isn't running also allows the lockspace create/remove routines to avoid waiting on the daemon for join/leave operations. Signed-off-by: David Teigland <teigland@redhat.com>
2008-08-28dlm: allow multiple lockspace createsDavid Teigland1-37/+70
Add a count for lockspace create and release so that create can be called multiple times to use the lockspace from different places. Also add the new flag DLM_LSFL_NEWEXCL to create a lockspace with the previous behavior of returning -EEXIST if the lockspace already exists. Signed-off-by: David Teigland <teigland@redhat.com>
2008-04-30fs: replace remaining __FUNCTION__ occurrencesHarvey Harrison1-1/+1
__FUNCTION__ is gcc-specific, use __func__ Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06dlm: add __init and __exit marks to init and exit functionsDenis Cheng1-1/+1
it moves 365 bytes from .text to .init.text, and 30 bytes from .text to .exit.text, saves memory. Signed-off-by: Denis Cheng <crquan@gmail.com> Signed-off-by: David Teigland <teigland@redhat.com>
2008-01-29dlm: use dlm prefix on alloc and free functionsDavid Teigland1-4/+4
The dlm functions in memory.c should use the dlm_ prefix. Also, use kzalloc/kfree directly for dlm_direntry's, removing the wrapper functions. Signed-off-by: David Teigland <teigland@redhat.com>
2008-01-29dlm: proper prototypesAdrian Bunk1-8/+0
This patch adds a proper prototype for some functions in fs/dlm/dlm_internal.h Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: David Teigland <teigland@redhat.com>
2008-01-24Kobject: convert fs/* from kobject_unregister() to kobject_put()Greg Kroah-Hartman1-2/+2
There is no need for kobject_unregister() anymore, thanks to Kay's kobject cleanup changes, so replace all instances of it with kobject_put(). Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24Kobject: change GFS2 to use kobject_init_and_addGreg Kroah-Hartman1-22/+4
Stop using kobject_register, as this way we can control the sending of the uevent properly, after everything is properly initialized. Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kobject: convert kernel_kset to be a kobjectGreg Kroah-Hartman1-1/+1
kernel_kset does not need to be a kset, but a much simpler kobject now that we have kobj_attributes. We also rename kernel_kset to kernel_kobj to catch all users of this symbol with a build error instead of an easy-to-ignore build warning. Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kset: convert kernel_subsys to use kset_createGreg Kroah-Hartman1-1/+1
Dynamically create the kset instead of declaring it statically. We also rename kernel_subsys to kernel_kset to catch all users of this symbol with a build error instead of an easy-to-ignore build warning. Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kset: convert dlm to use kset_createGreg Kroah-Hartman1-11/+9
Dynamically create the kset instead of declaring it statically. Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kobject: remove struct kobj_type from struct ksetGreg Kroah-Hartman1-4/+2
We don't need a "default" ktype for a kset. We should set this explicitly every time for each kset. This change is needed so that we can make ksets dynamic, and cleans up one of the odd, undocumented assumption that the kset/kobject/ktype model has. This patch is based on a lot of help from Kay Sievers. Nasty bug in the block code was found by Dave Young <hidave.darkstar@gmail.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/driver-2.6Linus Torvalds1-1/+1
* master.kernel.org:/pub/scm/linux/kernel/git/gregkh/driver-2.6: (75 commits) PM: merge device power-management source files sysfs: add copyrights kobject: update the copyrights kset: add some kerneldoc to help describe what these strange things are Driver core: rename ktype_edd and ktype_efivar Driver core: rename ktype_driver Driver core: rename ktype_device Driver core: rename ktype_class driver core: remove subsystem_init() sysfs: move sysfs file poll implementation to sysfs_open_dirent sysfs: implement sysfs_open_dirent sysfs: move sysfs_dirent->s_children into sysfs_dirent->s_dir sysfs: make sysfs_root a regular directory dirent sysfs: open code sysfs_attach_dentry() sysfs: make s_elem an anonymous union sysfs: make bin attr open get active reference of parent too sysfs: kill unnecessary NULL pointer check in sysfs_release() sysfs: kill unnecessary sysfs_get() in open paths sysfs: reposition sysfs_dirent->s_mode. sysfs: kill sysfs_update_file() ...
2007-10-12Drivers: clean up direct setting of the name of a ksetGreg Kroah-Hartman1-1/+1
A kset should not have its name set directly, so dynamically set the name at runtime. This is needed to remove the static array in the kobject structure which will be changed in a future patch. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-10[DLM] block dlm_recv in recovery transitionDavid Teigland1-0/+1
Introduce a per-lockspace rwsem that's held in read mode by dlm_recv threads while working in the dlm. This allows dlm_recv activity to be suspended when the lockspace transitions to, from and between recovery cycles. The specific bug prompting this change is one where an in-progress recovery cycle is aborted by a new recovery cycle. While dlm_recv was processing a recovery message, the recovery cycle was aborted and dlm_recoverd began cleaning up. dlm_recv decremented recover_locks_count on an rsb after dlm_recoverd had reset it to zero. This is fixed by suspending dlm_recv (taking write lock on the rwsem) before aborting the current recovery. The transitions to/from normal and recovery modes are simplified by using this new ability to block dlm_recv. The switch from normal to recovery mode means dlm_recv goes from processing locking messages, to saving them for later, and vice versa. Races are avoided by blocking dlm_recv when setting the flag that switches between modes. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09[DLM] don't require FS flag on all nodesDavid Teigland1-3/+4
Mask off the recently added DLM_LSFL_FS flag when setting the exflags. This way all the nodes in the lockspace aren't required to have the FS flag set, since we later check that exflags matches among all nodes. Signed-off-by: Patrick Caulfield <pcaulfie@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09[DLM] variable allocationPatrick Caulfield1-0/+5
Add a new flag, DLM_LSFL_FS, to be used when a file system creates a lockspace. This flag causes the dlm to use GFP_NOFS for allocations instead of GFP_KERNEL. (This updated version of the patch uses gfp_t for ls_allocation.) Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com> Signed-Off-By: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09[DLM] wait for config check during join [6/6]David Teigland1-0/+30
Joining the lockspace should wait for the initial round of inter-node config checks to complete before returning. This way, if there's a configuration mismatch between the joining node and the existing nodes, the join can fail and return an error to the application. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09[DLM] fix new_lockspace error exit [5/6]David Teigland1-13/+19
Fix the error path when exiting new_lockspace(). It was kfree'ing the lockspace struct at the end, but that's only valid if it exits before kobject_register occured. After kobject_register we have to let the kobject do the freeing. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09[DLM] add lock timeouts and warnings [2/6]David Teigland1-1/+9
New features: lock timeouts and time warnings. If the DLM_LKF_TIMEOUT flag is set, then the request/conversion will be canceled after waiting the specified number of centiseconds (specified per lock). This feature is only available for locks requested through libdlm (can be enabled for kernel dlm users if there's a use for it.) If the new DLM_LSFL_TIMEWARN flag is set when creating the lockspace, then a warning message will be sent to userspace (using genetlink) after a request/conversion has been waiting for a given number of centiseconds (configurable per node). The time warnings will be used in the future to do deadlock detection in userspace. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-07-09[DLM] block scand during recovery [1/6]David Teigland1-2/+6
Don't let dlm_scand run during recovery since it may try to do a resource directory removal while the directory nodes are changing. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-05-07Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmwLinus Torvalds1-1/+3
* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw: (34 commits) [GFS2] Uncomment sprintf_symbol calling code [DLM] lowcomms style [GFS2] printk warning fixes [GFS2] Patch to fix mmap of stuffed files [GFS2] use lib/parser for parsing mount options [DLM] Lowcomms nodeid range & initialisation fixes [DLM] Fix dlm_lowcoms_stop hang [DLM] fix mode munging [GFS2] lockdump improvements [GFS2] Patch to detect corrupt number of dir entries in leaf and/or inode blocks [GFS2] bz 236008: Kernel gpf doing cat /debugfs/gfs2/xxx (lock dump) [DLM] fs/dlm/ast.c should #include "ast.h" [DLM] Consolidate transport protocols [DLM] Remove redundant assignment [GFS2] Fix bz 234168 (ignoring rgrp flags) [DLM] change lkid format [DLM] interface for purge (2/2) [DLM] add orphan purging code (1/2) [DLM] split create_message function [GFS2] Set drop_count to 0 (off) by default ...