Merge tag 'dlm-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm

Pull dlm updates from David Teigland:

 - New flag DLM_LSFL_SOFTIRQ_SAFE can be set by code using dlm to
   indicate callbacks can be run from softirq

 - Change md-cluster to set DLM_LSFL_SOFTIRQ_SAFE

 - Clean up for previous changes, e.g. unused code and parameters

 - Remove custom pre-allocation of rsb structs which is unnecessary with
   kmem caches

 - Change idr to xarray for lkb structs in use

 - Change idr to xarray for rsb structs being recovered

 - Change outdated naming related to internal rsb states

 - Fix some incorrect add/remove of rsb on scan list

 - Use rcu to free rsb structs

* tag 'dlm-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm:
  dlm: add rcu_barrier before destroy kmem cache
  dlm: remove DLM_LSFL_SOFTIRQ from exflags
  fs: dlm: remove unused struct 'dlm_processed_nodes'
  md-cluster: use DLM_LSFL_SOFTIRQ for dlm_new_lockspace()
  dlm: implement LSFL_SOFTIRQ_SAFE
  dlm: introduce DLM_LSFL_SOFTIRQ_SAFE
  dlm: use LSFL_FS to check for kernel lockspace
  dlm: use rcu to avoid an extra rsb struct lookup
  dlm: fix add_scan and del_scan usage
  dlm: change list and timer names
  dlm: move recover idr to xarray datastructure
  dlm: move lkb idr to xarray datastructure
  dlm: drop own rsb pre allocation mechanism
  dlm: remove ls_local_handle from struct dlm_ls
  dlm: remove unused parameter in dlm_midcomms_addr
  dlm: don't kref_init rsbs created for toss list
  dlm: remove scand leftovers

2 files changed, 18 insertions, 1 deletions

diff --git a/include/linux/dlm.h b/include/linux/dlm.h
index c58c4f790c04..bacda9898f2b 100644
--- a/include/linux/dlm.h
+++ b/include/linux/dlm.h
@@ -35,6 +35,9 @@ struct dlm_lockspace_ops {
 			      int num_slots, int our_slot, uint32_t generation);
 };
 
+/* only relevant for kernel lockspaces, will be removed in future */
+#define DLM_LSFL_SOFTIRQ __DLM_LSFL_RESERVED0
+
 /*
  * dlm_new_lockspace
  *
@@ -55,6 +58,11 @@ struct dlm_lockspace_ops {
  *   used to select the directory node.  Must be the same on all nodes.
  * DLM_LSFL_NEWEXCL
  *   dlm_new_lockspace() should return -EEXIST if the lockspace exists.
+ * DLM_LSFL_SOFTIRQ
+ *   dlm request callbacks (ast, bast) are softirq safe. Flag should be
+ *   preferred by users. Will be default in some future. If set the
+ *   strongest context for ast, bast callback is softirq as it avoids
+ *   an additional context switch.
  *
  * lvblen: length of lvb in bytes.  Must be multiple of 8.
  *   dlm_new_lockspace() returns an error if this does not match
@@ -121,7 +129,14 @@ int dlm_release_lockspace(dlm_lockspace_t *lockspace, int force);
  * call.
  *
  * AST routines should not block (at least not for long), but may make
- * any locking calls they please.
+ * any locking calls they please. If DLM_LSFL_SOFTIRQ for kernel
+ * users of dlm_new_lockspace() is passed the ast and bast callbacks
+ * can be processed in softirq context. Also some of the callback
+ * contexts are in the same context as the DLM lock request API, users
+ * must not hold locks while calling dlm lock request API and trying
+ * to acquire this lock in the callback again, this will end in a
+ * lock recursion. For newer implementation the DLM_LSFL_SOFTIRQ
+ * should be used.
  */
 
 int dlm_lock(dlm_lockspace_t *lockspace,
diff --git a/include/uapi/linux/dlm.h b/include/uapi/linux/dlm.h
index e7e905fb0bb2..4eaf835780b0 100644
--- a/include/uapi/linux/dlm.h
+++ b/include/uapi/linux/dlm.h
@@ -71,6 +71,8 @@ struct dlm_lksb {
 /* DLM_LSFL_TIMEWARN is deprecated and reserved. DO NOT USE! */
 #define DLM_LSFL_TIMEWARN	0x00000002
 #define DLM_LSFL_NEWEXCL     	0x00000008
+/* currently reserved due in-kernel use */
+#define __DLM_LSFL_RESERVED0	0x00000010
 
 
 #endif /* _UAPI__DLM_DOT_H__ */