clean up critical section patch

5 files changed, 29 insertions, 13 deletions

diff --git a/lib/locking/locking.c b/lib/locking/locking.c
index 98f17a70..a9758130 100644
--- a/lib/locking/locking.c
+++ b/lib/locking/locking.c
@@ -574,11 +574,13 @@ int remote_lock_held(const char *vol, int *exclusive)
 int sync_local_dev_names(struct cmd_context* cmd)
 {
 	memlock_unlock(cmd);
-	return lock_vol(cmd, VG_SYNC_NAMES, LCK_NONE | LCK_CACHE | LCK_LOCAL);
+
+	return lock_vol(cmd, VG_SYNC_NAMES, LCK_VG_SYNC_LOCAL);
 }
 
 int sync_dev_names(struct cmd_context* cmd)
 {
 	memlock_unlock(cmd);
-	return lock_vol(cmd, VG_SYNC_NAMES, LCK_NONE | LCK_CACHE);
+
+	return lock_vol(cmd, VG_SYNC_NAMES, LCK_VG_SYNC);
 }
diff --git a/lib/locking/locking.h b/lib/locking/locking.h
index 5b137911..af99464e 100644
--- a/lib/locking/locking.h
+++ b/lib/locking/locking.h
@@ -39,6 +39,9 @@ int remote_lock_held(const char *vol, int *exclusive);
  *   acquired in alphabetical order of 'vol' (to avoid deadlocks), with
  *   VG_ORPHANS last.
  *
+ *   Use VG_SYNC_NAMES to wait for any outstanding asynchronous /dev nodes 
+ *   events to complete.
+ *
  * LCK_LV:
  *   Lock/unlock an individual logical volume
  *   char *vol holds lvid
@@ -127,6 +130,9 @@ int check_lvm1_vg_inactive(struct cmd_context *cmd, const char *vgname);
 
 #define LCK_VG_BACKUP		(LCK_VG | LCK_CACHE)
 
+#define LCK_VG_SYNC		(LCK_NONE | LCK_CACHE)
+#define LCK_VG_SYNC_LOCAL	(LCK_NONE | LCK_CACHE | LCK_LOCAL)
+
 #define LCK_LV_EXCLUSIVE	(LCK_LV | LCK_EXCL)
 #define LCK_LV_SUSPEND		(LCK_LV | LCK_WRITE)
 #define LCK_LV_RESUME		(LCK_LV | LCK_UNLOCK)
@@ -175,12 +181,7 @@ int check_lvm1_vg_inactive(struct cmd_context *cmd, const char *vgname);
 	lock_vol((vg)->cmd, (vg)->name, LCK_VG_REVERT)
 #define remote_backup_metadata(vg)	\
 	lock_vol((vg)->cmd, (vg)->name, LCK_VG_BACKUP)
-/* cleanup later
-#define sync_local_dev_names(cmd)	\
-	lock_vol(cmd, VG_SYNC_NAMES, LCK_NONE | LCK_CACHE | LCK_LOCAL)
-#define sync_dev_names(cmd)	\
-	lock_vol(cmd, VG_SYNC_NAMES, LCK_NONE | LCK_CACHE)
-*/
+
 int sync_local_dev_names(struct cmd_context* cmd);
 int sync_dev_names(struct cmd_context* cmd);
 
diff --git a/lib/metadata/metadata-exported.h b/lib/metadata/metadata-exported.h
index 80de552a..331dd74a 100644
--- a/lib/metadata/metadata-exported.h
+++ b/lib/metadata/metadata-exported.h
@@ -196,7 +196,7 @@ struct pv_segment {
 #define FMT_INSTANCE_PRIVATE_MDAS 	0x00000008U
 
 struct format_instance {
-	unsigned ref_count;
+	unsigned ref_count;	/* Refs to this fid from VG and PV structs */
 	struct dm_pool *mem;
 
 	uint32_t type;
diff --git a/lib/metadata/mirror.c b/lib/metadata/mirror.c
index 95d07bda..b02c7bb3 100644
--- a/lib/metadata/mirror.c
+++ b/lib/metadata/mirror.c
@@ -987,11 +987,11 @@ static int _remove_mirror_images(struct logical_volume *lv,
 	}
 
 	/* FIXME: second suspend should not be needed
-	 * Explicitly suspend temporary LV
-	 * This balance critical_section_inc() calls with critical_section_dec() in resume
-	 * (both localy and in cluster) and also properly propagates precommited
+	 * Explicitly suspend temporary LV.
+	 * This balances critical_section_inc() calls with critical_section_dec()
+	 * in resume (both local and cluster) and also properly propagates precommitted
 	 * metadata into dm table on other nodes.
-	 * (visible flag set causes the suspend is not properly propagated?)
+	 * FIXME: check propagation of suspend with visible flag
 	 */
 	if (temp_layer_lv && !suspend_lv(temp_layer_lv->vg->cmd, temp_layer_lv))
 		log_error("Problem suspending temporary LV %s", temp_layer_lv->name);
diff --git a/lib/mm/memlock.h b/lib/mm/memlock.h
index be143059..d9e53f7f 100644
--- a/lib/mm/memlock.h
+++ b/lib/mm/memlock.h
@@ -18,6 +18,19 @@
 
 struct cmd_context;
 
+/*
+ * Inside a critical section, memory is always locked.
+ *
+ * After leaving the critical section, memory stays locked until 
+ * memlock_unlock() is called.  This happens with
+ * sync_local_dev_names() and sync_dev_names().
+ *
+ * This allows critical sections to be entered and exited repeatedly without
+ * incurring the expense of locking memory every time.
+ *
+ * memlock_reset() is necessary to clear the state after forking (polldaemon).
+ */
+
 void critical_section_inc(struct cmd_context *cmd);
 void critical_section_dec(struct cmd_context *cmd);
 int critical_section(void);