dlm: remove callback reference counting

Get rid of the unnecessary refcounting on callback structs.
Copy interesting callback info into the lkb struct rather
than maintaining pointers to callback structs from the lkb.
This goes back to the way things were done prior to
commit 61bed0baa4db ("fs: dlm: use a non-static queue for callbacks").

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

7 files changed, 28 insertions, 55 deletions

diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
index e9da812352b4..03879c94fadb 100644
--- a/fs/dlm/ast.c
+++ b/fs/dlm/ast.c
@@ -18,25 +18,6 @@
 #include "user.h"
 #include "ast.h"
 
-void dlm_release_callback(struct kref *ref)
-{
-	struct dlm_callback *cb = container_of(ref, struct dlm_callback, ref);
-
-	dlm_free_cb(cb);
-}
-
-void dlm_callback_set_last_ptr(struct dlm_callback **from,
-			       struct dlm_callback *to)
-{
-	if (*from)
-		kref_put(&(*from)->ref, dlm_release_callback);
-
-	if (to)
-		kref_get(&to->ref);
-
-	*from = to;
-}
-
 static void dlm_callback_work(struct work_struct *work)
 {
 	struct dlm_callback *cb = container_of(work, struct dlm_callback, work);
@@ -53,7 +34,7 @@ static void dlm_callback_work(struct work_struct *work)
 		cb->astfn(cb->astparam);
 	}
 
-	kref_put(&cb->ref, dlm_release_callback);
+	dlm_free_cb(cb);
 }
 
 int dlm_queue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
@@ -70,11 +51,11 @@ int dlm_queue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
 		/* if cb is a bast, it should be skipped if the blocking mode is
 		 * compatible with the last granted mode
 		 */
-		if (lkb->lkb_last_cast) {
-			if (dlm_modes_compat(mode, lkb->lkb_last_cast->mode)) {
+		if (lkb->lkb_last_cast_cb_mode != -1) {
+			if (dlm_modes_compat(mode, lkb->lkb_last_cast_cb_mode)) {
 				log_debug(ls, "skip %x bast mode %d for cast mode %d",
 					  lkb->lkb_id, mode,
-					  lkb->lkb_last_cast->mode);
+					  lkb->lkb_last_cast_cb_mode);
 				goto out;
 			}
 		}
@@ -85,8 +66,9 @@ int dlm_queue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
 		 * is a bast for the same mode or a more restrictive mode.
 		 * (the addional > PR check is needed for PR/CW inversion)
 		 */
-		if (lkb->lkb_last_cb && lkb->lkb_last_cb->flags & DLM_CB_BAST) {
-			prev_mode = lkb->lkb_last_cb->mode;
+		if (lkb->lkb_last_cb_mode != -1 &&
+		    lkb->lkb_last_cb_flags & DLM_CB_BAST) {
+			prev_mode = lkb->lkb_last_cb_mode;
 
 			if ((prev_mode == mode) ||
 			    (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
@@ -95,19 +77,25 @@ int dlm_queue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
 				goto out;
 			}
 		}
+
+		lkb->lkb_last_bast_time = ktime_get();
+		lkb->lkb_last_bast_cb_mode = mode;
 	} else if (flags & DLM_CB_CAST) {
 		if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
-			if (lkb->lkb_last_cast)
-				prev_mode = lkb->lkb_last_cb->mode;
-			else
-				prev_mode = -1;
+			prev_mode = lkb->lkb_last_cast_cb_mode;
 
 			if (!status && lkb->lkb_lksb->sb_lvbptr &&
 			    dlm_lvb_operations[prev_mode + 1][mode + 1])
 				copy_lvb = 1;
 		}
+
+		lkb->lkb_last_cast_cb_mode = mode;
+		lkb->lkb_last_cast_time = ktime_get();
 	}
 
+	lkb->lkb_last_cb_mode = mode;
+	lkb->lkb_last_cb_flags = flags;
+
 	*cb = dlm_allocate_cb();
 	if (!*cb) {
 		rv = DLM_ENQUEUE_CALLBACK_FAILURE;
@@ -126,17 +114,7 @@ int dlm_queue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
 	(*cb)->sb_flags = (sbflags & 0x000000FF);
 	(*cb)->copy_lvb = copy_lvb;
 	(*cb)->lkb_lksb = lkb->lkb_lksb;
-	kref_init(&(*cb)->ref);
-
-	if (flags & DLM_CB_BAST) {
-		lkb->lkb_last_bast_time = ktime_get();
-		lkb->lkb_last_bast_mode = mode;
-	} else if (flags & DLM_CB_CAST) {
-		dlm_callback_set_last_ptr(&lkb->lkb_last_cast, *cb);
-		lkb->lkb_last_cast_time = ktime_get();
-	}
 
-	dlm_callback_set_last_ptr(&lkb->lkb_last_cb, *cb);
 	rv = DLM_ENQUEUE_CALLBACK_NEED_SCHED;
 
 out:
diff --git a/fs/dlm/ast.h b/fs/dlm/ast.h
index 9bd12409e1ee..9093ff043bee 100644
--- a/fs/dlm/ast.h
+++ b/fs/dlm/ast.h
@@ -19,10 +19,7 @@ int dlm_queue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
 			   struct dlm_callback **cb);
 void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
                 uint32_t sbflags);
-void dlm_callback_set_last_ptr(struct dlm_callback **from,
-			       struct dlm_callback *to);
 
-void dlm_release_callback(struct kref *ref);
 int dlm_callback_start(struct dlm_ls *ls);
 void dlm_callback_stop(struct dlm_ls *ls);
 void dlm_callback_suspend(struct dlm_ls *ls);
diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index 289d959c7700..19cdedd56629 100644
--- a/fs/dlm/debug_fs.c
+++ b/fs/dlm/debug_fs.c
@@ -247,7 +247,7 @@ static void print_format3_lock(struct seq_file *s, struct dlm_lkb *lkb,
 		   lkb->lkb_status,
 		   lkb->lkb_grmode,
 		   lkb->lkb_rqmode,
-		   lkb->lkb_last_bast_mode,
+		   lkb->lkb_last_bast_cb_mode,
 		   rsb_lookup,
 		   lkb->lkb_wait_type,
 		   lkb->lkb_lvbseq,
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index cda1526fd15b..1d2ee5c2d23d 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -258,7 +258,6 @@ struct dlm_callback {
 	uint32_t		lkb_id;
 
 	struct list_head	list;
-	struct kref		ref;
 };
 
 struct dlm_lkb {
@@ -289,9 +288,10 @@ struct dlm_lkb {
 	struct list_head	lkb_ownqueue;	/* list of locks for a process */
 	ktime_t			lkb_timestamp;
 
-	struct dlm_callback	*lkb_last_cast;
-	struct dlm_callback	*lkb_last_cb;
-	int			lkb_last_bast_mode;
+	int8_t			lkb_last_cast_cb_mode;
+	int8_t			lkb_last_bast_cb_mode;
+	int8_t			lkb_last_cb_mode;
+	uint8_t			lkb_last_cb_flags;
 	ktime_t			lkb_last_cast_time;	/* for debugging */
 	ktime_t			lkb_last_bast_time;	/* for debugging */
 
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 198672446dcd..c8426f6f518c 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1197,7 +1197,9 @@ static int _create_lkb(struct dlm_ls *ls, struct dlm_lkb **lkb_ret,
 	if (!lkb)
 		return -ENOMEM;
 
-	lkb->lkb_last_bast_mode = -1;
+	lkb->lkb_last_bast_cb_mode = DLM_LOCK_IV;
+	lkb->lkb_last_cast_cb_mode = DLM_LOCK_IV;
+	lkb->lkb_last_cb_mode = DLM_LOCK_IV;
 	lkb->lkb_nodeid = -1;
 	lkb->lkb_grmode = DLM_LOCK_IV;
 	kref_init(&lkb->lkb_ref);
@@ -6031,7 +6033,7 @@ void dlm_clear_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc)
 
 	list_for_each_entry_safe(cb, cb_safe, &proc->asts, list) {
 		list_del(&cb->list);
-		kref_put(&cb->ref, dlm_release_callback);
+		dlm_free_cb(cb);
 	}
 
 	spin_unlock(&ls->ls_clear_proc_locks);
@@ -6072,7 +6074,7 @@ static void purge_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc)
 	spin_lock(&proc->asts_spin);
 	list_for_each_entry_safe(cb, cb_safe, &proc->asts, list) {
 		list_del(&cb->list);
-		kref_put(&cb->ref, dlm_release_callback);
+		dlm_free_cb(cb);
 	}
 	spin_unlock(&proc->asts_spin);
 }
diff --git a/fs/dlm/memory.c b/fs/dlm/memory.c
index 64f212a066cf..be9398ddf357 100644
--- a/fs/dlm/memory.c
+++ b/fs/dlm/memory.c
@@ -127,10 +127,6 @@ void dlm_free_lkb(struct dlm_lkb *lkb)
 		}
 	}
 
-	/* drop references if they are set */
-	dlm_callback_set_last_ptr(&lkb->lkb_last_cast, NULL);
-	dlm_callback_set_last_ptr(&lkb->lkb_last_cb, NULL);
-
 	kmem_cache_free(lkb_cache, lkb);
 }
 
diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 334a6d64d413..b4971ba4bdd6 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -864,7 +864,7 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
 	ret = copy_result_to_user(&cb->ua,
 				  test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
 				  cb->flags, cb->mode, cb->copy_lvb, buf, count);
-	kref_put(&cb->ref, dlm_release_callback);
+	dlm_free_cb(cb);
 	return ret;
 }