[PATCH v6.9-rc1 10/10] dlm: remove callback reference counting

[Alexander Aring <aahringo@redhat.com>]

Since we copying all necessary callback information from the lkb to the
per callback structure this structure increased in the amount of memory
being used. As each lkb structure holds a callback structure reference
for the last callback that occurred this can hold more memory than
necessary. We just copy the necessary information as it was before since
commit 61bed0baa4db ("fs: dlm: use a non-static queue for callbacks").

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/ast.c          | 56 +++++++++++++------------------------------
 fs/dlm/ast.h          |  3 ---
 fs/dlm/debug_fs.c     |  2 +-
 fs/dlm/dlm_internal.h |  8 +++----
 fs/dlm/lock.c         |  8 ++++---
 fs/dlm/memory.c       |  4 ----
 fs/dlm/user.c         |  2 +-
 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 1c0d01dc7eca..f8516b532211 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;
 }
 
-- 
2.43.0