[PATCHv3 v6.8-rc6 12/18] dlm: convert ls_waiters_mutex to spinlock

[Alexander Aring <aahringo@redhat.com>]

This patch converts the per dlm lockspace waiters lock from a mutex to a
spinlock.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/debug_fs.c     |  4 ++--
 fs/dlm/dlm_internal.h |  2 +-
 fs/dlm/lock.c         | 20 ++++++++++----------
 fs/dlm/lockspace.c    |  2 +-
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index b9deffeabbd1..8e7683840315 100644
--- a/fs/dlm/debug_fs.c
+++ b/fs/dlm/debug_fs.c
@@ -824,7 +824,7 @@ static ssize_t waiters_read(struct file *file, char __user *userbuf,
 
 	mutex_lock(&debug_buf_lock);
 	dlm_lock_recovery(ls);
-	mutex_lock(&ls->ls_waiters_mutex);
+	spin_lock(&ls->ls_waiters_lock);
 	memset(debug_buf, 0, sizeof(debug_buf));
 
 	list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
@@ -835,7 +835,7 @@ static ssize_t waiters_read(struct file *file, char __user *userbuf,
 			break;
 		pos += ret;
 	}
-	mutex_unlock(&ls->ls_waiters_mutex);
+	spin_unlock(&ls->ls_waiters_lock);
 	dlm_unlock_recovery(ls);
 
 	rv = simple_read_from_buffer(userbuf, count, ppos, debug_buf, pos);
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 9aa1e3a09e02..5975d52f4061 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -565,7 +565,7 @@ struct dlm_ls {
 	struct dlm_rsbtable	*ls_rsbtbl;
 	uint32_t		ls_rsbtbl_size;
 
-	struct mutex		ls_waiters_mutex;
+	spinlock_t		ls_waiters_lock;
 	struct list_head	ls_waiters;	/* lkbs needing a reply */
 
 	struct mutex		ls_orphans_mutex;
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index bd9ff32984c7..525635f42938 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1407,7 +1407,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid)
 	int error = 0;
 	int wc;
 
-	mutex_lock(&ls->ls_waiters_mutex);
+	spin_lock(&ls->ls_waiters_lock);
 
 	if (is_overlap_unlock(lkb) ||
 	    (is_overlap_cancel(lkb) && (mstype == DLM_MSG_CANCEL))) {
@@ -1447,7 +1447,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid)
 		log_error(ls, "addwait error %x %d flags %x %d %d %s",
 			  lkb->lkb_id, error, dlm_iflags_val(lkb), mstype,
 			  lkb->lkb_wait_type, lkb->lkb_resource->res_name);
-	mutex_unlock(&ls->ls_waiters_mutex);
+	spin_unlock(&ls->ls_waiters_lock);
 	return error;
 }
 
@@ -1546,9 +1546,9 @@ static int remove_from_waiters(struct dlm_lkb *lkb, int mstype)
 	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 	int error;
 
-	mutex_lock(&ls->ls_waiters_mutex);
+	spin_lock(&ls->ls_waiters_lock);
 	error = _remove_from_waiters(lkb, mstype, NULL);
-	mutex_unlock(&ls->ls_waiters_mutex);
+	spin_unlock(&ls->ls_waiters_lock);
 	return error;
 }
 
@@ -1566,13 +1566,13 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb,
 	int error;
 
 	if (!local)
-		mutex_lock(&ls->ls_waiters_mutex);
+		spin_lock(&ls->ls_waiters_lock);
 	else
 		WARN_ON_ONCE(!rwsem_is_locked(&ls->ls_in_recovery) ||
 			     !dlm_locking_stopped(ls));
 	error = _remove_from_waiters(lkb, le32_to_cpu(ms->m_type), ms);
 	if (!local)
-		mutex_unlock(&ls->ls_waiters_mutex);
+		spin_unlock(&ls->ls_waiters_lock);
 	return error;
 }
 
@@ -4990,7 +4990,7 @@ static struct dlm_lkb *find_resend_waiter(struct dlm_ls *ls)
 {
 	struct dlm_lkb *lkb = NULL, *iter;
 
-	mutex_lock(&ls->ls_waiters_mutex);
+	spin_lock(&ls->ls_waiters_lock);
 	list_for_each_entry(iter, &ls->ls_waiters, lkb_wait_reply) {
 		if (test_bit(DLM_IFL_RESEND_BIT, &iter->lkb_iflags)) {
 			hold_lkb(iter);
@@ -4998,7 +4998,7 @@ static struct dlm_lkb *find_resend_waiter(struct dlm_ls *ls)
 			break;
 		}
 	}
-	mutex_unlock(&ls->ls_waiters_mutex);
+	spin_unlock(&ls->ls_waiters_lock);
 
 	return lkb;
 }
@@ -5062,14 +5062,14 @@ int dlm_recover_waiters_post(struct dlm_ls *ls)
 		/* drop all wait_count references we still
 		 * hold a reference for this iteration.
 		 */
-		mutex_lock(&ls->ls_waiters_mutex);
+		spin_lock(&ls->ls_waiters_lock);
 		while (atomic_read(&lkb->lkb_wait_count)) {
 			if (atomic_dec_and_test(&lkb->lkb_wait_count))
 				list_del_init(&lkb->lkb_wait_reply);
 
 			unhold_lkb(lkb);
 		}
-		mutex_unlock(&ls->ls_waiters_mutex);
+		spin_unlock(&ls->ls_waiters_lock);
 
 		if (oc || ou) {
 			/* do an unlock or cancel instead of resending */
diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index 5fe00bd1164d..42866190af38 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -515,7 +515,7 @@ static int new_lockspace(const char *name, const char *cluster,
 	spin_lock_init(&ls->ls_lkbidr_spin);
 
 	INIT_LIST_HEAD(&ls->ls_waiters);
-	mutex_init(&ls->ls_waiters_mutex);
+	spin_lock_init(&ls->ls_waiters_lock);
 	INIT_LIST_HEAD(&ls->ls_orphans);
 	mutex_init(&ls->ls_orphans_mutex);
 
-- 
2.43.0