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

Signed-off-by: Alexander Aring <aahri...@redhat.com>
---
 fs/dlm/debug_fs.c     |  4 ++--
 fs/dlm/dlm_internal.h |  2 +-
 fs/dlm/lock.c         | 33 +++++++++++++++++----------------
 fs/dlm/lockspace.c    |  2 +-
 4 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index 698d6b7a20f8..9d726971ba47 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,
        size_t len = DLM_DEBUG_BUF_LEN, pos = 0, ret, rv;
 
        mutex_lock(&debug_buf_lock);
-       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);
 
        rv = simple_read_from_buffer(userbuf, count, ppos, debug_buf, pos);
        mutex_unlock(&debug_buf_lock);
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index dfc444dad329..2f32e053a9dc 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -564,7 +564,7 @@ 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 61eb285c613c..5631623ce01a 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;
 }
 
@@ -1546,14 +1546,15 @@ 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;
 }
 
 /* Handles situations where we might be processing a "fake" or "local" reply in
-   which we can't try to take waiters_mutex again. */
+ * which we can't try to take waiters_lock again.
+ */
 
 static int remove_from_waiters_ms(struct dlm_lkb *lkb,
                                  const struct dlm_message *ms, bool local)
@@ -1562,10 +1563,10 @@ 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);
        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;
 }
 
@@ -4395,7 +4396,7 @@ static void _receive_convert_reply(struct dlm_lkb *lkb,
        if (error)
                goto out;
 
-       /* local reply can happen with waiters_mutex held */
+       /* local reply can happen with waiters_lock held */
        error = remove_from_waiters_ms(lkb, ms, local);
        if (error)
                goto out;
@@ -4434,7 +4435,7 @@ static void _receive_unlock_reply(struct dlm_lkb *lkb,
        if (error)
                goto out;
 
-       /* local reply can happen with waiters_mutex held */
+       /* local reply can happen with waiters_lock held */
        error = remove_from_waiters_ms(lkb, ms, local);
        if (error)
                goto out;
@@ -4486,7 +4487,7 @@ static void _receive_cancel_reply(struct dlm_lkb *lkb,
        if (error)
                goto out;
 
-       /* local reply can happen with waiters_mutex held */
+       /* local reply can happen with waiters_lock held */
        error = remove_from_waiters_ms(lkb, ms, local);
        if (error)
                goto out;
@@ -4887,7 +4888,7 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
        if (!ms_local)
                return;
 
-       mutex_lock(&ls->ls_waiters_mutex);
+       spin_lock(&ls->ls_waiters_lock);
 
        list_for_each_entry_safe(lkb, safe, &ls->ls_waiters, lkb_wait_reply) {
 
@@ -4980,7 +4981,7 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
                                  lkb->lkb_wait_type, wait_type);
                }
        }
-       mutex_unlock(&ls->ls_waiters_mutex);
+       spin_unlock(&ls->ls_waiters_lock);
        kfree(ms_local);
 }
 
@@ -4988,7 +4989,7 @@ 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);
@@ -4996,7 +4997,7 @@ 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;
 }
@@ -5063,9 +5064,9 @@ int dlm_recover_waiters_post(struct dlm_ls *ls)
                while (!atomic_dec_and_test(&lkb->lkb_wait_count))
                        unhold_lkb(lkb);
 
-               mutex_lock(&ls->ls_waiters_mutex);
+               spin_lock(&ls->ls_waiters_lock);
                list_del_init(&lkb->lkb_wait_reply);
-               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 0455dddb0797..79dd516bde5f 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);
 
-- 
2.31.1

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