Each time dlm_add_cb() queues work or adds the lkb for queuing later to
the ls->ls_cb_delay list it increments a refcount. However if the work
is already queued or being added to the list we need to revert the
incrementation of the refcount. The function dlm_add_cb() can be called
multiple times without handling the related dlm_callback_work() work
function where it's get a put call. This patch reverts the kref_get()
when it's necessary in cases if already queued or not.
In case of dlm_callback_resume() we need to ensure that the
LSFL_CB_DELAY bit is cleared after all ls->ls_cb_delay lkbs are queued for
work. As the ls->ls_cb_delay list handling is there for queuing work for
later it should not be the case that a work was already queued, if so we
drop a warning.
Cc: sta...@vger.kernel.org
Signed-off-by: Alexander Aring <aahri...@redhat.com>
---
fs/dlm/ast.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
index 0271796d36b1..68e09ed8234e 100644
--- a/fs/dlm/ast.c
+++ b/fs/dlm/ast.c
@@ -177,6 +177,7 @@ void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int
mode, int status,
{
struct dlm_ls *ls = lkb->lkb_resource->res_ls;
uint64_t new_seq, prev_seq;
+ bool queued = true;
int rv;
spin_lock(&dlm_cb_seq_spin);
@@ -202,13 +203,19 @@ void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int
mode, int status,
mutex_lock(&ls->ls_cb_mutex);
if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
- if (list_empty(&lkb->lkb_cb_list))
+ if (list_empty(&lkb->lkb_cb_list)) {
list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
+ queued = false;
+ }
} else {
- queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
+ queued = !queue_work(ls->ls_callback_wq,
&lkb->lkb_cb_work);
}
mutex_unlock(&ls->ls_cb_mutex);
+
+ if (queued)
+ dlm_put_lkb(lkb);
}
+
out:
mutex_unlock(&lkb->lkb_cb_mutex);
}
@@ -303,9 +310,7 @@ void dlm_callback_resume(struct dlm_ls *ls)
{
struct dlm_lkb *lkb, *safe;
int count = 0, sum = 0;
- bool empty;
-
- clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
+ bool empty, queued;
if (!ls->ls_callback_wq)
return;
@@ -314,12 +319,16 @@ void dlm_callback_resume(struct dlm_ls *ls)
mutex_lock(&ls->ls_cb_mutex);
list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
list_del_init(&lkb->lkb_cb_list);
- queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
+ queued = queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
+ WARN_ON_ONCE(!queued);
+
count++;
if (count == MAX_CB_QUEUE)
break;
}
empty = list_empty(&ls->ls_cb_delay);
+ if (empty)
+ clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
mutex_unlock(&ls->ls_cb_mutex);
sum += count;
--
2.31.1
