Commit 3cb5977c authored by Alexander Aring's avatar Alexander Aring Committed by David Teigland
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fs: dlm: ls_count busy wait to event based wait 



This patch changes the ls_count busy wait to use atomic counter values
and wait_event() to wait until ls_count reach zero. It will slightly
reduce the number of holding lslist_lock. At remove lockspace we need to
retry the wait because it a lockspace get could interefere between
wait_event() and holding the lock which deletes the lockspace list entry.

Signed-off-by: default avatarAlexander Aring <aahringo@redhat.com>
Signed-off-by: default avatarDavid Teigland <teigland@redhat.com>
parent 164d88ab

fs/dlm/dlm_internal.h

+2 −1
Original line number Diff line number Diff line
@@ -548,8 +548,9 @@ struct dlm_ls { 
	uint32_t		ls_generation;

	uint32_t		ls_exflags;

	int			ls_lvblen;

	int			ls_count;	/* refcount of processes in

	atomic_t		ls_count;	/* refcount of processes in

						   the dlm using this ls */

	wait_queue_head_t	ls_count_wait;

	int			ls_create_count; /* create/release refcount */

	unsigned long		ls_flags;	/* LSFL_ */

	unsigned long		ls_scan_time;

fs/dlm/lockspace.c

+17 −16
Original line number Diff line number Diff line
@@ -314,7 +314,7 @@ struct dlm_ls *dlm_find_lockspace_global(uint32_t id) 


	list_for_each_entry(ls, &lslist, ls_list) {

		if (ls->ls_global_id == id) {

			ls->ls_count++;

			atomic_inc(&ls->ls_count);

			goto out;

		}

	}
@@ -331,7 +331,7 @@ struct dlm_ls *dlm_find_lockspace_local(dlm_lockspace_t *lockspace) 
	spin_lock(&lslist_lock);

	list_for_each_entry(ls, &lslist, ls_list) {

		if (ls->ls_local_handle == lockspace) {

			ls->ls_count++;

			atomic_inc(&ls->ls_count);

			goto out;

		}

	}
@@ -348,7 +348,7 @@ struct dlm_ls *dlm_find_lockspace_device(int minor) 
	spin_lock(&lslist_lock);

	list_for_each_entry(ls, &lslist, ls_list) {

		if (ls->ls_device.minor == minor) {

			ls->ls_count++;

			atomic_inc(&ls->ls_count);

			goto out;

		}

	}
@@ -360,24 +360,24 @@ struct dlm_ls *dlm_find_lockspace_device(int minor) 


void dlm_put_lockspace(struct dlm_ls *ls)

{

	spin_lock(&lslist_lock);

	ls->ls_count--;

	spin_unlock(&lslist_lock);

	if (atomic_dec_and_test(&ls->ls_count))

		wake_up(&ls->ls_count_wait);

}



static void remove_lockspace(struct dlm_ls *ls)

{

	for (;;) {

retry:

	wait_event(ls->ls_count_wait, atomic_read(&ls->ls_count) == 0);



	spin_lock(&lslist_lock);

		if (ls->ls_count == 0) {

			WARN_ON(ls->ls_create_count != 0);

			list_del(&ls->ls_list);

	if (atomic_read(&ls->ls_count) != 0) {

		spin_unlock(&lslist_lock);

			return;

		goto retry;

	}



	WARN_ON(ls->ls_create_count != 0);

	list_del(&ls->ls_list);

	spin_unlock(&lslist_lock);

		ssleep(1);

	}

}



static int threads_start(void)
@@ -481,7 +481,8 @@ static int new_lockspace(const char *name, const char *cluster, 
	memcpy(ls->ls_name, name, namelen);

	ls->ls_namelen = namelen;

	ls->ls_lvblen = lvblen;

	ls->ls_count = 0;

	atomic_set(&ls->ls_count, 0);

	init_waitqueue_head(&ls->ls_count_wait);

	ls->ls_flags = 0;

	ls->ls_scan_time = jiffies;

fs/dlm/requestqueue.c

+1 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ static int purge_request(struct dlm_ls *ls, struct dlm_message *ms, int nodeid) 
	uint32_t type = ms->m_type;



	/* the ls is being cleaned up and freed by release_lockspace */

	if (!ls->ls_count)

	if (!atomic_read(&ls->ls_count))

		return 1;



	if (dlm_is_removed(ls, nodeid))