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Commit 86d8f67b authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: avoid block operation when !TASK_RUNNING (ceph_mdsc_close_sessions) 



use an atomic variable to track number of sessions, this can avoid block
operation inside wait loops.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent c4d4a582

fs/ceph/mds_client.c

+4 −9
Original line number Diff line number Diff line
@@ -480,6 +480,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc, 
		mdsc->max_sessions = newmax;

	}

	mdsc->sessions[mds] = s;

	atomic_inc(&mdsc->num_sessions);

	atomic_inc(&s->s_ref);  /* one ref to sessions[], one to caller */



	ceph_con_open(&s->s_con, CEPH_ENTITY_TYPE_MDS, mds,
@@ -503,6 +504,7 @@ static void __unregister_session(struct ceph_mds_client *mdsc, 
	mdsc->sessions[s->s_mds] = NULL;

	ceph_con_close(&s->s_con);

	ceph_put_mds_session(s);

	atomic_dec(&mdsc->num_sessions);

}



/*
@@ -3328,6 +3330,7 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc) 
	init_waitqueue_head(&mdsc->session_close_wq);

	INIT_LIST_HEAD(&mdsc->waiting_for_map);

	mdsc->sessions = NULL;

	atomic_set(&mdsc->num_sessions, 0);

	mdsc->max_sessions = 0;

	mdsc->stopping = 0;

	init_rwsem(&mdsc->snap_rwsem);
@@ -3479,17 +3482,9 @@ void ceph_mdsc_sync(struct ceph_mds_client *mdsc) 
 */

static bool done_closing_sessions(struct ceph_mds_client *mdsc)

{

	int i, n = 0;



	if (mdsc->fsc->mount_state == CEPH_MOUNT_SHUTDOWN)

		return true;



	mutex_lock(&mdsc->mutex);

	for (i = 0; i < mdsc->max_sessions; i++)

		if (mdsc->sessions[i])

			n++;

	mutex_unlock(&mdsc->mutex);

	return n == 0;

	return atomic_read(&mdsc->num_sessions) == 0;

}



/*

fs/ceph/mds_client.h

+1 −0
Original line number Diff line number Diff line
@@ -273,6 +273,7 @@ struct ceph_mds_client { 
	struct list_head        waiting_for_map;



	struct ceph_mds_session **sessions;    /* NULL for mds if no session */

	atomic_t		num_sessions;

	int                     max_sessions;  /* len of s_mds_sessions */

	int                     stopping;      /* true if shutting down */