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ceph: avoid block operation when !TASK_RUNNING (ceph_mdsc_close_sessions)

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

Signed-off-by: Yan, Zheng <zyan@redhat.com>
This commit is contained in:
Yan, Zheng 2015-01-09 17:00:42 +08:00 committed by Ilya Dryomov
parent c4d4a582c5
commit 86d8f67b26
2 changed files with 5 additions and 9 deletions
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13
fs/ceph/mds_client.c
View file

@ -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;
}
/*

1
fs/ceph/mds_client.h
View file

@ -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 */