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authorYan, Zheng <zyan@redhat.com>2015-01-09 10:00:42 +0100
committerIlya Dryomov <idryomov@gmail.com>2015-02-19 11:31:38 +0100
commit86d8f67b26a8b30228b5177b7e594bbc89798a23 (patch)
tree8d2c95e94f1718806d0aed91854394ec5cfabe5b /fs/ceph
parentceph: avoid block operation when !TASK_RUNNING (ceph_get_caps) (diff)
downloadlinux-86d8f67b26a8b30228b5177b7e594bbc89798a23.tar.xz
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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: Yan, Zheng <zyan@redhat.com>
Diffstat (limited to 'fs/ceph')
-rw-r--r--fs/ceph/mds_client.c13
-rw-r--r--fs/ceph/mds_client.h1
2 files changed, 5 insertions, 9 deletions
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index fdf5cc8737ee..c90ca99331be 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -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;
}
/*
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index a87b92f500bb..1875b5d985c6 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -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 */