ceph: improve reference tracking for snaprealm
When snaprealm is created, its initial reference count is zero.
But in some rare cases, the newly created snaprealm is not referenced
by anyone. This causes snaprealm with zero reference count not freed.
The fix is set reference count of newly snaprealm to 1. The reference
is return the function who requests to create the snaprealm. When the
function finishes its job, it releases the reference.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index c6c33b4..85c67ae 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2286,6 +2286,7 @@
struct ceph_mds_request *req;
struct ceph_mds_reply_head *head = msg->front.iov_base;
struct ceph_mds_reply_info_parsed *rinfo; /* parsed reply info */
+ struct ceph_snap_realm *realm;
u64 tid;
int err, result;
int mds = session->s_mds;
@@ -2401,11 +2402,13 @@
}
/* snap trace */
+ realm = NULL;
if (rinfo->snapblob_len) {
down_write(&mdsc->snap_rwsem);
ceph_update_snap_trace(mdsc, rinfo->snapblob,
- rinfo->snapblob + rinfo->snapblob_len,
- le32_to_cpu(head->op) == CEPH_MDS_OP_RMSNAP);
+ rinfo->snapblob + rinfo->snapblob_len,
+ le32_to_cpu(head->op) == CEPH_MDS_OP_RMSNAP,
+ &realm);
downgrade_write(&mdsc->snap_rwsem);
} else {
down_read(&mdsc->snap_rwsem);
@@ -2423,6 +2426,8 @@
mutex_unlock(&req->r_fill_mutex);
up_read(&mdsc->snap_rwsem);
+ if (realm)
+ ceph_put_snap_realm(mdsc, realm);
out_err:
mutex_lock(&mdsc->mutex);
if (!req->r_aborted) {
