[PATCH] ceph: correctly release memory from capsnap

[xiubli@redhat.com]

From: Xiubo Li <xiubli@redhat.com>

When force umounting, it will try to remove all the session caps.
If there has any capsnap is in the flushing list, the remove session
caps callback will try to release the capsnap->flush_cap memory to
"ceph_cap_flush_cachep" slab cache, while which is allocated from
kmalloc-256 slab cache.

URL: https://tracker.ceph.com/issues/52283
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
 fs/ceph/mds_client.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 00b3b0a0beb8..cb517753bb17 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1264,10 +1264,18 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
 	spin_unlock(&ci->i_ceph_lock);
 	while (!list_empty(&to_remove)) {
 		struct ceph_cap_flush *cf;
+		struct ceph_cap_snap *capsnap;
 		cf = list_first_entry(&to_remove,
 				      struct ceph_cap_flush, i_list);
 		list_del(&cf->i_list);
-		ceph_free_cap_flush(cf);
+		if (cf->caps) {
+			ceph_free_cap_flush(cf);
+		} else if (READ_ONCE(fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
+			capsnap = container_of(cf, struct ceph_cap_snap, cap_flush);
+			list_del(&capsnap->ci_item);
+			ceph_put_snap_context(capsnap->context);
+			ceph_put_cap_snap(capsnap);
+		}
 	}
 
 	wake_up_all(&ci->i_cap_wq);
-- 
2.27.0