ceph: fix ci->i_head_snapc leak

We missed two places that i_wrbuffer_ref_head, i_wr_ref, i_dirty_caps
and i_flushing_caps may change. When they are all zeros, we should free
i_head_snapc.

Cc: stable@vger.kernel.org
Link: https://tracker.ceph.com/issues/38224
Reported-and-tested-by: Luis Henriques <lhenriques@suse.com>
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

2 files changed, 15 insertions, 1 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index bc5d70d6bfe6..9049c2a3e972 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1414,6 +1414,15 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
                         list_add(&ci->i_prealloc_cap_flush->i_list, &to_remove);
                         ci->i_prealloc_cap_flush = NULL;
                 }
+
+               if (drop &&
+                  ci->i_wrbuffer_ref_head == 0 &&
+                  ci->i_wr_ref == 0 &&
+                  ci->i_dirty_caps == 0 &&
+                  ci->i_flushing_caps == 0) {
+                      ceph_put_snap_context(ci->i_head_snapc);
+                      ci->i_head_snapc = NULL;
+               }
         }
         spin_unlock(&ci->i_ceph_lock);
         while (!list_empty(&to_remove)) {
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 89aa37fa0f84..b26e12cd8ec3 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -572,7 +572,12 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
         old_snapc = NULL;
 
 update_snapc:
-        if (ci->i_head_snapc) {
+       if (ci->i_wrbuffer_ref_head == 0 &&
+           ci->i_wr_ref == 0 &&
+           ci->i_dirty_caps == 0 &&
+           ci->i_flushing_caps == 0) {
+               ci->i_head_snapc = NULL;
+       } else {
                 ci->i_head_snapc = ceph_get_snap_context(new_snapc);
                 dout(" new snapc is %p\n", new_snapc);
         }