Merge tag 'ceph-for-5.14-rc8' of git://github.com/ceph/ceph-client

Pull ceph fixes from Ilya Dryomov:
 "Two memory management fixes for the filesystem"

* tag 'ceph-for-5.14-rc8' of git://github.com/ceph/ceph-client:
  ceph: fix possible null-pointer dereference in ceph_mdsmap_decode()
  ceph: correctly handle releasing an embedded cap flush

fs/ceph/caps.c

@@ -1743,7 +1743,11 @@ int __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask,
 
 struct ceph_cap_flush *ceph_alloc_cap_flush(void)
 {
-	return kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL);
+	struct ceph_cap_flush *cf;
+
+	cf = kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL);
+	cf->is_capsnap = false;
+	return cf;
 }
 
 void ceph_free_cap_flush(struct ceph_cap_flush *cf)
@@ -1778,7 +1782,7 @@ static bool __detach_cap_flush_from_mdsc(struct ceph_mds_client *mdsc,
 		prev->wake = true;
 		wake = false;
 	}
-	list_del(&cf->g_list);
+	list_del_init(&cf->g_list);
 	return wake;
 }
 
@@ -1793,7 +1797,7 @@ static bool __detach_cap_flush_from_ci(struct ceph_inode_info *ci,
 		prev->wake = true;
 		wake = false;
 	}
-	list_del(&cf->i_list);
+	list_del_init(&cf->i_list);
 	return wake;
 }
 
@@ -2352,7 +2356,7 @@ static void __kick_flushing_caps(struct ceph_mds_client *mdsc,
 	ci->i_ceph_flags &= ~CEPH_I_KICK_FLUSH;
 
 	list_for_each_entry_reverse(cf, &ci->i_cap_flush_list, i_list) {
-		if (!cf->caps) {
+		if (cf->is_capsnap) {
 			last_snap_flush = cf->tid;
 			break;
 		}
@@ -2371,7 +2375,7 @@ static void __kick_flushing_caps(struct ceph_mds_client *mdsc,
 
 		first_tid = cf->tid + 1;
 
-		if (cf->caps) {
+		if (!cf->is_capsnap) {
 			struct cap_msg_args arg;
 
 			dout("kick_flushing_caps %p cap %p tid %llu %s\n",
@@ -3516,7 +3520,7 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid,
 			cleaned = cf->caps;
 
 		/* Is this a capsnap? */
-		if (cf->caps == 0)
+		if (cf->is_capsnap)
 			continue;
 
 		if (cf->tid <= flush_tid) {
@@ -3589,8 +3593,9 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid,
 	while (!list_empty(&to_remove)) {
 		cf = list_first_entry(&to_remove,
 				      struct ceph_cap_flush, i_list);
-		list_del(&cf->i_list);
-		ceph_free_cap_flush(cf);
+		list_del_init(&cf->i_list);
+		if (!cf->is_capsnap)
+			ceph_free_cap_flush(cf);
 	}
 
 	if (wake_ci)

fs/ceph/mds_client.c

@@ -1616,7 +1616,7 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
 		spin_lock(&mdsc->cap_dirty_lock);
 
 		list_for_each_entry(cf, &to_remove, i_list)
-			list_del(&cf->g_list);
+			list_del_init(&cf->g_list);
 
 		if (!list_empty(&ci->i_dirty_item)) {
 			pr_warn_ratelimited(
@@ -1668,8 +1668,9 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
 		struct ceph_cap_flush *cf;
 		cf = list_first_entry(&to_remove,
 				      struct ceph_cap_flush, i_list);
-		list_del(&cf->i_list);
-		ceph_free_cap_flush(cf);
+		list_del_init(&cf->i_list);
+		if (!cf->is_capsnap)
+			ceph_free_cap_flush(cf);
 	}
 
 	wake_up_all(&ci->i_cap_wq);

fs/ceph/mdsmap.c

@@ -394,9 +394,11 @@ void ceph_mdsmap_destroy(struct ceph_mdsmap *m)
 {
 	int i;
 
-	for (i = 0; i < m->possible_max_rank; i++)
-		kfree(m->m_info[i].export_targets);
-	kfree(m->m_info);
+	if (m->m_info) {
+		for (i = 0; i < m->possible_max_rank; i++)
+			kfree(m->m_info[i].export_targets);
+		kfree(m->m_info);
+	}
 	kfree(m->m_data_pg_pools);
 	kfree(m);
 }

fs/ceph/snap.c

@@ -487,6 +487,9 @@ static void ceph_queue_cap_snap(struct ceph_inode_info *ci)
 		pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode);
 		return;
 	}
+	capsnap->cap_flush.is_capsnap = true;
+	INIT_LIST_HEAD(&capsnap->cap_flush.i_list);
+	INIT_LIST_HEAD(&capsnap->cap_flush.g_list);
 
 	spin_lock(&ci->i_ceph_lock);
 	used = __ceph_caps_used(ci);

fs/ceph/super.h

@@ -182,8 +182,9 @@ struct ceph_cap {
 
 struct ceph_cap_flush {
 	u64 tid;
-	int caps; /* 0 means capsnap */
+	int caps;
 	bool wake; /* wake up flush waiters when finish ? */
+	bool is_capsnap; /* true means capsnap */
 	struct list_head g_list; // global
 	struct list_head i_list; // per inode
 };