bcachefs: Mark new snapshots earlier in create path

This fixes a null ptr deref when creating new snapshots:
bch2_create_trans() will lookup the subvolume and find the _new_
snapshot in the BCH_CREATE_SUBVOL path that's being created in that
transaction.

We have to call bch2_mark_snapshot() earlier so that it's properly
initialized, instead of leaving it for transaction commit.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/subvolume.c b/fs/bcachefs/subvolume.c
index d76239654a8912ff5fc8fdaa0d28d9935cb41a91..bcc67c0f5dfc95992c05827ade2b759fd20e913a 100644 (file)
--- a/fs/bcachefs/subvolume.c
+++ b/fs/bcachefs/subvolume.c
@@ -513,7 +513,9 @@ int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,
                n->v.pad        = 0;
                SET_BCH_SNAPSHOT_SUBVOL(&n->v, true);
 
-               ret   = bch2_trans_update(trans, &iter, &n->k_i, 0);
+               ret   = bch2_trans_update(trans, &iter, &n->k_i, 0) ?:
+                       bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
+                                          bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0);
                if (ret)
                        goto err;
 
@@ -540,7 +542,7 @@ int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,
                n->v.children[1] = cpu_to_le32(new_snapids[1]);
                n->v.subvol = 0;
                SET_BCH_SNAPSHOT_SUBVOL(&n->v, false);
-               ret = bch2_trans_update(trans, &iter, &n->k_i, 0);
+               ret   = bch2_trans_update(trans, &iter, &n->k_i, 0);
                if (ret)
                        goto err;
        }