bcachefs: Fix insert_snapshot_whiteouts()

 - We were failing to set the key type on the whiteouts it was creating,
   oops.

 - Also, we need to create whiteouts when generating front splits, not
   just back splits.

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

diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c
index 09a5fff339fe61f4d41a847d3531a8423d714c9f..c3adc7b32e19ace54344a67a8b8f35d1b50602c9 100644 (file)
--- a/fs/bcachefs/data_update.c
+++ b/fs/bcachefs/data_update.c
@@ -21,9 +21,10 @@ static int insert_snapshot_whiteouts(struct btree_trans *trans,
                                     struct bpos new_pos)
 {
        struct bch_fs *c = trans->c;
-       struct btree_iter iter;
-       struct bkey_s_c k;
+       struct btree_iter iter, iter2;
+       struct bkey_s_c k, k2;
        snapshot_id_list s;
+       struct bkey_i *update;
        int ret;
 
        if (!btree_type_has_snapshots(id))
@@ -31,10 +32,7 @@ static int insert_snapshot_whiteouts(struct btree_trans *trans,
 
        darray_init(&s);
 
-       if (bkey_eq(old_pos, new_pos))
-               return 0;
-
-       if (!snapshot_t(c, old_pos.snapshot)->children[0])
+       if (!bch2_snapshot_has_children(c, old_pos.snapshot))
                return 0;
 
        bch2_trans_iter_init(trans, &iter, id, old_pos,
@@ -46,27 +44,39 @@ static int insert_snapshot_whiteouts(struct btree_trans *trans,
                if (ret)
                        break;
 
+               if (!k.k)
+                       break;
+
                if (!bkey_eq(old_pos, k.k->p))
                        break;
 
-               if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, old_pos.snapshot)) {
-                       struct bkey_i *update;
+               if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, old_pos.snapshot) &&
+                   !snapshot_list_has_ancestor(c, &s, k.k->p.snapshot)) {
+                       struct bpos whiteout_pos = new_pos;
 
-                       if (snapshot_list_has_ancestor(c, &s, k.k->p.snapshot))
-                               continue;
+                       whiteout_pos.snapshot = k.k->p.snapshot;
 
-                       update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
+                       bch2_trans_iter_init(trans, &iter2, id, whiteout_pos,
+                                            BTREE_ITER_NOT_EXTENTS|
+                                            BTREE_ITER_INTENT);
+                       k2 = bch2_btree_iter_peek_slot(&iter2);
+                       ret = bkey_err(k2);
 
-                       ret = PTR_ERR_OR_ZERO(update);
-                       if (ret)
-                               break;
+                       if (!ret && k2.k->type == KEY_TYPE_deleted) {
+                               update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
+                               ret = PTR_ERR_OR_ZERO(update);
+                               if (ret)
+                                       break;
 
-                       bkey_init(&update->k);
-                       update->k.p = new_pos;
-                       update->k.p.snapshot = k.k->p.snapshot;
+                               bkey_init(&update->k);
+                               update->k.p             = whiteout_pos;
+                               update->k.type          = KEY_TYPE_whiteout;
+
+                               ret = bch2_trans_update(trans, &iter2, update,
+                                                       BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+                       }
+                       bch2_trans_iter_exit(trans, &iter2);
 
-                       ret  = bch2_btree_insert_nonextent(trans, id, update,
-                                         BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
                        if (ret)
                                break;
 
@@ -222,9 +232,21 @@ static int __bch2_data_update_index_update(struct btree_trans *trans,
 
                next_pos = insert->k.p;
 
-               ret   = insert_snapshot_whiteouts(trans, m->btree_id,
-                                                 k.k->p, insert->k.p) ?:
-                       bch2_trans_update(trans, &iter, insert,
+               if (!bkey_eq(bkey_start_pos(&insert->k), bkey_start_pos(k.k))) {
+                       ret = insert_snapshot_whiteouts(trans, m->btree_id, k.k->p,
+                                                       bkey_start_pos(&insert->k));
+                       if (ret)
+                               goto err;
+               }
+
+               if (!bkey_eq(insert->k.p, k.k->p)) {
+                       ret = insert_snapshot_whiteouts(trans, m->btree_id,
+                                                       k.k->p, insert->k.p);
+                       if (ret)
+                               goto err;
+               }
+
+               ret   = bch2_trans_update(trans, &iter, insert,
                                BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
                        bch2_trans_commit(trans, &op->res,
                                NULL,

diff --git a/fs/bcachefs/subvolume.h b/fs/bcachefs/subvolume.h
index 65f108a83835494fd2f6a0d7e1f52df7ca1d439b..7c488c3d78e0e31d0dfa26bf525ae9e04e71c85f 100644 (file)
--- a/fs/bcachefs/subvolume.h
+++ b/fs/bcachefs/subvolume.h
@@ -68,6 +68,13 @@ static inline bool bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ances
        return id == ancestor;
 }
 
+static inline bool bch2_snapshot_has_children(struct bch_fs *c, u32 id)
+{
+       struct snapshot_t *t = snapshot_t(c, id);
+
+       return (t->children[0]|t->children[1]) != 0;
+}
+
 static inline bool snapshot_list_has_id(snapshot_id_list *s, u32 id)
 {
        u32 *i;