bcachefs: Convert subvol code to for_each_btree_key_commit()

The new for_each_btree_key2() macro handles transaction retries,
allowing us to avoid nested transactions - which we want to avoid since
they're tricky to do completely correctly and upcoming assertions are
going to be checking for that.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/subvolume.c b/fs/bcachefs/subvolume.c
index 1a212bac2a04624709fde0d92aaa53a47af6b117..76be8735c700ff8839880bd42a700f205357310a 100644 (file)
--- a/fs/bcachefs/subvolume.c
+++ b/fs/bcachefs/subvolume.c
@@ -291,22 +291,14 @@ int bch2_fs_check_snapshots(struct bch_fs *c)
 }
 
 static int check_subvol(struct btree_trans *trans,
-                       struct btree_iter *iter)
+                       struct btree_iter *iter,
+                       struct bkey_s_c k)
 {
-       struct bkey_s_c k;
        struct bkey_s_c_subvolume subvol;
        struct bch_snapshot snapshot;
        unsigned snapid;
        int ret;
 
-       k = bch2_btree_iter_peek(iter);
-       if (!k.k)
-               return 0;
-
-       ret = bkey_err(k);
-       if (ret)
-               return ret;
-
        if (k.k->type != KEY_TYPE_subvolume)
                return 0;
 
@@ -336,22 +328,15 @@ int bch2_fs_check_subvols(struct bch_fs *c)
 {
        struct btree_trans trans;
        struct btree_iter iter;
+       struct bkey_s_c k;
        int ret;
 
        bch2_trans_init(&trans, c, 0, 0);
 
-       bch2_trans_iter_init(&trans, &iter, BTREE_ID_subvolumes,
-                            POS_MIN, BTREE_ITER_PREFETCH);
-
-       do {
-               ret = commit_do(&trans, NULL, NULL,
-                                     BTREE_INSERT_LAZY_RW|
-                                     BTREE_INSERT_NOFAIL,
-                                     check_subvol(&trans, &iter));
-               if (ret)
-                       break;
-       } while (bch2_btree_iter_advance(&iter));
-       bch2_trans_iter_exit(&trans, &iter);
+       ret = for_each_btree_key_commit(&trans, iter,
+                       BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_PREFETCH, k,
+                       NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
+               check_subvol(&trans, &iter, k));
 
        bch2_trans_exit(&trans);
 
@@ -595,59 +580,27 @@ err:
        return ret;
 }
 
-static int bch2_snapshot_delete_keys_btree(struct btree_trans *trans,
-                                          snapshot_id_list *deleted,
-                                          enum btree_id btree_id)
+static int snapshot_delete_key(struct btree_trans *trans,
+                              struct btree_iter *iter,
+                              struct bkey_s_c k,
+                              snapshot_id_list *deleted,
+                              snapshot_id_list *equiv_seen,
+                              struct bpos *last_pos)
 {
        struct bch_fs *c = trans->c;
-       struct btree_iter iter;
-       struct bkey_s_c k;
-       snapshot_id_list equiv_seen = { 0 };
-       struct bpos last_pos = POS_MIN;
-       int ret = 0;
+       u32 equiv = snapshot_t(c, k.k->p.snapshot)->equiv;
 
-       /*
-        * XXX: We should also delete whiteouts that no longer overwrite
-        * anything
-        */
-
-       bch2_trans_iter_init(trans, &iter, btree_id, POS_MIN,
-                            BTREE_ITER_INTENT|
-                            BTREE_ITER_PREFETCH|
-                            BTREE_ITER_NOT_EXTENTS|
-                            BTREE_ITER_ALL_SNAPSHOTS);
-
-       while ((bch2_trans_begin(trans),
-               (k = bch2_btree_iter_peek(&iter)).k) &&
-              !(ret = bkey_err(k))) {
-               u32 equiv = snapshot_t(c, k.k->p.snapshot)->equiv;
-
-               if (bkey_cmp(k.k->p, last_pos))
-                       equiv_seen.nr = 0;
-               last_pos = k.k->p;
-
-               if (snapshot_list_has_id(deleted, k.k->p.snapshot) ||
-                   snapshot_list_has_id(&equiv_seen, equiv)) {
-                       ret = commit_do(trans, NULL, NULL,
-                                             BTREE_INSERT_NOFAIL,
-                               bch2_btree_iter_traverse(&iter) ?:
-                               bch2_btree_delete_at(trans, &iter,
-                                       BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE));
-                       if (ret)
-                               break;
-               } else {
-                       ret = snapshot_list_add(c, &equiv_seen, equiv);
-                       if (ret)
-                               break;
-               }
+       if (bkey_cmp(k.k->p, *last_pos))
+               equiv_seen->nr = 0;
+       *last_pos = k.k->p;
 
-               bch2_btree_iter_advance(&iter);
+       if (snapshot_list_has_id(deleted, k.k->p.snapshot) ||
+           snapshot_list_has_id(equiv_seen, equiv)) {
+               return bch2_btree_delete_at(trans, iter,
+                                           BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+       } else {
+               return snapshot_list_add(c, equiv_seen, equiv);
        }
-       bch2_trans_iter_exit(trans, &iter);
-
-       darray_exit(&equiv_seen);
-
-       return ret;
 }
 
 static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct btree_iter *iter,
@@ -742,10 +695,20 @@ int bch2_delete_dead_snapshots(struct bch_fs *c)
        }
 
        for (id = 0; id < BTREE_ID_NR; id++) {
+               struct bpos last_pos = POS_MIN;
+               snapshot_id_list equiv_seen = { 0 };
+
                if (!btree_type_has_snapshots(id))
                        continue;
 
-               ret = bch2_snapshot_delete_keys_btree(&trans, &deleted, id);
+               ret = for_each_btree_key_commit(&trans, iter,
+                               id, POS_MIN,
+                               BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
+                               NULL, NULL, BTREE_INSERT_NOFAIL,
+                       snapshot_delete_key(&trans, &iter, k, &deleted, &equiv_seen, &last_pos));
+
+               darray_exit(&equiv_seen);
+
                if (ret) {
                        bch_err(c, "error deleting snapshot keys: %i", ret);
                        goto err;