bcachefs: bch2_hash_set_or_get_in_snapshot()

Add a variant of bch2_hash_set_in_snapshot() that returns the existing
key on -EEXIST.

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

diff --git a/fs/bcachefs/str_hash.h b/fs/bcachefs/str_hash.h
index d4b5718860bd6f11bc01cd1198ee9b0741aca024..ec2b1feea5204c9fa2fc709c50282286f0e976fa 100644 (file)
--- a/fs/bcachefs/str_hash.h
+++ b/fs/bcachefs/str_hash.h
@@ -252,19 +252,20 @@ int bch2_hash_needs_whiteout(struct btree_trans *trans,
 }
 
 static __always_inline
-int bch2_hash_set_in_snapshot(struct btree_trans *trans,
+struct bkey_s_c bch2_hash_set_or_get_in_snapshot(struct btree_trans *trans,
+                          struct btree_iter *iter,
                           const struct bch_hash_desc desc,
                           const struct bch_hash_info *info,
                           subvol_inum inum, u32 snapshot,
                           struct bkey_i *insert,
                           enum btree_iter_update_trigger_flags flags)
 {
-       struct btree_iter iter, slot = { NULL };
+       struct btree_iter slot = {};
        struct bkey_s_c k;
        bool found = false;
        int ret;
 
-       for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
+       for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
                           SPOS(insert->k.p.inode,
                                desc.hash_bkey(info, bkey_i_to_s_c(insert)),
                                snapshot),
@@ -279,7 +280,7 @@ int bch2_hash_set_in_snapshot(struct btree_trans *trans,
                }
 
                if (!slot.path && !(flags & STR_HASH_must_replace))
-                       bch2_trans_copy_iter(&slot, &iter);
+                       bch2_trans_copy_iter(&slot, iter);
 
                if (k.k->type != KEY_TYPE_hash_whiteout)
                        goto not_found;
@@ -289,28 +290,49 @@ int bch2_hash_set_in_snapshot(struct btree_trans *trans,
                ret = -BCH_ERR_ENOSPC_str_hash_create;
 out:
        bch2_trans_iter_exit(trans, &slot);
-       bch2_trans_iter_exit(trans, &iter);
-
-       return ret;
+       bch2_trans_iter_exit(trans, iter);
+       return ret ? bkey_s_c_err(ret) : bkey_s_c_null;
 found:
        found = true;
 not_found:
-
-       if (!found && (flags & STR_HASH_must_replace)) {
+       if (found && (flags & STR_HASH_must_create)) {
+               bch2_trans_iter_exit(trans, &slot);
+               return k;
+       } else if (!found && (flags & STR_HASH_must_replace)) {
                ret = -BCH_ERR_ENOENT_str_hash_set_must_replace;
-       } else if (found && (flags & STR_HASH_must_create)) {
-               ret = -BCH_ERR_EEXIST_str_hash_set;
        } else {
                if (!found && slot.path)
-                       swap(iter, slot);
+                       swap(*iter, slot);
 
-               insert->k.p = iter.pos;
-               ret = bch2_trans_update(trans, &iter, insert, flags);
+               insert->k.p = iter->pos;
+               ret = bch2_trans_update(trans, iter, insert, flags);
        }
 
        goto out;
 }
 
+static __always_inline
+int bch2_hash_set_in_snapshot(struct btree_trans *trans,
+                          const struct bch_hash_desc desc,
+                          const struct bch_hash_info *info,
+                          subvol_inum inum, u32 snapshot,
+                          struct bkey_i *insert,
+                          enum btree_iter_update_trigger_flags flags)
+{
+       struct btree_iter iter;
+       struct bkey_s_c k = bch2_hash_set_or_get_in_snapshot(trans, &iter, desc, info, inum,
+                                                            snapshot, insert, flags);
+       int ret = bkey_err(k);
+       if (ret)
+               return ret;
+       if (k.k) {
+               bch2_trans_iter_exit(trans, &iter);
+               return -BCH_ERR_EEXIST_str_hash_set;
+       }
+
+       return 0;
+}
+
 static __always_inline
 int bch2_hash_set(struct btree_trans *trans,
                  const struct bch_hash_desc desc,