git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/dirent.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_buf.h"
   5 #include "bkey_methods.h"
   6 #include "btree_update.h"
   7 #include "extents.h"
   8 #include "dirent.h"
   9 #include "fs.h"
  10 #include "keylist.h"
  11 #include "str_hash.h"
  12 #include "subvolume.h"
  13
  14 #include <linux/dcache.h>
  15
  16 static unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
  17 {
  18         unsigned bkey_u64s = bkey_val_u64s(d.k);
  19         unsigned bkey_bytes = bkey_u64s * sizeof(u64);
  20         u64 last_u64 = ((u64*)d.v)[bkey_u64s - 1];
  21 #if CPU_BIG_ENDIAN
  22         unsigned trailing_nuls = last_u64 ? __builtin_ctzll(last_u64) / 8 : 64 / 8;
  23 #else
  24         unsigned trailing_nuls = last_u64 ? __builtin_clzll(last_u64) / 8 : 64 / 8;
  25 #endif
  26
  27         return bkey_bytes -
  28                 offsetof(struct bch_dirent, d_name) -
  29                 trailing_nuls;
  30 }
  31
  32 struct qstr bch2_dirent_get_name(struct bkey_s_c_dirent d)
  33 {
  34         return (struct qstr) QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
  35 }
  36
  37 static u64 bch2_dirent_hash(const struct bch_hash_info *info,
  38                             const struct qstr *name)
  39 {
  40         struct bch_str_hash_ctx ctx;
  41
  42         bch2_str_hash_init(&ctx, info);
  43         bch2_str_hash_update(&ctx, info, name->name, name->len);
  44
  45         /* [0,2) reserved for dots */
  46         return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
  47 }
  48
  49 static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
  50 {
  51         return bch2_dirent_hash(info, key);
  52 }
  53
  54 static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
  55 {
  56         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  57         struct qstr name = bch2_dirent_get_name(d);
  58
  59         return bch2_dirent_hash(info, &name);
  60 }
  61
  62 static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
  63 {
  64         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  65         const struct qstr l_name = bch2_dirent_get_name(l);
  66         const struct qstr *r_name = _r;
  67
  68         return !qstr_eq(l_name, *r_name);
  69 }
  70
  71 static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
  72 {
  73         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  74         struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
  75         const struct qstr l_name = bch2_dirent_get_name(l);
  76         const struct qstr r_name = bch2_dirent_get_name(r);
  77
  78         return !qstr_eq(l_name, r_name);
  79 }
  80
  81 static bool dirent_is_visible(subvol_inum inum, struct bkey_s_c k)
  82 {
  83         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  84
  85         if (d.v->d_type == DT_SUBVOL)
  86                 return le32_to_cpu(d.v->d_parent_subvol) == inum.subvol;
  87         return true;
  88 }
  89
  90 const struct bch_hash_desc bch2_dirent_hash_desc = {
  91         .btree_id       = BTREE_ID_dirents,
  92         .key_type       = KEY_TYPE_dirent,
  93         .hash_key       = dirent_hash_key,
  94         .hash_bkey      = dirent_hash_bkey,
  95         .cmp_key        = dirent_cmp_key,
  96         .cmp_bkey       = dirent_cmp_bkey,
  97         .is_visible     = dirent_is_visible,
  98 };
  99
 100 int bch2_dirent_invalid(struct bch_fs *c, struct bkey_s_c k,
 101                         enum bkey_invalid_flags flags,
 102                         struct printbuf *err)
 103 {
 104         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 105         struct qstr d_name = bch2_dirent_get_name(d);
 106         int ret = 0;
 107
 108         bkey_fsck_err_on(!d_name.len, c, err,
 109                          dirent_empty_name,
 110                          "empty name");
 111
 112         bkey_fsck_err_on(bkey_val_u64s(k.k) > dirent_val_u64s(d_name.len), c, err,
 113                          dirent_val_too_big,
 114                          "value too big (%zu > %u)",
 115                          bkey_val_u64s(k.k), dirent_val_u64s(d_name.len));
 116
 117         /*
 118          * Check new keys don't exceed the max length
 119          * (older keys may be larger.)
 120          */
 121         bkey_fsck_err_on((flags & BKEY_INVALID_COMMIT) && d_name.len > BCH_NAME_MAX, c, err,
 122                          dirent_name_too_long,
 123                          "dirent name too big (%u > %u)",
 124                          d_name.len, BCH_NAME_MAX);
 125
 126         bkey_fsck_err_on(d_name.len != strnlen(d_name.name, d_name.len), c, err,
 127                          dirent_name_embedded_nul,
 128                          "dirent has stray data after name's NUL");
 129
 130         bkey_fsck_err_on((d_name.len == 1 && !memcmp(d_name.name, ".", 1)) ||
 131                          (d_name.len == 2 && !memcmp(d_name.name, "..", 2)), c, err,
 132                          dirent_name_dot_or_dotdot,
 133                          "invalid name");
 134
 135         bkey_fsck_err_on(memchr(d_name.name, '/', d_name.len), c, err,
 136                          dirent_name_has_slash,
 137                          "name with /");
 138
 139         bkey_fsck_err_on(d.v->d_type != DT_SUBVOL &&
 140                          le64_to_cpu(d.v->d_inum) == d.k->p.inode, c, err,
 141                          dirent_to_itself,
 142                          "dirent points to own directory");
 143 fsck_err:
 144         return ret;
 145 }
 146
 147 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 148 {
 149         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 150         struct qstr d_name = bch2_dirent_get_name(d);
 151
 152         prt_printf(out, "%.*s -> ", d_name.len, d_name.name);
 153
 154         if (d.v->d_type != DT_SUBVOL)
 155                 prt_printf(out, "%llu", le64_to_cpu(d.v->d_inum));
 156         else
 157                 prt_printf(out, "%u -> %u",
 158                            le32_to_cpu(d.v->d_parent_subvol),
 159                            le32_to_cpu(d.v->d_child_subvol));
 160
 161         prt_printf(out, " type %s", bch2_d_type_str(d.v->d_type));
 162 }
 163
 164 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 165                                 subvol_inum dir, u8 type,
 166                                 const struct qstr *name, u64 dst)
 167 {
 168         struct bkey_i_dirent *dirent;
 169         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 170
 171         if (name->len > BCH_NAME_MAX)
 172                 return ERR_PTR(-ENAMETOOLONG);
 173
 174         BUG_ON(u64s > U8_MAX);
 175
 176         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 177         if (IS_ERR(dirent))
 178                 return dirent;
 179
 180         bkey_dirent_init(&dirent->k_i);
 181         dirent->k.u64s = u64s;
 182
 183         if (type != DT_SUBVOL) {
 184                 dirent->v.d_inum = cpu_to_le64(dst);
 185         } else {
 186                 dirent->v.d_parent_subvol = cpu_to_le32(dir.subvol);
 187                 dirent->v.d_child_subvol = cpu_to_le32(dst);
 188         }
 189
 190         dirent->v.d_type = type;
 191
 192         memcpy(dirent->v.d_name, name->name, name->len);
 193         memset(dirent->v.d_name + name->len, 0,
 194                bkey_val_bytes(&dirent->k) -
 195                offsetof(struct bch_dirent, d_name) -
 196                name->len);
 197
 198         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 199
 200         return dirent;
 201 }
 202
 203 int bch2_dirent_create_snapshot(struct btree_trans *trans,
 204                         u32 dir_subvol, u64 dir, u32 snapshot,
 205                         const struct bch_hash_info *hash_info,
 206                         u8 type, const struct qstr *name, u64 dst_inum,
 207                         u64 *dir_offset,
 208                         bch_str_hash_flags_t str_hash_flags)
 209 {
 210         subvol_inum dir_inum = { .subvol = dir_subvol, .inum = dir };
 211         struct bkey_i_dirent *dirent;
 212         int ret;
 213
 214         dirent = dirent_create_key(trans, dir_inum, type, name, dst_inum);
 215         ret = PTR_ERR_OR_ZERO(dirent);
 216         if (ret)
 217                 return ret;
 218
 219         dirent->k.p.inode       = dir;
 220         dirent->k.p.snapshot    = snapshot;
 221
 222         ret = bch2_hash_set_in_snapshot(trans, bch2_dirent_hash_desc, hash_info,
 223                                         dir_inum, snapshot,
 224                                         &dirent->k_i, str_hash_flags,
 225                                         BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 226         *dir_offset = dirent->k.p.offset;
 227
 228         return ret;
 229 }
 230
 231 int bch2_dirent_create(struct btree_trans *trans, subvol_inum dir,
 232                        const struct bch_hash_info *hash_info,
 233                        u8 type, const struct qstr *name, u64 dst_inum,
 234                        u64 *dir_offset,
 235                        bch_str_hash_flags_t str_hash_flags)
 236 {
 237         struct bkey_i_dirent *dirent;
 238         int ret;
 239
 240         dirent = dirent_create_key(trans, dir, type, name, dst_inum);
 241         ret = PTR_ERR_OR_ZERO(dirent);
 242         if (ret)
 243                 return ret;
 244
 245         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 246                             dir, &dirent->k_i, str_hash_flags);
 247         *dir_offset = dirent->k.p.offset;
 248
 249         return ret;
 250 }
 251
 252 static void dirent_copy_target(struct bkey_i_dirent *dst,
 253                                struct bkey_s_c_dirent src)
 254 {
 255         dst->v.d_inum = src.v->d_inum;
 256         dst->v.d_type = src.v->d_type;
 257 }
 258
 259 int bch2_dirent_read_target(struct btree_trans *trans, subvol_inum dir,
 260                             struct bkey_s_c_dirent d, subvol_inum *target)
 261 {
 262         struct bch_subvolume s;
 263         int ret = 0;
 264
 265         if (d.v->d_type == DT_SUBVOL &&
 266             le32_to_cpu(d.v->d_parent_subvol) != dir.subvol)
 267                 return 1;
 268
 269         if (likely(d.v->d_type != DT_SUBVOL)) {
 270                 target->subvol  = dir.subvol;
 271                 target->inum    = le64_to_cpu(d.v->d_inum);
 272         } else {
 273                 target->subvol  = le32_to_cpu(d.v->d_child_subvol);
 274
 275                 ret = bch2_subvolume_get(trans, target->subvol, true, BTREE_ITER_CACHED, &s);
 276
 277                 target->inum    = le64_to_cpu(s.inode);
 278         }
 279
 280         return ret;
 281 }
 282
 283 int bch2_dirent_rename(struct btree_trans *trans,
 284                 subvol_inum src_dir, struct bch_hash_info *src_hash,
 285                 subvol_inum dst_dir, struct bch_hash_info *dst_hash,
 286                 const struct qstr *src_name, subvol_inum *src_inum, u64 *src_offset,
 287                 const struct qstr *dst_name, subvol_inum *dst_inum, u64 *dst_offset,
 288                 enum bch_rename_mode mode)
 289 {
 290         struct btree_iter src_iter = { NULL };
 291         struct btree_iter dst_iter = { NULL };
 292         struct bkey_s_c old_src, old_dst = bkey_s_c_null;
 293         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 294         struct bpos dst_pos =
 295                 POS(dst_dir.inum, bch2_dirent_hash(dst_hash, dst_name));
 296         unsigned src_update_flags = 0;
 297         bool delete_src, delete_dst;
 298         int ret = 0;
 299
 300         memset(src_inum, 0, sizeof(*src_inum));
 301         memset(dst_inum, 0, sizeof(*dst_inum));
 302
 303         /* Lookup src: */
 304         ret = bch2_hash_lookup(trans, &src_iter, bch2_dirent_hash_desc,
 305                                src_hash, src_dir, src_name,
 306                                BTREE_ITER_INTENT);
 307         if (ret)
 308                 goto out;
 309
 310         old_src = bch2_btree_iter_peek_slot(&src_iter);
 311         ret = bkey_err(old_src);
 312         if (ret)
 313                 goto out;
 314
 315         ret = bch2_dirent_read_target(trans, src_dir,
 316                         bkey_s_c_to_dirent(old_src), src_inum);
 317         if (ret)
 318                 goto out;
 319
 320         /* Lookup dst: */
 321         if (mode == BCH_RENAME) {
 322                 /*
 323                  * Note that we're _not_ checking if the target already exists -
 324                  * we're relying on the VFS to do that check for us for
 325                  * correctness:
 326                  */
 327                 ret = bch2_hash_hole(trans, &dst_iter, bch2_dirent_hash_desc,
 328                                      dst_hash, dst_dir, dst_name);
 329                 if (ret)
 330                         goto out;
 331         } else {
 332                 ret = bch2_hash_lookup(trans, &dst_iter, bch2_dirent_hash_desc,
 333                                        dst_hash, dst_dir, dst_name,
 334                                        BTREE_ITER_INTENT);
 335                 if (ret)
 336                         goto out;
 337
 338                 old_dst = bch2_btree_iter_peek_slot(&dst_iter);
 339                 ret = bkey_err(old_dst);
 340                 if (ret)
 341                         goto out;
 342
 343                 ret = bch2_dirent_read_target(trans, dst_dir,
 344                                 bkey_s_c_to_dirent(old_dst), dst_inum);
 345                 if (ret)
 346                         goto out;
 347         }
 348
 349         if (mode != BCH_RENAME_EXCHANGE)
 350                 *src_offset = dst_iter.pos.offset;
 351
 352         /* Create new dst key: */
 353         new_dst = dirent_create_key(trans, dst_dir, 0, dst_name, 0);
 354         ret = PTR_ERR_OR_ZERO(new_dst);
 355         if (ret)
 356                 goto out;
 357
 358         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 359         new_dst->k.p = dst_iter.pos;
 360
 361         /* Create new src key: */
 362         if (mode == BCH_RENAME_EXCHANGE) {
 363                 new_src = dirent_create_key(trans, src_dir, 0, src_name, 0);
 364                 ret = PTR_ERR_OR_ZERO(new_src);
 365                 if (ret)
 366                         goto out;
 367
 368                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 369                 new_src->k.p = src_iter.pos;
 370         } else {
 371                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 372                 ret = PTR_ERR_OR_ZERO(new_src);
 373                 if (ret)
 374                         goto out;
 375
 376                 bkey_init(&new_src->k);
 377                 new_src->k.p = src_iter.pos;
 378
 379                 if (bkey_le(dst_pos, src_iter.pos) &&
 380                     bkey_lt(src_iter.pos, dst_iter.pos)) {
 381                         /*
 382                          * We have a hash collision for the new dst key,
 383                          * and new_src - the key we're deleting - is between
 384                          * new_dst's hashed slot and the slot we're going to be
 385                          * inserting it into - oops.  This will break the hash
 386                          * table if we don't deal with it:
 387                          */
 388                         if (mode == BCH_RENAME) {
 389                                 /*
 390                                  * If we're not overwriting, we can just insert
 391                                  * new_dst at the src position:
 392                                  */
 393                                 new_src = new_dst;
 394                                 new_src->k.p = src_iter.pos;
 395                                 goto out_set_src;
 396                         } else {
 397                                 /* If we're overwriting, we can't insert new_dst
 398                                  * at a different slot because it has to
 399                                  * overwrite old_dst - just make sure to use a
 400                                  * whiteout when deleting src:
 401                                  */
 402                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 403                         }
 404                 } else {
 405                         /* Check if we need a whiteout to delete src: */
 406                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 407                                                        src_hash, &src_iter);
 408                         if (ret < 0)
 409                                 goto out;
 410
 411                         if (ret)
 412                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 413                 }
 414         }
 415
 416         if (new_dst->v.d_type == DT_SUBVOL)
 417                 new_dst->v.d_parent_subvol = cpu_to_le32(dst_dir.subvol);
 418
 419         if ((mode == BCH_RENAME_EXCHANGE) &&
 420             new_src->v.d_type == DT_SUBVOL)
 421                 new_src->v.d_parent_subvol = cpu_to_le32(src_dir.subvol);
 422
 423         ret = bch2_trans_update(trans, &dst_iter, &new_dst->k_i, 0);
 424         if (ret)
 425                 goto out;
 426 out_set_src:
 427         /*
 428          * If we're deleting a subvolume we need to really delete the dirent,
 429          * not just emit a whiteout in the current snapshot - there can only be
 430          * single dirent that points to a given subvolume.
 431          *
 432          * IOW, we don't maintain multiple versions in different snapshots of
 433          * dirents that point to subvolumes - dirents that point to subvolumes
 434          * are only visible in one particular subvolume so it's not necessary,
 435          * and it would be particularly confusing for fsck to have to deal with.
 436          */
 437         delete_src = bkey_s_c_to_dirent(old_src).v->d_type == DT_SUBVOL &&
 438                 new_src->k.p.snapshot != old_src.k->p.snapshot;
 439
 440         delete_dst = old_dst.k &&
 441                 bkey_s_c_to_dirent(old_dst).v->d_type == DT_SUBVOL &&
 442                 new_dst->k.p.snapshot != old_dst.k->p.snapshot;
 443
 444         if (!delete_src || !bkey_deleted(&new_src->k)) {
 445                 ret = bch2_trans_update(trans, &src_iter, &new_src->k_i, src_update_flags);
 446                 if (ret)
 447                         goto out;
 448         }
 449
 450         if (delete_src) {
 451                 bch2_btree_iter_set_snapshot(&src_iter, old_src.k->p.snapshot);
 452                 ret =   bch2_btree_iter_traverse(&src_iter) ?:
 453                         bch2_btree_delete_at(trans, &src_iter, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 454                 if (ret)
 455                         goto out;
 456         }
 457
 458         if (delete_dst) {
 459                 bch2_btree_iter_set_snapshot(&dst_iter, old_dst.k->p.snapshot);
 460                 ret =   bch2_btree_iter_traverse(&dst_iter) ?:
 461                         bch2_btree_delete_at(trans, &dst_iter, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 462                 if (ret)
 463                         goto out;
 464         }
 465
 466         if (mode == BCH_RENAME_EXCHANGE)
 467                 *src_offset = new_src->k.p.offset;
 468         *dst_offset = new_dst->k.p.offset;
 469 out:
 470         bch2_trans_iter_exit(trans, &src_iter);
 471         bch2_trans_iter_exit(trans, &dst_iter);
 472         return ret;
 473 }
 474
 475 int bch2_dirent_lookup_trans(struct btree_trans *trans,
 476                              struct btree_iter *iter,
 477                              subvol_inum dir,
 478                              const struct bch_hash_info *hash_info,
 479                              const struct qstr *name, subvol_inum *inum,
 480                              unsigned flags)
 481 {
 482         int ret = bch2_hash_lookup(trans, iter, bch2_dirent_hash_desc,
 483                                    hash_info, dir, name, flags);
 484         if (ret)
 485                 return ret;
 486
 487         struct bkey_s_c k = bch2_btree_iter_peek_slot(iter);
 488         ret = bkey_err(k);
 489         if (ret)
 490                 goto err;
 491
 492         ret = bch2_dirent_read_target(trans, dir, bkey_s_c_to_dirent(k), inum);
 493         if (ret > 0)
 494                 ret = -ENOENT;
 495 err:
 496         if (ret)
 497                 bch2_trans_iter_exit(trans, iter);
 498         return ret;
 499 }
 500
 501 u64 bch2_dirent_lookup(struct bch_fs *c, subvol_inum dir,
 502                        const struct bch_hash_info *hash_info,
 503                        const struct qstr *name, subvol_inum *inum)
 504 {
 505         struct btree_trans *trans = bch2_trans_get(c);
 506         struct btree_iter iter = { NULL };
 507
 508         int ret = lockrestart_do(trans,
 509                 bch2_dirent_lookup_trans(trans, &iter, dir, hash_info, name, inum, 0));
 510         bch2_trans_iter_exit(trans, &iter);
 511         bch2_trans_put(trans);
 512         return ret;
 513 }
 514
 515 int bch2_empty_dir_snapshot(struct btree_trans *trans, u64 dir, u32 subvol, u32 snapshot)
 516 {
 517         struct btree_iter iter;
 518         struct bkey_s_c k;
 519         int ret;
 520
 521         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 522                            SPOS(dir, 0, snapshot),
 523                            POS(dir, U64_MAX), 0, k, ret)
 524                 if (k.k->type == KEY_TYPE_dirent) {
 525                         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 526                         if (d.v->d_type == DT_SUBVOL && le32_to_cpu(d.v->d_parent_subvol) != subvol)
 527                                 continue;
 528                         ret = -BCH_ERR_ENOTEMPTY_dir_not_empty;
 529                         break;
 530                 }
 531         bch2_trans_iter_exit(trans, &iter);
 532
 533         return ret;
 534 }
 535
 536 int bch2_empty_dir_trans(struct btree_trans *trans, subvol_inum dir)
 537 {
 538         u32 snapshot;
 539
 540         return bch2_subvolume_get_snapshot(trans, dir.subvol, &snapshot) ?:
 541                 bch2_empty_dir_snapshot(trans, dir.inum, dir.subvol, snapshot);
 542 }
 543
 544 int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
 545 {
 546         struct btree_trans *trans = bch2_trans_get(c);
 547         struct btree_iter iter;
 548         struct bkey_s_c k;
 549         struct bkey_s_c_dirent dirent;
 550         subvol_inum target;
 551         u32 snapshot;
 552         struct bkey_buf sk;
 553         struct qstr name;
 554         int ret;
 555
 556         bch2_bkey_buf_init(&sk);
 557 retry:
 558         bch2_trans_begin(trans);
 559
 560         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 561         if (ret)
 562                 goto err;
 563
 564         for_each_btree_key_upto_norestart(trans, iter, BTREE_ID_dirents,
 565                            SPOS(inum.inum, ctx->pos, snapshot),
 566                            POS(inum.inum, U64_MAX), 0, k, ret) {
 567                 if (k.k->type != KEY_TYPE_dirent)
 568                         continue;
 569
 570                 dirent = bkey_s_c_to_dirent(k);
 571
 572                 ret = bch2_dirent_read_target(trans, inum, dirent, &target);
 573                 if (ret < 0)
 574                         break;
 575                 if (ret)
 576                         continue;
 577
 578                 /* dir_emit() can fault and block: */
 579                 bch2_bkey_buf_reassemble(&sk, c, k);
 580                 dirent = bkey_i_to_s_c_dirent(sk.k);
 581                 bch2_trans_unlock(trans);
 582
 583                 name = bch2_dirent_get_name(dirent);
 584
 585                 ctx->pos = dirent.k->p.offset;
 586                 if (!dir_emit(ctx, name.name,
 587                               name.len,
 588                               target.inum,
 589                               vfs_d_type(dirent.v->d_type)))
 590                         break;
 591                 ctx->pos = dirent.k->p.offset + 1;
 592
 593                 /*
 594                  * read_target looks up subvolumes, we can overflow paths if the
 595                  * directory has many subvolumes in it
 596                  */
 597                 ret = btree_trans_too_many_iters(trans);
 598                 if (ret)
 599                         break;
 600         }
 601         bch2_trans_iter_exit(trans, &iter);
 602 err:
 603         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 604                 goto retry;
 605
 606         bch2_trans_put(trans);
 607         bch2_bkey_buf_exit(&sk, c);
 608
 609         return ret;
 610 }