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_methods.h"
   5 #include "btree_update.h"
   6 #include "extents.h"
   7 #include "dirent.h"
   8 #include "fs.h"
   9 #include "keylist.h"
  10 #include "str_hash.h"
  11
  12 #include <linux/dcache.h>
  13
  14 unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
  15 {
  16         unsigned len = bkey_val_bytes(d.k) -
  17                 offsetof(struct bch_dirent, d_name);
  18
  19         return strnlen(d.v->d_name, len);
  20 }
  21
  22 static u64 bch2_dirent_hash(const struct bch_hash_info *info,
  23                             const struct qstr *name)
  24 {
  25         struct bch_str_hash_ctx ctx;
  26
  27         bch2_str_hash_init(&ctx, info);
  28         bch2_str_hash_update(&ctx, info, name->name, name->len);
  29
  30         /* [0,2) reserved for dots */
  31         return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
  32 }
  33
  34 static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
  35 {
  36         return bch2_dirent_hash(info, key);
  37 }
  38
  39 static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
  40 {
  41         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  42         struct qstr name = QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
  43
  44         return bch2_dirent_hash(info, &name);
  45 }
  46
  47 static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
  48 {
  49         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  50         int len = bch2_dirent_name_bytes(l);
  51         const struct qstr *r = _r;
  52
  53         return len - r->len ?: memcmp(l.v->d_name, r->name, len);
  54 }
  55
  56 static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
  57 {
  58         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  59         struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
  60         int l_len = bch2_dirent_name_bytes(l);
  61         int r_len = bch2_dirent_name_bytes(r);
  62
  63         return l_len - r_len ?: memcmp(l.v->d_name, r.v->d_name, l_len);
  64 }
  65
  66 const struct bch_hash_desc bch2_dirent_hash_desc = {
  67         .btree_id       = BTREE_ID_dirents,
  68         .key_type       = KEY_TYPE_dirent,
  69         .hash_key       = dirent_hash_key,
  70         .hash_bkey      = dirent_hash_bkey,
  71         .cmp_key        = dirent_cmp_key,
  72         .cmp_bkey       = dirent_cmp_bkey,
  73 };
  74
  75 const char *bch2_dirent_invalid(const struct bch_fs *c, struct bkey_s_c k)
  76 {
  77         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  78         unsigned len;
  79
  80         if (bkey_val_bytes(k.k) < sizeof(struct bch_dirent))
  81                 return "value too small";
  82
  83         len = bch2_dirent_name_bytes(d);
  84         if (!len)
  85                 return "empty name";
  86
  87         if (bkey_val_u64s(k.k) > dirent_val_u64s(len))
  88                 return "value too big";
  89
  90         if (len > BCH_NAME_MAX)
  91                 return "dirent name too big";
  92
  93         if (len == 1 && !memcmp(d.v->d_name, ".", 1))
  94                 return "invalid name";
  95
  96         if (len == 2 && !memcmp(d.v->d_name, "..", 2))
  97                 return "invalid name";
  98
  99         if (memchr(d.v->d_name, '/', len))
 100                 return "invalid name";
 101
 102         if (le64_to_cpu(d.v->d_inum) == d.k->p.inode)
 103                 return "dirent points to own directory";
 104
 105         return NULL;
 106 }
 107
 108 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c,
 109                          struct bkey_s_c k)
 110 {
 111         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 112
 113         bch_scnmemcpy(out, d.v->d_name,
 114                       bch2_dirent_name_bytes(d));
 115         pr_buf(out, " -> %llu type %s", d.v->d_inum,
 116                d.v->d_type < DT_MAX
 117                ? bch2_d_types[d.v->d_type]
 118                : "(bad d_type)");
 119 }
 120
 121 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 122                                 u8 type, const struct qstr *name, u64 dst)
 123 {
 124         struct bkey_i_dirent *dirent;
 125         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 126
 127         if (name->len > BCH_NAME_MAX)
 128                 return ERR_PTR(-ENAMETOOLONG);
 129
 130         BUG_ON(u64s > U8_MAX);
 131
 132         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 133         if (IS_ERR(dirent))
 134                 return dirent;
 135
 136         bkey_dirent_init(&dirent->k_i);
 137         dirent->k.u64s = u64s;
 138         dirent->v.d_inum = cpu_to_le64(dst);
 139         dirent->v.d_type = type;
 140
 141         memcpy(dirent->v.d_name, name->name, name->len);
 142         memset(dirent->v.d_name + name->len, 0,
 143                bkey_val_bytes(&dirent->k) -
 144                offsetof(struct bch_dirent, d_name) -
 145                name->len);
 146
 147         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 148
 149         return dirent;
 150 }
 151
 152 int bch2_dirent_create(struct btree_trans *trans,
 153                        u64 dir_inum, const struct bch_hash_info *hash_info,
 154                        u8 type, const struct qstr *name, u64 dst_inum,
 155                        u64 *dir_offset, int flags)
 156 {
 157         struct bkey_i_dirent *dirent;
 158         int ret;
 159
 160         dirent = dirent_create_key(trans, type, name, dst_inum);
 161         ret = PTR_ERR_OR_ZERO(dirent);
 162         if (ret)
 163                 return ret;
 164
 165         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 166                             dir_inum, &dirent->k_i, flags);
 167         *dir_offset = dirent->k.p.offset;
 168
 169         return ret;
 170 }
 171
 172 static void dirent_copy_target(struct bkey_i_dirent *dst,
 173                                struct bkey_s_c_dirent src)
 174 {
 175         dst->v.d_inum = src.v->d_inum;
 176         dst->v.d_type = src.v->d_type;
 177 }
 178
 179 int bch2_dirent_rename(struct btree_trans *trans,
 180                        u64 src_dir, struct bch_hash_info *src_hash,
 181                        u64 dst_dir, struct bch_hash_info *dst_hash,
 182                        const struct qstr *src_name, u64 *src_inum, u64 *src_offset,
 183                        const struct qstr *dst_name, u64 *dst_inum, u64 *dst_offset,
 184                        enum bch_rename_mode mode)
 185 {
 186         struct btree_iter *src_iter = NULL, *dst_iter = NULL;
 187         struct bkey_s_c old_src, old_dst;
 188         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 189         struct bpos dst_pos =
 190                 POS(dst_dir, bch2_dirent_hash(dst_hash, dst_name));
 191         int ret = 0;
 192
 193         *src_inum = *dst_inum = 0;
 194
 195         /*
 196          * Lookup dst:
 197          *
 198          * Note that in BCH_RENAME mode, we're _not_ checking if
 199          * the target already exists - we're relying on the VFS
 200          * to do that check for us for correctness:
 201          */
 202         dst_iter = mode == BCH_RENAME
 203                 ? bch2_hash_hole(trans, bch2_dirent_hash_desc,
 204                                  dst_hash, dst_dir, dst_name)
 205                 : bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 206                                    dst_hash, dst_dir, dst_name,
 207                                    BTREE_ITER_INTENT);
 208         ret = PTR_ERR_OR_ZERO(dst_iter);
 209         if (ret)
 210                 goto out;
 211
 212         old_dst = bch2_btree_iter_peek_slot(dst_iter);
 213
 214         if (mode != BCH_RENAME)
 215                 *dst_inum = le64_to_cpu(bkey_s_c_to_dirent(old_dst).v->d_inum);
 216         if (mode != BCH_RENAME_EXCHANGE)
 217                 *src_offset = dst_iter->pos.offset;
 218
 219         /* Lookup src: */
 220         src_iter = bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 221                                     src_hash, src_dir, src_name,
 222                                     BTREE_ITER_INTENT);
 223         ret = PTR_ERR_OR_ZERO(src_iter);
 224         if (ret)
 225                 goto out;
 226
 227         old_src = bch2_btree_iter_peek_slot(src_iter);
 228         *src_inum = le64_to_cpu(bkey_s_c_to_dirent(old_src).v->d_inum);
 229
 230         /* Create new dst key: */
 231         new_dst = dirent_create_key(trans, 0, dst_name, 0);
 232         ret = PTR_ERR_OR_ZERO(new_dst);
 233         if (ret)
 234                 goto out;
 235
 236         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 237         new_dst->k.p = dst_iter->pos;
 238
 239         /* Create new src key: */
 240         if (mode == BCH_RENAME_EXCHANGE) {
 241                 new_src = dirent_create_key(trans, 0, src_name, 0);
 242                 ret = PTR_ERR_OR_ZERO(new_src);
 243                 if (ret)
 244                         goto out;
 245
 246                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 247                 new_src->k.p = src_iter->pos;
 248         } else {
 249                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 250                 ret = PTR_ERR_OR_ZERO(new_src);
 251                 if (ret)
 252                         goto out;
 253
 254                 bkey_init(&new_src->k);
 255                 new_src->k.p = src_iter->pos;
 256
 257                 if (bkey_cmp(dst_pos, src_iter->pos) <= 0 &&
 258                     bkey_cmp(src_iter->pos, dst_iter->pos) < 0) {
 259                         /*
 260                          * We have a hash collision for the new dst key,
 261                          * and new_src - the key we're deleting - is between
 262                          * new_dst's hashed slot and the slot we're going to be
 263                          * inserting it into - oops.  This will break the hash
 264                          * table if we don't deal with it:
 265                          */
 266                         if (mode == BCH_RENAME) {
 267                                 /*
 268                                  * If we're not overwriting, we can just insert
 269                                  * new_dst at the src position:
 270                                  */
 271                                 new_dst->k.p = src_iter->pos;
 272                                 bch2_trans_update(trans, src_iter,
 273                                                   &new_dst->k_i, 0);
 274                                 goto out_set_offset;
 275                         } else {
 276                                 /* If we're overwriting, we can't insert new_dst
 277                                  * at a different slot because it has to
 278                                  * overwrite old_dst - just make sure to use a
 279                                  * whiteout when deleting src:
 280                                  */
 281                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 282                         }
 283                 } else {
 284                         /* Check if we need a whiteout to delete src: */
 285                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 286                                                        src_hash, src_iter);
 287                         if (ret < 0)
 288                                 goto out;
 289
 290                         if (ret)
 291                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 292                 }
 293         }
 294
 295         bch2_trans_update(trans, src_iter, &new_src->k_i, 0);
 296         bch2_trans_update(trans, dst_iter, &new_dst->k_i, 0);
 297 out_set_offset:
 298         if (mode == BCH_RENAME_EXCHANGE)
 299                 *src_offset = new_src->k.p.offset;
 300         *dst_offset = new_dst->k.p.offset;
 301 out:
 302         bch2_trans_iter_put(trans, src_iter);
 303         bch2_trans_iter_put(trans, dst_iter);
 304         return ret;
 305 }
 306
 307 int bch2_dirent_delete_at(struct btree_trans *trans,
 308                           const struct bch_hash_info *hash_info,
 309                           struct btree_iter *iter)
 310 {
 311         return bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
 312                                    hash_info, iter);
 313 }
 314
 315 struct btree_iter *
 316 __bch2_dirent_lookup_trans(struct btree_trans *trans, u64 dir_inum,
 317                            const struct bch_hash_info *hash_info,
 318                            const struct qstr *name, unsigned flags)
 319 {
 320         return bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 321                                 hash_info, dir_inum, name, flags);
 322 }
 323
 324 u64 bch2_dirent_lookup(struct bch_fs *c, u64 dir_inum,
 325                        const struct bch_hash_info *hash_info,
 326                        const struct qstr *name)
 327 {
 328         struct btree_trans trans;
 329         struct btree_iter *iter;
 330         struct bkey_s_c k;
 331         u64 inum = 0;
 332
 333         bch2_trans_init(&trans, c, 0, 0);
 334
 335         iter = __bch2_dirent_lookup_trans(&trans, dir_inum,
 336                                           hash_info, name, 0);
 337         if (IS_ERR(iter)) {
 338                 BUG_ON(PTR_ERR(iter) == -EINTR);
 339                 goto out;
 340         }
 341
 342         k = bch2_btree_iter_peek_slot(iter);
 343         inum = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum);
 344         bch2_trans_iter_put(&trans, iter);
 345 out:
 346         bch2_trans_exit(&trans);
 347         return inum;
 348 }
 349
 350 int bch2_empty_dir_trans(struct btree_trans *trans, u64 dir_inum)
 351 {
 352         struct btree_iter *iter;
 353         struct bkey_s_c k;
 354         int ret;
 355
 356         for_each_btree_key(trans, iter, BTREE_ID_dirents,
 357                            POS(dir_inum, 0), 0, k, ret) {
 358                 if (k.k->p.inode > dir_inum)
 359                         break;
 360
 361                 if (k.k->type == KEY_TYPE_dirent) {
 362                         ret = -ENOTEMPTY;
 363                         break;
 364                 }
 365         }
 366         bch2_trans_iter_put(trans, iter);
 367
 368         return ret;
 369 }
 370
 371 int bch2_readdir(struct bch_fs *c, u64 inum, struct dir_context *ctx)
 372 {
 373         struct btree_trans trans;
 374         struct btree_iter *iter;
 375         struct bkey_s_c k;
 376         struct bkey_s_c_dirent dirent;
 377         int ret;
 378
 379         bch2_trans_init(&trans, c, 0, 0);
 380
 381         for_each_btree_key(&trans, iter, BTREE_ID_dirents,
 382                            POS(inum, ctx->pos), 0, k, ret) {
 383                 if (k.k->p.inode > inum)
 384                         break;
 385
 386                 if (k.k->type != KEY_TYPE_dirent)
 387                         continue;
 388
 389                 dirent = bkey_s_c_to_dirent(k);
 390
 391                 /*
 392                  * XXX: dir_emit() can fault and block, while we're holding
 393                  * locks
 394                  */
 395                 ctx->pos = dirent.k->p.offset;
 396                 if (!dir_emit(ctx, dirent.v->d_name,
 397                               bch2_dirent_name_bytes(dirent),
 398                               le64_to_cpu(dirent.v->d_inum),
 399                               dirent.v->d_type))
 400                         break;
 401                 ctx->pos = dirent.k->p.offset + 1;
 402         }
 403         bch2_trans_iter_put(&trans, iter);
 404
 405         ret = bch2_trans_exit(&trans) ?: ret;
 406
 407         return ret;
 408 }