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

   1
   2 #include "bcachefs.h"
   3 #include "bkey_methods.h"
   4 #include "btree_update.h"
   5 #include "extents.h"
   6 #include "dirent.h"
   7 #include "fs.h"
   8 #include "keylist.h"
   9 #include "str_hash.h"
  10
  11 #include <linux/dcache.h>
  12
  13 unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
  14 {
  15         unsigned len = bkey_val_bytes(d.k) -
  16                 offsetof(struct bch_dirent, d_name);
  17
  18         while (len && !d.v->d_name[len - 1])
  19                 --len;
  20
  21         return len;
  22 }
  23
  24 static unsigned dirent_val_u64s(unsigned len)
  25 {
  26         return DIV_ROUND_UP(offsetof(struct bch_dirent, d_name) + len,
  27                             sizeof(u64));
  28 }
  29
  30 static u64 bch2_dirent_hash(const struct bch_hash_info *info,
  31                             const struct qstr *name)
  32 {
  33         struct bch_str_hash_ctx ctx;
  34
  35         bch2_str_hash_init(&ctx, info);
  36         bch2_str_hash_update(&ctx, info, name->name, name->len);
  37
  38         /* [0,2) reserved for dots */
  39         return max_t(u64, bch2_str_hash_end(&ctx, info), 2);
  40 }
  41
  42 static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key)
  43 {
  44         return bch2_dirent_hash(info, key);
  45 }
  46
  47 static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
  48 {
  49         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
  50         struct qstr name = QSTR_INIT(d.v->d_name, bch2_dirent_name_bytes(d));
  51
  52         return bch2_dirent_hash(info, &name);
  53 }
  54
  55 static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r)
  56 {
  57         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  58         int len = bch2_dirent_name_bytes(l);
  59         const struct qstr *r = _r;
  60
  61         return len - r->len ?: memcmp(l.v->d_name, r->name, len);
  62 }
  63
  64 static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
  65 {
  66         struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l);
  67         struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r);
  68         int l_len = bch2_dirent_name_bytes(l);
  69         int r_len = bch2_dirent_name_bytes(r);
  70
  71         return l_len - r_len ?: memcmp(l.v->d_name, r.v->d_name, l_len);
  72 }
  73
  74 const struct bch_hash_desc bch2_dirent_hash_desc = {
  75         .btree_id       = BTREE_ID_DIRENTS,
  76         .key_type       = BCH_DIRENT,
  77         .whiteout_type  = BCH_DIRENT_WHITEOUT,
  78         .hash_key       = dirent_hash_key,
  79         .hash_bkey      = dirent_hash_bkey,
  80         .cmp_key        = dirent_cmp_key,
  81         .cmp_bkey       = dirent_cmp_bkey,
  82 };
  83
  84 const char *bch2_dirent_invalid(const struct bch_fs *c, struct bkey_s_c k)
  85 {
  86         struct bkey_s_c_dirent d;
  87         unsigned len;
  88
  89         switch (k.k->type) {
  90         case BCH_DIRENT:
  91                 if (bkey_val_bytes(k.k) < sizeof(struct bch_dirent))
  92                         return "value too small";
  93
  94                 d = bkey_s_c_to_dirent(k);
  95                 len = bch2_dirent_name_bytes(d);
  96
  97                 if (!len)
  98                         return "empty name";
  99
 100                 /*
 101                  * older versions of bcachefs were buggy and creating dirent
 102                  * keys that were bigger than necessary:
 103                  */
 104                 if (bkey_val_u64s(k.k) > dirent_val_u64s(len + 7))
 105                         return "value too big";
 106
 107                 if (len > BCH_NAME_MAX)
 108                         return "dirent name too big";
 109
 110                 if (memchr(d.v->d_name, '/', len))
 111                         return "dirent name has invalid characters";
 112
 113                 return NULL;
 114         case BCH_DIRENT_WHITEOUT:
 115                 return bkey_val_bytes(k.k) != 0
 116                         ? "value size should be zero"
 117                         : NULL;
 118
 119         default:
 120                 return "invalid type";
 121         }
 122 }
 123
 124 void bch2_dirent_to_text(struct bch_fs *c, char *buf,
 125                          size_t size, struct bkey_s_c k)
 126 {
 127         struct bkey_s_c_dirent d;
 128         size_t n = 0;
 129
 130         switch (k.k->type) {
 131         case BCH_DIRENT:
 132                 d = bkey_s_c_to_dirent(k);
 133
 134                 n += bch_scnmemcpy(buf + n, size - n, d.v->d_name,
 135                                    bch2_dirent_name_bytes(d));
 136                 n += scnprintf(buf + n, size - n, " -> %llu", d.v->d_inum);
 137                 break;
 138         case BCH_DIRENT_WHITEOUT:
 139                 scnprintf(buf, size, "whiteout");
 140                 break;
 141         }
 142 }
 143
 144 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 145                                 u8 type, const struct qstr *name, u64 dst)
 146 {
 147         struct bkey_i_dirent *dirent;
 148         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 149
 150         if (name->len > BCH_NAME_MAX)
 151                 return ERR_PTR(-ENAMETOOLONG);
 152
 153         BUG_ON(u64s > U8_MAX);
 154
 155         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 156         if (IS_ERR(dirent))
 157                 return dirent;
 158
 159         bkey_dirent_init(&dirent->k_i);
 160         dirent->k.u64s = u64s;
 161         dirent->v.d_inum = cpu_to_le64(dst);
 162         dirent->v.d_type = type;
 163
 164         memcpy(dirent->v.d_name, name->name, name->len);
 165         memset(dirent->v.d_name + name->len, 0,
 166                bkey_val_bytes(&dirent->k) -
 167                offsetof(struct bch_dirent, d_name) -
 168                name->len);
 169
 170         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 171
 172         return dirent;
 173 }
 174
 175 int __bch2_dirent_create(struct btree_trans *trans,
 176                          u64 dir_inum, const struct bch_hash_info *hash_info,
 177                          u8 type, const struct qstr *name, u64 dst_inum,
 178                          int flags)
 179 {
 180         struct bkey_i_dirent *dirent;
 181         int ret;
 182
 183         dirent = dirent_create_key(trans, type, name, dst_inum);
 184         ret = PTR_ERR_OR_ZERO(dirent);
 185         if (ret)
 186                 return ret;
 187
 188         return __bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 189                                dir_inum, &dirent->k_i, flags);
 190 }
 191
 192 int bch2_dirent_create(struct bch_fs *c, u64 dir_inum,
 193                        const struct bch_hash_info *hash_info,
 194                        u8 type, const struct qstr *name, u64 dst_inum,
 195                        u64 *journal_seq, int flags)
 196 {
 197         return bch2_trans_do(c, journal_seq, flags,
 198                 __bch2_dirent_create(&trans, dir_inum, hash_info,
 199                                      type, name, dst_inum, flags));
 200 }
 201
 202 static void dirent_copy_target(struct bkey_i_dirent *dst,
 203                                struct bkey_s_c_dirent src)
 204 {
 205         dst->v.d_inum = src.v->d_inum;
 206         dst->v.d_type = src.v->d_type;
 207 }
 208
 209 static struct bpos bch2_dirent_pos(struct bch_inode_info *inode,
 210                                    const struct qstr *name)
 211 {
 212         return POS(inode->v.i_ino, bch2_dirent_hash(&inode->ei_str_hash, name));
 213 }
 214
 215 int bch2_dirent_rename(struct btree_trans *trans,
 216                 struct bch_inode_info *src_dir, const struct qstr *src_name,
 217                 struct bch_inode_info *dst_dir, const struct qstr *dst_name,
 218                 enum bch_rename_mode mode)
 219 {
 220         struct btree_iter *src_iter, *dst_iter;
 221         struct bkey_s_c old_src, old_dst;
 222         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 223         struct bpos dst_pos = bch2_dirent_pos(dst_dir, dst_name);
 224         int ret;
 225
 226         /*
 227          * Lookup dst:
 228          *
 229          * Note that in BCH_RENAME mode, we're _not_ checking if
 230          * the target already exists - we're relying on the VFS
 231          * to do that check for us for correctness:
 232          */
 233         dst_iter = mode == BCH_RENAME
 234                 ? bch2_hash_hole(trans, bch2_dirent_hash_desc,
 235                                  &dst_dir->ei_str_hash,
 236                                  dst_dir->v.i_ino, dst_name)
 237                 : bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 238                                    &dst_dir->ei_str_hash,
 239                                    dst_dir->v.i_ino, dst_name,
 240                                    BTREE_ITER_INTENT);
 241         if (IS_ERR(dst_iter))
 242                 return PTR_ERR(dst_iter);
 243         old_dst = bch2_btree_iter_peek_slot(dst_iter);
 244
 245         /* Lookup src: */
 246         src_iter = bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 247                                     &src_dir->ei_str_hash,
 248                                     src_dir->v.i_ino, src_name,
 249                                     BTREE_ITER_INTENT);
 250         if (IS_ERR(src_iter))
 251                 return PTR_ERR(src_iter);
 252         old_src = bch2_btree_iter_peek_slot(src_iter);
 253
 254         /* Create new dst key: */
 255         new_dst = dirent_create_key(trans, 0, dst_name, 0);
 256         if (IS_ERR(new_dst))
 257                 return PTR_ERR(new_dst);
 258
 259         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 260         new_dst->k.p = dst_iter->pos;
 261
 262         /* Create new src key: */
 263         if (mode == BCH_RENAME_EXCHANGE) {
 264                 new_src = dirent_create_key(trans, 0, src_name, 0);
 265                 if (IS_ERR(new_src))
 266                         return PTR_ERR(new_src);
 267
 268                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 269                 new_src->k.p = src_iter->pos;
 270         } else {
 271                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 272                 if (IS_ERR(new_src))
 273                         return PTR_ERR(new_src);
 274                 bkey_init(&new_src->k);
 275                 new_src->k.p = src_iter->pos;
 276
 277                 if (bkey_cmp(dst_pos, src_iter->pos) <= 0 &&
 278                     bkey_cmp(src_iter->pos, dst_iter->pos) < 0) {
 279                         /*
 280                          * We have a hash collision for the new dst key,
 281                          * and new_src - the key we're deleting - is between
 282                          * new_dst's hashed slot and the slot we're going to be
 283                          * inserting it into - oops.  This will break the hash
 284                          * table if we don't deal with it:
 285                          */
 286                         if (mode == BCH_RENAME) {
 287                                 /*
 288                                  * If we're not overwriting, we can just insert
 289                                  * new_dst at the src position:
 290                                  */
 291                                 new_dst->k.p = src_iter->pos;
 292                                 bch2_trans_update(trans, src_iter, &new_dst->k_i, 0);
 293                                 return 0;
 294                         } else {
 295                                 /* If we're overwriting, we can't insert new_dst
 296                                  * at a different slot because it has to
 297                                  * overwrite old_dst - just make sure to use a
 298                                  * whiteout when deleting src:
 299                                  */
 300                                 new_src->k.type = BCH_DIRENT_WHITEOUT;
 301                         }
 302                 } else {
 303                         /* Check if we need a whiteout to delete src: */
 304                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 305                                                        &src_dir->ei_str_hash,
 306                                                        src_iter);
 307                         if (ret < 0)
 308                                 return ret;
 309
 310                         if (ret)
 311                                 new_src->k.type = BCH_DIRENT_WHITEOUT;
 312                 }
 313         }
 314
 315         bch2_trans_update(trans, src_iter, &new_src->k_i, 0);
 316         bch2_trans_update(trans, dst_iter, &new_dst->k_i, 0);
 317         return 0;
 318 }
 319
 320 int __bch2_dirent_delete(struct btree_trans *trans, u64 dir_inum,
 321                          const struct bch_hash_info *hash_info,
 322                          const struct qstr *name)
 323 {
 324         return bch2_hash_delete(trans, bch2_dirent_hash_desc, hash_info,
 325                                 dir_inum, name);
 326 }
 327
 328 int bch2_dirent_delete(struct bch_fs *c, u64 dir_inum,
 329                        const struct bch_hash_info *hash_info,
 330                        const struct qstr *name,
 331                        u64 *journal_seq)
 332 {
 333         return bch2_trans_do(c, journal_seq,
 334                              BTREE_INSERT_ATOMIC|
 335                              BTREE_INSERT_NOFAIL,
 336                 __bch2_dirent_delete(&trans, dir_inum, hash_info, name));
 337 }
 338
 339 u64 bch2_dirent_lookup(struct bch_fs *c, u64 dir_inum,
 340                        const struct bch_hash_info *hash_info,
 341                        const struct qstr *name)
 342 {
 343         struct btree_trans trans;
 344         struct btree_iter *iter;
 345         struct bkey_s_c k;
 346         u64 inum = 0;
 347
 348         bch2_trans_init(&trans, c);
 349
 350         iter = bch2_hash_lookup(&trans, bch2_dirent_hash_desc,
 351                                 hash_info, dir_inum, name, 0);
 352         if (IS_ERR(iter)) {
 353                 BUG_ON(PTR_ERR(iter) == -EINTR);
 354                 goto out;
 355         }
 356
 357         k = bch2_btree_iter_peek_slot(iter);
 358         inum = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum);
 359 out:
 360         bch2_trans_exit(&trans);
 361         return inum;
 362 }
 363
 364 int bch2_empty_dir(struct bch_fs *c, u64 dir_inum)
 365 {
 366         struct btree_iter iter;
 367         struct bkey_s_c k;
 368         int ret = 0;
 369
 370         for_each_btree_key(&iter, c, BTREE_ID_DIRENTS, POS(dir_inum, 0), 0, k) {
 371                 if (k.k->p.inode > dir_inum)
 372                         break;
 373
 374                 if (k.k->type == BCH_DIRENT) {
 375                         ret = -ENOTEMPTY;
 376                         break;
 377                 }
 378         }
 379         bch2_btree_iter_unlock(&iter);
 380
 381         return ret;
 382 }
 383
 384 int bch2_readdir(struct bch_fs *c, struct file *file,
 385                  struct dir_context *ctx)
 386 {
 387         struct bch_inode_info *inode = file_bch_inode(file);
 388         struct btree_iter iter;
 389         struct bkey_s_c k;
 390         struct bkey_s_c_dirent dirent;
 391         unsigned len;
 392
 393         if (!dir_emit_dots(file, ctx))
 394                 return 0;
 395
 396         for_each_btree_key(&iter, c, BTREE_ID_DIRENTS,
 397                            POS(inode->v.i_ino, ctx->pos), 0, k) {
 398                 if (k.k->type != BCH_DIRENT)
 399                         continue;
 400
 401                 dirent = bkey_s_c_to_dirent(k);
 402
 403                 if (bkey_cmp(k.k->p, POS(inode->v.i_ino, ctx->pos)) < 0)
 404                         continue;
 405
 406                 if (k.k->p.inode > inode->v.i_ino)
 407                         break;
 408
 409                 len = bch2_dirent_name_bytes(dirent);
 410
 411                 /*
 412                  * XXX: dir_emit() can fault and block, while we're holding
 413                  * locks
 414                  */
 415                 if (!dir_emit(ctx, dirent.v->d_name, len,
 416                               le64_to_cpu(dirent.v->d_inum),
 417                               dirent.v->d_type))
 418                         break;
 419
 420                 ctx->pos = k.k->p.offset + 1;
 421         }
 422         bch2_btree_iter_unlock(&iter);
 423
 424         return 0;
 425 }