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