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 int bch2_dirent_to_text(struct bch_fs *c, char *buf,
 125                         size_t size, struct bkey_s_c k)
 126 {
 127         char *out = buf, *end = buf + size;
 128         struct bkey_s_c_dirent d;
 129
 130         switch (k.k->type) {
 131         case BCH_DIRENT:
 132                 d = bkey_s_c_to_dirent(k);
 133
 134                 out += bch_scnmemcpy(out, end - out, d.v->d_name,
 135                                      bch2_dirent_name_bytes(d));
 136                 out += scnprintf(out, end - out, " -> %llu", d.v->d_inum);
 137                 break;
 138         case BCH_DIRENT_WHITEOUT:
 139                 out += scnprintf(out, end - out, "whiteout");
 140                 break;
 141         }
 142
 143         return out - buf;
 144 }
 145
 146 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 147                                 u8 type, const struct qstr *name, u64 dst)
 148 {
 149         struct bkey_i_dirent *dirent;
 150         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 151
 152         if (name->len > BCH_NAME_MAX)
 153                 return ERR_PTR(-ENAMETOOLONG);
 154
 155         BUG_ON(u64s > U8_MAX);
 156
 157         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 158         if (IS_ERR(dirent))
 159                 return dirent;
 160
 161         bkey_dirent_init(&dirent->k_i);
 162         dirent->k.u64s = u64s;
 163         dirent->v.d_inum = cpu_to_le64(dst);
 164         dirent->v.d_type = type;
 165
 166         memcpy(dirent->v.d_name, name->name, name->len);
 167         memset(dirent->v.d_name + name->len, 0,
 168                bkey_val_bytes(&dirent->k) -
 169                offsetof(struct bch_dirent, d_name) -
 170                name->len);
 171
 172         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 173
 174         return dirent;
 175 }
 176
 177 int __bch2_dirent_create(struct btree_trans *trans,
 178                          u64 dir_inum, const struct bch_hash_info *hash_info,
 179                          u8 type, const struct qstr *name, u64 dst_inum,
 180                          int flags)
 181 {
 182         struct bkey_i_dirent *dirent;
 183         int ret;
 184
 185         dirent = dirent_create_key(trans, type, name, dst_inum);
 186         ret = PTR_ERR_OR_ZERO(dirent);
 187         if (ret)
 188                 return ret;
 189
 190         return __bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 191                                dir_inum, &dirent->k_i, flags);
 192 }
 193
 194 int bch2_dirent_create(struct bch_fs *c, u64 dir_inum,
 195                        const struct bch_hash_info *hash_info,
 196                        u8 type, const struct qstr *name, u64 dst_inum,
 197                        u64 *journal_seq, int flags)
 198 {
 199         return bch2_trans_do(c, journal_seq, flags,
 200                 __bch2_dirent_create(&trans, dir_inum, hash_info,
 201                                      type, name, dst_inum, flags));
 202 }
 203
 204 static void dirent_copy_target(struct bkey_i_dirent *dst,
 205                                struct bkey_s_c_dirent src)
 206 {
 207         dst->v.d_inum = src.v->d_inum;
 208         dst->v.d_type = src.v->d_type;
 209 }
 210
 211 static struct bpos bch2_dirent_pos(struct bch_inode_info *inode,
 212                                    const struct qstr *name)
 213 {
 214         return POS(inode->v.i_ino, bch2_dirent_hash(&inode->ei_str_hash, name));
 215 }
 216
 217 int bch2_dirent_rename(struct btree_trans *trans,
 218                 struct bch_inode_info *src_dir, const struct qstr *src_name,
 219                 struct bch_inode_info *dst_dir, const struct qstr *dst_name,
 220                 enum bch_rename_mode mode)
 221 {
 222         struct btree_iter *src_iter, *dst_iter;
 223         struct bkey_s_c old_src, old_dst;
 224         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 225         struct bpos dst_pos = bch2_dirent_pos(dst_dir, dst_name);
 226         int ret;
 227
 228         /*
 229          * Lookup dst:
 230          *
 231          * Note that in BCH_RENAME mode, we're _not_ checking if
 232          * the target already exists - we're relying on the VFS
 233          * to do that check for us for correctness:
 234          */
 235         dst_iter = mode == BCH_RENAME
 236                 ? bch2_hash_hole(trans, bch2_dirent_hash_desc,
 237                                  &dst_dir->ei_str_hash,
 238                                  dst_dir->v.i_ino, dst_name)
 239                 : bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 240                                    &dst_dir->ei_str_hash,
 241                                    dst_dir->v.i_ino, dst_name,
 242                                    BTREE_ITER_INTENT);
 243         if (IS_ERR(dst_iter))
 244                 return PTR_ERR(dst_iter);
 245         old_dst = bch2_btree_iter_peek_slot(dst_iter);
 246
 247         /* Lookup src: */
 248         src_iter = bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 249                                     &src_dir->ei_str_hash,
 250                                     src_dir->v.i_ino, src_name,
 251                                     BTREE_ITER_INTENT);
 252         if (IS_ERR(src_iter))
 253                 return PTR_ERR(src_iter);
 254         old_src = bch2_btree_iter_peek_slot(src_iter);
 255
 256         /* Create new dst key: */
 257         new_dst = dirent_create_key(trans, 0, dst_name, 0);
 258         if (IS_ERR(new_dst))
 259                 return PTR_ERR(new_dst);
 260
 261         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 262         new_dst->k.p = dst_iter->pos;
 263
 264         /* Create new src key: */
 265         if (mode == BCH_RENAME_EXCHANGE) {
 266                 new_src = dirent_create_key(trans, 0, src_name, 0);
 267                 if (IS_ERR(new_src))
 268                         return PTR_ERR(new_src);
 269
 270                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 271                 new_src->k.p = src_iter->pos;
 272         } else {
 273                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 274                 if (IS_ERR(new_src))
 275                         return PTR_ERR(new_src);
 276                 bkey_init(&new_src->k);
 277                 new_src->k.p = src_iter->pos;
 278
 279                 if (bkey_cmp(dst_pos, src_iter->pos) <= 0 &&
 280                     bkey_cmp(src_iter->pos, dst_iter->pos) < 0) {
 281                         /*
 282                          * We have a hash collision for the new dst key,
 283                          * and new_src - the key we're deleting - is between
 284                          * new_dst's hashed slot and the slot we're going to be
 285                          * inserting it into - oops.  This will break the hash
 286                          * table if we don't deal with it:
 287                          */
 288                         if (mode == BCH_RENAME) {
 289                                 /*
 290                                  * If we're not overwriting, we can just insert
 291                                  * new_dst at the src position:
 292                                  */
 293                                 new_dst->k.p = src_iter->pos;
 294                                 bch2_trans_update(trans,
 295                                         BTREE_INSERT_ENTRY(src_iter,
 296                                                            &new_dst->k_i));
 297                                 return 0;
 298                         } else {
 299                                 /* If we're overwriting, we can't insert new_dst
 300                                  * at a different slot because it has to
 301                                  * overwrite old_dst - just make sure to use a
 302                                  * whiteout when deleting src:
 303                                  */
 304                                 new_src->k.type = BCH_DIRENT_WHITEOUT;
 305                         }
 306                 } else {
 307                         /* Check if we need a whiteout to delete src: */
 308                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 309                                                        &src_dir->ei_str_hash,
 310                                                        src_iter);
 311                         if (ret < 0)
 312                                 return ret;
 313
 314                         if (ret)
 315                                 new_src->k.type = BCH_DIRENT_WHITEOUT;
 316                 }
 317         }
 318
 319         bch2_trans_update(trans, BTREE_INSERT_ENTRY(src_iter, &new_src->k_i));
 320         bch2_trans_update(trans, BTREE_INSERT_ENTRY(dst_iter, &new_dst->k_i));
 321         return 0;
 322 }
 323
 324 int __bch2_dirent_delete(struct btree_trans *trans, u64 dir_inum,
 325                          const struct bch_hash_info *hash_info,
 326                          const struct qstr *name)
 327 {
 328         return bch2_hash_delete(trans, bch2_dirent_hash_desc, hash_info,
 329                                 dir_inum, name);
 330 }
 331
 332 int bch2_dirent_delete(struct bch_fs *c, u64 dir_inum,
 333                        const struct bch_hash_info *hash_info,
 334                        const struct qstr *name,
 335                        u64 *journal_seq)
 336 {
 337         return bch2_trans_do(c, journal_seq,
 338                              BTREE_INSERT_ATOMIC|
 339                              BTREE_INSERT_NOFAIL,
 340                 __bch2_dirent_delete(&trans, dir_inum, hash_info, name));
 341 }
 342
 343 u64 bch2_dirent_lookup(struct bch_fs *c, u64 dir_inum,
 344                        const struct bch_hash_info *hash_info,
 345                        const struct qstr *name)
 346 {
 347         struct btree_trans trans;
 348         struct btree_iter *iter;
 349         struct bkey_s_c k;
 350         u64 inum = 0;
 351
 352         bch2_trans_init(&trans, c);
 353
 354         iter = bch2_hash_lookup(&trans, bch2_dirent_hash_desc,
 355                                 hash_info, dir_inum, name, 0);
 356         if (IS_ERR(iter)) {
 357                 BUG_ON(PTR_ERR(iter) == -EINTR);
 358                 goto out;
 359         }
 360
 361         k = bch2_btree_iter_peek_slot(iter);
 362         inum = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum);
 363 out:
 364         bch2_trans_exit(&trans);
 365         return inum;
 366 }
 367
 368 int bch2_empty_dir(struct bch_fs *c, u64 dir_inum)
 369 {
 370         struct btree_iter iter;
 371         struct bkey_s_c k;
 372         int ret = 0;
 373
 374         for_each_btree_key(&iter, c, BTREE_ID_DIRENTS, POS(dir_inum, 0), 0, k) {
 375                 if (k.k->p.inode > dir_inum)
 376                         break;
 377
 378                 if (k.k->type == BCH_DIRENT) {
 379                         ret = -ENOTEMPTY;
 380                         break;
 381                 }
 382         }
 383         bch2_btree_iter_unlock(&iter);
 384
 385         return ret;
 386 }
 387
 388 int bch2_readdir(struct bch_fs *c, struct file *file,
 389                  struct dir_context *ctx)
 390 {
 391         struct bch_inode_info *inode = file_bch_inode(file);
 392         struct btree_iter iter;
 393         struct bkey_s_c k;
 394         struct bkey_s_c_dirent dirent;
 395         unsigned len;
 396
 397         if (!dir_emit_dots(file, ctx))
 398                 return 0;
 399
 400         for_each_btree_key(&iter, c, BTREE_ID_DIRENTS,
 401                            POS(inode->v.i_ino, ctx->pos), 0, k) {
 402                 if (k.k->type != BCH_DIRENT)
 403                         continue;
 404
 405                 dirent = bkey_s_c_to_dirent(k);
 406
 407                 if (bkey_cmp(k.k->p, POS(inode->v.i_ino, ctx->pos)) < 0)
 408                         continue;
 409
 410                 if (k.k->p.inode > inode->v.i_ino)
 411                         break;
 412
 413                 len = bch2_dirent_name_bytes(dirent);
 414
 415                 /*
 416                  * XXX: dir_emit() can fault and block, while we're holding
 417                  * locks
 418                  */
 419                 if (!dir_emit(ctx, dirent.v->d_name, len,
 420                               le64_to_cpu(dirent.v->d_inum),
 421                               dirent.v->d_type))
 422                         break;
 423
 424                 ctx->pos = k.k->p.offset + 1;
 425         }
 426         bch2_btree_iter_unlock(&iter);
 427
 428         return 0;
 429 }