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         /*
  88          * older versions of bcachefs were buggy and creating dirent
  89          * keys that were bigger than necessary:
  90          */
  91         if (bkey_val_u64s(k.k) > dirent_val_u64s(len + 7))
  92                 return "value too big";
  93
  94         if (len > BCH_NAME_MAX)
  95                 return "dirent name too big";
  96
  97         return NULL;
  98 }
  99
 100 void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c,
 101                          struct bkey_s_c k)
 102 {
 103         struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k);
 104
 105         bch_scnmemcpy(out, d.v->d_name,
 106                       bch2_dirent_name_bytes(d));
 107         pr_buf(out, " -> %llu type %u", d.v->d_inum, d.v->d_type);
 108 }
 109
 110 static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 111                                 u8 type, const struct qstr *name, u64 dst)
 112 {
 113         struct bkey_i_dirent *dirent;
 114         unsigned u64s = BKEY_U64s + dirent_val_u64s(name->len);
 115
 116         if (name->len > BCH_NAME_MAX)
 117                 return ERR_PTR(-ENAMETOOLONG);
 118
 119         BUG_ON(u64s > U8_MAX);
 120
 121         dirent = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 122         if (IS_ERR(dirent))
 123                 return dirent;
 124
 125         bkey_dirent_init(&dirent->k_i);
 126         dirent->k.u64s = u64s;
 127         dirent->v.d_inum = cpu_to_le64(dst);
 128         dirent->v.d_type = type;
 129
 130         memcpy(dirent->v.d_name, name->name, name->len);
 131         memset(dirent->v.d_name + name->len, 0,
 132                bkey_val_bytes(&dirent->k) -
 133                offsetof(struct bch_dirent, d_name) -
 134                name->len);
 135
 136         EBUG_ON(bch2_dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len);
 137
 138         return dirent;
 139 }
 140
 141 int bch2_dirent_create(struct btree_trans *trans,
 142                        u64 dir_inum, const struct bch_hash_info *hash_info,
 143                        u8 type, const struct qstr *name, u64 dst_inum,
 144                        u64 *dir_offset, int flags)
 145 {
 146         struct bkey_i_dirent *dirent;
 147         int ret;
 148
 149         dirent = dirent_create_key(trans, type, name, dst_inum);
 150         ret = PTR_ERR_OR_ZERO(dirent);
 151         if (ret)
 152                 return ret;
 153
 154         ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 155                             dir_inum, &dirent->k_i, flags);
 156         *dir_offset = dirent->k.p.offset;
 157
 158         return ret;
 159 }
 160
 161 static void dirent_copy_target(struct bkey_i_dirent *dst,
 162                                struct bkey_s_c_dirent src)
 163 {
 164         dst->v.d_inum = src.v->d_inum;
 165         dst->v.d_type = src.v->d_type;
 166 }
 167
 168 int bch2_dirent_rename(struct btree_trans *trans,
 169                        u64 src_dir, struct bch_hash_info *src_hash,
 170                        u64 dst_dir, struct bch_hash_info *dst_hash,
 171                        const struct qstr *src_name, u64 *src_inum, u64 *src_offset,
 172                        const struct qstr *dst_name, u64 *dst_inum, u64 *dst_offset,
 173                        enum bch_rename_mode mode)
 174 {
 175         struct btree_iter *src_iter = NULL, *dst_iter = NULL;
 176         struct bkey_s_c old_src, old_dst;
 177         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 178         struct bpos dst_pos =
 179                 POS(dst_dir, bch2_dirent_hash(dst_hash, dst_name));
 180         int ret = 0;
 181
 182         *src_inum = *dst_inum = 0;
 183
 184         /*
 185          * Lookup dst:
 186          *
 187          * Note that in BCH_RENAME mode, we're _not_ checking if
 188          * the target already exists - we're relying on the VFS
 189          * to do that check for us for correctness:
 190          */
 191         dst_iter = mode == BCH_RENAME
 192                 ? bch2_hash_hole(trans, bch2_dirent_hash_desc,
 193                                  dst_hash, dst_dir, dst_name)
 194                 : bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 195                                    dst_hash, dst_dir, dst_name,
 196                                    BTREE_ITER_INTENT);
 197         ret = PTR_ERR_OR_ZERO(dst_iter);
 198         if (ret)
 199                 goto out;
 200
 201         old_dst = bch2_btree_iter_peek_slot(dst_iter);
 202
 203         if (mode != BCH_RENAME)
 204                 *dst_inum = le64_to_cpu(bkey_s_c_to_dirent(old_dst).v->d_inum);
 205
 206         /* Lookup src: */
 207         src_iter = bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 208                                     src_hash, src_dir, src_name,
 209                                     BTREE_ITER_INTENT);
 210         ret = PTR_ERR_OR_ZERO(src_iter);
 211         if (ret)
 212                 goto out;
 213
 214         old_src = bch2_btree_iter_peek_slot(src_iter);
 215         *src_inum = le64_to_cpu(bkey_s_c_to_dirent(old_src).v->d_inum);
 216
 217         /* Create new dst key: */
 218         new_dst = dirent_create_key(trans, 0, dst_name, 0);
 219         ret = PTR_ERR_OR_ZERO(new_dst);
 220         if (ret)
 221                 goto out;
 222
 223         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 224         new_dst->k.p = dst_iter->pos;
 225
 226         /* Create new src key: */
 227         if (mode == BCH_RENAME_EXCHANGE) {
 228                 new_src = dirent_create_key(trans, 0, src_name, 0);
 229                 ret = PTR_ERR_OR_ZERO(new_src);
 230                 if (ret)
 231                         goto out;
 232
 233                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 234                 new_src->k.p = src_iter->pos;
 235         } else {
 236                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 237                 ret = PTR_ERR_OR_ZERO(new_src);
 238                 if (ret)
 239                         goto out;
 240
 241                 bkey_init(&new_src->k);
 242                 new_src->k.p = src_iter->pos;
 243
 244                 if (bkey_cmp(dst_pos, src_iter->pos) <= 0 &&
 245                     bkey_cmp(src_iter->pos, dst_iter->pos) < 0) {
 246                         /*
 247                          * We have a hash collision for the new dst key,
 248                          * and new_src - the key we're deleting - is between
 249                          * new_dst's hashed slot and the slot we're going to be
 250                          * inserting it into - oops.  This will break the hash
 251                          * table if we don't deal with it:
 252                          */
 253                         if (mode == BCH_RENAME) {
 254                                 /*
 255                                  * If we're not overwriting, we can just insert
 256                                  * new_dst at the src position:
 257                                  */
 258                                 new_dst->k.p = src_iter->pos;
 259                                 bch2_trans_update(trans, src_iter,
 260                                                   &new_dst->k_i, 0);
 261                                 goto out_set_offset;
 262                         } else {
 263                                 /* If we're overwriting, we can't insert new_dst
 264                                  * at a different slot because it has to
 265                                  * overwrite old_dst - just make sure to use a
 266                                  * whiteout when deleting src:
 267                                  */
 268                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 269                         }
 270                 } else {
 271                         /* Check if we need a whiteout to delete src: */
 272                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 273                                                        src_hash, src_iter);
 274                         if (ret < 0)
 275                                 goto out;
 276
 277                         if (ret)
 278                                 new_src->k.type = KEY_TYPE_hash_whiteout;
 279                 }
 280         }
 281
 282         bch2_trans_update(trans, src_iter, &new_src->k_i, 0);
 283         bch2_trans_update(trans, dst_iter, &new_dst->k_i, 0);
 284 out_set_offset:
 285         *src_offset = new_src->k.p.offset;
 286         *dst_offset = new_dst->k.p.offset;
 287 out:
 288         bch2_trans_iter_put(trans, src_iter);
 289         bch2_trans_iter_put(trans, dst_iter);
 290         return ret;
 291 }
 292
 293 int bch2_dirent_delete_at(struct btree_trans *trans,
 294                           const struct bch_hash_info *hash_info,
 295                           struct btree_iter *iter)
 296 {
 297         return bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
 298                                    hash_info, iter);
 299 }
 300
 301 struct btree_iter *
 302 __bch2_dirent_lookup_trans(struct btree_trans *trans, u64 dir_inum,
 303                            const struct bch_hash_info *hash_info,
 304                            const struct qstr *name, unsigned flags)
 305 {
 306         return bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 307                                 hash_info, dir_inum, name, flags);
 308 }
 309
 310 u64 bch2_dirent_lookup(struct bch_fs *c, u64 dir_inum,
 311                        const struct bch_hash_info *hash_info,
 312                        const struct qstr *name)
 313 {
 314         struct btree_trans trans;
 315         struct btree_iter *iter;
 316         struct bkey_s_c k;
 317         u64 inum = 0;
 318
 319         bch2_trans_init(&trans, c, 0, 0);
 320
 321         iter = __bch2_dirent_lookup_trans(&trans, dir_inum,
 322                                           hash_info, name, 0);
 323         if (IS_ERR(iter)) {
 324                 BUG_ON(PTR_ERR(iter) == -EINTR);
 325                 goto out;
 326         }
 327
 328         k = bch2_btree_iter_peek_slot(iter);
 329         inum = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum);
 330         bch2_trans_iter_put(&trans, iter);
 331 out:
 332         bch2_trans_exit(&trans);
 333         return inum;
 334 }
 335
 336 int bch2_empty_dir_trans(struct btree_trans *trans, u64 dir_inum)
 337 {
 338         struct btree_iter *iter;
 339         struct bkey_s_c k;
 340         int ret;
 341
 342         for_each_btree_key(trans, iter, BTREE_ID_dirents,
 343                            POS(dir_inum, 0), 0, k, ret) {
 344                 if (k.k->p.inode > dir_inum)
 345                         break;
 346
 347                 if (k.k->type == KEY_TYPE_dirent) {
 348                         ret = -ENOTEMPTY;
 349                         break;
 350                 }
 351         }
 352         bch2_trans_iter_put(trans, iter);
 353
 354         return ret;
 355 }
 356
 357 int bch2_readdir(struct bch_fs *c, u64 inum, struct dir_context *ctx)
 358 {
 359         struct btree_trans trans;
 360         struct btree_iter *iter;
 361         struct bkey_s_c k;
 362         struct bkey_s_c_dirent dirent;
 363         int ret;
 364
 365         bch2_trans_init(&trans, c, 0, 0);
 366
 367         for_each_btree_key(&trans, iter, BTREE_ID_dirents,
 368                            POS(inum, ctx->pos), 0, k, ret) {
 369                 if (k.k->p.inode > inum)
 370                         break;
 371
 372                 if (k.k->type != KEY_TYPE_dirent)
 373                         continue;
 374
 375                 dirent = bkey_s_c_to_dirent(k);
 376
 377                 /*
 378                  * XXX: dir_emit() can fault and block, while we're holding
 379                  * locks
 380                  */
 381                 ctx->pos = dirent.k->p.offset;
 382                 if (!dir_emit(ctx, dirent.v->d_name,
 383                               bch2_dirent_name_bytes(dirent),
 384                               le64_to_cpu(dirent.v->d_inum),
 385                               dirent.v->d_type))
 386                         break;
 387                 ctx->pos = dirent.k->p.offset + 1;
 388         }
 389         bch2_trans_iter_put(&trans, iter);
 390
 391         ret = bch2_trans_exit(&trans) ?: ret;
 392
 393         return ret;
 394 }