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", d.v->d_inum);
 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                        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         return bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
 155                              dir_inum, &dirent->k_i, flags);
 156 }
 157
 158 static void dirent_copy_target(struct bkey_i_dirent *dst,
 159                                struct bkey_s_c_dirent src)
 160 {
 161         dst->v.d_inum = src.v->d_inum;
 162         dst->v.d_type = src.v->d_type;
 163 }
 164
 165 int bch2_dirent_rename(struct btree_trans *trans,
 166                        u64 src_dir, struct bch_hash_info *src_hash,
 167                        u64 dst_dir, struct bch_hash_info *dst_hash,
 168                        const struct qstr *src_name, u64 *src_inum,
 169                        const struct qstr *dst_name, u64 *dst_inum,
 170                        enum bch_rename_mode mode)
 171 {
 172         struct btree_iter *src_iter, *dst_iter;
 173         struct bkey_s_c old_src, old_dst;
 174         struct bkey_i_dirent *new_src = NULL, *new_dst = NULL;
 175         struct bpos dst_pos =
 176                 POS(dst_dir, bch2_dirent_hash(dst_hash, dst_name));
 177         int ret;
 178
 179         *src_inum = *dst_inum = 0;
 180
 181         /*
 182          * Lookup dst:
 183          *
 184          * Note that in BCH_RENAME mode, we're _not_ checking if
 185          * the target already exists - we're relying on the VFS
 186          * to do that check for us for correctness:
 187          */
 188         dst_iter = mode == BCH_RENAME
 189                 ? bch2_hash_hole(trans, bch2_dirent_hash_desc,
 190                                  dst_hash, dst_dir, dst_name)
 191                 : bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 192                                    dst_hash, dst_dir, dst_name,
 193                                    BTREE_ITER_INTENT);
 194         if (IS_ERR(dst_iter))
 195                 return PTR_ERR(dst_iter);
 196         old_dst = bch2_btree_iter_peek_slot(dst_iter);
 197
 198         if (mode != BCH_RENAME)
 199                 *dst_inum = le64_to_cpu(bkey_s_c_to_dirent(old_dst).v->d_inum);
 200
 201         /* Lookup src: */
 202         src_iter = bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 203                                     src_hash, src_dir, src_name,
 204                                     BTREE_ITER_INTENT);
 205         if (IS_ERR(src_iter))
 206                 return PTR_ERR(src_iter);
 207         old_src = bch2_btree_iter_peek_slot(src_iter);
 208         *src_inum = le64_to_cpu(bkey_s_c_to_dirent(old_src).v->d_inum);
 209
 210         /* Create new dst key: */
 211         new_dst = dirent_create_key(trans, 0, dst_name, 0);
 212         if (IS_ERR(new_dst))
 213                 return PTR_ERR(new_dst);
 214
 215         dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src));
 216         new_dst->k.p = dst_iter->pos;
 217
 218         /* Create new src key: */
 219         if (mode == BCH_RENAME_EXCHANGE) {
 220                 new_src = dirent_create_key(trans, 0, src_name, 0);
 221                 if (IS_ERR(new_src))
 222                         return PTR_ERR(new_src);
 223
 224                 dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst));
 225                 new_src->k.p = src_iter->pos;
 226         } else {
 227                 new_src = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
 228                 if (IS_ERR(new_src))
 229                         return PTR_ERR(new_src);
 230                 bkey_init(&new_src->k);
 231                 new_src->k.p = src_iter->pos;
 232
 233                 if (bkey_cmp(dst_pos, src_iter->pos) <= 0 &&
 234                     bkey_cmp(src_iter->pos, dst_iter->pos) < 0) {
 235                         /*
 236                          * We have a hash collision for the new dst key,
 237                          * and new_src - the key we're deleting - is between
 238                          * new_dst's hashed slot and the slot we're going to be
 239                          * inserting it into - oops.  This will break the hash
 240                          * table if we don't deal with it:
 241                          */
 242                         if (mode == BCH_RENAME) {
 243                                 /*
 244                                  * If we're not overwriting, we can just insert
 245                                  * new_dst at the src position:
 246                                  */
 247                                 new_dst->k.p = src_iter->pos;
 248                                 bch2_trans_update(trans, src_iter,
 249                                                   &new_dst->k_i, 0);
 250                                 return 0;
 251                         } else {
 252                                 /* If we're overwriting, we can't insert new_dst
 253                                  * at a different slot because it has to
 254                                  * overwrite old_dst - just make sure to use a
 255                                  * whiteout when deleting src:
 256                                  */
 257                                 new_src->k.type = KEY_TYPE_whiteout;
 258                         }
 259                 } else {
 260                         /* Check if we need a whiteout to delete src: */
 261                         ret = bch2_hash_needs_whiteout(trans, bch2_dirent_hash_desc,
 262                                                        src_hash, src_iter);
 263                         if (ret < 0)
 264                                 return ret;
 265
 266                         if (ret)
 267                                 new_src->k.type = KEY_TYPE_whiteout;
 268                 }
 269         }
 270
 271         bch2_trans_update(trans, src_iter, &new_src->k_i, 0);
 272         bch2_trans_update(trans, dst_iter, &new_dst->k_i, 0);
 273         return 0;
 274 }
 275
 276 int bch2_dirent_delete_at(struct btree_trans *trans,
 277                           const struct bch_hash_info *hash_info,
 278                           struct btree_iter *iter)
 279 {
 280         return bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
 281                                    hash_info, iter);
 282 }
 283
 284 struct btree_iter *
 285 __bch2_dirent_lookup_trans(struct btree_trans *trans, u64 dir_inum,
 286                            const struct bch_hash_info *hash_info,
 287                            const struct qstr *name, unsigned flags)
 288 {
 289         return bch2_hash_lookup(trans, bch2_dirent_hash_desc,
 290                                 hash_info, dir_inum, name, flags);
 291 }
 292
 293 u64 bch2_dirent_lookup(struct bch_fs *c, u64 dir_inum,
 294                        const struct bch_hash_info *hash_info,
 295                        const struct qstr *name)
 296 {
 297         struct btree_trans trans;
 298         struct btree_iter *iter;
 299         struct bkey_s_c k;
 300         u64 inum = 0;
 301
 302         bch2_trans_init(&trans, c, 0, 0);
 303
 304         iter = __bch2_dirent_lookup_trans(&trans, dir_inum,
 305                                           hash_info, name, 0);
 306         if (IS_ERR(iter)) {
 307                 BUG_ON(PTR_ERR(iter) == -EINTR);
 308                 goto out;
 309         }
 310
 311         k = bch2_btree_iter_peek_slot(iter);
 312         inum = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum);
 313 out:
 314         bch2_trans_exit(&trans);
 315         return inum;
 316 }
 317
 318 int bch2_empty_dir_trans(struct btree_trans *trans, u64 dir_inum)
 319 {
 320         struct btree_iter *iter;
 321         struct bkey_s_c k;
 322         int ret;
 323
 324         for_each_btree_key(trans, iter, BTREE_ID_DIRENTS,
 325                            POS(dir_inum, 0), 0, k, ret) {
 326                 if (k.k->p.inode > dir_inum)
 327                         break;
 328
 329                 if (k.k->type == KEY_TYPE_dirent) {
 330                         ret = -ENOTEMPTY;
 331                         break;
 332                 }
 333         }
 334
 335         if (!IS_ERR(iter))
 336                 bch2_trans_iter_put(trans, iter);
 337
 338         return ret;
 339 }
 340
 341 int bch2_readdir(struct bch_fs *c, u64 inum, struct dir_context *ctx)
 342 {
 343         struct btree_trans trans;
 344         struct btree_iter *iter;
 345         struct bkey_s_c k;
 346         struct bkey_s_c_dirent dirent;
 347         int ret;
 348
 349         bch2_trans_init(&trans, c, 0, 0);
 350
 351         for_each_btree_key(&trans, iter, BTREE_ID_DIRENTS,
 352                            POS(inum, ctx->pos), 0, k, ret) {
 353                 if (k.k->p.inode > inum)
 354                         break;
 355
 356                 if (k.k->type != KEY_TYPE_dirent)
 357                         continue;
 358
 359                 dirent = bkey_s_c_to_dirent(k);
 360
 361                 /*
 362                  * XXX: dir_emit() can fault and block, while we're holding
 363                  * locks
 364                  */
 365                 ctx->pos = dirent.k->p.offset;
 366                 if (!dir_emit(ctx, dirent.v->d_name,
 367                               bch2_dirent_name_bytes(dirent),
 368                               le64_to_cpu(dirent.v->d_inum),
 369                               dirent.v->d_type))
 370                         break;
 371                 ctx->pos = dirent.k->p.offset + 1;
 372         }
 373         ret = bch2_trans_exit(&trans) ?: ret;
 374
 375         return ret;
 376 }