fs/omfs/dir.c

   1 /*
   2  * OMFS (as used by RIO Karma) directory operations.
   3  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
   4  * Released under GPL v2.
   5  */
   6
   7 #include <linux/fs.h>
   8 #include <linux/ctype.h>
   9 #include <linux/buffer_head.h>
  10 #include "omfs.h"
  11
  12 static int omfs_hash(const char *name, int namelen, int mod)
  13 {
  14         int i, hash = 0;
  15         for (i = 0; i < namelen; i++)
  16                 hash ^= tolower(name[i]) << (i % 24);
  17         return hash % mod;
  18 }
  19
  20 /*
  21  * Finds the bucket for a given name and reads the containing block;
  22  * *ofs is set to the offset of the first list entry.
  23  */
  24 static struct buffer_head *omfs_get_bucket(struct inode *dir,
  25                 const char *name, int namelen, int *ofs)
  26 {
  27         int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
  28         int bucket = omfs_hash(name, namelen, nbuckets);
  29
  30         *ofs = OMFS_DIR_START + bucket * 8;
  31         return omfs_bread(dir->i_sb, dir->i_ino);
  32 }
  33
  34 static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
  35                                 const char *name, int namelen,
  36                                 u64 *prev_block)
  37 {
  38         struct buffer_head *bh;
  39         struct omfs_inode *oi;
  40         int err = -ENOENT;
  41         *prev_block = ~0;
  42
  43         while (block != ~0) {
  44                 bh = omfs_bread(dir->i_sb, block);
  45                 if (!bh) {
  46                         err = -EIO;
  47                         goto err;
  48                 }
  49
  50                 oi = (struct omfs_inode *) bh->b_data;
  51                 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
  52                         brelse(bh);
  53                         goto err;
  54                 }
  55
  56                 if (strncmp(oi->i_name, name, namelen) == 0)
  57                         return bh;
  58
  59                 *prev_block = block;
  60                 block = be64_to_cpu(oi->i_sibling);
  61                 brelse(bh);
  62         }
  63 err:
  64         return ERR_PTR(err);
  65 }
  66
  67 static struct buffer_head *omfs_find_entry(struct inode *dir,
  68                                            const char *name, int namelen)
  69 {
  70         struct buffer_head *bh;
  71         int ofs;
  72         u64 block, dummy;
  73
  74         bh = omfs_get_bucket(dir, name, namelen, &ofs);
  75         if (!bh)
  76                 return ERR_PTR(-EIO);
  77
  78         block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
  79         brelse(bh);
  80
  81         return omfs_scan_list(dir, block, name, namelen, &dummy);
  82 }
  83
  84 int omfs_make_empty(struct inode *inode, struct super_block *sb)
  85 {
  86         struct omfs_sb_info *sbi = OMFS_SB(sb);
  87         struct buffer_head *bh;
  88         struct omfs_inode *oi;
  89
  90         bh = omfs_bread(sb, inode->i_ino);
  91         if (!bh)
  92                 return -ENOMEM;
  93
  94         memset(bh->b_data, 0, sizeof(struct omfs_inode));
  95
  96         if (inode->i_mode & S_IFDIR) {
  97                 memset(&bh->b_data[OMFS_DIR_START], 0xff,
  98                         sbi->s_sys_blocksize - OMFS_DIR_START);
  99         } else
 100                 omfs_make_empty_table(bh, OMFS_EXTENT_START);
 101
 102         oi = (struct omfs_inode *) bh->b_data;
 103         oi->i_head.h_self = cpu_to_be64(inode->i_ino);
 104         oi->i_sibling = ~cpu_to_be64(0ULL);
 105
 106         mark_buffer_dirty(bh);
 107         brelse(bh);
 108         return 0;
 109 }
 110
 111 static int omfs_add_link(struct dentry *dentry, struct inode *inode)
 112 {
 113         struct inode *dir = dentry->d_parent->d_inode;
 114         const char *name = dentry->d_name.name;
 115         int namelen = dentry->d_name.len;
 116         struct omfs_inode *oi;
 117         struct buffer_head *bh;
 118         u64 block;
 119         __be64 *entry;
 120         int ofs;
 121
 122         /* just prepend to head of queue in proper bucket */
 123         bh = omfs_get_bucket(dir, name, namelen, &ofs);
 124         if (!bh)
 125                 goto out;
 126
 127         entry = (__be64 *) &bh->b_data[ofs];
 128         block = be64_to_cpu(*entry);
 129         *entry = cpu_to_be64(inode->i_ino);
 130         mark_buffer_dirty(bh);
 131         brelse(bh);
 132
 133         /* now set the sibling and parent pointers on the new inode */
 134         bh = omfs_bread(dir->i_sb, inode->i_ino);
 135         if (!bh)
 136                 goto out;
 137
 138         oi = (struct omfs_inode *) bh->b_data;
 139         memcpy(oi->i_name, name, namelen);
 140         memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
 141         oi->i_sibling = cpu_to_be64(block);
 142         oi->i_parent = cpu_to_be64(dir->i_ino);
 143         mark_buffer_dirty(bh);
 144         brelse(bh);
 145
 146         dir->i_ctime = CURRENT_TIME_SEC;
 147
 148         /* mark affected inodes dirty to rebuild checksums */
 149         mark_inode_dirty(dir);
 150         mark_inode_dirty(inode);
 151         return 0;
 152 out:
 153         return -ENOMEM;
 154 }
 155
 156 static int omfs_delete_entry(struct dentry *dentry)
 157 {
 158         struct inode *dir = dentry->d_parent->d_inode;
 159         struct inode *dirty;
 160         const char *name = dentry->d_name.name;
 161         int namelen = dentry->d_name.len;
 162         struct omfs_inode *oi;
 163         struct buffer_head *bh, *bh2;
 164         __be64 *entry, next;
 165         u64 block, prev;
 166         int ofs;
 167         int err = -ENOMEM;
 168
 169         /* delete the proper node in the bucket's linked list */
 170         bh = omfs_get_bucket(dir, name, namelen, &ofs);
 171         if (!bh)
 172                 goto out;
 173
 174         entry = (__be64 *) &bh->b_data[ofs];
 175         block = be64_to_cpu(*entry);
 176
 177         bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
 178         if (IS_ERR(bh2)) {
 179                 err = PTR_ERR(bh2);
 180                 goto out_free_bh;
 181         }
 182
 183         oi = (struct omfs_inode *) bh2->b_data;
 184         next = oi->i_sibling;
 185         brelse(bh2);
 186
 187         if (prev != ~0) {
 188                 /* found in middle of list, get list ptr */
 189                 brelse(bh);
 190                 bh = omfs_bread(dir->i_sb, prev);
 191                 if (!bh)
 192                         goto out;
 193
 194                 oi = (struct omfs_inode *) bh->b_data;
 195                 entry = &oi->i_sibling;
 196         }
 197
 198         *entry = next;
 199         mark_buffer_dirty(bh);
 200
 201         if (prev != ~0) {
 202                 dirty = omfs_iget(dir->i_sb, prev);
 203                 if (!IS_ERR(dirty)) {
 204                         mark_inode_dirty(dirty);
 205                         iput(dirty);
 206                 }
 207         }
 208
 209         err = 0;
 210 out_free_bh:
 211         brelse(bh);
 212 out:
 213         return err;
 214 }
 215
 216 static int omfs_dir_is_empty(struct inode *inode)
 217 {
 218         int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
 219         struct buffer_head *bh;
 220         u64 *ptr;
 221         int i;
 222
 223         bh = omfs_bread(inode->i_sb, inode->i_ino);
 224
 225         if (!bh)
 226                 return 0;
 227
 228         ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
 229
 230         for (i = 0; i < nbuckets; i++, ptr++)
 231                 if (*ptr != ~0)
 232                         break;
 233
 234         brelse(bh);
 235         return *ptr != ~0;
 236 }
 237
 238 static int omfs_remove(struct inode *dir, struct dentry *dentry)
 239 {
 240         struct inode *inode = dentry->d_inode;
 241         int ret;
 242
 243         if (S_ISDIR(inode->i_mode) && !omfs_dir_is_empty(inode))
 244                 return -ENOTEMPTY;
 245
 246         ret = omfs_delete_entry(dentry);
 247         if (ret)
 248                 return ret;
 249
 250         clear_nlink(inode);
 251         mark_inode_dirty(inode);
 252         mark_inode_dirty(dir);
 253         return 0;
 254 }
 255
 256 static int omfs_add_node(struct inode *dir, struct dentry *dentry, int mode)
 257 {
 258         int err;
 259         struct inode *inode = omfs_new_inode(dir, mode);
 260
 261         if (IS_ERR(inode))
 262                 return PTR_ERR(inode);
 263
 264         err = omfs_make_empty(inode, dir->i_sb);
 265         if (err)
 266                 goto out_free_inode;
 267
 268         err = omfs_add_link(dentry, inode);
 269         if (err)
 270                 goto out_free_inode;
 271
 272         d_instantiate(dentry, inode);
 273         return 0;
 274
 275 out_free_inode:
 276         iput(inode);
 277         return err;
 278 }
 279
 280 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 281 {
 282         return omfs_add_node(dir, dentry, mode | S_IFDIR);
 283 }
 284
 285 static int omfs_create(struct inode *dir, struct dentry *dentry, int mode,
 286                 struct nameidata *nd)
 287 {
 288         return omfs_add_node(dir, dentry, mode | S_IFREG);
 289 }
 290
 291 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
 292                                   struct nameidata *nd)
 293 {
 294         struct buffer_head *bh;
 295         struct inode *inode = NULL;
 296
 297         if (dentry->d_name.len > OMFS_NAMELEN)
 298                 return ERR_PTR(-ENAMETOOLONG);
 299
 300         bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
 301         if (!IS_ERR(bh)) {
 302                 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
 303                 ino_t ino = be64_to_cpu(oi->i_head.h_self);
 304                 brelse(bh);
 305                 inode = omfs_iget(dir->i_sb, ino);
 306                 if (IS_ERR(inode))
 307                         return ERR_CAST(inode);
 308         }
 309         d_add(dentry, inode);
 310         return NULL;
 311 }
 312
 313 /* sanity check block's self pointer */
 314 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
 315         u64 fsblock)
 316 {
 317         int is_bad;
 318         u64 ino = be64_to_cpu(header->h_self);
 319         is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
 320                 (ino > sbi->s_num_blocks));
 321
 322         if (is_bad)
 323                 printk(KERN_WARNING "omfs: bad hash chain detected\n");
 324
 325         return is_bad;
 326 }
 327
 328 static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir,
 329                 u64 fsblock, int hindex)
 330 {
 331         struct inode *dir = filp->f_dentry->d_inode;
 332         struct buffer_head *bh;
 333         struct omfs_inode *oi;
 334         u64 self;
 335         int res = 0;
 336         unsigned char d_type;
 337
 338         /* follow chain in this bucket */
 339         while (fsblock != ~0) {
 340                 bh = omfs_bread(dir->i_sb, fsblock);
 341                 if (!bh)
 342                         goto out;
 343
 344                 oi = (struct omfs_inode *) bh->b_data;
 345                 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
 346                         brelse(bh);
 347                         goto out;
 348                 }
 349
 350                 self = fsblock;
 351                 fsblock = be64_to_cpu(oi->i_sibling);
 352
 353                 /* skip visited nodes */
 354                 if (hindex) {
 355                         hindex--;
 356                         brelse(bh);
 357                         continue;
 358                 }
 359
 360                 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
 361
 362                 res = filldir(dirent, oi->i_name, strnlen(oi->i_name,
 363                         OMFS_NAMELEN), filp->f_pos, self, d_type);
 364                 brelse(bh);
 365                 if (res < 0)
 366                         break;
 367                 filp->f_pos++;
 368         }
 369 out:
 370         return res;
 371 }
 372
 373 static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 374                 struct inode *new_dir, struct dentry *new_dentry)
 375 {
 376         struct inode *new_inode = new_dentry->d_inode;
 377         struct inode *old_inode = old_dentry->d_inode;
 378         int err;
 379
 380         if (new_inode) {
 381                 /* overwriting existing file/dir */
 382                 err = omfs_remove(new_dir, new_dentry);
 383                 if (err)
 384                         goto out;
 385         }
 386
 387         /* since omfs locates files by name, we need to unlink _before_
 388          * adding the new link or we won't find the old one */
 389         err = omfs_delete_entry(old_dentry);
 390         if (err)
 391                 goto out;
 392
 393         mark_inode_dirty(old_dir);
 394         err = omfs_add_link(new_dentry, old_inode);
 395         if (err)
 396                 goto out;
 397
 398         old_inode->i_ctime = CURRENT_TIME_SEC;
 399         mark_inode_dirty(old_inode);
 400 out:
 401         return err;
 402 }
 403
 404 static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 405 {
 406         struct inode *dir = filp->f_dentry->d_inode;
 407         struct buffer_head *bh;
 408         loff_t offset, res;
 409         unsigned int hchain, hindex;
 410         int nbuckets;
 411         u64 fsblock;
 412         int ret = -EINVAL;
 413
 414         if (filp->f_pos >> 32)
 415                 goto success;
 416
 417         switch ((unsigned long) filp->f_pos) {
 418         case 0:
 419                 if (filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR) < 0)
 420                         goto success;
 421                 filp->f_pos++;
 422                 /* fall through */
 423         case 1:
 424                 if (filldir(dirent, "..", 2, 1,
 425                     parent_ino(filp->f_dentry), DT_DIR) < 0)
 426                         goto success;
 427                 filp->f_pos = 1 << 20;
 428                 /* fall through */
 429         }
 430
 431         nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
 432
 433         /* high 12 bits store bucket + 1 and low 20 bits store hash index */
 434         hchain = (filp->f_pos >> 20) - 1;
 435         hindex = filp->f_pos & 0xfffff;
 436
 437         bh = omfs_bread(dir->i_sb, dir->i_ino);
 438         if (!bh)
 439                 goto out;
 440
 441         offset = OMFS_DIR_START + hchain * 8;
 442
 443         for (; hchain < nbuckets; hchain++, offset += 8) {
 444                 fsblock = be64_to_cpu(*((__be64 *) &bh->b_data[offset]));
 445
 446                 res = omfs_fill_chain(filp, dirent, filldir, fsblock, hindex);
 447                 hindex = 0;
 448                 if (res < 0)
 449                         break;
 450
 451                 filp->f_pos = (hchain+2) << 20;
 452         }
 453         brelse(bh);
 454 success:
 455         ret = 0;
 456 out:
 457         return ret;
 458 }
 459
 460 const struct inode_operations omfs_dir_inops = {
 461         .lookup = omfs_lookup,
 462         .mkdir = omfs_mkdir,
 463         .rename = omfs_rename,
 464         .create = omfs_create,
 465         .unlink = omfs_remove,
 466         .rmdir = omfs_remove,
 467 };
 468
 469 const struct file_operations omfs_dir_operations = {
 470         .read = generic_read_dir,
 471         .readdir = omfs_readdir,
 472         .llseek = generic_file_llseek,
 473 };