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 block = clus_to_blk(OMFS_SB(dir->i_sb), dir->i_ino);
  29         int bucket = omfs_hash(name, namelen, nbuckets);
  30
  31         *ofs = OMFS_DIR_START + bucket * 8;
  32         return sb_bread(dir->i_sb, block);
  33 }
  34
  35 static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
  36                                 const char *name, int namelen,
  37                                 u64 *prev_block)
  38 {
  39         struct buffer_head *bh;
  40         struct omfs_inode *oi;
  41         int err = -ENOENT;
  42         *prev_block = ~0;
  43
  44         while (block != ~0) {
  45                 bh = sb_bread(dir->i_sb,
  46                         clus_to_blk(OMFS_SB(dir->i_sb), block));
  47                 if (!bh) {
  48                         err = -EIO;
  49                         goto err;
  50                 }
  51
  52                 oi = (struct omfs_inode *) bh->b_data;
  53                 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
  54                         brelse(bh);
  55                         goto err;
  56                 }
  57
  58                 if (strncmp(oi->i_name, name, namelen) == 0)
  59                         return bh;
  60
  61                 *prev_block = block;
  62                 block = be64_to_cpu(oi->i_sibling);
  63                 brelse(bh);
  64         }
  65 err:
  66         return ERR_PTR(err);
  67 }
  68
  69 static struct buffer_head *omfs_find_entry(struct inode *dir,
  70                                            const char *name, int namelen)
  71 {
  72         struct buffer_head *bh;
  73         int ofs;
  74         u64 block, dummy;
  75
  76         bh = omfs_get_bucket(dir, name, namelen, &ofs);
  77         if (!bh)
  78                 return ERR_PTR(-EIO);
  79
  80         block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
  81         brelse(bh);
  82
  83         return omfs_scan_list(dir, block, name, namelen, &dummy);
  84 }
  85
  86 int omfs_make_empty(struct inode *inode, struct super_block *sb)
  87 {
  88         struct omfs_sb_info *sbi = OMFS_SB(sb);
  89         int block = clus_to_blk(sbi, inode->i_ino);
  90         struct buffer_head *bh;
  91         struct omfs_inode *oi;
  92
  93         bh = sb_bread(sb, block);
  94         if (!bh)
  95                 return -ENOMEM;
  96
  97         memset(bh->b_data, 0, sizeof(struct omfs_inode));
  98
  99         if (inode->i_mode & S_IFDIR) {
 100                 memset(&bh->b_data[OMFS_DIR_START], 0xff,
 101                         sbi->s_sys_blocksize - OMFS_DIR_START);
 102         } else
 103                 omfs_make_empty_table(bh, OMFS_EXTENT_START);
 104
 105         oi = (struct omfs_inode *) bh->b_data;
 106         oi->i_head.h_self = cpu_to_be64(inode->i_ino);
 107         oi->i_sibling = ~cpu_to_be64(0ULL);
 108
 109         mark_buffer_dirty(bh);
 110         brelse(bh);
 111         return 0;
 112 }
 113
 114 static int omfs_add_link(struct dentry *dentry, struct inode *inode)
 115 {
 116         struct inode *dir = dentry->d_parent->d_inode;
 117         const char *name = dentry->d_name.name;
 118         int namelen = dentry->d_name.len;
 119         struct omfs_inode *oi;
 120         struct buffer_head *bh;
 121         u64 block;
 122         __be64 *entry;
 123         int ofs;
 124
 125         /* just prepend to head of queue in proper bucket */
 126         bh = omfs_get_bucket(dir, name, namelen, &ofs);
 127         if (!bh)
 128                 goto out;
 129
 130         entry = (__be64 *) &bh->b_data[ofs];
 131         block = be64_to_cpu(*entry);
 132         *entry = cpu_to_be64(inode->i_ino);
 133         mark_buffer_dirty(bh);
 134         brelse(bh);
 135
 136         /* now set the sibling and parent pointers on the new inode */
 137         bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb), inode->i_ino));
 138         if (!bh)
 139                 goto out;
 140
 141         oi = (struct omfs_inode *) bh->b_data;
 142         memcpy(oi->i_name, name, namelen);
 143         memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
 144         oi->i_sibling = cpu_to_be64(block);
 145         oi->i_parent = cpu_to_be64(dir->i_ino);
 146         mark_buffer_dirty(bh);
 147         brelse(bh);
 148
 149         dir->i_ctime = CURRENT_TIME_SEC;
 150
 151         /* mark affected inodes dirty to rebuild checksums */
 152         mark_inode_dirty(dir);
 153         mark_inode_dirty(inode);
 154         return 0;
 155 out:
 156         return -ENOMEM;
 157 }
 158
 159 static int omfs_delete_entry(struct dentry *dentry)
 160 {
 161         struct inode *dir = dentry->d_parent->d_inode;
 162         struct inode *dirty;
 163         const char *name = dentry->d_name.name;
 164         int namelen = dentry->d_name.len;
 165         struct omfs_inode *oi;
 166         struct buffer_head *bh, *bh2;
 167         __be64 *entry, next;
 168         u64 block, prev;
 169         int ofs;
 170         int err = -ENOMEM;
 171
 172         /* delete the proper node in the bucket's linked list */
 173         bh = omfs_get_bucket(dir, name, namelen, &ofs);
 174         if (!bh)
 175                 goto out;
 176
 177         entry = (__be64 *) &bh->b_data[ofs];
 178         block = be64_to_cpu(*entry);
 179
 180         bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
 181         if (IS_ERR(bh2)) {
 182                 err = PTR_ERR(bh2);
 183                 goto out_free_bh;
 184         }
 185
 186         oi = (struct omfs_inode *) bh2->b_data;
 187         next = oi->i_sibling;
 188         brelse(bh2);
 189
 190         if (prev != ~0) {
 191                 /* found in middle of list, get list ptr */
 192                 brelse(bh);
 193                 bh = sb_bread(dir->i_sb,
 194                         clus_to_blk(OMFS_SB(dir->i_sb), prev));
 195                 if (!bh)
 196                         goto out;
 197
 198                 oi = (struct omfs_inode *) bh->b_data;
 199                 entry = &oi->i_sibling;
 200         }
 201
 202         *entry = next;
 203         mark_buffer_dirty(bh);
 204
 205         if (prev != ~0) {
 206                 dirty = omfs_iget(dir->i_sb, prev);
 207                 if (!IS_ERR(dirty)) {
 208                         mark_inode_dirty(dirty);
 209                         iput(dirty);
 210                 }
 211         }
 212
 213         err = 0;
 214 out_free_bh:
 215         brelse(bh);
 216 out:
 217         return err;
 218 }
 219
 220 static int omfs_dir_is_empty(struct inode *inode)
 221 {
 222         int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
 223         struct buffer_head *bh;
 224         u64 *ptr;
 225         int i;
 226
 227         bh = sb_bread(inode->i_sb, clus_to_blk(OMFS_SB(inode->i_sb),
 228                         inode->i_ino));
 229
 230         if (!bh)
 231                 return 0;
 232
 233         ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
 234
 235         for (i = 0; i < nbuckets; i++, ptr++)
 236                 if (*ptr != ~0)
 237                         break;
 238
 239         brelse(bh);
 240         return *ptr != ~0;
 241 }
 242
 243 static int omfs_unlink(struct inode *dir, struct dentry *dentry)
 244 {
 245         int ret;
 246         struct inode *inode = dentry->d_inode;
 247
 248         ret = omfs_delete_entry(dentry);
 249         if (ret)
 250                 goto end_unlink;
 251
 252         inode_dec_link_count(inode);
 253         mark_inode_dirty(dir);
 254
 255 end_unlink:
 256         return ret;
 257 }
 258
 259 static int omfs_rmdir(struct inode *dir, struct dentry *dentry)
 260 {
 261         int err = -ENOTEMPTY;
 262         struct inode *inode = dentry->d_inode;
 263
 264         if (omfs_dir_is_empty(inode)) {
 265                 err = omfs_unlink(dir, dentry);
 266                 if (!err)
 267                         inode_dec_link_count(inode);
 268         }
 269         return err;
 270 }
 271
 272 static int omfs_add_node(struct inode *dir, struct dentry *dentry, int mode)
 273 {
 274         int err;
 275         struct inode *inode = omfs_new_inode(dir, mode);
 276
 277         if (IS_ERR(inode))
 278                 return PTR_ERR(inode);
 279
 280         err = omfs_make_empty(inode, dir->i_sb);
 281         if (err)
 282                 goto out_free_inode;
 283
 284         err = omfs_add_link(dentry, inode);
 285         if (err)
 286                 goto out_free_inode;
 287
 288         d_instantiate(dentry, inode);
 289         return 0;
 290
 291 out_free_inode:
 292         iput(inode);
 293         return err;
 294 }
 295
 296 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 297 {
 298         return omfs_add_node(dir, dentry, mode | S_IFDIR);
 299 }
 300
 301 static int omfs_create(struct inode *dir, struct dentry *dentry, int mode,
 302                 struct nameidata *nd)
 303 {
 304         return omfs_add_node(dir, dentry, mode | S_IFREG);
 305 }
 306
 307 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
 308                                   struct nameidata *nd)
 309 {
 310         struct buffer_head *bh;
 311         struct inode *inode = NULL;
 312
 313         if (dentry->d_name.len > OMFS_NAMELEN)
 314                 return ERR_PTR(-ENAMETOOLONG);
 315
 316         bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
 317         if (!IS_ERR(bh)) {
 318                 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
 319                 ino_t ino = be64_to_cpu(oi->i_head.h_self);
 320                 brelse(bh);
 321                 inode = omfs_iget(dir->i_sb, ino);
 322                 if (IS_ERR(inode))
 323                         return ERR_CAST(inode);
 324         }
 325         d_add(dentry, inode);
 326         return NULL;
 327 }
 328
 329 /* sanity check block's self pointer */
 330 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
 331         u64 fsblock)
 332 {
 333         int is_bad;
 334         u64 ino = be64_to_cpu(header->h_self);
 335         is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
 336                 (ino > sbi->s_num_blocks));
 337
 338         if (is_bad)
 339                 printk(KERN_WARNING "omfs: bad hash chain detected\n");
 340
 341         return is_bad;
 342 }
 343
 344 static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir,
 345                 u64 fsblock, int hindex)
 346 {
 347         struct inode *dir = filp->f_dentry->d_inode;
 348         struct buffer_head *bh;
 349         struct omfs_inode *oi;
 350         u64 self;
 351         int res = 0;
 352         unsigned char d_type;
 353
 354         /* follow chain in this bucket */
 355         while (fsblock != ~0) {
 356                 bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb),
 357                                 fsblock));
 358                 if (!bh)
 359                         goto out;
 360
 361                 oi = (struct omfs_inode *) bh->b_data;
 362                 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
 363                         brelse(bh);
 364                         goto out;
 365                 }
 366
 367                 self = fsblock;
 368                 fsblock = be64_to_cpu(oi->i_sibling);
 369
 370                 /* skip visited nodes */
 371                 if (hindex) {
 372                         hindex--;
 373                         brelse(bh);
 374                         continue;
 375                 }
 376
 377                 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
 378
 379                 res = filldir(dirent, oi->i_name, strnlen(oi->i_name,
 380                         OMFS_NAMELEN), filp->f_pos, self, d_type);
 381                 if (res == 0)
 382                         filp->f_pos++;
 383                 brelse(bh);
 384         }
 385 out:
 386         return res;
 387 }
 388
 389 static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 390                 struct inode *new_dir, struct dentry *new_dentry)
 391 {
 392         struct inode *new_inode = new_dentry->d_inode;
 393         struct inode *old_inode = old_dentry->d_inode;
 394         struct buffer_head *bh;
 395         int is_dir;
 396         int err;
 397
 398         is_dir = S_ISDIR(old_inode->i_mode);
 399
 400         if (new_inode) {
 401                 /* overwriting existing file/dir */
 402                 err = -ENOTEMPTY;
 403                 if (is_dir && !omfs_dir_is_empty(new_inode))
 404                         goto out;
 405
 406                 err = -ENOENT;
 407                 bh = omfs_find_entry(new_dir, new_dentry->d_name.name,
 408                         new_dentry->d_name.len);
 409                 if (IS_ERR(bh))
 410                         goto out;
 411                 brelse(bh);
 412
 413                 err = omfs_unlink(new_dir, new_dentry);
 414                 if (err)
 415                         goto out;
 416         }
 417
 418         /* since omfs locates files by name, we need to unlink _before_
 419          * adding the new link or we won't find the old one */
 420         inode_inc_link_count(old_inode);
 421         err = omfs_unlink(old_dir, old_dentry);
 422         if (err) {
 423                 inode_dec_link_count(old_inode);
 424                 goto out;
 425         }
 426
 427         err = omfs_add_link(new_dentry, old_inode);
 428         if (err)
 429                 goto out;
 430
 431         old_inode->i_ctime = CURRENT_TIME_SEC;
 432 out:
 433         return err;
 434 }
 435
 436 static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 437 {
 438         struct inode *dir = filp->f_dentry->d_inode;
 439         struct buffer_head *bh;
 440         loff_t offset, res;
 441         unsigned int hchain, hindex;
 442         int nbuckets;
 443         u64 fsblock;
 444         int ret = -EINVAL;
 445
 446         if (filp->f_pos >> 32)
 447                 goto success;
 448
 449         switch ((unsigned long) filp->f_pos) {
 450         case 0:
 451                 if (filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR) < 0)
 452                         goto success;
 453                 filp->f_pos++;
 454                 /* fall through */
 455         case 1:
 456                 if (filldir(dirent, "..", 2, 1,
 457                     parent_ino(filp->f_dentry), DT_DIR) < 0)
 458                         goto success;
 459                 filp->f_pos = 1 << 20;
 460                 /* fall through */
 461         }
 462
 463         nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
 464
 465         /* high 12 bits store bucket + 1 and low 20 bits store hash index */
 466         hchain = (filp->f_pos >> 20) - 1;
 467         hindex = filp->f_pos & 0xfffff;
 468
 469         bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb), dir->i_ino));
 470         if (!bh)
 471                 goto out;
 472
 473         offset = OMFS_DIR_START + hchain * 8;
 474
 475         for (; hchain < nbuckets; hchain++, offset += 8) {
 476                 fsblock = be64_to_cpu(*((__be64 *) &bh->b_data[offset]));
 477
 478                 res = omfs_fill_chain(filp, dirent, filldir, fsblock, hindex);
 479                 hindex = 0;
 480                 if (res < 0)
 481                         break;
 482
 483                 filp->f_pos = (hchain+2) << 20;
 484         }
 485         brelse(bh);
 486 success:
 487         ret = 0;
 488 out:
 489         return ret;
 490 }
 491
 492 const struct inode_operations omfs_dir_inops = {
 493         .lookup = omfs_lookup,
 494         .mkdir = omfs_mkdir,
 495         .rename = omfs_rename,
 496         .create = omfs_create,
 497         .unlink = omfs_unlink,
 498         .rmdir = omfs_rmdir,
 499 };
 500
 501 const struct file_operations omfs_dir_operations = {
 502         .read = generic_read_dir,
 503         .readdir = omfs_readdir,
 504         .llseek = generic_file_llseek,
 505 };