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 (S_ISDIR(inode->i_mode)) {
  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 = d_inode(dentry->d_parent);
 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 = d_inode(dentry->d_parent);
 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 = d_inode(dentry);
 241         int ret;
 242
 243
 244         if (S_ISDIR(inode->i_mode) &&
 245             !omfs_dir_is_empty(inode))
 246                 return -ENOTEMPTY;
 247
 248         ret = omfs_delete_entry(dentry);
 249         if (ret)
 250                 return ret;
 251
 252         clear_nlink(inode);
 253         mark_inode_dirty(inode);
 254         mark_inode_dirty(dir);
 255         return 0;
 256 }
 257
 258 static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
 259 {
 260         int err;
 261         struct inode *inode = omfs_new_inode(dir, mode);
 262
 263         if (IS_ERR(inode))
 264                 return PTR_ERR(inode);
 265
 266         err = omfs_make_empty(inode, dir->i_sb);
 267         if (err)
 268                 goto out_free_inode;
 269
 270         err = omfs_add_link(dentry, inode);
 271         if (err)
 272                 goto out_free_inode;
 273
 274         d_instantiate(dentry, inode);
 275         return 0;
 276
 277 out_free_inode:
 278         iput(inode);
 279         return err;
 280 }
 281
 282 static int omfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 283 {
 284         return omfs_add_node(dir, dentry, mode | S_IFDIR);
 285 }
 286
 287 static int omfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 288                 bool excl)
 289 {
 290         return omfs_add_node(dir, dentry, mode | S_IFREG);
 291 }
 292
 293 static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
 294                                   unsigned int flags)
 295 {
 296         struct buffer_head *bh;
 297         struct inode *inode = NULL;
 298
 299         if (dentry->d_name.len > OMFS_NAMELEN)
 300                 return ERR_PTR(-ENAMETOOLONG);
 301
 302         bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
 303         if (!IS_ERR(bh)) {
 304                 struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
 305                 ino_t ino = be64_to_cpu(oi->i_head.h_self);
 306                 brelse(bh);
 307                 inode = omfs_iget(dir->i_sb, ino);
 308                 if (IS_ERR(inode))
 309                         return ERR_CAST(inode);
 310         }
 311         d_add(dentry, inode);
 312         return NULL;
 313 }
 314
 315 /* sanity check block's self pointer */
 316 int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
 317         u64 fsblock)
 318 {
 319         int is_bad;
 320         u64 ino = be64_to_cpu(header->h_self);
 321         is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
 322                 (ino > sbi->s_num_blocks));
 323
 324         if (is_bad)
 325                 printk(KERN_WARNING "omfs: bad hash chain detected\n");
 326
 327         return is_bad;
 328 }
 329
 330 static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
 331                 u64 fsblock, int hindex)
 332 {
 333         /* follow chain in this bucket */
 334         while (fsblock != ~0) {
 335                 struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
 336                 struct omfs_inode *oi;
 337                 u64 self;
 338                 unsigned char d_type;
 339
 340                 if (!bh)
 341                         return true;
 342
 343                 oi = (struct omfs_inode *) bh->b_data;
 344                 if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
 345                         brelse(bh);
 346                         return true;
 347                 }
 348
 349                 self = fsblock;
 350                 fsblock = be64_to_cpu(oi->i_sibling);
 351
 352                 /* skip visited nodes */
 353                 if (hindex) {
 354                         hindex--;
 355                         brelse(bh);
 356                         continue;
 357                 }
 358
 359                 d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
 360
 361                 if (!dir_emit(ctx, oi->i_name,
 362                               strnlen(oi->i_name, OMFS_NAMELEN),
 363                               self, d_type)) {
 364                         brelse(bh);
 365                         return false;
 366                 }
 367                 brelse(bh);
 368                 ctx->pos++;
 369         }
 370         return true;
 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 = d_inode(new_dentry);
 377         struct inode *old_inode = d_inode(old_dentry);
 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 *file, struct dir_context *ctx)
 405 {
 406         struct inode *dir = file_inode(file);
 407         struct buffer_head *bh;
 408         __be64 *p;
 409         unsigned int hchain, hindex;
 410         int nbuckets;
 411
 412         if (ctx->pos >> 32)
 413                 return -EINVAL;
 414
 415         if (ctx->pos < 1 << 20) {
 416                 if (!dir_emit_dots(file, ctx))
 417                         return 0;
 418                 ctx->pos = 1 << 20;
 419         }
 420
 421         nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
 422
 423         /* high 12 bits store bucket + 1 and low 20 bits store hash index */
 424         hchain = (ctx->pos >> 20) - 1;
 425         hindex = ctx->pos & 0xfffff;
 426
 427         bh = omfs_bread(dir->i_sb, dir->i_ino);
 428         if (!bh)
 429                 return -EINVAL;
 430
 431         p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;
 432
 433         for (; hchain < nbuckets; hchain++) {
 434                 __u64 fsblock = be64_to_cpu(*p++);
 435                 if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
 436                         break;
 437                 hindex = 0;
 438                 ctx->pos = (hchain+2) << 20;
 439         }
 440         brelse(bh);
 441         return 0;
 442 }
 443
 444 const struct inode_operations omfs_dir_inops = {
 445         .lookup = omfs_lookup,
 446         .mkdir = omfs_mkdir,
 447         .rename = omfs_rename,
 448         .create = omfs_create,
 449         .unlink = omfs_remove,
 450         .rmdir = omfs_remove,
 451 };
 452
 453 const struct file_operations omfs_dir_operations = {
 454         .read = generic_read_dir,
 455         .iterate = omfs_readdir,
 456         .llseek = generic_file_llseek,
 457 };