1/* 2 * linux/fs/ext3/dir.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * from 10 * 11 * linux/fs/minix/dir.c 12 * 13 * Copyright (C) 1991, 1992 Linus Torvalds 14 * 15 * ext3 directory handling functions 16 * 17 * Big-endian to little-endian byte-swapping/bitmaps by 18 * David S. Miller (davem@caip.rutgers.edu), 1995 19 * 20 * Hash Tree Directory indexing (c) 2001 Daniel Phillips 21 * 22 */ 23 24#include <linux/fs.h> 25#include <linux/jbd.h> 26#include <linux/ext3_fs.h> 27#include <linux/buffer_head.h> 28#include <linux/slab.h> 29#include <linux/rbtree.h> 30 31static unsigned char ext3_filetype_table[] = { 32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK 33}; 34 35static int ext3_readdir(struct file *, void *, filldir_t); 36static int ext3_dx_readdir(struct file * filp, 37 void * dirent, filldir_t filldir); 38static int ext3_release_dir (struct inode * inode, 39 struct file * filp); 40 41const struct file_operations ext3_dir_operations = { 42 .llseek = generic_file_llseek, 43 .read = generic_read_dir, 44 .readdir = ext3_readdir, /* we take BKL. needed?*/ 45 .unlocked_ioctl = ext3_ioctl, 46#ifdef CONFIG_COMPAT 47 .compat_ioctl = ext3_compat_ioctl, 48#endif 49 .fsync = ext3_sync_file, /* BKL held */ 50 .release = ext3_release_dir, 51}; 52 53 54static unsigned char get_dtype(struct super_block *sb, int filetype) 55{ 56 if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) || 57 (filetype >= EXT3_FT_MAX)) 58 return DT_UNKNOWN; 59 60 return (ext3_filetype_table[filetype]); 61} 62 63 64int ext3_check_dir_entry (const char * function, struct inode * dir, 65 struct ext3_dir_entry_2 * de, 66 struct buffer_head * bh, 67 unsigned long offset) 68{ 69 const char * error_msg = NULL; 70 const int rlen = ext3_rec_len_from_disk(de->rec_len); 71 72 if (rlen < EXT3_DIR_REC_LEN(1)) 73 error_msg = "rec_len is smaller than minimal"; 74 else if (rlen % 4 != 0) 75 error_msg = "rec_len % 4 != 0"; 76 else if (rlen < EXT3_DIR_REC_LEN(de->name_len)) 77 error_msg = "rec_len is too small for name_len"; 78 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 79 error_msg = "directory entry across blocks"; 80 else if (le32_to_cpu(de->inode) > 81 le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count)) 82 error_msg = "inode out of bounds"; 83 84 if (error_msg != NULL) 85 ext3_error (dir->i_sb, function, 86 "bad entry in directory #%lu: %s - " 87 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", 88 dir->i_ino, error_msg, offset, 89 (unsigned long) le32_to_cpu(de->inode), 90 rlen, de->name_len); 91 return error_msg == NULL ? 1 : 0; 92} 93 94static int ext3_readdir(struct file * filp, 95 void * dirent, filldir_t filldir) 96{ 97 int error = 0; 98 unsigned long offset; 99 int i, stored; 100 struct ext3_dir_entry_2 *de; 101 struct super_block *sb; 102 int err; 103 struct inode *inode = filp->f_path.dentry->d_inode; 104 int ret = 0; 105 int dir_has_error = 0; 106 107 sb = inode->i_sb; 108 109 if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb, 110 EXT3_FEATURE_COMPAT_DIR_INDEX) && 111 ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) || 112 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 113 err = ext3_dx_readdir(filp, dirent, filldir); 114 if (err != ERR_BAD_DX_DIR) { 115 ret = err; 116 goto out; 117 } 118 /* 119 * We don't set the inode dirty flag since it's not 120 * critical that it get flushed back to the disk. 121 */ 122 EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL; 123 } 124 stored = 0; 125 offset = filp->f_pos & (sb->s_blocksize - 1); 126 127 while (!error && !stored && filp->f_pos < inode->i_size) { 128 unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb); 129 struct buffer_head map_bh; 130 struct buffer_head *bh = NULL; 131 132 map_bh.b_state = 0; 133 err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0); 134 if (err > 0) { 135 pgoff_t index = map_bh.b_blocknr >> 136 (PAGE_CACHE_SHIFT - inode->i_blkbits); 137 if (!ra_has_index(&filp->f_ra, index)) 138 page_cache_sync_readahead( 139 sb->s_bdev->bd_inode->i_mapping, 140 &filp->f_ra, filp, 141 index, 1); 142 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 143 bh = ext3_bread(NULL, inode, blk, 0, &err); 144 } 145 146 /* 147 * We ignore I/O errors on directories so users have a chance 148 * of recovering data when there's a bad sector 149 */ 150 if (!bh) { 151 if (!dir_has_error) { 152 ext3_error(sb, __func__, "directory #%lu " 153 "contains a hole at offset %lld", 154 inode->i_ino, filp->f_pos); 155 dir_has_error = 1; 156 } 157 /* corrupt size? Maybe no more blocks to read */ 158 if (filp->f_pos > inode->i_blocks << 9) 159 break; 160 filp->f_pos += sb->s_blocksize - offset; 161 continue; 162 } 163 164revalidate: 165 /* If the dir block has changed since the last call to 166 * readdir(2), then we might be pointing to an invalid 167 * dirent right now. Scan from the start of the block 168 * to make sure. */ 169 if (filp->f_version != inode->i_version) { 170 for (i = 0; i < sb->s_blocksize && i < offset; ) { 171 de = (struct ext3_dir_entry_2 *) 172 (bh->b_data + i); 173 /* It's too expensive to do a full 174 * dirent test each time round this 175 * loop, but we do have to test at 176 * least that it is non-zero. A 177 * failure will be detected in the 178 * dirent test below. */ 179 if (ext3_rec_len_from_disk(de->rec_len) < 180 EXT3_DIR_REC_LEN(1)) 181 break; 182 i += ext3_rec_len_from_disk(de->rec_len); 183 } 184 offset = i; 185 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 186 | offset; 187 filp->f_version = inode->i_version; 188 } 189 190 while (!error && filp->f_pos < inode->i_size 191 && offset < sb->s_blocksize) { 192 de = (struct ext3_dir_entry_2 *) (bh->b_data + offset); 193 if (!ext3_check_dir_entry ("ext3_readdir", inode, de, 194 bh, offset)) { 195 /* On error, skip the f_pos to the 196 next block. */ 197 filp->f_pos = (filp->f_pos | 198 (sb->s_blocksize - 1)) + 1; 199 brelse (bh); 200 ret = stored; 201 goto out; 202 } 203 offset += ext3_rec_len_from_disk(de->rec_len); 204 if (le32_to_cpu(de->inode)) { 205 /* We might block in the next section 206 * if the data destination is 207 * currently swapped out. So, use a 208 * version stamp to detect whether or 209 * not the directory has been modified 210 * during the copy operation. 211 */ 212 u64 version = filp->f_version; 213 214 error = filldir(dirent, de->name, 215 de->name_len, 216 filp->f_pos, 217 le32_to_cpu(de->inode), 218 get_dtype(sb, de->file_type)); 219 if (error) 220 break; 221 if (version != filp->f_version) 222 goto revalidate; 223 stored ++; 224 } 225 filp->f_pos += ext3_rec_len_from_disk(de->rec_len); 226 } 227 offset = 0; 228 brelse (bh); 229 } 230out: 231 return ret; 232} 233 234/* 235 * These functions convert from the major/minor hash to an f_pos 236 * value. 237 * 238 * Currently we only use major hash numer. This is unfortunate, but 239 * on 32-bit machines, the same VFS interface is used for lseek and 240 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 241 * lseek/telldir/seekdir will blow out spectacularly, and from within 242 * the ext2 low-level routine, we don't know if we're being called by 243 * a 64-bit version of the system call or the 32-bit version of the 244 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 245 * cookie. Sigh. 246 */ 247#define hash2pos(major, minor) (major >> 1) 248#define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 249#define pos2min_hash(pos) (0) 250 251/* 252 * This structure holds the nodes of the red-black tree used to store 253 * the directory entry in hash order. 254 */ 255struct fname { 256 __u32 hash; 257 __u32 minor_hash; 258 struct rb_node rb_hash; 259 struct fname *next; 260 __u32 inode; 261 __u8 name_len; 262 __u8 file_type; 263 char name[0]; 264}; 265 266/* 267 * This functoin implements a non-recursive way of freeing all of the 268 * nodes in the red-black tree. 269 */ 270static void free_rb_tree_fname(struct rb_root *root) 271{ 272 struct rb_node *n = root->rb_node; 273 struct rb_node *parent; 274 struct fname *fname; 275 276 while (n) { 277 /* Do the node's children first */ 278 if (n->rb_left) { 279 n = n->rb_left; 280 continue; 281 } 282 if (n->rb_right) { 283 n = n->rb_right; 284 continue; 285 } 286 /* 287 * The node has no children; free it, and then zero 288 * out parent's link to it. Finally go to the 289 * beginning of the loop and try to free the parent 290 * node. 291 */ 292 parent = rb_parent(n); 293 fname = rb_entry(n, struct fname, rb_hash); 294 while (fname) { 295 struct fname * old = fname; 296 fname = fname->next; 297 kfree (old); 298 } 299 if (!parent) 300 *root = RB_ROOT; 301 else if (parent->rb_left == n) 302 parent->rb_left = NULL; 303 else if (parent->rb_right == n) 304 parent->rb_right = NULL; 305 n = parent; 306 } 307} 308 309 310static struct dir_private_info *ext3_htree_create_dir_info(loff_t pos) 311{ 312 struct dir_private_info *p; 313 314 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 315 if (!p) 316 return NULL; 317 p->curr_hash = pos2maj_hash(pos); 318 p->curr_minor_hash = pos2min_hash(pos); 319 return p; 320} 321 322void ext3_htree_free_dir_info(struct dir_private_info *p) 323{ 324 free_rb_tree_fname(&p->root); 325 kfree(p); 326} 327 328/* 329 * Given a directory entry, enter it into the fname rb tree. 330 */ 331int ext3_htree_store_dirent(struct file *dir_file, __u32 hash, 332 __u32 minor_hash, 333 struct ext3_dir_entry_2 *dirent) 334{ 335 struct rb_node **p, *parent = NULL; 336 struct fname * fname, *new_fn; 337 struct dir_private_info *info; 338 int len; 339 340 info = (struct dir_private_info *) dir_file->private_data; 341 p = &info->root.rb_node; 342 343 /* Create and allocate the fname structure */ 344 len = sizeof(struct fname) + dirent->name_len + 1; 345 new_fn = kzalloc(len, GFP_KERNEL); 346 if (!new_fn) 347 return -ENOMEM; 348 new_fn->hash = hash; 349 new_fn->minor_hash = minor_hash; 350 new_fn->inode = le32_to_cpu(dirent->inode); 351 new_fn->name_len = dirent->name_len; 352 new_fn->file_type = dirent->file_type; 353 memcpy(new_fn->name, dirent->name, dirent->name_len); 354 new_fn->name[dirent->name_len] = 0; 355 356 while (*p) { 357 parent = *p; 358 fname = rb_entry(parent, struct fname, rb_hash); 359 360 /* 361 * If the hash and minor hash match up, then we put 362 * them on a linked list. This rarely happens... 363 */ 364 if ((new_fn->hash == fname->hash) && 365 (new_fn->minor_hash == fname->minor_hash)) { 366 new_fn->next = fname->next; 367 fname->next = new_fn; 368 return 0; 369 } 370 371 if (new_fn->hash < fname->hash) 372 p = &(*p)->rb_left; 373 else if (new_fn->hash > fname->hash) 374 p = &(*p)->rb_right; 375 else if (new_fn->minor_hash < fname->minor_hash) 376 p = &(*p)->rb_left; 377 else /* if (new_fn->minor_hash > fname->minor_hash) */ 378 p = &(*p)->rb_right; 379 } 380 381 rb_link_node(&new_fn->rb_hash, parent, p); 382 rb_insert_color(&new_fn->rb_hash, &info->root); 383 return 0; 384} 385 386 387 388/* 389 * This is a helper function for ext3_dx_readdir. It calls filldir 390 * for all entres on the fname linked list. (Normally there is only 391 * one entry on the linked list, unless there are 62 bit hash collisions.) 392 */ 393static int call_filldir(struct file * filp, void * dirent, 394 filldir_t filldir, struct fname *fname) 395{ 396 struct dir_private_info *info = filp->private_data; 397 loff_t curr_pos; 398 struct inode *inode = filp->f_path.dentry->d_inode; 399 struct super_block * sb; 400 int error; 401 402 sb = inode->i_sb; 403 404 if (!fname) { 405 printk("call_filldir: called with null fname?!?\n"); 406 return 0; 407 } 408 curr_pos = hash2pos(fname->hash, fname->minor_hash); 409 while (fname) { 410 error = filldir(dirent, fname->name, 411 fname->name_len, curr_pos, 412 fname->inode, 413 get_dtype(sb, fname->file_type)); 414 if (error) { 415 filp->f_pos = curr_pos; 416 info->extra_fname = fname; 417 return error; 418 } 419 fname = fname->next; 420 } 421 return 0; 422} 423 424static int ext3_dx_readdir(struct file * filp, 425 void * dirent, filldir_t filldir) 426{ 427 struct dir_private_info *info = filp->private_data; 428 struct inode *inode = filp->f_path.dentry->d_inode; 429 struct fname *fname; 430 int ret; 431 432 if (!info) { 433 info = ext3_htree_create_dir_info(filp->f_pos); 434 if (!info) 435 return -ENOMEM; 436 filp->private_data = info; 437 } 438 439 if (filp->f_pos == EXT3_HTREE_EOF) 440 return 0; /* EOF */ 441 442 /* Some one has messed with f_pos; reset the world */ 443 if (info->last_pos != filp->f_pos) { 444 free_rb_tree_fname(&info->root); 445 info->curr_node = NULL; 446 info->extra_fname = NULL; 447 info->curr_hash = pos2maj_hash(filp->f_pos); 448 info->curr_minor_hash = pos2min_hash(filp->f_pos); 449 } 450 451 /* 452 * If there are any leftover names on the hash collision 453 * chain, return them first. 454 */ 455 if (info->extra_fname) { 456 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 457 goto finished; 458 info->extra_fname = NULL; 459 goto next_node; 460 } else if (!info->curr_node) 461 info->curr_node = rb_first(&info->root); 462 463 while (1) { 464 /* 465 * Fill the rbtree if we have no more entries, 466 * or the inode has changed since we last read in the 467 * cached entries. 468 */ 469 if ((!info->curr_node) || 470 (filp->f_version != inode->i_version)) { 471 info->curr_node = NULL; 472 free_rb_tree_fname(&info->root); 473 filp->f_version = inode->i_version; 474 ret = ext3_htree_fill_tree(filp, info->curr_hash, 475 info->curr_minor_hash, 476 &info->next_hash); 477 if (ret < 0) 478 return ret; 479 if (ret == 0) { 480 filp->f_pos = EXT3_HTREE_EOF; 481 break; 482 } 483 info->curr_node = rb_first(&info->root); 484 } 485 486 fname = rb_entry(info->curr_node, struct fname, rb_hash); 487 info->curr_hash = fname->hash; 488 info->curr_minor_hash = fname->minor_hash; 489 if (call_filldir(filp, dirent, filldir, fname)) 490 break; 491 next_node: 492 info->curr_node = rb_next(info->curr_node); 493 if (info->curr_node) { 494 fname = rb_entry(info->curr_node, struct fname, 495 rb_hash); 496 info->curr_hash = fname->hash; 497 info->curr_minor_hash = fname->minor_hash; 498 } else { 499 if (info->next_hash == ~0) { 500 filp->f_pos = EXT3_HTREE_EOF; 501 break; 502 } 503 info->curr_hash = info->next_hash; 504 info->curr_minor_hash = 0; 505 } 506 } 507finished: 508 info->last_pos = filp->f_pos; 509 return 0; 510} 511 512static int ext3_release_dir (struct inode * inode, struct file * filp) 513{ 514 if (filp->private_data) 515 ext3_htree_free_dir_info(filp->private_data); 516 517 return 0; 518} 519