1/* 2 * linux/fs/ext4/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 * ext4 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/jbd2.h> 26#include <linux/buffer_head.h> 27#include <linux/slab.h> 28#include <linux/rbtree.h> 29#include "ext4.h" 30 31static unsigned char ext4_filetype_table[] = { 32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK 33}; 34 35static int ext4_readdir(struct file *, void *, filldir_t); 36static int ext4_dx_readdir(struct file *filp, 37 void *dirent, filldir_t filldir); 38static int ext4_release_dir(struct inode *inode, 39 struct file *filp); 40 41const struct file_operations ext4_dir_operations = { 42 .llseek = generic_file_llseek, 43 .read = generic_read_dir, 44 .readdir = ext4_readdir, /* we take BKL. needed?*/ 45 .unlocked_ioctl = ext4_ioctl, 46#ifdef CONFIG_COMPAT 47 .compat_ioctl = ext4_compat_ioctl, 48#endif 49 .fsync = ext4_sync_file, 50 .release = ext4_release_dir, 51}; 52 53 54static unsigned char get_dtype(struct super_block *sb, int filetype) 55{ 56 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) || 57 (filetype >= EXT4_FT_MAX)) 58 return DT_UNKNOWN; 59 60 return (ext4_filetype_table[filetype]); 61} 62 63 64int __ext4_check_dir_entry(const char *function, unsigned int line, 65 struct inode *dir, 66 struct ext4_dir_entry_2 *de, 67 struct buffer_head *bh, 68 unsigned int offset) 69{ 70 const char *error_msg = NULL; 71 const int rlen = ext4_rec_len_from_disk(de->rec_len, 72 dir->i_sb->s_blocksize); 73 74 if (rlen < EXT4_DIR_REC_LEN(1)) 75 error_msg = "rec_len is smaller than minimal"; 76 else if (rlen % 4 != 0) 77 error_msg = "rec_len % 4 != 0"; 78 else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) 79 error_msg = "rec_len is too small for name_len"; 80 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 81 error_msg = "directory entry across blocks"; 82 else if (le32_to_cpu(de->inode) > 83 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) 84 error_msg = "inode out of bounds"; 85 86 if (error_msg != NULL) 87 ext4_error_inode(dir, function, line, bh->b_blocknr, 88 "bad entry in directory: %s - " 89 "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d", 90 error_msg, (unsigned) (offset%bh->b_size), offset, 91 le32_to_cpu(de->inode), 92 rlen, de->name_len); 93 return error_msg == NULL ? 1 : 0; 94} 95 96static int ext4_readdir(struct file *filp, 97 void *dirent, filldir_t filldir) 98{ 99 int error = 0; 100 unsigned int offset; 101 int i, stored; 102 struct ext4_dir_entry_2 *de; 103 struct super_block *sb; 104 int err; 105 struct inode *inode = filp->f_path.dentry->d_inode; 106 int ret = 0; 107 int dir_has_error = 0; 108 109 sb = inode->i_sb; 110 111 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 112 EXT4_FEATURE_COMPAT_DIR_INDEX) && 113 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 114 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 115 err = ext4_dx_readdir(filp, dirent, filldir); 116 if (err != ERR_BAD_DX_DIR) { 117 ret = err; 118 goto out; 119 } 120 /* 121 * We don't set the inode dirty flag since it's not 122 * critical that it get flushed back to the disk. 123 */ 124 ext4_clear_inode_flag(filp->f_path.dentry->d_inode, 125 EXT4_INODE_INDEX); 126 } 127 stored = 0; 128 offset = filp->f_pos & (sb->s_blocksize - 1); 129 130 while (!error && !stored && filp->f_pos < inode->i_size) { 131 struct ext4_map_blocks map; 132 struct buffer_head *bh = NULL; 133 134 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 135 map.m_len = 1; 136 err = ext4_map_blocks(NULL, inode, &map, 0); 137 if (err > 0) { 138 pgoff_t index = map.m_pblk >> 139 (PAGE_CACHE_SHIFT - inode->i_blkbits); 140 if (!ra_has_index(&filp->f_ra, index)) 141 page_cache_sync_readahead( 142 sb->s_bdev->bd_inode->i_mapping, 143 &filp->f_ra, filp, 144 index, 1); 145 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 146 bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err); 147 } 148 149 /* 150 * We ignore I/O errors on directories so users have a chance 151 * of recovering data when there's a bad sector 152 */ 153 if (!bh) { 154 if (!dir_has_error) { 155 EXT4_ERROR_INODE(inode, "directory " 156 "contains a hole at offset %Lu", 157 (unsigned long long) filp->f_pos); 158 dir_has_error = 1; 159 } 160 /* corrupt size? Maybe no more blocks to read */ 161 if (filp->f_pos > inode->i_blocks << 9) 162 break; 163 filp->f_pos += sb->s_blocksize - offset; 164 continue; 165 } 166 167revalidate: 168 /* If the dir block has changed since the last call to 169 * readdir(2), then we might be pointing to an invalid 170 * dirent right now. Scan from the start of the block 171 * to make sure. */ 172 if (filp->f_version != inode->i_version) { 173 for (i = 0; i < sb->s_blocksize && i < offset; ) { 174 de = (struct ext4_dir_entry_2 *) 175 (bh->b_data + i); 176 /* It's too expensive to do a full 177 * dirent test each time round this 178 * loop, but we do have to test at 179 * least that it is non-zero. A 180 * failure will be detected in the 181 * dirent test below. */ 182 if (ext4_rec_len_from_disk(de->rec_len, 183 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 184 break; 185 i += ext4_rec_len_from_disk(de->rec_len, 186 sb->s_blocksize); 187 } 188 offset = i; 189 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 190 | offset; 191 filp->f_version = inode->i_version; 192 } 193 194 while (!error && filp->f_pos < inode->i_size 195 && offset < sb->s_blocksize) { 196 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 197 if (!ext4_check_dir_entry(inode, de, 198 bh, offset)) { 199 /* 200 * On error, skip the f_pos to the next block 201 */ 202 filp->f_pos = (filp->f_pos | 203 (sb->s_blocksize - 1)) + 1; 204 brelse(bh); 205 ret = stored; 206 goto out; 207 } 208 offset += ext4_rec_len_from_disk(de->rec_len, 209 sb->s_blocksize); 210 if (le32_to_cpu(de->inode)) { 211 /* We might block in the next section 212 * if the data destination is 213 * currently swapped out. So, use a 214 * version stamp to detect whether or 215 * not the directory has been modified 216 * during the copy operation. 217 */ 218 u64 version = filp->f_version; 219 220 error = filldir(dirent, de->name, 221 de->name_len, 222 filp->f_pos, 223 le32_to_cpu(de->inode), 224 get_dtype(sb, de->file_type)); 225 if (error) 226 break; 227 if (version != filp->f_version) 228 goto revalidate; 229 stored++; 230 } 231 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 232 sb->s_blocksize); 233 } 234 offset = 0; 235 brelse(bh); 236 } 237out: 238 return ret; 239} 240 241/* 242 * These functions convert from the major/minor hash to an f_pos 243 * value. 244 * 245 * Currently we only use major hash numer. This is unfortunate, but 246 * on 32-bit machines, the same VFS interface is used for lseek and 247 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 248 * lseek/telldir/seekdir will blow out spectacularly, and from within 249 * the ext2 low-level routine, we don't know if we're being called by 250 * a 64-bit version of the system call or the 32-bit version of the 251 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 252 * cookie. Sigh. 253 */ 254#define hash2pos(major, minor) (major >> 1) 255#define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 256#define pos2min_hash(pos) (0) 257 258/* 259 * This structure holds the nodes of the red-black tree used to store 260 * the directory entry in hash order. 261 */ 262struct fname { 263 __u32 hash; 264 __u32 minor_hash; 265 struct rb_node rb_hash; 266 struct fname *next; 267 __u32 inode; 268 __u8 name_len; 269 __u8 file_type; 270 char name[0]; 271}; 272 273/* 274 * This functoin implements a non-recursive way of freeing all of the 275 * nodes in the red-black tree. 276 */ 277static void free_rb_tree_fname(struct rb_root *root) 278{ 279 struct rb_node *n = root->rb_node; 280 struct rb_node *parent; 281 struct fname *fname; 282 283 while (n) { 284 /* Do the node's children first */ 285 if (n->rb_left) { 286 n = n->rb_left; 287 continue; 288 } 289 if (n->rb_right) { 290 n = n->rb_right; 291 continue; 292 } 293 /* 294 * The node has no children; free it, and then zero 295 * out parent's link to it. Finally go to the 296 * beginning of the loop and try to free the parent 297 * node. 298 */ 299 parent = rb_parent(n); 300 fname = rb_entry(n, struct fname, rb_hash); 301 while (fname) { 302 struct fname *old = fname; 303 fname = fname->next; 304 kfree(old); 305 } 306 if (!parent) 307 *root = RB_ROOT; 308 else if (parent->rb_left == n) 309 parent->rb_left = NULL; 310 else if (parent->rb_right == n) 311 parent->rb_right = NULL; 312 n = parent; 313 } 314} 315 316 317static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos) 318{ 319 struct dir_private_info *p; 320 321 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 322 if (!p) 323 return NULL; 324 p->curr_hash = pos2maj_hash(pos); 325 p->curr_minor_hash = pos2min_hash(pos); 326 return p; 327} 328 329void ext4_htree_free_dir_info(struct dir_private_info *p) 330{ 331 free_rb_tree_fname(&p->root); 332 kfree(p); 333} 334 335/* 336 * Given a directory entry, enter it into the fname rb tree. 337 */ 338int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 339 __u32 minor_hash, 340 struct ext4_dir_entry_2 *dirent) 341{ 342 struct rb_node **p, *parent = NULL; 343 struct fname *fname, *new_fn; 344 struct dir_private_info *info; 345 int len; 346 347 info = dir_file->private_data; 348 p = &info->root.rb_node; 349 350 /* Create and allocate the fname structure */ 351 len = sizeof(struct fname) + dirent->name_len + 1; 352 new_fn = kzalloc(len, GFP_KERNEL); 353 if (!new_fn) 354 return -ENOMEM; 355 new_fn->hash = hash; 356 new_fn->minor_hash = minor_hash; 357 new_fn->inode = le32_to_cpu(dirent->inode); 358 new_fn->name_len = dirent->name_len; 359 new_fn->file_type = dirent->file_type; 360 memcpy(new_fn->name, dirent->name, dirent->name_len); 361 new_fn->name[dirent->name_len] = 0; 362 363 while (*p) { 364 parent = *p; 365 fname = rb_entry(parent, struct fname, rb_hash); 366 367 /* 368 * If the hash and minor hash match up, then we put 369 * them on a linked list. This rarely happens... 370 */ 371 if ((new_fn->hash == fname->hash) && 372 (new_fn->minor_hash == fname->minor_hash)) { 373 new_fn->next = fname->next; 374 fname->next = new_fn; 375 return 0; 376 } 377 378 if (new_fn->hash < fname->hash) 379 p = &(*p)->rb_left; 380 else if (new_fn->hash > fname->hash) 381 p = &(*p)->rb_right; 382 else if (new_fn->minor_hash < fname->minor_hash) 383 p = &(*p)->rb_left; 384 else /* if (new_fn->minor_hash > fname->minor_hash) */ 385 p = &(*p)->rb_right; 386 } 387 388 rb_link_node(&new_fn->rb_hash, parent, p); 389 rb_insert_color(&new_fn->rb_hash, &info->root); 390 return 0; 391} 392 393 394 395/* 396 * This is a helper function for ext4_dx_readdir. It calls filldir 397 * for all entres on the fname linked list. (Normally there is only 398 * one entry on the linked list, unless there are 62 bit hash collisions.) 399 */ 400static int call_filldir(struct file *filp, void *dirent, 401 filldir_t filldir, struct fname *fname) 402{ 403 struct dir_private_info *info = filp->private_data; 404 loff_t curr_pos; 405 struct inode *inode = filp->f_path.dentry->d_inode; 406 struct super_block *sb; 407 int error; 408 409 sb = inode->i_sb; 410 411 if (!fname) { 412 printk(KERN_ERR "EXT4-fs: call_filldir: called with " 413 "null fname?!?\n"); 414 return 0; 415 } 416 curr_pos = hash2pos(fname->hash, fname->minor_hash); 417 while (fname) { 418 error = filldir(dirent, fname->name, 419 fname->name_len, curr_pos, 420 fname->inode, 421 get_dtype(sb, fname->file_type)); 422 if (error) { 423 filp->f_pos = curr_pos; 424 info->extra_fname = fname; 425 return error; 426 } 427 fname = fname->next; 428 } 429 return 0; 430} 431 432static int ext4_dx_readdir(struct file *filp, 433 void *dirent, filldir_t filldir) 434{ 435 struct dir_private_info *info = filp->private_data; 436 struct inode *inode = filp->f_path.dentry->d_inode; 437 struct fname *fname; 438 int ret; 439 440 if (!info) { 441 info = ext4_htree_create_dir_info(filp->f_pos); 442 if (!info) 443 return -ENOMEM; 444 filp->private_data = info; 445 } 446 447 if (filp->f_pos == EXT4_HTREE_EOF) 448 return 0; /* EOF */ 449 450 /* Some one has messed with f_pos; reset the world */ 451 if (info->last_pos != filp->f_pos) { 452 free_rb_tree_fname(&info->root); 453 info->curr_node = NULL; 454 info->extra_fname = NULL; 455 info->curr_hash = pos2maj_hash(filp->f_pos); 456 info->curr_minor_hash = pos2min_hash(filp->f_pos); 457 } 458 459 /* 460 * If there are any leftover names on the hash collision 461 * chain, return them first. 462 */ 463 if (info->extra_fname) { 464 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 465 goto finished; 466 info->extra_fname = NULL; 467 goto next_node; 468 } else if (!info->curr_node) 469 info->curr_node = rb_first(&info->root); 470 471 while (1) { 472 /* 473 * Fill the rbtree if we have no more entries, 474 * or the inode has changed since we last read in the 475 * cached entries. 476 */ 477 if ((!info->curr_node) || 478 (filp->f_version != inode->i_version)) { 479 info->curr_node = NULL; 480 free_rb_tree_fname(&info->root); 481 filp->f_version = inode->i_version; 482 ret = ext4_htree_fill_tree(filp, info->curr_hash, 483 info->curr_minor_hash, 484 &info->next_hash); 485 if (ret < 0) 486 return ret; 487 if (ret == 0) { 488 filp->f_pos = EXT4_HTREE_EOF; 489 break; 490 } 491 info->curr_node = rb_first(&info->root); 492 } 493 494 fname = rb_entry(info->curr_node, struct fname, rb_hash); 495 info->curr_hash = fname->hash; 496 info->curr_minor_hash = fname->minor_hash; 497 if (call_filldir(filp, dirent, filldir, fname)) 498 break; 499 next_node: 500 info->curr_node = rb_next(info->curr_node); 501 if (info->curr_node) { 502 fname = rb_entry(info->curr_node, struct fname, 503 rb_hash); 504 info->curr_hash = fname->hash; 505 info->curr_minor_hash = fname->minor_hash; 506 } else { 507 if (info->next_hash == ~0) { 508 filp->f_pos = EXT4_HTREE_EOF; 509 break; 510 } 511 info->curr_hash = info->next_hash; 512 info->curr_minor_hash = 0; 513 } 514 } 515finished: 516 info->last_pos = filp->f_pos; 517 return 0; 518} 519 520static int ext4_release_dir(struct inode *inode, struct file *filp) 521{ 522 if (filp->private_data) 523 ext4_htree_free_dir_info(filp->private_data); 524 525 return 0; 526} 527