dir.c 16.3 KB
Newer Older
1
/*
2
 *  linux/fs/ext4/dir.c
3 4 5 6 7 8 9 10 11 12 13 14
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
15
 *  ext4 directory handling functions
16 17 18 19 20 21 22 23 24
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *
 * Hash Tree Directory indexing (c) 2001  Daniel Phillips
 *
 */

#include <linux/fs.h>
25
#include <linux/jbd2.h>
26 27 28
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
29
#include "ext4.h"
30
#include "xattr.h"
31

32 33
static int ext4_dx_readdir(struct file *filp,
			   void *dirent, filldir_t filldir);
34

35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
/**
 * Check if the given dir-inode refers to an htree-indexed directory
 * (or a directory which chould potentially get coverted to use htree
 * indexing).
 *
 * Return 1 if it is a dx dir, 0 if not
 */
static int is_dx_dir(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;

	if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
		     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
	     ((inode->i_size >> sb->s_blocksize_bits) == 1)))
		return 1;

	return 0;
}

55 56 57 58
/*
 * Return 0 if the directory entry is OK, and 1 if there is a problem
 *
 * Note: this is the opposite of what ext2 and ext3 historically returned...
59 60 61
 *
 * bh passed here can be an inode block or a dir data block, depending
 * on the inode inline data flag.
62
 */
63
int __ext4_check_dir_entry(const char *function, unsigned int line,
64
			   struct inode *dir, struct file *filp,
65
			   struct ext4_dir_entry_2 *de,
66
			   struct buffer_head *bh, char *buf, int size,
67
			   unsigned int offset)
68
{
69
	const char *error_msg = NULL;
70 71
	const int rlen = ext4_rec_len_from_disk(de->rec_len,
						dir->i_sb->s_blocksize);
72

73
	if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
74
		error_msg = "rec_len is smaller than minimal";
75
	else if (unlikely(rlen % 4 != 0))
76
		error_msg = "rec_len % 4 != 0";
77
	else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
78
		error_msg = "rec_len is too small for name_len";
79 80
	else if (unlikely(((char *) de - buf) + rlen > size))
		error_msg = "directory entry across range";
81 82
	else if (unlikely(le32_to_cpu(de->inode) >
			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
83
		error_msg = "inode out of bounds";
84 85 86
	else
		return 0;

87
	if (filp)
88
		ext4_error_file(filp, function, line, bh->b_blocknr,
89 90
				"bad entry in directory: %s - offset=%u(%u), "
				"inode=%u, rec_len=%d, name_len=%d",
91
				error_msg, (unsigned) (offset % size),
92 93 94
				offset, le32_to_cpu(de->inode),
				rlen, de->name_len);
	else
95
		ext4_error_inode(dir, function, line, bh->b_blocknr,
96 97
				"bad entry in directory: %s - offset=%u(%u), "
				"inode=%u, rec_len=%d, name_len=%d",
98
				error_msg, (unsigned) (offset % size),
99 100 101
				offset, le32_to_cpu(de->inode),
				rlen, de->name_len);

102
	return 1;
103 104
}

105 106
static int ext4_readdir(struct file *filp,
			 void *dirent, filldir_t filldir)
107 108
{
	int error = 0;
109
	unsigned int offset;
110
	int i, stored;
111
	struct ext4_dir_entry_2 *de;
112
	int err;
113
	struct inode *inode = filp->f_path.dentry->d_inode;
114
	struct super_block *sb = inode->i_sb;
115
	int ret = 0;
116
	int dir_has_error = 0;
117

118 119 120 121 122 123 124 125
	if (ext4_has_inline_data(inode)) {
		int has_inline_data = 1;
		ret = ext4_read_inline_dir(filp, dirent, filldir,
					   &has_inline_data);
		if (has_inline_data)
			return ret;
	}

126
	if (is_dx_dir(inode)) {
127
		err = ext4_dx_readdir(filp, dirent, filldir);
128 129 130 131 132 133 134 135
		if (err != ERR_BAD_DX_DIR) {
			ret = err;
			goto out;
		}
		/*
		 * We don't set the inode dirty flag since it's not
		 * critical that it get flushed back to the disk.
		 */
136 137
		ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
				      EXT4_INODE_INDEX);
138 139 140 141 142
	}
	stored = 0;
	offset = filp->f_pos & (sb->s_blocksize - 1);

	while (!error && !stored && filp->f_pos < inode->i_size) {
143
		struct ext4_map_blocks map;
144 145
		struct buffer_head *bh = NULL;

146 147 148
		map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
		map.m_len = 1;
		err = ext4_map_blocks(NULL, inode, &map, 0);
149
		if (err > 0) {
150
			pgoff_t index = map.m_pblk >>
151 152
					(PAGE_CACHE_SHIFT - inode->i_blkbits);
			if (!ra_has_index(&filp->f_ra, index))
153
				page_cache_sync_readahead(
154 155
					sb->s_bdev->bd_inode->i_mapping,
					&filp->f_ra, filp,
156
					index, 1);
157
			filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
158
			bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
159 160 161 162 163 164 165
		}

		/*
		 * We ignore I/O errors on directories so users have a chance
		 * of recovering data when there's a bad sector
		 */
		if (!bh) {
166
			if (!dir_has_error) {
167 168 169
				EXT4_ERROR_FILE(filp, 0,
						"directory contains a "
						"hole at offset %llu",
170 171 172
					   (unsigned long long) filp->f_pos);
				dir_has_error = 1;
			}
173 174 175
			/* corrupt size?  Maybe no more blocks to read */
			if (filp->f_pos > inode->i_blocks << 9)
				break;
176 177 178 179
			filp->f_pos += sb->s_blocksize - offset;
			continue;
		}

180 181 182 183 184 185 186 187
		/* Check the checksum */
		if (!buffer_verified(bh) &&
		    !ext4_dirent_csum_verify(inode,
				(struct ext4_dir_entry *)bh->b_data)) {
			EXT4_ERROR_FILE(filp, 0, "directory fails checksum "
					"at offset %llu",
					(unsigned long long)filp->f_pos);
			filp->f_pos += sb->s_blocksize - offset;
188
			brelse(bh);
189 190 191 192
			continue;
		}
		set_buffer_verified(bh);

193 194 195 196 197 198 199
revalidate:
		/* If the dir block has changed since the last call to
		 * readdir(2), then we might be pointing to an invalid
		 * dirent right now.  Scan from the start of the block
		 * to make sure. */
		if (filp->f_version != inode->i_version) {
			for (i = 0; i < sb->s_blocksize && i < offset; ) {
200
				de = (struct ext4_dir_entry_2 *)
201 202 203 204 205 206 207
					(bh->b_data + i);
				/* It's too expensive to do a full
				 * dirent test each time round this
				 * loop, but we do have to test at
				 * least that it is non-zero.  A
				 * failure will be detected in the
				 * dirent test below. */
208 209
				if (ext4_rec_len_from_disk(de->rec_len,
					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
210
					break;
211 212
				i += ext4_rec_len_from_disk(de->rec_len,
							    sb->s_blocksize);
213 214 215 216 217 218 219 220 221
			}
			offset = i;
			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
				| offset;
			filp->f_version = inode->i_version;
		}

		while (!error && filp->f_pos < inode->i_size
		       && offset < sb->s_blocksize) {
222
			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
223 224 225
			if (ext4_check_dir_entry(inode, filp, de, bh,
						 bh->b_data, bh->b_size,
						 offset)) {
226 227 228
				/*
				 * On error, skip the f_pos to the next block
				 */
229 230
				filp->f_pos = (filp->f_pos |
						(sb->s_blocksize - 1)) + 1;
231
				brelse(bh);
232 233 234
				ret = stored;
				goto out;
			}
235 236
			offset += ext4_rec_len_from_disk(de->rec_len,
					sb->s_blocksize);
237 238 239 240 241 242 243 244
			if (le32_to_cpu(de->inode)) {
				/* We might block in the next section
				 * if the data destination is
				 * currently swapped out.  So, use a
				 * version stamp to detect whether or
				 * not the directory has been modified
				 * during the copy operation.
				 */
245
				u64 version = filp->f_version;
246 247 248 249 250 251 252 253 254 255

				error = filldir(dirent, de->name,
						de->name_len,
						filp->f_pos,
						le32_to_cpu(de->inode),
						get_dtype(sb, de->file_type));
				if (error)
					break;
				if (version != filp->f_version)
					goto revalidate;
256
				stored++;
257
			}
258 259
			filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
						sb->s_blocksize);
260 261
		}
		offset = 0;
262
		brelse(bh);
263 264 265 266 267
	}
out:
	return ret;
}

268 269 270 271 272 273 274 275 276
static inline int is_32bit_api(void)
{
#ifdef CONFIG_COMPAT
	return is_compat_task();
#else
	return (BITS_PER_LONG == 32);
#endif
}

277 278
/*
 * These functions convert from the major/minor hash to an f_pos
279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326
 * value for dx directories
 *
 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 * directly on both 32-bit and 64-bit nodes, under such case, neither
 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 */
static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
{
	if ((filp->f_mode & FMODE_32BITHASH) ||
	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
		return major >> 1;
	else
		return ((__u64)(major >> 1) << 32) | (__u64)minor;
}

static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
{
	if ((filp->f_mode & FMODE_32BITHASH) ||
	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
		return (pos << 1) & 0xffffffff;
	else
		return ((pos >> 32) << 1) & 0xffffffff;
}

static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
{
	if ((filp->f_mode & FMODE_32BITHASH) ||
	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
		return 0;
	else
		return pos & 0xffffffff;
}

/*
 * Return 32- or 64-bit end-of-file for dx directories
 */
static inline loff_t ext4_get_htree_eof(struct file *filp)
{
	if ((filp->f_mode & FMODE_32BITHASH) ||
	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
		return EXT4_HTREE_EOF_32BIT;
	else
		return EXT4_HTREE_EOF_64BIT;
}


/*
327 328 329
 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 * directories, where the "offset" is in terms of the filename hash
 * value instead of the byte offset.
330
 *
331 332 333 334 335
 * Because we may return a 64-bit hash that is well beyond offset limits,
 * we need to pass the max hash as the maximum allowable offset in
 * the htree directory case.
 *
 * For non-htree, ext4_llseek already chooses the proper max offset.
336
 */
337
static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
338 339 340
{
	struct inode *inode = file->f_mapping->host;
	int dx_dir = is_dx_dir(inode);
341
	loff_t htree_max = ext4_get_htree_eof(file);
342

343
	if (likely(dx_dir))
344
		return generic_file_llseek_size(file, offset, whence,
345 346
						    htree_max, htree_max);
	else
347
		return ext4_llseek(file, offset, whence);
348
}
349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376

/*
 * This structure holds the nodes of the red-black tree used to store
 * the directory entry in hash order.
 */
struct fname {
	__u32		hash;
	__u32		minor_hash;
	struct rb_node	rb_hash;
	struct fname	*next;
	__u32		inode;
	__u8		name_len;
	__u8		file_type;
	char		name[0];
};

/*
 * This functoin implements a non-recursive way of freeing all of the
 * nodes in the red-black tree.
 */
static void free_rb_tree_fname(struct rb_root *root)
{
	struct rb_node	*n = root->rb_node;
	struct rb_node	*parent;
	struct fname	*fname;

	while (n) {
		/* Do the node's children first */
377
		if (n->rb_left) {
378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393
			n = n->rb_left;
			continue;
		}
		if (n->rb_right) {
			n = n->rb_right;
			continue;
		}
		/*
		 * The node has no children; free it, and then zero
		 * out parent's link to it.  Finally go to the
		 * beginning of the loop and try to free the parent
		 * node.
		 */
		parent = rb_parent(n);
		fname = rb_entry(n, struct fname, rb_hash);
		while (fname) {
394
			struct fname *old = fname;
395
			fname = fname->next;
396
			kfree(old);
397 398
		}
		if (!parent)
399
			*root = RB_ROOT;
400 401 402 403 404 405 406 407 408
		else if (parent->rb_left == n)
			parent->rb_left = NULL;
		else if (parent->rb_right == n)
			parent->rb_right = NULL;
		n = parent;
	}
}


409 410
static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
							   loff_t pos)
411 412 413
{
	struct dir_private_info *p;

414
	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
415 416
	if (!p)
		return NULL;
417 418
	p->curr_hash = pos2maj_hash(filp, pos);
	p->curr_minor_hash = pos2min_hash(filp, pos);
419 420 421
	return p;
}

422
void ext4_htree_free_dir_info(struct dir_private_info *p)
423 424 425 426 427 428 429 430
{
	free_rb_tree_fname(&p->root);
	kfree(p);
}

/*
 * Given a directory entry, enter it into the fname rb tree.
 */
431
int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
432
			     __u32 minor_hash,
433
			     struct ext4_dir_entry_2 *dirent)
434 435
{
	struct rb_node **p, *parent = NULL;
436
	struct fname *fname, *new_fn;
437 438 439
	struct dir_private_info *info;
	int len;

440
	info = dir_file->private_data;
441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488
	p = &info->root.rb_node;

	/* Create and allocate the fname structure */
	len = sizeof(struct fname) + dirent->name_len + 1;
	new_fn = kzalloc(len, GFP_KERNEL);
	if (!new_fn)
		return -ENOMEM;
	new_fn->hash = hash;
	new_fn->minor_hash = minor_hash;
	new_fn->inode = le32_to_cpu(dirent->inode);
	new_fn->name_len = dirent->name_len;
	new_fn->file_type = dirent->file_type;
	memcpy(new_fn->name, dirent->name, dirent->name_len);
	new_fn->name[dirent->name_len] = 0;

	while (*p) {
		parent = *p;
		fname = rb_entry(parent, struct fname, rb_hash);

		/*
		 * If the hash and minor hash match up, then we put
		 * them on a linked list.  This rarely happens...
		 */
		if ((new_fn->hash == fname->hash) &&
		    (new_fn->minor_hash == fname->minor_hash)) {
			new_fn->next = fname->next;
			fname->next = new_fn;
			return 0;
		}

		if (new_fn->hash < fname->hash)
			p = &(*p)->rb_left;
		else if (new_fn->hash > fname->hash)
			p = &(*p)->rb_right;
		else if (new_fn->minor_hash < fname->minor_hash)
			p = &(*p)->rb_left;
		else /* if (new_fn->minor_hash > fname->minor_hash) */
			p = &(*p)->rb_right;
	}

	rb_link_node(&new_fn->rb_hash, parent, p);
	rb_insert_color(&new_fn->rb_hash, &info->root);
	return 0;
}



/*
489
 * This is a helper function for ext4_dx_readdir.  It calls filldir
490 491 492
 * for all entres on the fname linked list.  (Normally there is only
 * one entry on the linked list, unless there are 62 bit hash collisions.)
 */
493
static int call_filldir(struct file *filp, void *dirent,
494 495 496 497
			filldir_t filldir, struct fname *fname)
{
	struct dir_private_info *info = filp->private_data;
	loff_t	curr_pos;
498
	struct inode *inode = filp->f_path.dentry->d_inode;
499
	struct super_block *sb;
500 501 502 503 504
	int error;

	sb = inode->i_sb;

	if (!fname) {
505 506 507
		ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
			 "called with null fname?!?", __func__, __LINE__,
			 inode->i_ino, current->comm);
508 509
		return 0;
	}
510
	curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
511 512 513 514 515 516 517
	while (fname) {
		error = filldir(dirent, fname->name,
				fname->name_len, curr_pos,
				fname->inode,
				get_dtype(sb, fname->file_type));
		if (error) {
			filp->f_pos = curr_pos;
518
			info->extra_fname = fname;
519 520 521 522 523 524 525
			return error;
		}
		fname = fname->next;
	}
	return 0;
}

526 527
static int ext4_dx_readdir(struct file *filp,
			 void *dirent, filldir_t filldir)
528 529
{
	struct dir_private_info *info = filp->private_data;
530
	struct inode *inode = filp->f_path.dentry->d_inode;
531 532 533 534
	struct fname *fname;
	int	ret;

	if (!info) {
535
		info = ext4_htree_create_dir_info(filp, filp->f_pos);
536 537 538 539 540
		if (!info)
			return -ENOMEM;
		filp->private_data = info;
	}

541
	if (filp->f_pos == ext4_get_htree_eof(filp))
542 543 544 545 546 547 548
		return 0;	/* EOF */

	/* Some one has messed with f_pos; reset the world */
	if (info->last_pos != filp->f_pos) {
		free_rb_tree_fname(&info->root);
		info->curr_node = NULL;
		info->extra_fname = NULL;
549 550
		info->curr_hash = pos2maj_hash(filp, filp->f_pos);
		info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
551 552 553 554 555 556
	}

	/*
	 * If there are any leftover names on the hash collision
	 * chain, return them first.
	 */
557 558 559 560
	if (info->extra_fname) {
		if (call_filldir(filp, dirent, filldir, info->extra_fname))
			goto finished;
		info->extra_fname = NULL;
561
		goto next_node;
562
	} else if (!info->curr_node)
563 564 565 566 567 568 569 570 571 572 573 574 575
		info->curr_node = rb_first(&info->root);

	while (1) {
		/*
		 * Fill the rbtree if we have no more entries,
		 * or the inode has changed since we last read in the
		 * cached entries.
		 */
		if ((!info->curr_node) ||
		    (filp->f_version != inode->i_version)) {
			info->curr_node = NULL;
			free_rb_tree_fname(&info->root);
			filp->f_version = inode->i_version;
576
			ret = ext4_htree_fill_tree(filp, info->curr_hash,
577 578 579 580 581
						   info->curr_minor_hash,
						   &info->next_hash);
			if (ret < 0)
				return ret;
			if (ret == 0) {
582
				filp->f_pos = ext4_get_htree_eof(filp);
583 584 585 586 587 588 589 590 591 592
				break;
			}
			info->curr_node = rb_first(&info->root);
		}

		fname = rb_entry(info->curr_node, struct fname, rb_hash);
		info->curr_hash = fname->hash;
		info->curr_minor_hash = fname->minor_hash;
		if (call_filldir(filp, dirent, filldir, fname))
			break;
593
	next_node:
594
		info->curr_node = rb_next(info->curr_node);
595 596 597 598 599 600
		if (info->curr_node) {
			fname = rb_entry(info->curr_node, struct fname,
					 rb_hash);
			info->curr_hash = fname->hash;
			info->curr_minor_hash = fname->minor_hash;
		} else {
601
			if (info->next_hash == ~0) {
602
				filp->f_pos = ext4_get_htree_eof(filp);
603 604 605 606 607 608 609 610 611 612 613
				break;
			}
			info->curr_hash = info->next_hash;
			info->curr_minor_hash = 0;
		}
	}
finished:
	info->last_pos = filp->f_pos;
	return 0;
}

614
static int ext4_release_dir(struct inode *inode, struct file *filp)
615
{
616
	if (filp->private_data)
617
		ext4_htree_free_dir_info(filp->private_data);
618 619 620

	return 0;
}
621 622 623 624 625 626 627 628 629 630 631 632

const struct file_operations ext4_dir_operations = {
	.llseek		= ext4_dir_llseek,
	.read		= generic_read_dir,
	.readdir	= ext4_readdir,
	.unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= ext4_compat_ioctl,
#endif
	.fsync		= ext4_sync_file,
	.release	= ext4_release_dir,
};