dir.c 15.6 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

Al Viro's avatar
Al Viro committed
32
static int ext4_dx_readdir(struct file *, struct dir_context *);
33

34 35
/**
 * Check if the given dir-inode refers to an htree-indexed directory
36
 * (or a directory which could potentially get converted to use htree
37 38 39 40 41 42 43 44 45 46 47
 * 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)) ||
48 49
	     ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
	     ext4_has_inline_data(inode)))
50 51 52 53 54
		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
}

Al Viro's avatar
Al Viro committed
105
static int ext4_readdir(struct file *file, struct dir_context *ctx)
106
{
107
	unsigned int offset;
108
	int i, stored;
109
	struct ext4_dir_entry_2 *de;
110
	int err;
Al Viro's avatar
Al Viro committed
111
	struct inode *inode = file_inode(file);
112
	struct super_block *sb = inode->i_sb;
113
	int dir_has_error = 0;
114

115
	if (is_dx_dir(inode)) {
Al Viro's avatar
Al Viro committed
116
		err = ext4_dx_readdir(file, ctx);
117
		if (err != ERR_BAD_DX_DIR) {
Al Viro's avatar
Al Viro committed
118
			return err;
119 120 121 122 123
		}
		/*
		 * We don't set the inode dirty flag since it's not
		 * critical that it get flushed back to the disk.
		 */
Al Viro's avatar
Al Viro committed
124
		ext4_clear_inode_flag(file_inode(file),
125
				      EXT4_INODE_INDEX);
126
	}
127 128 129

	if (ext4_has_inline_data(inode)) {
		int has_inline_data = 1;
Al Viro's avatar
Al Viro committed
130
		int ret = ext4_read_inline_dir(file, ctx,
131 132 133 134 135
					   &has_inline_data);
		if (has_inline_data)
			return ret;
	}

136
	stored = 0;
Al Viro's avatar
Al Viro committed
137
	offset = ctx->pos & (sb->s_blocksize - 1);
138

Al Viro's avatar
Al Viro committed
139
	while (ctx->pos < inode->i_size) {
140
		struct ext4_map_blocks map;
141 142
		struct buffer_head *bh = NULL;

Al Viro's avatar
Al Viro committed
143
		map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
144 145
		map.m_len = 1;
		err = ext4_map_blocks(NULL, inode, &map, 0);
146
		if (err > 0) {
147
			pgoff_t index = map.m_pblk >>
148
					(PAGE_CACHE_SHIFT - inode->i_blkbits);
Al Viro's avatar
Al Viro committed
149
			if (!ra_has_index(&file->f_ra, index))
150
				page_cache_sync_readahead(
151
					sb->s_bdev->bd_inode->i_mapping,
Al Viro's avatar
Al Viro committed
152
					&file->f_ra, file,
153
					index, 1);
Al Viro's avatar
Al Viro committed
154
			file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
155
			bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
156 157 158 159 160 161 162
		}

		/*
		 * We ignore I/O errors on directories so users have a chance
		 * of recovering data when there's a bad sector
		 */
		if (!bh) {
163
			if (!dir_has_error) {
Al Viro's avatar
Al Viro committed
164
				EXT4_ERROR_FILE(file, 0,
165 166
						"directory contains a "
						"hole at offset %llu",
Al Viro's avatar
Al Viro committed
167
					   (unsigned long long) ctx->pos);
168 169
				dir_has_error = 1;
			}
170
			/* corrupt size?  Maybe no more blocks to read */
Al Viro's avatar
Al Viro committed
171
			if (ctx->pos > inode->i_blocks << 9)
172
				break;
Al Viro's avatar
Al Viro committed
173
			ctx->pos += sb->s_blocksize - offset;
174 175 176
			continue;
		}

177 178 179 180
		/* Check the checksum */
		if (!buffer_verified(bh) &&
		    !ext4_dirent_csum_verify(inode,
				(struct ext4_dir_entry *)bh->b_data)) {
Al Viro's avatar
Al Viro committed
181
			EXT4_ERROR_FILE(file, 0, "directory fails checksum "
182
					"at offset %llu",
Al Viro's avatar
Al Viro committed
183 184
					(unsigned long long)ctx->pos);
			ctx->pos += sb->s_blocksize - offset;
185
			brelse(bh);
186 187 188 189
			continue;
		}
		set_buffer_verified(bh);

190 191 192 193
		/* 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. */
Al Viro's avatar
Al Viro committed
194
		if (file->f_version != inode->i_version) {
195
			for (i = 0; i < sb->s_blocksize && i < offset; ) {
196
				de = (struct ext4_dir_entry_2 *)
197 198 199 200 201 202 203
					(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. */
204 205
				if (ext4_rec_len_from_disk(de->rec_len,
					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
206
					break;
207 208
				i += ext4_rec_len_from_disk(de->rec_len,
							    sb->s_blocksize);
209 210
			}
			offset = i;
Al Viro's avatar
Al Viro committed
211
			ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
212
				| offset;
Al Viro's avatar
Al Viro committed
213
			file->f_version = inode->i_version;
214 215
		}

Al Viro's avatar
Al Viro committed
216
		while (ctx->pos < inode->i_size
217
		       && offset < sb->s_blocksize) {
218
			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
Al Viro's avatar
Al Viro committed
219
			if (ext4_check_dir_entry(inode, file, de, bh,
220 221
						 bh->b_data, bh->b_size,
						 offset)) {
222
				/*
Al Viro's avatar
Al Viro committed
223
				 * On error, skip to the next block
224
				 */
Al Viro's avatar
Al Viro committed
225
				ctx->pos = (ctx->pos |
226
						(sb->s_blocksize - 1)) + 1;
Al Viro's avatar
Al Viro committed
227
				break;
228
			}
229 230
			offset += ext4_rec_len_from_disk(de->rec_len,
					sb->s_blocksize);
231
			if (le32_to_cpu(de->inode)) {
Al Viro's avatar
Al Viro committed
232
				if (!dir_emit(ctx, de->name,
233 234
						de->name_len,
						le32_to_cpu(de->inode),
Al Viro's avatar
Al Viro committed
235 236 237 238
						get_dtype(sb, de->file_type))) {
					brelse(bh);
					return 0;
				}
239
			}
Al Viro's avatar
Al Viro committed
240
			ctx->pos += ext4_rec_len_from_disk(de->rec_len,
241
						sb->s_blocksize);
242 243
		}
		offset = 0;
244
		brelse(bh);
Al Viro's avatar
Al Viro committed
245 246 247 248
		if (ctx->pos < inode->i_size) {
			if (!dir_relax(inode))
				return 0;
		}
249
	}
Al Viro's avatar
Al Viro committed
250
	return 0;
251 252
}

253 254 255 256 257 258 259 260 261
static inline int is_32bit_api(void)
{
#ifdef CONFIG_COMPAT
	return is_compat_task();
#else
	return (BITS_PER_LONG == 32);
#endif
}

262 263
/*
 * These functions convert from the major/minor hash to an f_pos
264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311
 * 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;
}


/*
312 313 314
 * 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.
315
 *
316 317 318 319 320
 * 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.
321
 */
322
static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
323 324 325
{
	struct inode *inode = file->f_mapping->host;
	int dx_dir = is_dx_dir(inode);
326
	loff_t htree_max = ext4_get_htree_eof(file);
327

328
	if (likely(dx_dir))
329
		return generic_file_llseek_size(file, offset, whence,
330 331
						    htree_max, htree_max);
	else
332
		return ext4_llseek(file, offset, whence);
333
}
334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361

/*
 * 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 */
362
		if (n->rb_left) {
363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378
			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) {
379
			struct fname *old = fname;
380
			fname = fname->next;
381
			kfree(old);
382 383
		}
		if (!parent)
384
			*root = RB_ROOT;
385 386 387 388 389 390 391 392 393
		else if (parent->rb_left == n)
			parent->rb_left = NULL;
		else if (parent->rb_right == n)
			parent->rb_right = NULL;
		n = parent;
	}
}


394 395
static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
							   loff_t pos)
396 397 398
{
	struct dir_private_info *p;

399
	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
400 401
	if (!p)
		return NULL;
402 403
	p->curr_hash = pos2maj_hash(filp, pos);
	p->curr_minor_hash = pos2min_hash(filp, pos);
404 405 406
	return p;
}

407
void ext4_htree_free_dir_info(struct dir_private_info *p)
408 409 410 411 412 413 414 415
{
	free_rb_tree_fname(&p->root);
	kfree(p);
}

/*
 * Given a directory entry, enter it into the fname rb tree.
 */
416
int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
417
			     __u32 minor_hash,
418
			     struct ext4_dir_entry_2 *dirent)
419 420
{
	struct rb_node **p, *parent = NULL;
421
	struct fname *fname, *new_fn;
422 423 424
	struct dir_private_info *info;
	int len;

425
	info = dir_file->private_data;
426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473
	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;
}



/*
474
 * This is a helper function for ext4_dx_readdir.  It calls filldir
475 476 477
 * 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.)
 */
Al Viro's avatar
Al Viro committed
478 479
static int call_filldir(struct file *file, struct dir_context *ctx,
			struct fname *fname)
480
{
Al Viro's avatar
Al Viro committed
481 482 483
	struct dir_private_info *info = file->private_data;
	struct inode *inode = file_inode(file);
	struct super_block *sb = inode->i_sb;
484 485

	if (!fname) {
486 487 488
		ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
			 "called with null fname?!?", __func__, __LINE__,
			 inode->i_ino, current->comm);
489 490
		return 0;
	}
Al Viro's avatar
Al Viro committed
491
	ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
492
	while (fname) {
Al Viro's avatar
Al Viro committed
493 494
		if (!dir_emit(ctx, fname->name,
				fname->name_len,
495
				fname->inode,
Al Viro's avatar
Al Viro committed
496
				get_dtype(sb, fname->file_type))) {
497
			info->extra_fname = fname;
Al Viro's avatar
Al Viro committed
498
			return 1;
499 500 501 502 503 504
		}
		fname = fname->next;
	}
	return 0;
}

Al Viro's avatar
Al Viro committed
505
static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
506
{
Al Viro's avatar
Al Viro committed
507 508
	struct dir_private_info *info = file->private_data;
	struct inode *inode = file_inode(file);
509 510 511 512
	struct fname *fname;
	int	ret;

	if (!info) {
Al Viro's avatar
Al Viro committed
513
		info = ext4_htree_create_dir_info(file, ctx->pos);
514 515
		if (!info)
			return -ENOMEM;
Al Viro's avatar
Al Viro committed
516
		file->private_data = info;
517 518
	}

Al Viro's avatar
Al Viro committed
519
	if (ctx->pos == ext4_get_htree_eof(file))
520 521 522
		return 0;	/* EOF */

	/* Some one has messed with f_pos; reset the world */
Al Viro's avatar
Al Viro committed
523
	if (info->last_pos != ctx->pos) {
524 525 526
		free_rb_tree_fname(&info->root);
		info->curr_node = NULL;
		info->extra_fname = NULL;
Al Viro's avatar
Al Viro committed
527 528
		info->curr_hash = pos2maj_hash(file, ctx->pos);
		info->curr_minor_hash = pos2min_hash(file, ctx->pos);
529 530 531 532 533 534
	}

	/*
	 * If there are any leftover names on the hash collision
	 * chain, return them first.
	 */
535
	if (info->extra_fname) {
Al Viro's avatar
Al Viro committed
536
		if (call_filldir(file, ctx, info->extra_fname))
537 538
			goto finished;
		info->extra_fname = NULL;
539
		goto next_node;
540
	} else if (!info->curr_node)
541 542 543 544 545 546 547 548 549
		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) ||
Al Viro's avatar
Al Viro committed
550
		    (file->f_version != inode->i_version)) {
551 552
			info->curr_node = NULL;
			free_rb_tree_fname(&info->root);
Al Viro's avatar
Al Viro committed
553 554
			file->f_version = inode->i_version;
			ret = ext4_htree_fill_tree(file, info->curr_hash,
555 556 557 558 559
						   info->curr_minor_hash,
						   &info->next_hash);
			if (ret < 0)
				return ret;
			if (ret == 0) {
Al Viro's avatar
Al Viro committed
560
				ctx->pos = ext4_get_htree_eof(file);
561 562 563 564 565 566 567 568
				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;
Al Viro's avatar
Al Viro committed
569
		if (call_filldir(file, ctx, fname))
570
			break;
571
	next_node:
572
		info->curr_node = rb_next(info->curr_node);
573 574 575 576 577 578
		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 {
579
			if (info->next_hash == ~0) {
Al Viro's avatar
Al Viro committed
580
				ctx->pos = ext4_get_htree_eof(file);
581 582 583 584 585 586 587
				break;
			}
			info->curr_hash = info->next_hash;
			info->curr_minor_hash = 0;
		}
	}
finished:
Al Viro's avatar
Al Viro committed
588
	info->last_pos = ctx->pos;
589 590 591
	return 0;
}

592
static int ext4_release_dir(struct inode *inode, struct file *filp)
593
{
594
	if (filp->private_data)
595
		ext4_htree_free_dir_info(filp->private_data);
596 597 598

	return 0;
}
599 600 601 602

const struct file_operations ext4_dir_operations = {
	.llseek		= ext4_dir_llseek,
	.read		= generic_read_dir,
Al Viro's avatar
Al Viro committed
603
	.iterate	= ext4_readdir,
604 605 606 607 608 609 610
	.unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= ext4_compat_ioctl,
#endif
	.fsync		= ext4_sync_file,
	.release	= ext4_release_dir,
};