dir.c 13.8 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

31
static unsigned char ext4_filetype_table[] = {
32 33 34
	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
};

35
static int ext4_readdir(struct file *, void *, filldir_t);
36 37 38 39
static int ext4_dx_readdir(struct file *filp,
			   void *dirent, filldir_t filldir);
static int ext4_release_dir(struct inode *inode,
				struct file *filp);
40

41
const struct file_operations ext4_dir_operations = {
42
	.llseek		= ext4_llseek,
43
	.read		= generic_read_dir,
44
	.readdir	= ext4_readdir,		/* we take BKL. needed?*/
A
Andi Kleen 已提交
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 54 55
};


static unsigned char get_dtype(struct super_block *sb, int filetype)
{
56 57
	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
	    (filetype >= EXT4_FT_MAX))
58 59
		return DT_UNKNOWN;

60
	return (ext4_filetype_table[filetype]);
61 62
}

63 64 65 66 67
/*
 * 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...
 */
68 69 70 71 72
int __ext4_check_dir_entry(const char *function, unsigned int line,
			   struct inode *dir,
			   struct ext4_dir_entry_2 *de,
			   struct buffer_head *bh,
			   unsigned int offset)
73
{
74
	const char *error_msg = NULL;
75 76
	const int rlen = ext4_rec_len_from_disk(de->rec_len,
						dir->i_sb->s_blocksize);
77

78
	if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
79
		error_msg = "rec_len is smaller than minimal";
80
	else if (unlikely(rlen % 4 != 0))
81
		error_msg = "rec_len % 4 != 0";
82
	else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
83
		error_msg = "rec_len is too small for name_len";
84 85
	else if (unlikely(((char *) de - bh->b_data) + rlen >
			  dir->i_sb->s_blocksize))
86
		error_msg = "directory entry across blocks";
87 88
	else if (unlikely(le32_to_cpu(de->inode) >
			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
89
		error_msg = "inode out of bounds";
90 91 92 93 94 95 96 97 98 99
	else
		return 0;

	ext4_error_inode(dir, function, line, bh->b_blocknr,
			 "bad entry in directory: %s - "
			 "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d",
			 error_msg, (unsigned) (offset%bh->b_size), offset,
			 le32_to_cpu(de->inode),
			 rlen, de->name_len);
	return 1;
100 101
}

102 103
static int ext4_readdir(struct file *filp,
			 void *dirent, filldir_t filldir)
104 105
{
	int error = 0;
106
	unsigned int offset;
107
	int i, stored;
108
	struct ext4_dir_entry_2 *de;
109 110
	struct super_block *sb;
	int err;
111
	struct inode *inode = filp->f_path.dentry->d_inode;
112
	int ret = 0;
113
	int dir_has_error = 0;
114 115 116

	sb = inode->i_sb;

117 118
	if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
				    EXT4_FEATURE_COMPAT_DIR_INDEX) &&
119
	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
120
	     ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
121
		err = ext4_dx_readdir(filp, dirent, filldir);
122 123 124 125 126 127 128 129
		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.
		 */
130 131
		ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
				      EXT4_INODE_INDEX);
132 133 134 135 136
	}
	stored = 0;
	offset = filp->f_pos & (sb->s_blocksize - 1);

	while (!error && !stored && filp->f_pos < inode->i_size) {
137
		struct ext4_map_blocks map;
138 139
		struct buffer_head *bh = NULL;

140 141 142
		map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
		map.m_len = 1;
		err = ext4_map_blocks(NULL, inode, &map, 0);
143
		if (err > 0) {
144
			pgoff_t index = map.m_pblk >>
145 146
					(PAGE_CACHE_SHIFT - inode->i_blkbits);
			if (!ra_has_index(&filp->f_ra, index))
147
				page_cache_sync_readahead(
148 149
					sb->s_bdev->bd_inode->i_mapping,
					&filp->f_ra, filp,
150
					index, 1);
151
			filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
152
			bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
153 154 155 156 157 158 159
		}

		/*
		 * We ignore I/O errors on directories so users have a chance
		 * of recovering data when there's a bad sector
		 */
		if (!bh) {
160
			if (!dir_has_error) {
161
				EXT4_ERROR_INODE(inode, "directory "
162 163 164 165
					   "contains a hole at offset %Lu",
					   (unsigned long long) filp->f_pos);
				dir_has_error = 1;
			}
166 167 168
			/* corrupt size?  Maybe no more blocks to read */
			if (filp->f_pos > inode->i_blocks << 9)
				break;
169 170 171 172 173 174 175 176 177 178 179
			filp->f_pos += sb->s_blocksize - offset;
			continue;
		}

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; ) {
180
				de = (struct ext4_dir_entry_2 *)
181 182 183 184 185 186 187
					(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. */
188 189
				if (ext4_rec_len_from_disk(de->rec_len,
					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
190
					break;
191 192
				i += ext4_rec_len_from_disk(de->rec_len,
							    sb->s_blocksize);
193 194 195 196 197 198 199 200 201
			}
			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) {
202
			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
203 204
			if (ext4_check_dir_entry(inode, de,
						 bh, offset)) {
A
Andrew Morton 已提交
205 206 207
				/*
				 * On error, skip the f_pos to the next block
				 */
208 209
				filp->f_pos = (filp->f_pos |
						(sb->s_blocksize - 1)) + 1;
210
				brelse(bh);
211 212 213
				ret = stored;
				goto out;
			}
214 215
			offset += ext4_rec_len_from_disk(de->rec_len,
					sb->s_blocksize);
216 217 218 219 220 221 222 223
			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.
				 */
224
				u64 version = filp->f_version;
225 226 227 228 229 230 231 232 233 234

				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;
235
				stored++;
236
			}
237 238
			filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
						sb->s_blocksize);
239 240
		}
		offset = 0;
241
		brelse(bh);
242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290
	}
out:
	return ret;
}

/*
 * These functions convert from the major/minor hash to an f_pos
 * value.
 *
 * Currently we only use major hash numer.  This is unfortunate, but
 * on 32-bit machines, the same VFS interface is used for lseek and
 * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 * lseek/telldir/seekdir will blow out spectacularly, and from within
 * the ext2 low-level routine, we don't know if we're being called by
 * a 64-bit version of the system call or the 32-bit version of the
 * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 * cookie.  Sigh.
 */
#define hash2pos(major, minor)	(major >> 1)
#define pos2maj_hash(pos)	((pos << 1) & 0xffffffff)
#define pos2min_hash(pos)	(0)

/*
 * 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 */
291
		if (n->rb_left) {
292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307
			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) {
308
			struct fname *old = fname;
309
			fname = fname->next;
310
			kfree(old);
311 312
		}
		if (!parent)
313
			*root = RB_ROOT;
314 315 316 317 318 319 320 321 322
		else if (parent->rb_left == n)
			parent->rb_left = NULL;
		else if (parent->rb_right == n)
			parent->rb_right = NULL;
		n = parent;
	}
}


323
static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
324 325 326
{
	struct dir_private_info *p;

327
	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
328 329 330 331 332 333 334
	if (!p)
		return NULL;
	p->curr_hash = pos2maj_hash(pos);
	p->curr_minor_hash = pos2min_hash(pos);
	return p;
}

335
void ext4_htree_free_dir_info(struct dir_private_info *p)
336 337 338 339 340 341 342 343
{
	free_rb_tree_fname(&p->root);
	kfree(p);
}

/*
 * Given a directory entry, enter it into the fname rb tree.
 */
344
int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
345
			     __u32 minor_hash,
346
			     struct ext4_dir_entry_2 *dirent)
347 348
{
	struct rb_node **p, *parent = NULL;
349
	struct fname *fname, *new_fn;
350 351 352
	struct dir_private_info *info;
	int len;

353
	info = dir_file->private_data;
354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401
	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;
}



/*
402
 * This is a helper function for ext4_dx_readdir.  It calls filldir
403 404 405
 * 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.)
 */
406
static int call_filldir(struct file *filp, void *dirent,
407 408 409 410
			filldir_t filldir, struct fname *fname)
{
	struct dir_private_info *info = filp->private_data;
	loff_t	curr_pos;
411
	struct inode *inode = filp->f_path.dentry->d_inode;
412
	struct super_block *sb;
413 414 415 416 417
	int error;

	sb = inode->i_sb;

	if (!fname) {
418
		printk(KERN_ERR "EXT4-fs: call_filldir: called with "
419
		       "null fname?!?\n");
420 421 422 423 424 425 426 427 428 429
		return 0;
	}
	curr_pos = hash2pos(fname->hash, fname->minor_hash);
	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;
430
			info->extra_fname = fname;
431 432 433 434 435 436 437
			return error;
		}
		fname = fname->next;
	}
	return 0;
}

438 439
static int ext4_dx_readdir(struct file *filp,
			 void *dirent, filldir_t filldir)
440 441
{
	struct dir_private_info *info = filp->private_data;
442
	struct inode *inode = filp->f_path.dentry->d_inode;
443 444 445 446
	struct fname *fname;
	int	ret;

	if (!info) {
447
		info = ext4_htree_create_dir_info(filp->f_pos);
448 449 450 451 452
		if (!info)
			return -ENOMEM;
		filp->private_data = info;
	}

453
	if (filp->f_pos == EXT4_HTREE_EOF)
454 455 456 457 458 459 460 461 462 463 464 465 466 467 468
		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;
		info->curr_hash = pos2maj_hash(filp->f_pos);
		info->curr_minor_hash = pos2min_hash(filp->f_pos);
	}

	/*
	 * If there are any leftover names on the hash collision
	 * chain, return them first.
	 */
469 470 471 472
	if (info->extra_fname) {
		if (call_filldir(filp, dirent, filldir, info->extra_fname))
			goto finished;
		info->extra_fname = NULL;
473
		goto next_node;
474
	} else if (!info->curr_node)
475 476 477 478 479 480 481 482 483 484 485 486 487
		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;
488
			ret = ext4_htree_fill_tree(filp, info->curr_hash,
489 490 491 492 493
						   info->curr_minor_hash,
						   &info->next_hash);
			if (ret < 0)
				return ret;
			if (ret == 0) {
494
				filp->f_pos = EXT4_HTREE_EOF;
495 496 497 498 499 500 501 502 503 504
				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;
505
	next_node:
506
		info->curr_node = rb_next(info->curr_node);
507 508 509 510 511 512
		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 {
513
			if (info->next_hash == ~0) {
514
				filp->f_pos = EXT4_HTREE_EOF;
515 516 517 518 519 520 521 522 523 524 525
				break;
			}
			info->curr_hash = info->next_hash;
			info->curr_minor_hash = 0;
		}
	}
finished:
	info->last_pos = filp->f_pos;
	return 0;
}

526
static int ext4_release_dir(struct inode *inode, struct file *filp)
527
{
A
Andrew Morton 已提交
528
	if (filp->private_data)
529
		ext4_htree_free_dir_info(filp->private_data);
530 531 532

	return 0;
}