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	.ioctl		= ext3_ioctl,		/* BKL held */
46#ifdef CONFIG_COMPAT
47	.compat_ioctl	= ext3_compat_ioctl,
48#endif
49	.fsync		= ext3_sync_file,	/* BKL held */
50#ifdef CONFIG_EXT3_INDEX
51	.release	= ext3_release_dir,
52#endif
53};
54
55
56static unsigned char get_dtype(struct super_block *sb, int filetype)
57{
58	if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
59	    (filetype >= EXT3_FT_MAX))
60		return DT_UNKNOWN;
61
62	return (ext3_filetype_table[filetype]);
63}
64
65
66int ext3_check_dir_entry (const char * function, struct inode * dir,
67			  struct ext3_dir_entry_2 * de,
68			  struct buffer_head * bh,
69			  unsigned long offset)
70{
71	const char * error_msg = NULL;
72	const int rlen = le16_to_cpu(de->rec_len);
73
74	if (rlen < EXT3_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 < EXT3_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(EXT3_SB(dir->i_sb)->s_es->s_inodes_count))
84		error_msg = "inode out of bounds";
85
86	if (error_msg != NULL)
87		ext3_error (dir->i_sb, function,
88			"bad entry in directory #%lu: %s - "
89			"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
90			dir->i_ino, error_msg, offset,
91			(unsigned long) le32_to_cpu(de->inode),
92			rlen, de->name_len);
93	return error_msg == NULL ? 1 : 0;
94}
95
96static int ext3_readdir(struct file * filp,
97			 void * dirent, filldir_t filldir)
98{
99	int error = 0;
100	unsigned long offset;
101	int i, stored;
102	struct ext3_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
108	sb = inode->i_sb;
109
110#ifdef CONFIG_EXT3_INDEX
111	if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
112				    EXT3_FEATURE_COMPAT_DIR_INDEX) &&
113	    ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
114	     ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
115		err = ext3_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		EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
125	}
126#endif
127	stored = 0;
128	offset = filp->f_pos & (sb->s_blocksize - 1);
129
130	while (!error && !stored && filp->f_pos < inode->i_size) {
131		unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
132		struct buffer_head map_bh;
133		struct buffer_head *bh = NULL;
134
135		map_bh.b_state = 0;
136		err = ext3_get_blocks_handle(NULL, inode, blk, 1,
137						&map_bh, 0, 0);
138		if (err > 0) {
139			page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
140				&filp->f_ra,
141				filp,
142				map_bh.b_blocknr >>
143					(PAGE_CACHE_SHIFT - inode->i_blkbits),
144				1);
145			bh = ext3_bread(NULL, inode, blk, 0, &err);
146		}
147
148		/*
149		 * We ignore I/O errors on directories so users have a chance
150		 * of recovering data when there's a bad sector
151		 */
152		if (!bh) {
153			ext3_error (sb, "ext3_readdir",
154				"directory #%lu contains a hole at offset %lu",
155				inode->i_ino, (unsigned long)filp->f_pos);
156			/* corrupt size?  Maybe no more blocks to read */
157			if (filp->f_pos > inode->i_blocks << 9)
158				break;
159			filp->f_pos += sb->s_blocksize - offset;
160			continue;
161		}
162
163revalidate:
164		/* If the dir block has changed since the last call to
165		 * readdir(2), then we might be pointing to an invalid
166		 * dirent right now.  Scan from the start of the block
167		 * to make sure. */
168		if (filp->f_version != inode->i_version) {
169			for (i = 0; i < sb->s_blocksize && i < offset; ) {
170				de = (struct ext3_dir_entry_2 *)
171					(bh->b_data + i);
172				/* It's too expensive to do a full
173				 * dirent test each time round this
174				 * loop, but we do have to test at
175				 * least that it is non-zero.  A
176				 * failure will be detected in the
177				 * dirent test below. */
178				if (le16_to_cpu(de->rec_len) <
179						EXT3_DIR_REC_LEN(1))
180					break;
181				i += le16_to_cpu(de->rec_len);
182			}
183			offset = i;
184			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
185				| offset;
186			filp->f_version = inode->i_version;
187		}
188
189		while (!error && filp->f_pos < inode->i_size
190		       && offset < sb->s_blocksize) {
191			de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
192			if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
193						   bh, offset)) {
194				/* On error, skip the f_pos to the
195                                   next block. */
196				filp->f_pos = (filp->f_pos |
197						(sb->s_blocksize - 1)) + 1;
198				brelse (bh);
199				ret = stored;
200				goto out;
201			}
202			offset += le16_to_cpu(de->rec_len);
203			if (le32_to_cpu(de->inode)) {
204				/* We might block in the next section
205				 * if the data destination is
206				 * currently swapped out.  So, use a
207				 * version stamp to detect whether or
208				 * not the directory has been modified
209				 * during the copy operation.
210				 */
211				unsigned long version = filp->f_version;
212
213				error = filldir(dirent, de->name,
214						de->name_len,
215						filp->f_pos,
216						le32_to_cpu(de->inode),
217						get_dtype(sb, de->file_type));
218				if (error)
219					break;
220				if (version != filp->f_version)
221					goto revalidate;
222				stored ++;
223			}
224			filp->f_pos += le16_to_cpu(de->rec_len);
225		}
226		offset = 0;
227		brelse (bh);
228	}
229out:
230	return ret;
231}
232
233#ifdef CONFIG_EXT3_INDEX
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_node = NULL;
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	root->rb_node = NULL;
308}
309
310
311static struct dir_private_info *create_dir_info(loff_t pos)
312{
313	struct dir_private_info *p;
314
315	p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
316	if (!p)
317		return NULL;
318	p->root.rb_node = NULL;
319	p->curr_node = NULL;
320	p->extra_fname = NULL;
321	p->last_pos = 0;
322	p->curr_hash = pos2maj_hash(pos);
323	p->curr_minor_hash = pos2min_hash(pos);
324	p->next_hash = 0;
325	return p;
326}
327
328void ext3_htree_free_dir_info(struct dir_private_info *p)
329{
330	free_rb_tree_fname(&p->root);
331	kfree(p);
332}
333
334/*
335 * Given a directory entry, enter it into the fname rb tree.
336 */
337int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
338			     __u32 minor_hash,
339			     struct ext3_dir_entry_2 *dirent)
340{
341	struct rb_node **p, *parent = NULL;
342	struct fname * fname, *new_fn;
343	struct dir_private_info *info;
344	int len;
345
346	info = (struct dir_private_info *) dir_file->private_data;
347	p = &info->root.rb_node;
348
349	/* Create and allocate the fname structure */
350	len = sizeof(struct fname) + dirent->name_len + 1;
351	new_fn = kzalloc(len, GFP_KERNEL);
352	if (!new_fn)
353		return -ENOMEM;
354	new_fn->hash = hash;
355	new_fn->minor_hash = minor_hash;
356	new_fn->inode = le32_to_cpu(dirent->inode);
357	new_fn->name_len = dirent->name_len;
358	new_fn->file_type = dirent->file_type;
359	memcpy(new_fn->name, dirent->name, dirent->name_len);
360	new_fn->name[dirent->name_len] = 0;
361
362	while (*p) {
363		parent = *p;
364		fname = rb_entry(parent, struct fname, rb_hash);
365
366		/*
367		 * If the hash and minor hash match up, then we put
368		 * them on a linked list.  This rarely happens...
369		 */
370		if ((new_fn->hash == fname->hash) &&
371		    (new_fn->minor_hash == fname->minor_hash)) {
372			new_fn->next = fname->next;
373			fname->next = new_fn;
374			return 0;
375		}
376
377		if (new_fn->hash < fname->hash)
378			p = &(*p)->rb_left;
379		else if (new_fn->hash > fname->hash)
380			p = &(*p)->rb_right;
381		else if (new_fn->minor_hash < fname->minor_hash)
382			p = &(*p)->rb_left;
383		else /* if (new_fn->minor_hash > fname->minor_hash) */
384			p = &(*p)->rb_right;
385	}
386
387	rb_link_node(&new_fn->rb_hash, parent, p);
388	rb_insert_color(&new_fn->rb_hash, &info->root);
389	return 0;
390}
391
392
393
394/*
395 * This is a helper function for ext3_dx_readdir.  It calls filldir
396 * for all entres on the fname linked list.  (Normally there is only
397 * one entry on the linked list, unless there are 62 bit hash collisions.)
398 */
399static int call_filldir(struct file * filp, void * dirent,
400			filldir_t filldir, struct fname *fname)
401{
402	struct dir_private_info *info = filp->private_data;
403	loff_t	curr_pos;
404	struct inode *inode = filp->f_path.dentry->d_inode;
405	struct super_block * sb;
406	int error;
407
408	sb = inode->i_sb;
409
410	if (!fname) {
411		printk("call_filldir: called with null fname?!?\n");
412		return 0;
413	}
414	curr_pos = hash2pos(fname->hash, fname->minor_hash);
415	while (fname) {
416		error = filldir(dirent, fname->name,
417				fname->name_len, curr_pos,
418				fname->inode,
419				get_dtype(sb, fname->file_type));
420		if (error) {
421			filp->f_pos = curr_pos;
422			info->extra_fname = fname->next;
423			return error;
424		}
425		fname = fname->next;
426	}
427	return 0;
428}
429
430static int ext3_dx_readdir(struct file * filp,
431			 void * dirent, filldir_t filldir)
432{
433	struct dir_private_info *info = filp->private_data;
434	struct inode *inode = filp->f_path.dentry->d_inode;
435	struct fname *fname;
436	int	ret;
437
438	if (!info) {
439		info = create_dir_info(filp->f_pos);
440		if (!info)
441			return -ENOMEM;
442		filp->private_data = info;
443	}
444
445	if (filp->f_pos == EXT3_HTREE_EOF)
446		return 0;	/* EOF */
447
448	/* Some one has messed with f_pos; reset the world */
449	if (info->last_pos != filp->f_pos) {
450		free_rb_tree_fname(&info->root);
451		info->curr_node = NULL;
452		info->extra_fname = NULL;
453		info->curr_hash = pos2maj_hash(filp->f_pos);
454		info->curr_minor_hash = pos2min_hash(filp->f_pos);
455	}
456
457	/*
458	 * If there are any leftover names on the hash collision
459	 * chain, return them first.
460	 */
461	if (info->extra_fname &&
462	    call_filldir(filp, dirent, filldir, info->extra_fname))
463		goto finished;
464
465	if (!info->curr_node)
466		info->curr_node = rb_first(&info->root);
467
468	while (1) {
469		/*
470		 * Fill the rbtree if we have no more entries,
471		 * or the inode has changed since we last read in the
472		 * cached entries.
473		 */
474		if ((!info->curr_node) ||
475		    (filp->f_version != inode->i_version)) {
476			info->curr_node = NULL;
477			free_rb_tree_fname(&info->root);
478			filp->f_version = inode->i_version;
479			ret = ext3_htree_fill_tree(filp, info->curr_hash,
480						   info->curr_minor_hash,
481						   &info->next_hash);
482			if (ret < 0)
483				return ret;
484			if (ret == 0) {
485				filp->f_pos = EXT3_HTREE_EOF;
486				break;
487			}
488			info->curr_node = rb_first(&info->root);
489		}
490
491		fname = rb_entry(info->curr_node, struct fname, rb_hash);
492		info->curr_hash = fname->hash;
493		info->curr_minor_hash = fname->minor_hash;
494		if (call_filldir(filp, dirent, filldir, fname))
495			break;
496
497		info->curr_node = rb_next(info->curr_node);
498		if (!info->curr_node) {
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
520#endif
521