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	.unlocked_ioctl	= ext3_ioctl,
46#ifdef CONFIG_COMPAT
47	.compat_ioctl	= ext3_compat_ioctl,
48#endif
49	.fsync		= ext3_sync_file,	/* BKL held */
50	.release	= ext3_release_dir,
51};
52
53
54static unsigned char get_dtype(struct super_block *sb, int filetype)
55{
56	if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
57	    (filetype >= EXT3_FT_MAX))
58		return DT_UNKNOWN;
59
60	return (ext3_filetype_table[filetype]);
61}
62
63
64int ext3_check_dir_entry (const char * function, struct inode * dir,
65			  struct ext3_dir_entry_2 * de,
66			  struct buffer_head * bh,
67			  unsigned long offset)
68{
69	const char * error_msg = NULL;
70	const int rlen = ext3_rec_len_from_disk(de->rec_len);
71
72	if (rlen < EXT3_DIR_REC_LEN(1))
73		error_msg = "rec_len is smaller than minimal";
74	else if (rlen % 4 != 0)
75		error_msg = "rec_len % 4 != 0";
76	else if (rlen < EXT3_DIR_REC_LEN(de->name_len))
77		error_msg = "rec_len is too small for name_len";
78	else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
79		error_msg = "directory entry across blocks";
80	else if (le32_to_cpu(de->inode) >
81			le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count))
82		error_msg = "inode out of bounds";
83
84	if (error_msg != NULL)
85		ext3_error (dir->i_sb, function,
86			"bad entry in directory #%lu: %s - "
87			"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
88			dir->i_ino, error_msg, offset,
89			(unsigned long) le32_to_cpu(de->inode),
90			rlen, de->name_len);
91	return error_msg == NULL ? 1 : 0;
92}
93
94static int ext3_readdir(struct file * filp,
95			 void * dirent, filldir_t filldir)
96{
97	int error = 0;
98	unsigned long offset;
99	int i, stored;
100	struct ext3_dir_entry_2 *de;
101	struct super_block *sb;
102	int err;
103	struct inode *inode = filp->f_path.dentry->d_inode;
104	int ret = 0;
105	int dir_has_error = 0;
106
107	sb = inode->i_sb;
108
109	if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
110				    EXT3_FEATURE_COMPAT_DIR_INDEX) &&
111	    ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
112	     ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
113		err = ext3_dx_readdir(filp, dirent, filldir);
114		if (err != ERR_BAD_DX_DIR) {
115			ret = err;
116			goto out;
117		}
118		/*
119		 * We don't set the inode dirty flag since it's not
120		 * critical that it get flushed back to the disk.
121		 */
122		EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
123	}
124	stored = 0;
125	offset = filp->f_pos & (sb->s_blocksize - 1);
126
127	while (!error && !stored && filp->f_pos < inode->i_size) {
128		unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
129		struct buffer_head map_bh;
130		struct buffer_head *bh = NULL;
131
132		map_bh.b_state = 0;
133		err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0);
134		if (err > 0) {
135			pgoff_t index = map_bh.b_blocknr >>
136					(PAGE_CACHE_SHIFT - inode->i_blkbits);
137			if (!ra_has_index(&filp->f_ra, index))
138				page_cache_sync_readahead(
139					sb->s_bdev->bd_inode->i_mapping,
140					&filp->f_ra, filp,
141					index, 1);
142			filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
143			bh = ext3_bread(NULL, inode, blk, 0, &err);
144		}
145
146		/*
147		 * We ignore I/O errors on directories so users have a chance
148		 * of recovering data when there's a bad sector
149		 */
150		if (!bh) {
151			if (!dir_has_error) {
152				ext3_error(sb, __func__, "directory #%lu "
153					"contains a hole at offset %lld",
154					inode->i_ino, filp->f_pos);
155				dir_has_error = 1;
156			}
157			/* corrupt size?  Maybe no more blocks to read */
158			if (filp->f_pos > inode->i_blocks << 9)
159				break;
160			filp->f_pos += sb->s_blocksize - offset;
161			continue;
162		}
163
164revalidate:
165		/* If the dir block has changed since the last call to
166		 * readdir(2), then we might be pointing to an invalid
167		 * dirent right now.  Scan from the start of the block
168		 * to make sure. */
169		if (filp->f_version != inode->i_version) {
170			for (i = 0; i < sb->s_blocksize && i < offset; ) {
171				de = (struct ext3_dir_entry_2 *)
172					(bh->b_data + i);
173				/* It's too expensive to do a full
174				 * dirent test each time round this
175				 * loop, but we do have to test at
176				 * least that it is non-zero.  A
177				 * failure will be detected in the
178				 * dirent test below. */
179				if (ext3_rec_len_from_disk(de->rec_len) <
180						EXT3_DIR_REC_LEN(1))
181					break;
182				i += ext3_rec_len_from_disk(de->rec_len);
183			}
184			offset = i;
185			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
186				| offset;
187			filp->f_version = inode->i_version;
188		}
189
190		while (!error && filp->f_pos < inode->i_size
191		       && offset < sb->s_blocksize) {
192			de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
193			if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
194						   bh, offset)) {
195				/* On error, skip the f_pos to the
196                                   next block. */
197				filp->f_pos = (filp->f_pos |
198						(sb->s_blocksize - 1)) + 1;
199				brelse (bh);
200				ret = stored;
201				goto out;
202			}
203			offset += ext3_rec_len_from_disk(de->rec_len);
204			if (le32_to_cpu(de->inode)) {
205				/* We might block in the next section
206				 * if the data destination is
207				 * currently swapped out.  So, use a
208				 * version stamp to detect whether or
209				 * not the directory has been modified
210				 * during the copy operation.
211				 */
212				u64 version = filp->f_version;
213
214				error = filldir(dirent, de->name,
215						de->name_len,
216						filp->f_pos,
217						le32_to_cpu(de->inode),
218						get_dtype(sb, de->file_type));
219				if (error)
220					break;
221				if (version != filp->f_version)
222					goto revalidate;
223				stored ++;
224			}
225			filp->f_pos += ext3_rec_len_from_disk(de->rec_len);
226		}
227		offset = 0;
228		brelse (bh);
229	}
230out:
231	return ret;
232}
233
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_ROOT;
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}
308
309
310static struct dir_private_info *ext3_htree_create_dir_info(loff_t pos)
311{
312	struct dir_private_info *p;
313
314	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
315	if (!p)
316		return NULL;
317	p->curr_hash = pos2maj_hash(pos);
318	p->curr_minor_hash = pos2min_hash(pos);
319	return p;
320}
321
322void ext3_htree_free_dir_info(struct dir_private_info *p)
323{
324	free_rb_tree_fname(&p->root);
325	kfree(p);
326}
327
328/*
329 * Given a directory entry, enter it into the fname rb tree.
330 */
331int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
332			     __u32 minor_hash,
333			     struct ext3_dir_entry_2 *dirent)
334{
335	struct rb_node **p, *parent = NULL;
336	struct fname * fname, *new_fn;
337	struct dir_private_info *info;
338	int len;
339
340	info = (struct dir_private_info *) dir_file->private_data;
341	p = &info->root.rb_node;
342
343	/* Create and allocate the fname structure */
344	len = sizeof(struct fname) + dirent->name_len + 1;
345	new_fn = kzalloc(len, GFP_KERNEL);
346	if (!new_fn)
347		return -ENOMEM;
348	new_fn->hash = hash;
349	new_fn->minor_hash = minor_hash;
350	new_fn->inode = le32_to_cpu(dirent->inode);
351	new_fn->name_len = dirent->name_len;
352	new_fn->file_type = dirent->file_type;
353	memcpy(new_fn->name, dirent->name, dirent->name_len);
354	new_fn->name[dirent->name_len] = 0;
355
356	while (*p) {
357		parent = *p;
358		fname = rb_entry(parent, struct fname, rb_hash);
359
360		/*
361		 * If the hash and minor hash match up, then we put
362		 * them on a linked list.  This rarely happens...
363		 */
364		if ((new_fn->hash == fname->hash) &&
365		    (new_fn->minor_hash == fname->minor_hash)) {
366			new_fn->next = fname->next;
367			fname->next = new_fn;
368			return 0;
369		}
370
371		if (new_fn->hash < fname->hash)
372			p = &(*p)->rb_left;
373		else if (new_fn->hash > fname->hash)
374			p = &(*p)->rb_right;
375		else if (new_fn->minor_hash < fname->minor_hash)
376			p = &(*p)->rb_left;
377		else /* if (new_fn->minor_hash > fname->minor_hash) */
378			p = &(*p)->rb_right;
379	}
380
381	rb_link_node(&new_fn->rb_hash, parent, p);
382	rb_insert_color(&new_fn->rb_hash, &info->root);
383	return 0;
384}
385
386
387
388/*
389 * This is a helper function for ext3_dx_readdir.  It calls filldir
390 * for all entres on the fname linked list.  (Normally there is only
391 * one entry on the linked list, unless there are 62 bit hash collisions.)
392 */
393static int call_filldir(struct file * filp, void * dirent,
394			filldir_t filldir, struct fname *fname)
395{
396	struct dir_private_info *info = filp->private_data;
397	loff_t	curr_pos;
398	struct inode *inode = filp->f_path.dentry->d_inode;
399	struct super_block * sb;
400	int error;
401
402	sb = inode->i_sb;
403
404	if (!fname) {
405		printk("call_filldir: called with null fname?!?\n");
406		return 0;
407	}
408	curr_pos = hash2pos(fname->hash, fname->minor_hash);
409	while (fname) {
410		error = filldir(dirent, fname->name,
411				fname->name_len, curr_pos,
412				fname->inode,
413				get_dtype(sb, fname->file_type));
414		if (error) {
415			filp->f_pos = curr_pos;
416			info->extra_fname = fname;
417			return error;
418		}
419		fname = fname->next;
420	}
421	return 0;
422}
423
424static int ext3_dx_readdir(struct file * filp,
425			 void * dirent, filldir_t filldir)
426{
427	struct dir_private_info *info = filp->private_data;
428	struct inode *inode = filp->f_path.dentry->d_inode;
429	struct fname *fname;
430	int	ret;
431
432	if (!info) {
433		info = ext3_htree_create_dir_info(filp->f_pos);
434		if (!info)
435			return -ENOMEM;
436		filp->private_data = info;
437	}
438
439	if (filp->f_pos == EXT3_HTREE_EOF)
440		return 0;	/* EOF */
441
442	/* Some one has messed with f_pos; reset the world */
443	if (info->last_pos != filp->f_pos) {
444		free_rb_tree_fname(&info->root);
445		info->curr_node = NULL;
446		info->extra_fname = NULL;
447		info->curr_hash = pos2maj_hash(filp->f_pos);
448		info->curr_minor_hash = pos2min_hash(filp->f_pos);
449	}
450
451	/*
452	 * If there are any leftover names on the hash collision
453	 * chain, return them first.
454	 */
455	if (info->extra_fname) {
456		if (call_filldir(filp, dirent, filldir, info->extra_fname))
457			goto finished;
458		info->extra_fname = NULL;
459		goto next_node;
460	} else if (!info->curr_node)
461		info->curr_node = rb_first(&info->root);
462
463	while (1) {
464		/*
465		 * Fill the rbtree if we have no more entries,
466		 * or the inode has changed since we last read in the
467		 * cached entries.
468		 */
469		if ((!info->curr_node) ||
470		    (filp->f_version != inode->i_version)) {
471			info->curr_node = NULL;
472			free_rb_tree_fname(&info->root);
473			filp->f_version = inode->i_version;
474			ret = ext3_htree_fill_tree(filp, info->curr_hash,
475						   info->curr_minor_hash,
476						   &info->next_hash);
477			if (ret < 0)
478				return ret;
479			if (ret == 0) {
480				filp->f_pos = EXT3_HTREE_EOF;
481				break;
482			}
483			info->curr_node = rb_first(&info->root);
484		}
485
486		fname = rb_entry(info->curr_node, struct fname, rb_hash);
487		info->curr_hash = fname->hash;
488		info->curr_minor_hash = fname->minor_hash;
489		if (call_filldir(filp, dirent, filldir, fname))
490			break;
491	next_node:
492		info->curr_node = rb_next(info->curr_node);
493		if (info->curr_node) {
494			fname = rb_entry(info->curr_node, struct fname,
495					 rb_hash);
496			info->curr_hash = fname->hash;
497			info->curr_minor_hash = fname->minor_hash;
498		} else {
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