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/fs/ext4/dir.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 542 lines | 386 code | 49 blank | 107 comment | 85 complexity | 040f4dfc05c6601240bf91c344b93cde MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 *  linux/fs/ext4/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 *  ext4 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/jbd2.h>
 26#include <linux/buffer_head.h>
 27#include <linux/slab.h>
 28#include <linux/rbtree.h>
 29#include "ext4.h"
 30
 31static unsigned char ext4_filetype_table[] = {
 32	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
 33};
 34
 35static int ext4_readdir(struct file *, void *, filldir_t);
 36static int ext4_dx_readdir(struct file *filp,
 37			   void *dirent, filldir_t filldir);
 38static int ext4_release_dir(struct inode *inode,
 39				struct file *filp);
 40
 41const struct file_operations ext4_dir_operations = {
 42	.llseek		= ext4_llseek,
 43	.read		= generic_read_dir,
 44	.readdir	= ext4_readdir,		/* we take BKL. needed?*/
 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
 54static unsigned char get_dtype(struct super_block *sb, int filetype)
 55{
 56	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
 57	    (filetype >= EXT4_FT_MAX))
 58		return DT_UNKNOWN;
 59
 60	return (ext4_filetype_table[filetype]);
 61}
 62
 63/*
 64 * Return 0 if the directory entry is OK, and 1 if there is a problem
 65 *
 66 * Note: this is the opposite of what ext2 and ext3 historically returned...
 67 */
 68int __ext4_check_dir_entry(const char *function, unsigned int line,
 69			   struct inode *dir, struct file *filp,
 70			   struct ext4_dir_entry_2 *de,
 71			   struct buffer_head *bh,
 72			   unsigned int offset)
 73{
 74	const char *error_msg = NULL;
 75	const int rlen = ext4_rec_len_from_disk(de->rec_len,
 76						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	else if (unlikely(((char *) de - bh->b_data) + rlen >
 85			  dir->i_sb->s_blocksize))
 86		error_msg = "directory entry across blocks";
 87	else if (unlikely(le32_to_cpu(de->inode) >
 88			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
 89		error_msg = "inode out of bounds";
 90	else
 91		return 0;
 92
 93	if (filp)
 94		ext4_error_file(filp, function, line, bh ? bh->b_blocknr : 0,
 95				"bad entry in directory: %s - offset=%u(%u), "
 96				"inode=%u, rec_len=%d, name_len=%d",
 97				error_msg, (unsigned) (offset%bh->b_size),
 98				offset, le32_to_cpu(de->inode),
 99				rlen, de->name_len);
100	else
101		ext4_error_inode(dir, function, line, bh ? bh->b_blocknr : 0,
102				"bad entry in directory: %s - offset=%u(%u), "
103				"inode=%u, rec_len=%d, name_len=%d",
104				error_msg, (unsigned) (offset%bh->b_size),
105				offset, le32_to_cpu(de->inode),
106				rlen, de->name_len);
107
108	return 1;
109}
110
111static int ext4_readdir(struct file *filp,
112			 void *dirent, filldir_t filldir)
113{
114	int error = 0;
115	unsigned int offset;
116	int i, stored;
117	struct ext4_dir_entry_2 *de;
118	struct super_block *sb;
119	int err;
120	struct inode *inode = filp->f_path.dentry->d_inode;
121	int ret = 0;
122	int dir_has_error = 0;
123
124	sb = inode->i_sb;
125
126	if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
127				    EXT4_FEATURE_COMPAT_DIR_INDEX) &&
128	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
129	     ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
130		err = ext4_dx_readdir(filp, dirent, filldir);
131		if (err != ERR_BAD_DX_DIR) {
132			ret = err;
133			goto out;
134		}
135		/*
136		 * We don't set the inode dirty flag since it's not
137		 * critical that it get flushed back to the disk.
138		 */
139		ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
140				      EXT4_INODE_INDEX);
141	}
142	stored = 0;
143	offset = filp->f_pos & (sb->s_blocksize - 1);
144
145	while (!error && !stored && filp->f_pos < inode->i_size) {
146		struct ext4_map_blocks map;
147		struct buffer_head *bh = NULL;
148
149		map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
150		map.m_len = 1;
151		err = ext4_map_blocks(NULL, inode, &map, 0);
152		if (err > 0) {
153			pgoff_t index = map.m_pblk >>
154					(PAGE_CACHE_SHIFT - inode->i_blkbits);
155			if (!ra_has_index(&filp->f_ra, index))
156				page_cache_sync_readahead(
157					sb->s_bdev->bd_inode->i_mapping,
158					&filp->f_ra, filp,
159					index, 1);
160			filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
161			bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
162		}
163
164		/*
165		 * We ignore I/O errors on directories so users have a chance
166		 * of recovering data when there's a bad sector
167		 */
168		if (!bh) {
169			if (!dir_has_error) {
170				EXT4_ERROR_FILE(filp, 0,
171						"directory contains a "
172						"hole at offset %llu",
173					   (unsigned long long) filp->f_pos);
174				dir_has_error = 1;
175			}
176			/* corrupt size?  Maybe no more blocks to read */
177			if (filp->f_pos > inode->i_blocks << 9)
178				break;
179			filp->f_pos += sb->s_blocksize - offset;
180			continue;
181		}
182
183revalidate:
184		/* If the dir block has changed since the last call to
185		 * readdir(2), then we might be pointing to an invalid
186		 * dirent right now.  Scan from the start of the block
187		 * to make sure. */
188		if (filp->f_version != inode->i_version) {
189			for (i = 0; i < sb->s_blocksize && i < offset; ) {
190				de = (struct ext4_dir_entry_2 *)
191					(bh->b_data + i);
192				/* It's too expensive to do a full
193				 * dirent test each time round this
194				 * loop, but we do have to test at
195				 * least that it is non-zero.  A
196				 * failure will be detected in the
197				 * dirent test below. */
198				if (ext4_rec_len_from_disk(de->rec_len,
199					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
200					break;
201				i += ext4_rec_len_from_disk(de->rec_len,
202							    sb->s_blocksize);
203			}
204			offset = i;
205			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
206				| offset;
207			filp->f_version = inode->i_version;
208		}
209
210		while (!error && filp->f_pos < inode->i_size
211		       && offset < sb->s_blocksize) {
212			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
213			if (ext4_check_dir_entry(inode, filp, de,
214						 bh, offset)) {
215				/*
216				 * On error, skip the f_pos to the next block
217				 */
218				filp->f_pos = (filp->f_pos |
219						(sb->s_blocksize - 1)) + 1;
220				brelse(bh);
221				ret = stored;
222				goto out;
223			}
224			offset += ext4_rec_len_from_disk(de->rec_len,
225					sb->s_blocksize);
226			if (le32_to_cpu(de->inode)) {
227				/* We might block in the next section
228				 * if the data destination is
229				 * currently swapped out.  So, use a
230				 * version stamp to detect whether or
231				 * not the directory has been modified
232				 * during the copy operation.
233				 */
234				u64 version = filp->f_version;
235
236				error = filldir(dirent, de->name,
237						de->name_len,
238						filp->f_pos,
239						le32_to_cpu(de->inode),
240						get_dtype(sb, de->file_type));
241				if (error)
242					break;
243				if (version != filp->f_version)
244					goto revalidate;
245				stored++;
246			}
247			filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
248						sb->s_blocksize);
249		}
250		offset = 0;
251		brelse(bh);
252	}
253out:
254	return ret;
255}
256
257/*
258 * These functions convert from the major/minor hash to an f_pos
259 * value.
260 *
261 * Currently we only use major hash numer.  This is unfortunate, but
262 * on 32-bit machines, the same VFS interface is used for lseek and
263 * llseek, so if we use the 64 bit offset, then the 32-bit versions of
264 * lseek/telldir/seekdir will blow out spectacularly, and from within
265 * the ext2 low-level routine, we don't know if we're being called by
266 * a 64-bit version of the system call or the 32-bit version of the
267 * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
268 * cookie.  Sigh.
269 */
270#define hash2pos(major, minor)	(major >> 1)
271#define pos2maj_hash(pos)	((pos << 1) & 0xffffffff)
272#define pos2min_hash(pos)	(0)
273
274/*
275 * This structure holds the nodes of the red-black tree used to store
276 * the directory entry in hash order.
277 */
278struct fname {
279	__u32		hash;
280	__u32		minor_hash;
281	struct rb_node	rb_hash;
282	struct fname	*next;
283	__u32		inode;
284	__u8		name_len;
285	__u8		file_type;
286	char		name[0];
287};
288
289/*
290 * This functoin implements a non-recursive way of freeing all of the
291 * nodes in the red-black tree.
292 */
293static void free_rb_tree_fname(struct rb_root *root)
294{
295	struct rb_node	*n = root->rb_node;
296	struct rb_node	*parent;
297	struct fname	*fname;
298
299	while (n) {
300		/* Do the node's children first */
301		if (n->rb_left) {
302			n = n->rb_left;
303			continue;
304		}
305		if (n->rb_right) {
306			n = n->rb_right;
307			continue;
308		}
309		/*
310		 * The node has no children; free it, and then zero
311		 * out parent's link to it.  Finally go to the
312		 * beginning of the loop and try to free the parent
313		 * node.
314		 */
315		parent = rb_parent(n);
316		fname = rb_entry(n, struct fname, rb_hash);
317		while (fname) {
318			struct fname *old = fname;
319			fname = fname->next;
320			kfree(old);
321		}
322		if (!parent)
323			*root = RB_ROOT;
324		else if (parent->rb_left == n)
325			parent->rb_left = NULL;
326		else if (parent->rb_right == n)
327			parent->rb_right = NULL;
328		n = parent;
329	}
330}
331
332
333static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
334{
335	struct dir_private_info *p;
336
337	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
338	if (!p)
339		return NULL;
340	p->curr_hash = pos2maj_hash(pos);
341	p->curr_minor_hash = pos2min_hash(pos);
342	return p;
343}
344
345void ext4_htree_free_dir_info(struct dir_private_info *p)
346{
347	free_rb_tree_fname(&p->root);
348	kfree(p);
349}
350
351/*
352 * Given a directory entry, enter it into the fname rb tree.
353 */
354int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
355			     __u32 minor_hash,
356			     struct ext4_dir_entry_2 *dirent)
357{
358	struct rb_node **p, *parent = NULL;
359	struct fname *fname, *new_fn;
360	struct dir_private_info *info;
361	int len;
362
363	info = dir_file->private_data;
364	p = &info->root.rb_node;
365
366	/* Create and allocate the fname structure */
367	len = sizeof(struct fname) + dirent->name_len + 1;
368	new_fn = kzalloc(len, GFP_KERNEL);
369	if (!new_fn)
370		return -ENOMEM;
371	new_fn->hash = hash;
372	new_fn->minor_hash = minor_hash;
373	new_fn->inode = le32_to_cpu(dirent->inode);
374	new_fn->name_len = dirent->name_len;
375	new_fn->file_type = dirent->file_type;
376	memcpy(new_fn->name, dirent->name, dirent->name_len);
377	new_fn->name[dirent->name_len] = 0;
378
379	while (*p) {
380		parent = *p;
381		fname = rb_entry(parent, struct fname, rb_hash);
382
383		/*
384		 * If the hash and minor hash match up, then we put
385		 * them on a linked list.  This rarely happens...
386		 */
387		if ((new_fn->hash == fname->hash) &&
388		    (new_fn->minor_hash == fname->minor_hash)) {
389			new_fn->next = fname->next;
390			fname->next = new_fn;
391			return 0;
392		}
393
394		if (new_fn->hash < fname->hash)
395			p = &(*p)->rb_left;
396		else if (new_fn->hash > fname->hash)
397			p = &(*p)->rb_right;
398		else if (new_fn->minor_hash < fname->minor_hash)
399			p = &(*p)->rb_left;
400		else /* if (new_fn->minor_hash > fname->minor_hash) */
401			p = &(*p)->rb_right;
402	}
403
404	rb_link_node(&new_fn->rb_hash, parent, p);
405	rb_insert_color(&new_fn->rb_hash, &info->root);
406	return 0;
407}
408
409
410
411/*
412 * This is a helper function for ext4_dx_readdir.  It calls filldir
413 * for all entres on the fname linked list.  (Normally there is only
414 * one entry on the linked list, unless there are 62 bit hash collisions.)
415 */
416static int call_filldir(struct file *filp, void *dirent,
417			filldir_t filldir, struct fname *fname)
418{
419	struct dir_private_info *info = filp->private_data;
420	loff_t	curr_pos;
421	struct inode *inode = filp->f_path.dentry->d_inode;
422	struct super_block *sb;
423	int error;
424
425	sb = inode->i_sb;
426
427	if (!fname) {
428		printk(KERN_ERR "EXT4-fs: call_filldir: called with "
429		       "null fname?!?\n");
430		return 0;
431	}
432	curr_pos = hash2pos(fname->hash, fname->minor_hash);
433	while (fname) {
434		error = filldir(dirent, fname->name,
435				fname->name_len, curr_pos,
436				fname->inode,
437				get_dtype(sb, fname->file_type));
438		if (error) {
439			filp->f_pos = curr_pos;
440			info->extra_fname = fname;
441			return error;
442		}
443		fname = fname->next;
444	}
445	return 0;
446}
447
448static int ext4_dx_readdir(struct file *filp,
449			 void *dirent, filldir_t filldir)
450{
451	struct dir_private_info *info = filp->private_data;
452	struct inode *inode = filp->f_path.dentry->d_inode;
453	struct fname *fname;
454	int	ret;
455
456	if (!info) {
457		info = ext4_htree_create_dir_info(filp->f_pos);
458		if (!info)
459			return -ENOMEM;
460		filp->private_data = info;
461	}
462
463	if (filp->f_pos == EXT4_HTREE_EOF)
464		return 0;	/* EOF */
465
466	/* Some one has messed with f_pos; reset the world */
467	if (info->last_pos != filp->f_pos) {
468		free_rb_tree_fname(&info->root);
469		info->curr_node = NULL;
470		info->extra_fname = NULL;
471		info->curr_hash = pos2maj_hash(filp->f_pos);
472		info->curr_minor_hash = pos2min_hash(filp->f_pos);
473	}
474
475	/*
476	 * If there are any leftover names on the hash collision
477	 * chain, return them first.
478	 */
479	if (info->extra_fname) {
480		if (call_filldir(filp, dirent, filldir, info->extra_fname))
481			goto finished;
482		info->extra_fname = NULL;
483		goto next_node;
484	} else if (!info->curr_node)
485		info->curr_node = rb_first(&info->root);
486
487	while (1) {
488		/*
489		 * Fill the rbtree if we have no more entries,
490		 * or the inode has changed since we last read in the
491		 * cached entries.
492		 */
493		if ((!info->curr_node) ||
494		    (filp->f_version != inode->i_version)) {
495			info->curr_node = NULL;
496			free_rb_tree_fname(&info->root);
497			filp->f_version = inode->i_version;
498			ret = ext4_htree_fill_tree(filp, info->curr_hash,
499						   info->curr_minor_hash,
500						   &info->next_hash);
501			if (ret < 0)
502				return ret;
503			if (ret == 0) {
504				filp->f_pos = EXT4_HTREE_EOF;
505				break;
506			}
507			info->curr_node = rb_first(&info->root);
508		}
509
510		fname = rb_entry(info->curr_node, struct fname, rb_hash);
511		info->curr_hash = fname->hash;
512		info->curr_minor_hash = fname->minor_hash;
513		if (call_filldir(filp, dirent, filldir, fname))
514			break;
515	next_node:
516		info->curr_node = rb_next(info->curr_node);
517		if (info->curr_node) {
518			fname = rb_entry(info->curr_node, struct fname,
519					 rb_hash);
520			info->curr_hash = fname->hash;
521			info->curr_minor_hash = fname->minor_hash;
522		} else {
523			if (info->next_hash == ~0) {
524				filp->f_pos = EXT4_HTREE_EOF;
525				break;
526			}
527			info->curr_hash = info->next_hash;
528			info->curr_minor_hash = 0;
529		}
530	}
531finished:
532	info->last_pos = filp->f_pos;
533	return 0;
534}
535
536static int ext4_release_dir(struct inode *inode, struct file *filp)
537{
538	if (filp->private_data)
539		ext4_htree_free_dir_info(filp->private_data);
540
541	return 0;
542}