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
31 static unsigned char ext4_filetype_table[] = {
32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
33 };
34
35 static int ext4_readdir(struct file *, void *, filldir_t);
36 static int ext4_dx_readdir(struct file *filp,
37 void *dirent, filldir_t filldir);
38 static int ext4_release_dir(struct inode *inode,
39 struct file *filp);
40
41 const struct file_operations ext4_dir_operations = {
42 .llseek = generic_file_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
get_dtype(struct super_block * sb,int filetype)54 static 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
ext4_check_dir_entry(const char * function,struct inode * dir,struct ext4_dir_entry_2 * de,struct buffer_head * bh,unsigned int offset)64 int ext4_check_dir_entry(const char *function, struct inode *dir,
65 struct ext4_dir_entry_2 *de,
66 struct buffer_head *bh,
67 unsigned int offset)
68 {
69 const char *error_msg = NULL;
70 const int rlen = ext4_rec_len_from_disk(de->rec_len);
71
72 if (rlen < EXT4_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 < EXT4_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(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
82 error_msg = "inode out of bounds";
83
84 if (error_msg != NULL)
85 ext4_error(dir->i_sb, function,
86 "bad entry in directory #%lu: %s - "
87 "offset=%u, inode=%u, rec_len=%d, name_len=%d",
88 dir->i_ino, error_msg, offset,
89 le32_to_cpu(de->inode),
90 rlen, de->name_len);
91 return error_msg == NULL ? 1 : 0;
92 }
93
ext4_readdir(struct file * filp,void * dirent,filldir_t filldir)94 static int ext4_readdir(struct file *filp,
95 void *dirent, filldir_t filldir)
96 {
97 int error = 0;
98 unsigned int offset;
99 int i, stored;
100 struct ext4_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 (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
110 EXT4_FEATURE_COMPAT_DIR_INDEX) &&
111 ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
112 ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
113 err = ext4_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 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_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 ext4_lblk_t blk = filp->f_pos >> EXT4_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 = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh,
134 0, 0, 0);
135 if (err > 0) {
136 pgoff_t index = map_bh.b_blocknr >>
137 (PAGE_CACHE_SHIFT - inode->i_blkbits);
138 if (!ra_has_index(&filp->f_ra, index))
139 page_cache_sync_readahead(
140 sb->s_bdev->bd_inode->i_mapping,
141 &filp->f_ra, filp,
142 index, 1);
143 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
144 bh = ext4_bread(NULL, inode, blk, 0, &err);
145 }
146
147 /*
148 * We ignore I/O errors on directories so users have a chance
149 * of recovering data when there's a bad sector
150 */
151 if (!bh) {
152 if (!dir_has_error) {
153 ext4_error(sb, __func__, "directory #%lu "
154 "contains a hole at offset %Lu",
155 inode->i_ino,
156 (unsigned long long) filp->f_pos);
157 dir_has_error = 1;
158 }
159 /* corrupt size? Maybe no more blocks to read */
160 if (filp->f_pos > inode->i_blocks << 9)
161 break;
162 filp->f_pos += sb->s_blocksize - offset;
163 continue;
164 }
165
166 revalidate:
167 /* If the dir block has changed since the last call to
168 * readdir(2), then we might be pointing to an invalid
169 * dirent right now. Scan from the start of the block
170 * to make sure. */
171 if (filp->f_version != inode->i_version) {
172 for (i = 0; i < sb->s_blocksize && i < offset; ) {
173 de = (struct ext4_dir_entry_2 *)
174 (bh->b_data + i);
175 /* It's too expensive to do a full
176 * dirent test each time round this
177 * loop, but we do have to test at
178 * least that it is non-zero. A
179 * failure will be detected in the
180 * dirent test below. */
181 if (ext4_rec_len_from_disk(de->rec_len)
182 < EXT4_DIR_REC_LEN(1))
183 break;
184 i += ext4_rec_len_from_disk(de->rec_len);
185 }
186 offset = i;
187 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
188 | offset;
189 filp->f_version = inode->i_version;
190 }
191
192 while (!error && filp->f_pos < inode->i_size
193 && offset < sb->s_blocksize) {
194 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
195 if (!ext4_check_dir_entry("ext4_readdir", inode, de,
196 bh, offset)) {
197 /*
198 * On error, skip the f_pos to the next block
199 */
200 filp->f_pos = (filp->f_pos |
201 (sb->s_blocksize - 1)) + 1;
202 brelse(bh);
203 ret = stored;
204 goto out;
205 }
206 offset += ext4_rec_len_from_disk(de->rec_len);
207 if (le32_to_cpu(de->inode)) {
208 /* We might block in the next section
209 * if the data destination is
210 * currently swapped out. So, use a
211 * version stamp to detect whether or
212 * not the directory has been modified
213 * during the copy operation.
214 */
215 u64 version = filp->f_version;
216
217 error = filldir(dirent, de->name,
218 de->name_len,
219 filp->f_pos,
220 le32_to_cpu(de->inode),
221 get_dtype(sb, de->file_type));
222 if (error)
223 break;
224 if (version != filp->f_version)
225 goto revalidate;
226 stored++;
227 }
228 filp->f_pos += ext4_rec_len_from_disk(de->rec_len);
229 }
230 offset = 0;
231 brelse(bh);
232 }
233 out:
234 return ret;
235 }
236
237 /*
238 * These functions convert from the major/minor hash to an f_pos
239 * value.
240 *
241 * Currently we only use major hash numer. This is unfortunate, but
242 * on 32-bit machines, the same VFS interface is used for lseek and
243 * llseek, so if we use the 64 bit offset, then the 32-bit versions of
244 * lseek/telldir/seekdir will blow out spectacularly, and from within
245 * the ext2 low-level routine, we don't know if we're being called by
246 * a 64-bit version of the system call or the 32-bit version of the
247 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir
248 * cookie. Sigh.
249 */
250 #define hash2pos(major, minor) (major >> 1)
251 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
252 #define pos2min_hash(pos) (0)
253
254 /*
255 * This structure holds the nodes of the red-black tree used to store
256 * the directory entry in hash order.
257 */
258 struct fname {
259 __u32 hash;
260 __u32 minor_hash;
261 struct rb_node rb_hash;
262 struct fname *next;
263 __u32 inode;
264 __u8 name_len;
265 __u8 file_type;
266 char name[0];
267 };
268
269 /*
270 * This functoin implements a non-recursive way of freeing all of the
271 * nodes in the red-black tree.
272 */
free_rb_tree_fname(struct rb_root * root)273 static void free_rb_tree_fname(struct rb_root *root)
274 {
275 struct rb_node *n = root->rb_node;
276 struct rb_node *parent;
277 struct fname *fname;
278
279 while (n) {
280 /* Do the node's children first */
281 if (n->rb_left) {
282 n = n->rb_left;
283 continue;
284 }
285 if (n->rb_right) {
286 n = n->rb_right;
287 continue;
288 }
289 /*
290 * The node has no children; free it, and then zero
291 * out parent's link to it. Finally go to the
292 * beginning of the loop and try to free the parent
293 * node.
294 */
295 parent = rb_parent(n);
296 fname = rb_entry(n, struct fname, rb_hash);
297 while (fname) {
298 struct fname *old = fname;
299 fname = fname->next;
300 kfree(old);
301 }
302 if (!parent)
303 root->rb_node = NULL;
304 else if (parent->rb_left == n)
305 parent->rb_left = NULL;
306 else if (parent->rb_right == n)
307 parent->rb_right = NULL;
308 n = parent;
309 }
310 }
311
312
ext4_htree_create_dir_info(loff_t pos)313 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
314 {
315 struct dir_private_info *p;
316
317 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
318 if (!p)
319 return NULL;
320 p->curr_hash = pos2maj_hash(pos);
321 p->curr_minor_hash = pos2min_hash(pos);
322 return p;
323 }
324
ext4_htree_free_dir_info(struct dir_private_info * p)325 void ext4_htree_free_dir_info(struct dir_private_info *p)
326 {
327 free_rb_tree_fname(&p->root);
328 kfree(p);
329 }
330
331 /*
332 * Given a directory entry, enter it into the fname rb tree.
333 */
ext4_htree_store_dirent(struct file * dir_file,__u32 hash,__u32 minor_hash,struct ext4_dir_entry_2 * dirent)334 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
335 __u32 minor_hash,
336 struct ext4_dir_entry_2 *dirent)
337 {
338 struct rb_node **p, *parent = NULL;
339 struct fname *fname, *new_fn;
340 struct dir_private_info *info;
341 int len;
342
343 info = (struct dir_private_info *) dir_file->private_data;
344 p = &info->root.rb_node;
345
346 /* Create and allocate the fname structure */
347 len = sizeof(struct fname) + dirent->name_len + 1;
348 new_fn = kzalloc(len, GFP_KERNEL);
349 if (!new_fn)
350 return -ENOMEM;
351 new_fn->hash = hash;
352 new_fn->minor_hash = minor_hash;
353 new_fn->inode = le32_to_cpu(dirent->inode);
354 new_fn->name_len = dirent->name_len;
355 new_fn->file_type = dirent->file_type;
356 memcpy(new_fn->name, dirent->name, dirent->name_len);
357 new_fn->name[dirent->name_len] = 0;
358
359 while (*p) {
360 parent = *p;
361 fname = rb_entry(parent, struct fname, rb_hash);
362
363 /*
364 * If the hash and minor hash match up, then we put
365 * them on a linked list. This rarely happens...
366 */
367 if ((new_fn->hash == fname->hash) &&
368 (new_fn->minor_hash == fname->minor_hash)) {
369 new_fn->next = fname->next;
370 fname->next = new_fn;
371 return 0;
372 }
373
374 if (new_fn->hash < fname->hash)
375 p = &(*p)->rb_left;
376 else if (new_fn->hash > fname->hash)
377 p = &(*p)->rb_right;
378 else if (new_fn->minor_hash < fname->minor_hash)
379 p = &(*p)->rb_left;
380 else /* if (new_fn->minor_hash > fname->minor_hash) */
381 p = &(*p)->rb_right;
382 }
383
384 rb_link_node(&new_fn->rb_hash, parent, p);
385 rb_insert_color(&new_fn->rb_hash, &info->root);
386 return 0;
387 }
388
389
390
391 /*
392 * This is a helper function for ext4_dx_readdir. It calls filldir
393 * for all entres on the fname linked list. (Normally there is only
394 * one entry on the linked list, unless there are 62 bit hash collisions.)
395 */
call_filldir(struct file * filp,void * dirent,filldir_t filldir,struct fname * fname)396 static int call_filldir(struct file *filp, void *dirent,
397 filldir_t filldir, struct fname *fname)
398 {
399 struct dir_private_info *info = filp->private_data;
400 loff_t curr_pos;
401 struct inode *inode = filp->f_path.dentry->d_inode;
402 struct super_block *sb;
403 int error;
404
405 sb = inode->i_sb;
406
407 if (!fname) {
408 printk(KERN_ERR "EXT4-fs: call_filldir: called with "
409 "null fname?!?\n");
410 return 0;
411 }
412 curr_pos = hash2pos(fname->hash, fname->minor_hash);
413 while (fname) {
414 error = filldir(dirent, fname->name,
415 fname->name_len, curr_pos,
416 fname->inode,
417 get_dtype(sb, fname->file_type));
418 if (error) {
419 filp->f_pos = curr_pos;
420 info->extra_fname = fname;
421 return error;
422 }
423 fname = fname->next;
424 }
425 return 0;
426 }
427
ext4_dx_readdir(struct file * filp,void * dirent,filldir_t filldir)428 static int ext4_dx_readdir(struct file *filp,
429 void *dirent, filldir_t filldir)
430 {
431 struct dir_private_info *info = filp->private_data;
432 struct inode *inode = filp->f_path.dentry->d_inode;
433 struct fname *fname;
434 int ret;
435
436 if (!info) {
437 info = ext4_htree_create_dir_info(filp->f_pos);
438 if (!info)
439 return -ENOMEM;
440 filp->private_data = info;
441 }
442
443 if (filp->f_pos == EXT4_HTREE_EOF)
444 return 0; /* EOF */
445
446 /* Some one has messed with f_pos; reset the world */
447 if (info->last_pos != filp->f_pos) {
448 free_rb_tree_fname(&info->root);
449 info->curr_node = NULL;
450 info->extra_fname = NULL;
451 info->curr_hash = pos2maj_hash(filp->f_pos);
452 info->curr_minor_hash = pos2min_hash(filp->f_pos);
453 }
454
455 /*
456 * If there are any leftover names on the hash collision
457 * chain, return them first.
458 */
459 if (info->extra_fname) {
460 if (call_filldir(filp, dirent, filldir, info->extra_fname))
461 goto finished;
462 info->extra_fname = NULL;
463 goto next_node;
464 } else if (!info->curr_node)
465 info->curr_node = rb_first(&info->root);
466
467 while (1) {
468 /*
469 * Fill the rbtree if we have no more entries,
470 * or the inode has changed since we last read in the
471 * cached entries.
472 */
473 if ((!info->curr_node) ||
474 (filp->f_version != inode->i_version)) {
475 info->curr_node = NULL;
476 free_rb_tree_fname(&info->root);
477 filp->f_version = inode->i_version;
478 ret = ext4_htree_fill_tree(filp, info->curr_hash,
479 info->curr_minor_hash,
480 &info->next_hash);
481 if (ret < 0)
482 return ret;
483 if (ret == 0) {
484 filp->f_pos = EXT4_HTREE_EOF;
485 break;
486 }
487 info->curr_node = rb_first(&info->root);
488 }
489
490 fname = rb_entry(info->curr_node, struct fname, rb_hash);
491 info->curr_hash = fname->hash;
492 info->curr_minor_hash = fname->minor_hash;
493 if (call_filldir(filp, dirent, filldir, fname))
494 break;
495 next_node:
496 info->curr_node = rb_next(info->curr_node);
497 if (info->curr_node) {
498 fname = rb_entry(info->curr_node, struct fname,
499 rb_hash);
500 info->curr_hash = fname->hash;
501 info->curr_minor_hash = fname->minor_hash;
502 } else {
503 if (info->next_hash == ~0) {
504 filp->f_pos = EXT4_HTREE_EOF;
505 break;
506 }
507 info->curr_hash = info->next_hash;
508 info->curr_minor_hash = 0;
509 }
510 }
511 finished:
512 info->last_pos = filp->f_pos;
513 return 0;
514 }
515
ext4_release_dir(struct inode * inode,struct file * filp)516 static int ext4_release_dir(struct inode *inode, struct file *filp)
517 {
518 if (filp->private_data)
519 ext4_htree_free_dir_info(filp->private_data);
520
521 return 0;
522 }
523