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/smp_lock.h>
29 : #include <linux/slab.h>
30 : #include <linux/rbtree.h>
31 :
32 : static unsigned char ext3_filetype_table[] = {
33 : DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
34 : };
35 :
36 : static int ext3_readdir(struct file *, void *, filldir_t);
37 : static int ext3_dx_readdir(struct file * filp,
38 : void * dirent, filldir_t filldir);
39 : static int ext3_release_dir (struct inode * inode,
40 : struct file * filp);
41 :
42 : struct file_operations ext3_dir_operations = {
43 : .llseek = generic_file_llseek,
44 : .read = generic_read_dir,
45 : .readdir = ext3_readdir, /* we take BKL. needed?*/
46 : .ioctl = ext3_ioctl, /* BKL held */
47 : .fsync = ext3_sync_file, /* BKL held */
48 : #ifdef CONFIG_EXT3_INDEX
49 : .release = ext3_release_dir,
50 : #endif
51 : };
52 :
53 :
54 : static unsigned char get_dtype(struct super_block *sb, int filetype)
55 6636 : {
56 6636 : if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
57 : (filetype >= EXT3_FT_MAX))
58 0 : return DT_UNKNOWN;
59 :
60 6636 : return (ext3_filetype_table[filetype]);
61 : }
62 :
63 :
64 : int 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 37932 : {
69 37932 : const char * error_msg = NULL;
70 37932 : const int rlen = le16_to_cpu(de->rec_len);
71 :
72 37932 : if (rlen < EXT3_DIR_REC_LEN(1))
73 0 : error_msg = "rec_len is smaller than minimal";
74 37932 : else if (rlen % 4 != 0)
75 0 : error_msg = "rec_len % 4 != 0";
76 37932 : else if (rlen < EXT3_DIR_REC_LEN(de->name_len))
77 0 : error_msg = "rec_len is too small for name_len";
78 37932 : else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
79 0 : error_msg = "directory entry across blocks";
80 37932 : else if (le32_to_cpu(de->inode) >
81 : le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count))
82 0 : error_msg = "inode out of bounds";
83 :
84 0 : if (error_msg != NULL)
85 0 : 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 37932 : return error_msg == NULL ? 1 : 0;
92 : }
93 :
94 : static int ext3_readdir(struct file * filp,
95 : void * dirent, filldir_t filldir)
96 2267 : {
97 2267 : int error = 0;
98 2267 : unsigned long offset, blk;
99 2267 : int i, num, stored;
100 2267 : struct buffer_head * bh, * tmp, * bha[16];
101 2267 : struct ext3_dir_entry_2 * de;
102 2267 : struct super_block * sb;
103 2267 : int err;
104 2267 : struct inode *inode = filp->f_dentry->d_inode;
105 2267 : int ret = 0;
106 :
107 2267 : sb = inode->i_sb;
108 :
109 : #ifdef CONFIG_EXT3_INDEX
110 2267 : if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
111 : EXT3_FEATURE_COMPAT_DIR_INDEX) &&
112 : ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
113 : ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
114 0 : err = ext3_dx_readdir(filp, dirent, filldir);
115 0 : if (err != ERR_BAD_DX_DIR) {
116 0 : ret = err;
117 0 : goto out;
118 : }
119 : /*
120 : * We don't set the inode dirty flag since it's not
121 : * critical that it get flushed back to the disk.
122 : */
123 0 : EXT3_I(filp->f_dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
124 : }
125 : #endif
126 2267 : stored = 0;
127 2267 : bh = NULL;
128 2267 : offset = filp->f_pos & (sb->s_blocksize - 1);
129 :
130 2267 : while (!error && !stored && filp->f_pos < inode->i_size) {
131 1143 : blk = (filp->f_pos) >> EXT3_BLOCK_SIZE_BITS(sb);
132 1143 : bh = ext3_bread(NULL, inode, blk, 0, &err);
133 1143 : if (!bh) {
134 0 : ext3_error (sb, "ext3_readdir",
135 : "directory #%lu contains a hole at offset %lu",
136 : inode->i_ino, (unsigned long)filp->f_pos);
137 0 : filp->f_pos += sb->s_blocksize - offset;
138 0 : continue;
139 : }
140 :
141 : /*
142 : * Do the readahead
143 : */
144 1143 : if (!offset) {
145 3429 : for (i = 16 >> (EXT3_BLOCK_SIZE_BITS(sb) - 9), num = 0;
146 : i > 0; i--) {
147 2286 : tmp = ext3_getblk (NULL, inode, ++blk, 0, &err);
148 2286 : if (tmp && !buffer_uptodate(tmp) &&
149 : !buffer_locked(tmp))
150 1 : bha[num++] = tmp;
151 : else
152 10 : brelse (tmp);
153 : }
154 1143 : if (num) {
155 1 : ll_rw_block (READA, num, bha);
156 2 : for (i = 0; i < num; i++)
157 1 : brelse (bha[i]);
158 : }
159 : }
160 :
161 : revalidate:
162 : /* If the dir block has changed since the last call to
163 : * readdir(2), then we might be pointing to an invalid
164 : * dirent right now. Scan from the start of the block
165 : * to make sure. */
166 1143 : if (filp->f_version != inode->i_version) {
167 1143 : for (i = 0; i < sb->s_blocksize && i < offset; ) {
168 0 : de = (struct ext3_dir_entry_2 *)
169 : (bh->b_data + i);
170 : /* It's too expensive to do a full
171 : * dirent test each time round this
172 : * loop, but we do have to test at
173 : * least that it is non-zero. A
174 : * failure will be detected in the
175 : * dirent test below. */
176 0 : if (le16_to_cpu(de->rec_len) <
177 : EXT3_DIR_REC_LEN(1))
178 0 : break;
179 0 : i += le16_to_cpu(de->rec_len);
180 : }
181 1143 : offset = i;
182 1143 : filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
183 : | offset;
184 1143 : filp->f_version = inode->i_version;
185 : }
186 :
187 1143 : while (!error && filp->f_pos < inode->i_size
188 : && offset < sb->s_blocksize) {
189 6636 : de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
190 6636 : if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
191 : bh, offset)) {
192 : /* On error, skip the f_pos to the
193 : next block. */
194 0 : filp->f_pos = (filp->f_pos |
195 : (sb->s_blocksize - 1)) + 1;
196 0 : brelse (bh);
197 0 : ret = stored;
198 0 : goto out;
199 : }
200 6636 : offset += le16_to_cpu(de->rec_len);
201 6636 : if (le32_to_cpu(de->inode)) {
202 : /* We might block in the next section
203 : * if the data destination is
204 : * currently swapped out. So, use a
205 : * version stamp to detect whether or
206 : * not the directory has been modified
207 : * during the copy operation.
208 : */
209 6636 : unsigned long version = filp->f_version;
210 :
211 6636 : error = filldir(dirent, de->name,
212 : de->name_len,
213 : filp->f_pos,
214 : le32_to_cpu(de->inode),
215 : get_dtype(sb, de->file_type));
216 6636 : if (error)
217 6625 : break;
218 6625 : if (version != filp->f_version)
219 6625 : goto revalidate;
220 6625 : stored ++;
221 : }
222 6625 : filp->f_pos += le16_to_cpu(de->rec_len);
223 : }
224 1143 : offset = 0;
225 1143 : brelse (bh);
226 : }
227 : out:
228 2267 : return ret;
229 : }
230 :
231 : #ifdef CONFIG_EXT3_INDEX
232 : /*
233 : * These functions convert from the major/minor hash to an f_pos
234 : * value.
235 : *
236 : * Currently we only use major hash numer. This is unfortunate, but
237 : * on 32-bit machines, the same VFS interface is used for lseek and
238 : * llseek, so if we use the 64 bit offset, then the 32-bit versions of
239 : * lseek/telldir/seekdir will blow out spectacularly, and from within
240 : * the ext2 low-level routine, we don't know if we're being called by
241 : * a 64-bit version of the system call or the 32-bit version of the
242 : * system call. Worse yet, NFSv2 only allows for a 32-bit readdir
243 : * cookie. Sigh.
244 : */
245 : #define hash2pos(major, minor) (major >> 1)
246 : #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
247 : #define pos2min_hash(pos) (0)
248 :
249 : /*
250 : * This structure holds the nodes of the red-black tree used to store
251 : * the directory entry in hash order.
252 : */
253 : struct fname {
254 : __u32 hash;
255 : __u32 minor_hash;
256 : struct rb_node rb_hash;
257 : struct fname *next;
258 : __u32 inode;
259 : __u8 name_len;
260 : __u8 file_type;
261 : char name[0];
262 : };
263 :
264 : /*
265 : * This functoin implements a non-recursive way of freeing all of the
266 : * nodes in the red-black tree.
267 : */
268 : static void free_rb_tree_fname(struct rb_root *root)
269 0 : {
270 0 : struct rb_node *n = root->rb_node;
271 0 : struct rb_node *parent;
272 0 : struct fname *fname;
273 :
274 0 : while (n) {
275 : /* Do the node's children first */
276 0 : if ((n)->rb_left) {
277 0 : n = n->rb_left;
278 0 : continue;
279 : }
280 0 : if (n->rb_right) {
281 0 : n = n->rb_right;
282 0 : continue;
283 : }
284 : /*
285 : * The node has no children; free it, and then zero
286 : * out parent's link to it. Finally go to the
287 : * beginning of the loop and try to free the parent
288 : * node.
289 : */
290 0 : parent = n->rb_parent;
291 0 : fname = rb_entry(n, struct fname, rb_hash);
292 0 : while (fname) {
293 0 : struct fname * old = fname;
294 0 : fname = fname->next;
295 0 : kfree (old);
296 : }
297 0 : if (!parent)
298 0 : root->rb_node = NULL;
299 0 : else if (parent->rb_left == n)
300 0 : parent->rb_left = NULL;
301 0 : else if (parent->rb_right == n)
302 0 : parent->rb_right = NULL;
303 0 : n = parent;
304 : }
305 0 : root->rb_node = NULL;
306 : }
307 :
308 :
309 : static struct dir_private_info *create_dir_info(loff_t pos)
310 0 : {
311 0 : struct dir_private_info *p;
312 :
313 0 : p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
314 0 : if (!p)
315 0 : return NULL;
316 0 : p->root.rb_node = NULL;
317 0 : p->curr_node = NULL;
318 0 : p->extra_fname = NULL;
319 0 : p->last_pos = 0;
320 0 : p->curr_hash = pos2maj_hash(pos);
321 0 : p->curr_minor_hash = pos2min_hash(pos);
322 0 : p->next_hash = 0;
323 0 : return p;
324 : }
325 :
326 : void ext3_htree_free_dir_info(struct dir_private_info *p)
327 0 : {
328 0 : free_rb_tree_fname(&p->root);
329 0 : kfree(p);
330 : }
331 :
332 : /*
333 : * Given a directory entry, enter it into the fname rb tree.
334 : */
335 : int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
336 : __u32 minor_hash,
337 : struct ext3_dir_entry_2 *dirent)
338 0 : {
339 0 : struct rb_node **p, *parent = NULL;
340 0 : struct fname * fname, *new_fn;
341 0 : struct dir_private_info *info;
342 0 : int len;
343 :
344 0 : info = (struct dir_private_info *) dir_file->private_data;
345 0 : p = &info->root.rb_node;
346 :
347 : /* Create and allocate the fname structure */
348 0 : len = sizeof(struct fname) + dirent->name_len + 1;
349 0 : new_fn = kmalloc(len, GFP_KERNEL);
350 0 : if (!new_fn)
351 0 : return -ENOMEM;
352 0 : memset(new_fn, 0, len);
353 0 : new_fn->hash = hash;
354 0 : new_fn->minor_hash = minor_hash;
355 0 : new_fn->inode = le32_to_cpu(dirent->inode);
356 0 : new_fn->name_len = dirent->name_len;
357 0 : new_fn->file_type = dirent->file_type;
358 0 : memcpy(new_fn->name, dirent->name, dirent->name_len);
359 0 : new_fn->name[dirent->name_len] = 0;
360 :
361 0 : while (*p) {
362 0 : parent = *p;
363 0 : fname = rb_entry(parent, struct fname, rb_hash);
364 :
365 : /*
366 : * If the hash and minor hash match up, then we put
367 : * them on a linked list. This rarely happens...
368 : */
369 0 : if ((new_fn->hash == fname->hash) &&
370 : (new_fn->minor_hash == fname->minor_hash)) {
371 0 : new_fn->next = fname->next;
372 0 : fname->next = new_fn;
373 0 : return 0;
374 : }
375 :
376 0 : if (new_fn->hash < fname->hash)
377 0 : p = &(*p)->rb_left;
378 0 : else if (new_fn->hash > fname->hash)
379 0 : p = &(*p)->rb_right;
380 0 : else if (new_fn->minor_hash < fname->minor_hash)
381 0 : p = &(*p)->rb_left;
382 : else /* if (new_fn->minor_hash > fname->minor_hash) */
383 0 : p = &(*p)->rb_right;
384 : }
385 :
386 0 : rb_link_node(&new_fn->rb_hash, parent, p);
387 0 : rb_insert_color(&new_fn->rb_hash, &info->root);
388 0 : return 0;
389 : }
390 :
391 :
392 :
393 : /*
394 : * This is a helper function for ext3_dx_readdir. It calls filldir
395 : * for all entres on the fname linked list. (Normally there is only
396 : * one entry on the linked list, unless there are 62 bit hash collisions.)
397 : */
398 : static int call_filldir(struct file * filp, void * dirent,
399 : filldir_t filldir, struct fname *fname)
400 0 : {
401 0 : struct dir_private_info *info = filp->private_data;
402 0 : loff_t curr_pos;
403 0 : struct inode *inode = filp->f_dentry->d_inode;
404 0 : struct super_block * sb;
405 0 : int error;
406 :
407 0 : sb = inode->i_sb;
408 :
409 0 : if (!fname) {
410 0 : printk("call_filldir: called with null fname?!?\n");
411 0 : return 0;
412 : }
413 0 : curr_pos = hash2pos(fname->hash, fname->minor_hash);
414 0 : while (fname) {
415 0 : error = filldir(dirent, fname->name,
416 : fname->name_len, curr_pos,
417 : fname->inode,
418 : get_dtype(sb, fname->file_type));
419 0 : if (error) {
420 0 : filp->f_pos = curr_pos;
421 0 : info->extra_fname = fname->next;
422 0 : return error;
423 : }
424 0 : fname = fname->next;
425 : }
426 0 : return 0;
427 : }
428 :
429 : static int ext3_dx_readdir(struct file * filp,
430 : void * dirent, filldir_t filldir)
431 0 : {
432 0 : struct dir_private_info *info = filp->private_data;
433 0 : struct inode *inode = filp->f_dentry->d_inode;
434 0 : struct fname *fname;
435 0 : int ret;
436 :
437 0 : if (!info) {
438 0 : info = create_dir_info(filp->f_pos);
439 0 : if (!info)
440 0 : return -ENOMEM;
441 0 : filp->private_data = info;
442 : }
443 :
444 0 : if (filp->f_pos == EXT3_HTREE_EOF)
445 0 : return 0; /* EOF */
446 :
447 : /* Some one has messed with f_pos; reset the world */
448 0 : if (info->last_pos != filp->f_pos) {
449 0 : free_rb_tree_fname(&info->root);
450 0 : info->curr_node = NULL;
451 0 : info->extra_fname = NULL;
452 0 : info->curr_hash = pos2maj_hash(filp->f_pos);
453 0 : info->curr_minor_hash = pos2min_hash(filp->f_pos);
454 : }
455 :
456 : /*
457 : * If there are any leftover names on the hash collision
458 : * chain, return them first.
459 : */
460 0 : if (info->extra_fname &&
461 : call_filldir(filp, dirent, filldir, info->extra_fname))
462 0 : goto finished;
463 :
464 0 : if (!info->curr_node)
465 0 : info->curr_node = rb_first(&info->root);
466 :
467 0 : 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 0 : if ((!info->curr_node) ||
474 : (filp->f_version != inode->i_version)) {
475 0 : info->curr_node = NULL;
476 0 : free_rb_tree_fname(&info->root);
477 0 : filp->f_version = inode->i_version;
478 0 : ret = ext3_htree_fill_tree(filp, info->curr_hash,
479 : info->curr_minor_hash,
480 : &info->next_hash);
481 0 : if (ret < 0)
482 0 : return ret;
483 0 : if (ret == 0) {
484 0 : filp->f_pos = EXT3_HTREE_EOF;
485 0 : break;
486 : }
487 0 : info->curr_node = rb_first(&info->root);
488 : }
489 :
490 0 : fname = rb_entry(info->curr_node, struct fname, rb_hash);
491 0 : info->curr_hash = fname->hash;
492 0 : info->curr_minor_hash = fname->minor_hash;
493 0 : if (call_filldir(filp, dirent, filldir, fname))
494 0 : break;
495 :
496 0 : info->curr_node = rb_next(info->curr_node);
497 0 : if (!info->curr_node) {
498 0 : if (info->next_hash == ~0) {
499 0 : filp->f_pos = EXT3_HTREE_EOF;
500 0 : break;
501 : }
502 0 : info->curr_hash = info->next_hash;
503 0 : info->curr_minor_hash = 0;
504 : }
505 : }
506 : finished:
507 0 : info->last_pos = filp->f_pos;
508 0 : return 0;
509 : }
510 :
511 : static int ext3_release_dir (struct inode * inode, struct file * filp)
512 1177 : {
513 1177 : if (filp->private_data)
514 0 : ext3_htree_free_dir_info(filp->private_data);
515 :
516 1177 : return 0;
517 : }
518 :
519 : #endif
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