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/compat.h>
25 #include "ext3.h"
26
27 static unsigned char ext3_filetype_table[] = {
28 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
29 };
30
31 static int ext3_dx_readdir(struct file *, struct dir_context *);
32
get_dtype(struct super_block * sb,int filetype)33 static unsigned char get_dtype(struct super_block *sb, int filetype)
34 {
35 if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
36 (filetype >= EXT3_FT_MAX))
37 return DT_UNKNOWN;
38
39 return (ext3_filetype_table[filetype]);
40 }
41
42 /**
43 * Check if the given dir-inode refers to an htree-indexed directory
44 * (or a directory which could potentially get converted to use htree
45 * indexing).
46 *
47 * Return 1 if it is a dx dir, 0 if not
48 */
is_dx_dir(struct inode * inode)49 static int is_dx_dir(struct inode *inode)
50 {
51 struct super_block *sb = inode->i_sb;
52
53 if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
54 EXT3_FEATURE_COMPAT_DIR_INDEX) &&
55 ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
56 ((inode->i_size >> sb->s_blocksize_bits) == 1)))
57 return 1;
58
59 return 0;
60 }
61
ext3_check_dir_entry(const char * function,struct inode * dir,struct ext3_dir_entry_2 * de,struct buffer_head * bh,unsigned long offset)62 int ext3_check_dir_entry (const char * function, struct inode * dir,
63 struct ext3_dir_entry_2 * de,
64 struct buffer_head * bh,
65 unsigned long offset)
66 {
67 const char * error_msg = NULL;
68 const int rlen = ext3_rec_len_from_disk(de->rec_len);
69
70 if (unlikely(rlen < EXT3_DIR_REC_LEN(1)))
71 error_msg = "rec_len is smaller than minimal";
72 else if (unlikely(rlen % 4 != 0))
73 error_msg = "rec_len % 4 != 0";
74 else if (unlikely(rlen < EXT3_DIR_REC_LEN(de->name_len)))
75 error_msg = "rec_len is too small for name_len";
76 else if (unlikely((((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)))
77 error_msg = "directory entry across blocks";
78 else if (unlikely(le32_to_cpu(de->inode) >
79 le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count)))
80 error_msg = "inode out of bounds";
81
82 if (unlikely(error_msg != NULL))
83 ext3_error (dir->i_sb, function,
84 "bad entry in directory #%lu: %s - "
85 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
86 dir->i_ino, error_msg, offset,
87 (unsigned long) le32_to_cpu(de->inode),
88 rlen, de->name_len);
89
90 return error_msg == NULL ? 1 : 0;
91 }
92
ext3_readdir(struct file * file,struct dir_context * ctx)93 static int ext3_readdir(struct file *file, struct dir_context *ctx)
94 {
95 unsigned long offset;
96 int i;
97 struct ext3_dir_entry_2 *de;
98 int err;
99 struct inode *inode = file_inode(file);
100 struct super_block *sb = inode->i_sb;
101 int dir_has_error = 0;
102
103 if (is_dx_dir(inode)) {
104 err = ext3_dx_readdir(file, ctx);
105 if (err != ERR_BAD_DX_DIR)
106 return err;
107 /*
108 * We don't set the inode dirty flag since it's not
109 * critical that it get flushed back to the disk.
110 */
111 EXT3_I(inode)->i_flags &= ~EXT3_INDEX_FL;
112 }
113 offset = ctx->pos & (sb->s_blocksize - 1);
114
115 while (ctx->pos < inode->i_size) {
116 unsigned long blk = ctx->pos >> EXT3_BLOCK_SIZE_BITS(sb);
117 struct buffer_head map_bh;
118 struct buffer_head *bh = NULL;
119
120 map_bh.b_state = 0;
121 err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0);
122 if (err > 0) {
123 pgoff_t index = map_bh.b_blocknr >>
124 (PAGE_CACHE_SHIFT - inode->i_blkbits);
125 if (!ra_has_index(&file->f_ra, index))
126 page_cache_sync_readahead(
127 sb->s_bdev->bd_inode->i_mapping,
128 &file->f_ra, file,
129 index, 1);
130 file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
131 bh = ext3_bread(NULL, inode, blk, 0, &err);
132 }
133
134 /*
135 * We ignore I/O errors on directories so users have a chance
136 * of recovering data when there's a bad sector
137 */
138 if (!bh) {
139 if (!dir_has_error) {
140 ext3_error(sb, __func__, "directory #%lu "
141 "contains a hole at offset %lld",
142 inode->i_ino, ctx->pos);
143 dir_has_error = 1;
144 }
145 /* corrupt size? Maybe no more blocks to read */
146 if (ctx->pos > inode->i_blocks << 9)
147 break;
148 ctx->pos += sb->s_blocksize - offset;
149 continue;
150 }
151
152 /* If the dir block has changed since the last call to
153 * readdir(2), then we might be pointing to an invalid
154 * dirent right now. Scan from the start of the block
155 * to make sure. */
156 if (offset && file->f_version != inode->i_version) {
157 for (i = 0; i < sb->s_blocksize && i < offset; ) {
158 de = (struct ext3_dir_entry_2 *)
159 (bh->b_data + i);
160 /* It's too expensive to do a full
161 * dirent test each time round this
162 * loop, but we do have to test at
163 * least that it is non-zero. A
164 * failure will be detected in the
165 * dirent test below. */
166 if (ext3_rec_len_from_disk(de->rec_len) <
167 EXT3_DIR_REC_LEN(1))
168 break;
169 i += ext3_rec_len_from_disk(de->rec_len);
170 }
171 offset = i;
172 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
173 | offset;
174 file->f_version = inode->i_version;
175 }
176
177 while (ctx->pos < inode->i_size
178 && offset < sb->s_blocksize) {
179 de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
180 if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
181 bh, offset)) {
182 /* On error, skip the to the
183 next block. */
184 ctx->pos = (ctx->pos |
185 (sb->s_blocksize - 1)) + 1;
186 break;
187 }
188 offset += ext3_rec_len_from_disk(de->rec_len);
189 if (le32_to_cpu(de->inode)) {
190 if (!dir_emit(ctx, de->name, de->name_len,
191 le32_to_cpu(de->inode),
192 get_dtype(sb, de->file_type))) {
193 brelse(bh);
194 return 0;
195 }
196 }
197 ctx->pos += ext3_rec_len_from_disk(de->rec_len);
198 }
199 offset = 0;
200 brelse (bh);
201 if (ctx->pos < inode->i_size)
202 if (!dir_relax(inode))
203 return 0;
204 }
205 return 0;
206 }
207
is_32bit_api(void)208 static inline int is_32bit_api(void)
209 {
210 #ifdef CONFIG_COMPAT
211 return is_compat_task();
212 #else
213 return (BITS_PER_LONG == 32);
214 #endif
215 }
216
217 /*
218 * These functions convert from the major/minor hash to an f_pos
219 * value for dx directories
220 *
221 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
222 * FMODE_64BITHASH explicitly. On the other hand, we allow ext3 to be mounted
223 * directly on both 32-bit and 64-bit nodes, under such case, neither
224 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
225 */
hash2pos(struct file * filp,__u32 major,__u32 minor)226 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
227 {
228 if ((filp->f_mode & FMODE_32BITHASH) ||
229 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
230 return major >> 1;
231 else
232 return ((__u64)(major >> 1) << 32) | (__u64)minor;
233 }
234
pos2maj_hash(struct file * filp,loff_t pos)235 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
236 {
237 if ((filp->f_mode & FMODE_32BITHASH) ||
238 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
239 return (pos << 1) & 0xffffffff;
240 else
241 return ((pos >> 32) << 1) & 0xffffffff;
242 }
243
pos2min_hash(struct file * filp,loff_t pos)244 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
245 {
246 if ((filp->f_mode & FMODE_32BITHASH) ||
247 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
248 return 0;
249 else
250 return pos & 0xffffffff;
251 }
252
253 /*
254 * Return 32- or 64-bit end-of-file for dx directories
255 */
ext3_get_htree_eof(struct file * filp)256 static inline loff_t ext3_get_htree_eof(struct file *filp)
257 {
258 if ((filp->f_mode & FMODE_32BITHASH) ||
259 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
260 return EXT3_HTREE_EOF_32BIT;
261 else
262 return EXT3_HTREE_EOF_64BIT;
263 }
264
265
266 /*
267 * ext3_dir_llseek() calls generic_file_llseek[_size]() to handle both
268 * non-htree and htree directories, where the "offset" is in terms
269 * of the filename hash value instead of the byte offset.
270 *
271 * Because we may return a 64-bit hash that is well beyond s_maxbytes,
272 * we need to pass the max hash as the maximum allowable offset in
273 * the htree directory case.
274 *
275 * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX)
276 * will be invalid once the directory was converted into a dx directory
277 */
ext3_dir_llseek(struct file * file,loff_t offset,int whence)278 static loff_t ext3_dir_llseek(struct file *file, loff_t offset, int whence)
279 {
280 struct inode *inode = file->f_mapping->host;
281 int dx_dir = is_dx_dir(inode);
282 loff_t htree_max = ext3_get_htree_eof(file);
283
284 if (likely(dx_dir))
285 return generic_file_llseek_size(file, offset, whence,
286 htree_max, htree_max);
287 else
288 return generic_file_llseek(file, offset, whence);
289 }
290
291 /*
292 * This structure holds the nodes of the red-black tree used to store
293 * the directory entry in hash order.
294 */
295 struct fname {
296 __u32 hash;
297 __u32 minor_hash;
298 struct rb_node rb_hash;
299 struct fname *next;
300 __u32 inode;
301 __u8 name_len;
302 __u8 file_type;
303 char name[0];
304 };
305
306 /*
307 * This functoin implements a non-recursive way of freeing all of the
308 * nodes in the red-black tree.
309 */
free_rb_tree_fname(struct rb_root * root)310 static void free_rb_tree_fname(struct rb_root *root)
311 {
312 struct fname *fname, *next;
313
314 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
315 do {
316 struct fname *old = fname;
317 fname = fname->next;
318 kfree(old);
319 } while (fname);
320
321 *root = RB_ROOT;
322 }
323
ext3_htree_create_dir_info(struct file * filp,loff_t pos)324 static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp,
325 loff_t pos)
326 {
327 struct dir_private_info *p;
328
329 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
330 if (!p)
331 return NULL;
332 p->curr_hash = pos2maj_hash(filp, pos);
333 p->curr_minor_hash = pos2min_hash(filp, pos);
334 return p;
335 }
336
ext3_htree_free_dir_info(struct dir_private_info * p)337 void ext3_htree_free_dir_info(struct dir_private_info *p)
338 {
339 free_rb_tree_fname(&p->root);
340 kfree(p);
341 }
342
343 /*
344 * Given a directory entry, enter it into the fname rb tree.
345 */
ext3_htree_store_dirent(struct file * dir_file,__u32 hash,__u32 minor_hash,struct ext3_dir_entry_2 * dirent)346 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
347 __u32 minor_hash,
348 struct ext3_dir_entry_2 *dirent)
349 {
350 struct rb_node **p, *parent = NULL;
351 struct fname * fname, *new_fn;
352 struct dir_private_info *info;
353 int len;
354
355 info = (struct dir_private_info *) dir_file->private_data;
356 p = &info->root.rb_node;
357
358 /* Create and allocate the fname structure */
359 len = sizeof(struct fname) + dirent->name_len + 1;
360 new_fn = kzalloc(len, GFP_KERNEL);
361 if (!new_fn)
362 return -ENOMEM;
363 new_fn->hash = hash;
364 new_fn->minor_hash = minor_hash;
365 new_fn->inode = le32_to_cpu(dirent->inode);
366 new_fn->name_len = dirent->name_len;
367 new_fn->file_type = dirent->file_type;
368 memcpy(new_fn->name, dirent->name, dirent->name_len);
369 new_fn->name[dirent->name_len] = 0;
370
371 while (*p) {
372 parent = *p;
373 fname = rb_entry(parent, struct fname, rb_hash);
374
375 /*
376 * If the hash and minor hash match up, then we put
377 * them on a linked list. This rarely happens...
378 */
379 if ((new_fn->hash == fname->hash) &&
380 (new_fn->minor_hash == fname->minor_hash)) {
381 new_fn->next = fname->next;
382 fname->next = new_fn;
383 return 0;
384 }
385
386 if (new_fn->hash < fname->hash)
387 p = &(*p)->rb_left;
388 else if (new_fn->hash > fname->hash)
389 p = &(*p)->rb_right;
390 else if (new_fn->minor_hash < fname->minor_hash)
391 p = &(*p)->rb_left;
392 else /* if (new_fn->minor_hash > fname->minor_hash) */
393 p = &(*p)->rb_right;
394 }
395
396 rb_link_node(&new_fn->rb_hash, parent, p);
397 rb_insert_color(&new_fn->rb_hash, &info->root);
398 return 0;
399 }
400
401
402
403 /*
404 * This is a helper function for ext3_dx_readdir. It calls filldir
405 * for all entres on the fname linked list. (Normally there is only
406 * one entry on the linked list, unless there are 62 bit hash collisions.)
407 */
call_filldir(struct file * file,struct dir_context * ctx,struct fname * fname)408 static bool call_filldir(struct file *file, struct dir_context *ctx,
409 struct fname *fname)
410 {
411 struct dir_private_info *info = file->private_data;
412 struct inode *inode = file_inode(file);
413 struct super_block *sb = inode->i_sb;
414
415 if (!fname) {
416 printk("call_filldir: called with null fname?!?\n");
417 return true;
418 }
419 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
420 while (fname) {
421 if (!dir_emit(ctx, fname->name, fname->name_len,
422 fname->inode,
423 get_dtype(sb, fname->file_type))) {
424 info->extra_fname = fname;
425 return false;
426 }
427 fname = fname->next;
428 }
429 return true;
430 }
431
ext3_dx_readdir(struct file * file,struct dir_context * ctx)432 static int ext3_dx_readdir(struct file *file, struct dir_context *ctx)
433 {
434 struct dir_private_info *info = file->private_data;
435 struct inode *inode = file_inode(file);
436 struct fname *fname;
437 int ret;
438
439 if (!info) {
440 info = ext3_htree_create_dir_info(file, ctx->pos);
441 if (!info)
442 return -ENOMEM;
443 file->private_data = info;
444 }
445
446 if (ctx->pos == ext3_get_htree_eof(file))
447 return 0; /* EOF */
448
449 /* Some one has messed with f_pos; reset the world */
450 if (info->last_pos != ctx->pos) {
451 free_rb_tree_fname(&info->root);
452 info->curr_node = NULL;
453 info->extra_fname = NULL;
454 info->curr_hash = pos2maj_hash(file, ctx->pos);
455 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
456 }
457
458 /*
459 * If there are any leftover names on the hash collision
460 * chain, return them first.
461 */
462 if (info->extra_fname) {
463 if (!call_filldir(file, ctx, info->extra_fname))
464 goto finished;
465 info->extra_fname = NULL;
466 goto next_node;
467 } else if (!info->curr_node)
468 info->curr_node = rb_first(&info->root);
469
470 while (1) {
471 /*
472 * Fill the rbtree if we have no more entries,
473 * or the inode has changed since we last read in the
474 * cached entries.
475 */
476 if ((!info->curr_node) ||
477 (file->f_version != inode->i_version)) {
478 info->curr_node = NULL;
479 free_rb_tree_fname(&info->root);
480 file->f_version = inode->i_version;
481 ret = ext3_htree_fill_tree(file, info->curr_hash,
482 info->curr_minor_hash,
483 &info->next_hash);
484 if (ret < 0)
485 return ret;
486 if (ret == 0) {
487 ctx->pos = ext3_get_htree_eof(file);
488 break;
489 }
490 info->curr_node = rb_first(&info->root);
491 }
492
493 fname = rb_entry(info->curr_node, struct fname, rb_hash);
494 info->curr_hash = fname->hash;
495 info->curr_minor_hash = fname->minor_hash;
496 if (!call_filldir(file, ctx, fname))
497 break;
498 next_node:
499 info->curr_node = rb_next(info->curr_node);
500 if (info->curr_node) {
501 fname = rb_entry(info->curr_node, struct fname,
502 rb_hash);
503 info->curr_hash = fname->hash;
504 info->curr_minor_hash = fname->minor_hash;
505 } else {
506 if (info->next_hash == ~0) {
507 ctx->pos = ext3_get_htree_eof(file);
508 break;
509 }
510 info->curr_hash = info->next_hash;
511 info->curr_minor_hash = 0;
512 }
513 }
514 finished:
515 info->last_pos = ctx->pos;
516 return 0;
517 }
518
ext3_release_dir(struct inode * inode,struct file * filp)519 static int ext3_release_dir (struct inode * inode, struct file * filp)
520 {
521 if (filp->private_data)
522 ext3_htree_free_dir_info(filp->private_data);
523
524 return 0;
525 }
526
527 const struct file_operations ext3_dir_operations = {
528 .llseek = ext3_dir_llseek,
529 .read = generic_read_dir,
530 .iterate = ext3_readdir,
531 .unlocked_ioctl = ext3_ioctl,
532 #ifdef CONFIG_COMPAT
533 .compat_ioctl = ext3_compat_ioctl,
534 #endif
535 .fsync = ext3_sync_file,
536 .release = ext3_release_dir,
537 };
538