ia64/linux-2.6.18-xen.hg

view fs/ext3/dir.c @ 524:7f8b544237bf

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Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children
line source
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 */
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>
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 };
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);
42 const 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 };
54 static 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;
60 return (ext3_filetype_table[filetype]);
61 }
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 {
69 const char * error_msg = NULL;
70 const int rlen = le16_to_cpu(de->rec_len);
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";
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 }
94 static 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_dentry->d_inode;
104 int ret = 0;
106 sb = inode->i_sb;
108 #ifdef CONFIG_EXT3_INDEX
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_dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
123 }
124 #endif
125 stored = 0;
126 offset = filp->f_pos & (sb->s_blocksize - 1);
128 while (!error && !stored && filp->f_pos < inode->i_size) {
129 unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
130 struct buffer_head map_bh;
131 struct buffer_head *bh = NULL;
133 map_bh.b_state = 0;
134 err = ext3_get_blocks_handle(NULL, inode, blk, 1,
135 &map_bh, 0, 0);
136 if (err > 0) {
137 page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
138 &filp->f_ra,
139 filp,
140 map_bh.b_blocknr >>
141 (PAGE_CACHE_SHIFT - inode->i_blkbits),
142 1);
143 bh = ext3_bread(NULL, inode, blk, 0, &err);
144 }
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 ext3_error (sb, "ext3_readdir",
152 "directory #%lu contains a hole at offset %lu",
153 inode->i_ino, (unsigned long)filp->f_pos);
154 filp->f_pos += sb->s_blocksize - offset;
155 continue;
156 }
158 revalidate:
159 /* If the dir block has changed since the last call to
160 * readdir(2), then we might be pointing to an invalid
161 * dirent right now. Scan from the start of the block
162 * to make sure. */
163 if (filp->f_version != inode->i_version) {
164 for (i = 0; i < sb->s_blocksize && i < offset; ) {
165 de = (struct ext3_dir_entry_2 *)
166 (bh->b_data + i);
167 /* It's too expensive to do a full
168 * dirent test each time round this
169 * loop, but we do have to test at
170 * least that it is non-zero. A
171 * failure will be detected in the
172 * dirent test below. */
173 if (le16_to_cpu(de->rec_len) <
174 EXT3_DIR_REC_LEN(1))
175 break;
176 i += le16_to_cpu(de->rec_len);
177 }
178 offset = i;
179 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
180 | offset;
181 filp->f_version = inode->i_version;
182 }
184 while (!error && filp->f_pos < inode->i_size
185 && offset < sb->s_blocksize) {
186 de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
187 if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
188 bh, offset)) {
189 /* On error, skip the f_pos to the
190 next block. */
191 filp->f_pos = (filp->f_pos |
192 (sb->s_blocksize - 1)) + 1;
193 brelse (bh);
194 ret = stored;
195 goto out;
196 }
197 offset += le16_to_cpu(de->rec_len);
198 if (le32_to_cpu(de->inode)) {
199 /* We might block in the next section
200 * if the data destination is
201 * currently swapped out. So, use a
202 * version stamp to detect whether or
203 * not the directory has been modified
204 * during the copy operation.
205 */
206 unsigned long version = filp->f_version;
208 error = filldir(dirent, de->name,
209 de->name_len,
210 filp->f_pos,
211 le32_to_cpu(de->inode),
212 get_dtype(sb, de->file_type));
213 if (error)
214 break;
215 if (version != filp->f_version)
216 goto revalidate;
217 stored ++;
218 }
219 filp->f_pos += le16_to_cpu(de->rec_len);
220 }
221 offset = 0;
222 brelse (bh);
223 }
224 out:
225 return ret;
226 }
228 #ifdef CONFIG_EXT3_INDEX
229 /*
230 * These functions convert from the major/minor hash to an f_pos
231 * value.
232 *
233 * Currently we only use major hash numer. This is unfortunate, but
234 * on 32-bit machines, the same VFS interface is used for lseek and
235 * llseek, so if we use the 64 bit offset, then the 32-bit versions of
236 * lseek/telldir/seekdir will blow out spectacularly, and from within
237 * the ext2 low-level routine, we don't know if we're being called by
238 * a 64-bit version of the system call or the 32-bit version of the
239 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir
240 * cookie. Sigh.
241 */
242 #define hash2pos(major, minor) (major >> 1)
243 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
244 #define pos2min_hash(pos) (0)
246 /*
247 * This structure holds the nodes of the red-black tree used to store
248 * the directory entry in hash order.
249 */
250 struct fname {
251 __u32 hash;
252 __u32 minor_hash;
253 struct rb_node rb_hash;
254 struct fname *next;
255 __u32 inode;
256 __u8 name_len;
257 __u8 file_type;
258 char name[0];
259 };
261 /*
262 * This functoin implements a non-recursive way of freeing all of the
263 * nodes in the red-black tree.
264 */
265 static void free_rb_tree_fname(struct rb_root *root)
266 {
267 struct rb_node *n = root->rb_node;
268 struct rb_node *parent;
269 struct fname *fname;
271 while (n) {
272 /* Do the node's children first */
273 if ((n)->rb_left) {
274 n = n->rb_left;
275 continue;
276 }
277 if (n->rb_right) {
278 n = n->rb_right;
279 continue;
280 }
281 /*
282 * The node has no children; free it, and then zero
283 * out parent's link to it. Finally go to the
284 * beginning of the loop and try to free the parent
285 * node.
286 */
287 parent = rb_parent(n);
288 fname = rb_entry(n, struct fname, rb_hash);
289 while (fname) {
290 struct fname * old = fname;
291 fname = fname->next;
292 kfree (old);
293 }
294 if (!parent)
295 root->rb_node = NULL;
296 else if (parent->rb_left == n)
297 parent->rb_left = NULL;
298 else if (parent->rb_right == n)
299 parent->rb_right = NULL;
300 n = parent;
301 }
302 root->rb_node = NULL;
303 }
306 static struct dir_private_info *create_dir_info(loff_t pos)
307 {
308 struct dir_private_info *p;
310 p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
311 if (!p)
312 return NULL;
313 p->root.rb_node = NULL;
314 p->curr_node = NULL;
315 p->extra_fname = NULL;
316 p->last_pos = 0;
317 p->curr_hash = pos2maj_hash(pos);
318 p->curr_minor_hash = pos2min_hash(pos);
319 p->next_hash = 0;
320 return p;
321 }
323 void ext3_htree_free_dir_info(struct dir_private_info *p)
324 {
325 free_rb_tree_fname(&p->root);
326 kfree(p);
327 }
329 /*
330 * Given a directory entry, enter it into the fname rb tree.
331 */
332 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
333 __u32 minor_hash,
334 struct ext3_dir_entry_2 *dirent)
335 {
336 struct rb_node **p, *parent = NULL;
337 struct fname * fname, *new_fn;
338 struct dir_private_info *info;
339 int len;
341 info = (struct dir_private_info *) dir_file->private_data;
342 p = &info->root.rb_node;
344 /* Create and allocate the fname structure */
345 len = sizeof(struct fname) + dirent->name_len + 1;
346 new_fn = kmalloc(len, GFP_KERNEL);
347 if (!new_fn)
348 return -ENOMEM;
349 memset(new_fn, 0, len);
350 new_fn->hash = hash;
351 new_fn->minor_hash = minor_hash;
352 new_fn->inode = le32_to_cpu(dirent->inode);
353 new_fn->name_len = dirent->name_len;
354 new_fn->file_type = dirent->file_type;
355 memcpy(new_fn->name, dirent->name, dirent->name_len);
356 new_fn->name[dirent->name_len] = 0;
358 while (*p) {
359 parent = *p;
360 fname = rb_entry(parent, struct fname, rb_hash);
362 /*
363 * If the hash and minor hash match up, then we put
364 * them on a linked list. This rarely happens...
365 */
366 if ((new_fn->hash == fname->hash) &&
367 (new_fn->minor_hash == fname->minor_hash)) {
368 new_fn->next = fname->next;
369 fname->next = new_fn;
370 return 0;
371 }
373 if (new_fn->hash < fname->hash)
374 p = &(*p)->rb_left;
375 else if (new_fn->hash > fname->hash)
376 p = &(*p)->rb_right;
377 else if (new_fn->minor_hash < fname->minor_hash)
378 p = &(*p)->rb_left;
379 else /* if (new_fn->minor_hash > fname->minor_hash) */
380 p = &(*p)->rb_right;
381 }
383 rb_link_node(&new_fn->rb_hash, parent, p);
384 rb_insert_color(&new_fn->rb_hash, &info->root);
385 return 0;
386 }
390 /*
391 * This is a helper function for ext3_dx_readdir. It calls filldir
392 * for all entres on the fname linked list. (Normally there is only
393 * one entry on the linked list, unless there are 62 bit hash collisions.)
394 */
395 static int call_filldir(struct file * filp, void * dirent,
396 filldir_t filldir, struct fname *fname)
397 {
398 struct dir_private_info *info = filp->private_data;
399 loff_t curr_pos;
400 struct inode *inode = filp->f_dentry->d_inode;
401 struct super_block * sb;
402 int error;
404 sb = inode->i_sb;
406 if (!fname) {
407 printk("call_filldir: called with null fname?!?\n");
408 return 0;
409 }
410 curr_pos = hash2pos(fname->hash, fname->minor_hash);
411 while (fname) {
412 error = filldir(dirent, fname->name,
413 fname->name_len, curr_pos,
414 fname->inode,
415 get_dtype(sb, fname->file_type));
416 if (error) {
417 filp->f_pos = curr_pos;
418 info->extra_fname = fname->next;
419 return error;
420 }
421 fname = fname->next;
422 }
423 return 0;
424 }
426 static int ext3_dx_readdir(struct file * filp,
427 void * dirent, filldir_t filldir)
428 {
429 struct dir_private_info *info = filp->private_data;
430 struct inode *inode = filp->f_dentry->d_inode;
431 struct fname *fname;
432 int ret;
434 if (!info) {
435 info = create_dir_info(filp->f_pos);
436 if (!info)
437 return -ENOMEM;
438 filp->private_data = info;
439 }
441 if (filp->f_pos == EXT3_HTREE_EOF)
442 return 0; /* EOF */
444 /* Some one has messed with f_pos; reset the world */
445 if (info->last_pos != filp->f_pos) {
446 free_rb_tree_fname(&info->root);
447 info->curr_node = NULL;
448 info->extra_fname = NULL;
449 info->curr_hash = pos2maj_hash(filp->f_pos);
450 info->curr_minor_hash = pos2min_hash(filp->f_pos);
451 }
453 /*
454 * If there are any leftover names on the hash collision
455 * chain, return them first.
456 */
457 if (info->extra_fname &&
458 call_filldir(filp, dirent, filldir, info->extra_fname))
459 goto finished;
461 if (!info->curr_node)
462 info->curr_node = rb_first(&info->root);
464 while (1) {
465 /*
466 * Fill the rbtree if we have no more entries,
467 * or the inode has changed since we last read in the
468 * cached entries.
469 */
470 if ((!info->curr_node) ||
471 (filp->f_version != inode->i_version)) {
472 info->curr_node = NULL;
473 free_rb_tree_fname(&info->root);
474 filp->f_version = inode->i_version;
475 ret = ext3_htree_fill_tree(filp, info->curr_hash,
476 info->curr_minor_hash,
477 &info->next_hash);
478 if (ret < 0)
479 return ret;
480 if (ret == 0) {
481 filp->f_pos = EXT3_HTREE_EOF;
482 break;
483 }
484 info->curr_node = rb_first(&info->root);
485 }
487 fname = rb_entry(info->curr_node, struct fname, rb_hash);
488 info->curr_hash = fname->hash;
489 info->curr_minor_hash = fname->minor_hash;
490 if (call_filldir(filp, dirent, filldir, fname))
491 break;
493 info->curr_node = rb_next(info->curr_node);
494 if (!info->curr_node) {
495 if (info->next_hash == ~0) {
496 filp->f_pos = EXT3_HTREE_EOF;
497 break;
498 }
499 info->curr_hash = info->next_hash;
500 info->curr_minor_hash = 0;
501 }
502 }
503 finished:
504 info->last_pos = filp->f_pos;
505 return 0;
506 }
508 static int ext3_release_dir (struct inode * inode, struct file * filp)
509 {
510 if (filp->private_data)
511 ext3_htree_free_dir_info(filp->private_data);
513 return 0;
514 }
516 #endif