x86: rodata config hookup
[wrt350n-kernel.git] / fs / ext4 / dir.c
blob33888bb58144fc1660d4106dbcbd689b560d2aa0
1 /*
2 * linux/fs/ext4/dir.c
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)
9 * from
11 * linux/fs/minix/dir.c
13 * Copyright (C) 1991, 1992 Linus Torvalds
15 * ext4 directory handling functions
17 * Big-endian to little-endian byte-swapping/bitmaps by
18 * David S. Miller (davem@caip.rutgers.edu), 1995
20 * Hash Tree Directory indexing (c) 2001 Daniel Phillips
24 #include <linux/fs.h>
25 #include <linux/jbd2.h>
26 #include <linux/ext4_fs.h>
27 #include <linux/buffer_head.h>
28 #include <linux/slab.h>
29 #include <linux/rbtree.h>
31 static unsigned char ext4_filetype_table[] = {
32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
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);
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 .ioctl = ext4_ioctl, /* BKL held */
46 #ifdef CONFIG_COMPAT
47 .compat_ioctl = ext4_compat_ioctl,
48 #endif
49 .fsync = ext4_sync_file, /* BKL held */
50 .release = ext4_release_dir,
54 static unsigned char get_dtype(struct super_block *sb, int filetype)
56 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
57 (filetype >= EXT4_FT_MAX))
58 return DT_UNKNOWN;
60 return (ext4_filetype_table[filetype]);
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 long offset)
69 const char * error_msg = NULL;
70 const int rlen = ext4_rec_len_from_disk(de->rec_len);
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";
84 if (error_msg != NULL)
85 ext4_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;
94 static int ext4_readdir(struct file * filp,
95 void * dirent, filldir_t filldir)
97 int error = 0;
98 unsigned long 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;
106 sb = inode->i_sb;
108 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
109 EXT4_FEATURE_COMPAT_DIR_INDEX) &&
110 ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
111 ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
112 err = ext4_dx_readdir(filp, dirent, filldir);
113 if (err != ERR_BAD_DX_DIR) {
114 ret = err;
115 goto out;
118 * We don't set the inode dirty flag since it's not
119 * critical that it get flushed back to the disk.
121 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
123 stored = 0;
124 offset = filp->f_pos & (sb->s_blocksize - 1);
126 while (!error && !stored && filp->f_pos < inode->i_size) {
127 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
128 struct buffer_head map_bh;
129 struct buffer_head *bh = NULL;
131 map_bh.b_state = 0;
132 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0);
133 if (err > 0) {
134 pgoff_t index = map_bh.b_blocknr >>
135 (PAGE_CACHE_SHIFT - inode->i_blkbits);
136 if (!ra_has_index(&filp->f_ra, index))
137 page_cache_sync_readahead(
138 sb->s_bdev->bd_inode->i_mapping,
139 &filp->f_ra, filp,
140 index, 1);
141 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
142 bh = ext4_bread(NULL, inode, blk, 0, &err);
146 * We ignore I/O errors on directories so users have a chance
147 * of recovering data when there's a bad sector
149 if (!bh) {
150 ext4_error (sb, "ext4_readdir",
151 "directory #%lu contains a hole at offset %lu",
152 inode->i_ino, (unsigned long)filp->f_pos);
153 /* corrupt size? Maybe no more blocks to read */
154 if (filp->f_pos > inode->i_blocks << 9)
155 break;
156 filp->f_pos += sb->s_blocksize - offset;
157 continue;
160 revalidate:
161 /* If the dir block has changed since the last call to
162 * readdir(2), then we might be pointing to an invalid
163 * dirent right now. Scan from the start of the block
164 * to make sure. */
165 if (filp->f_version != inode->i_version) {
166 for (i = 0; i < sb->s_blocksize && i < offset; ) {
167 de = (struct ext4_dir_entry_2 *)
168 (bh->b_data + i);
169 /* It's too expensive to do a full
170 * dirent test each time round this
171 * loop, but we do have to test at
172 * least that it is non-zero. A
173 * failure will be detected in the
174 * dirent test below. */
175 if (ext4_rec_len_from_disk(de->rec_len)
176 < EXT4_DIR_REC_LEN(1))
177 break;
178 i += ext4_rec_len_from_disk(de->rec_len);
180 offset = i;
181 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
182 | offset;
183 filp->f_version = inode->i_version;
186 while (!error && filp->f_pos < inode->i_size
187 && offset < sb->s_blocksize) {
188 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
189 if (!ext4_check_dir_entry ("ext4_readdir", inode, de,
190 bh, offset)) {
192 * On error, skip the f_pos to the next block
194 filp->f_pos = (filp->f_pos |
195 (sb->s_blocksize - 1)) + 1;
196 brelse (bh);
197 ret = stored;
198 goto out;
200 offset += ext4_rec_len_from_disk(de->rec_len);
201 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.
209 u64 version = filp->f_version;
211 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 if (error)
217 break;
218 if (version != filp->f_version)
219 goto revalidate;
220 stored ++;
222 filp->f_pos += ext4_rec_len_from_disk(de->rec_len);
224 offset = 0;
225 brelse (bh);
227 out:
228 return ret;
232 * These functions convert from the major/minor hash to an f_pos
233 * value.
235 * Currently we only use major hash numer. This is unfortunate, but
236 * on 32-bit machines, the same VFS interface is used for lseek and
237 * llseek, so if we use the 64 bit offset, then the 32-bit versions of
238 * lseek/telldir/seekdir will blow out spectacularly, and from within
239 * the ext2 low-level routine, we don't know if we're being called by
240 * a 64-bit version of the system call or the 32-bit version of the
241 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir
242 * cookie. Sigh.
244 #define hash2pos(major, minor) (major >> 1)
245 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
246 #define pos2min_hash(pos) (0)
249 * This structure holds the nodes of the red-black tree used to store
250 * the directory entry in hash order.
252 struct fname {
253 __u32 hash;
254 __u32 minor_hash;
255 struct rb_node rb_hash;
256 struct fname *next;
257 __u32 inode;
258 __u8 name_len;
259 __u8 file_type;
260 char name[0];
264 * This functoin implements a non-recursive way of freeing all of the
265 * nodes in the red-black tree.
267 static void free_rb_tree_fname(struct rb_root *root)
269 struct rb_node *n = root->rb_node;
270 struct rb_node *parent;
271 struct fname *fname;
273 while (n) {
274 /* Do the node's children first */
275 if ((n)->rb_left) {
276 n = n->rb_left;
277 continue;
279 if (n->rb_right) {
280 n = n->rb_right;
281 continue;
284 * The node has no children; free it, and then zero
285 * out parent's link to it. Finally go to the
286 * beginning of the loop and try to free the parent
287 * node.
289 parent = rb_parent(n);
290 fname = rb_entry(n, struct fname, rb_hash);
291 while (fname) {
292 struct fname * old = fname;
293 fname = fname->next;
294 kfree (old);
296 if (!parent)
297 root->rb_node = NULL;
298 else if (parent->rb_left == n)
299 parent->rb_left = NULL;
300 else if (parent->rb_right == n)
301 parent->rb_right = NULL;
302 n = parent;
304 root->rb_node = NULL;
308 static struct dir_private_info *create_dir_info(loff_t pos)
310 struct dir_private_info *p;
312 p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
313 if (!p)
314 return NULL;
315 p->root.rb_node = NULL;
316 p->curr_node = NULL;
317 p->extra_fname = NULL;
318 p->last_pos = 0;
319 p->curr_hash = pos2maj_hash(pos);
320 p->curr_minor_hash = pos2min_hash(pos);
321 p->next_hash = 0;
322 return p;
325 void ext4_htree_free_dir_info(struct dir_private_info *p)
327 free_rb_tree_fname(&p->root);
328 kfree(p);
332 * Given a directory entry, enter it into the fname rb tree.
334 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
335 __u32 minor_hash,
336 struct ext4_dir_entry_2 *dirent)
338 struct rb_node **p, *parent = NULL;
339 struct fname * fname, *new_fn;
340 struct dir_private_info *info;
341 int len;
343 info = (struct dir_private_info *) dir_file->private_data;
344 p = &info->root.rb_node;
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;
359 while (*p) {
360 parent = *p;
361 fname = rb_entry(parent, struct fname, rb_hash);
364 * If the hash and minor hash match up, then we put
365 * them on a linked list. This rarely happens...
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;
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;
384 rb_link_node(&new_fn->rb_hash, parent, p);
385 rb_insert_color(&new_fn->rb_hash, &info->root);
386 return 0;
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.)
396 static int call_filldir(struct file * filp, void * dirent,
397 filldir_t filldir, struct fname *fname)
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;
405 sb = inode->i_sb;
407 if (!fname) {
408 printk("call_filldir: called with null fname?!?\n");
409 return 0;
411 curr_pos = hash2pos(fname->hash, fname->minor_hash);
412 while (fname) {
413 error = filldir(dirent, fname->name,
414 fname->name_len, curr_pos,
415 fname->inode,
416 get_dtype(sb, fname->file_type));
417 if (error) {
418 filp->f_pos = curr_pos;
419 info->extra_fname = fname->next;
420 return error;
422 fname = fname->next;
424 return 0;
427 static int ext4_dx_readdir(struct file * filp,
428 void * dirent, filldir_t filldir)
430 struct dir_private_info *info = filp->private_data;
431 struct inode *inode = filp->f_path.dentry->d_inode;
432 struct fname *fname;
433 int ret;
435 if (!info) {
436 info = create_dir_info(filp->f_pos);
437 if (!info)
438 return -ENOMEM;
439 filp->private_data = info;
442 if (filp->f_pos == EXT4_HTREE_EOF)
443 return 0; /* EOF */
445 /* Some one has messed with f_pos; reset the world */
446 if (info->last_pos != filp->f_pos) {
447 free_rb_tree_fname(&info->root);
448 info->curr_node = NULL;
449 info->extra_fname = NULL;
450 info->curr_hash = pos2maj_hash(filp->f_pos);
451 info->curr_minor_hash = pos2min_hash(filp->f_pos);
455 * If there are any leftover names on the hash collision
456 * chain, return them first.
458 if (info->extra_fname &&
459 call_filldir(filp, dirent, filldir, info->extra_fname))
460 goto finished;
462 if (!info->curr_node)
463 info->curr_node = rb_first(&info->root);
465 while (1) {
467 * Fill the rbtree if we have no more entries,
468 * or the inode has changed since we last read in the
469 * cached entries.
471 if ((!info->curr_node) ||
472 (filp->f_version != inode->i_version)) {
473 info->curr_node = NULL;
474 free_rb_tree_fname(&info->root);
475 filp->f_version = inode->i_version;
476 ret = ext4_htree_fill_tree(filp, info->curr_hash,
477 info->curr_minor_hash,
478 &info->next_hash);
479 if (ret < 0)
480 return ret;
481 if (ret == 0) {
482 filp->f_pos = EXT4_HTREE_EOF;
483 break;
485 info->curr_node = rb_first(&info->root);
488 fname = rb_entry(info->curr_node, struct fname, rb_hash);
489 info->curr_hash = fname->hash;
490 info->curr_minor_hash = fname->minor_hash;
491 if (call_filldir(filp, dirent, filldir, fname))
492 break;
494 info->curr_node = rb_next(info->curr_node);
495 if (!info->curr_node) {
496 if (info->next_hash == ~0) {
497 filp->f_pos = EXT4_HTREE_EOF;
498 break;
500 info->curr_hash = info->next_hash;
501 info->curr_minor_hash = 0;
504 finished:
505 info->last_pos = filp->f_pos;
506 return 0;
509 static int ext4_release_dir (struct inode * inode, struct file * filp)
511 if (filp->private_data)
512 ext4_htree_free_dir_info(filp->private_data);
514 return 0;