SLUB slab validation: Move tracking information alloc outside of lock
[linux-2.6] / fs / ext4 / dir.c
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/ext4_fs.h>
27 #include <linux/buffer_head.h>
28 #include <linux/slab.h>
29 #include <linux/rbtree.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         .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 #ifdef CONFIG_EXT4_INDEX
51         .release        = ext4_release_dir,
52 #endif
53 };
54
55
56 static unsigned char get_dtype(struct super_block *sb, int filetype)
57 {
58         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
59             (filetype >= EXT4_FT_MAX))
60                 return DT_UNKNOWN;
61
62         return (ext4_filetype_table[filetype]);
63 }
64
65
66 int ext4_check_dir_entry (const char * function, struct inode * dir,
67                           struct ext4_dir_entry_2 * de,
68                           struct buffer_head * bh,
69                           unsigned long offset)
70 {
71         const char * error_msg = NULL;
72         const int rlen = le16_to_cpu(de->rec_len);
73
74         if (rlen < EXT4_DIR_REC_LEN(1))
75                 error_msg = "rec_len is smaller than minimal";
76         else if (rlen % 4 != 0)
77                 error_msg = "rec_len % 4 != 0";
78         else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
79                 error_msg = "rec_len is too small for name_len";
80         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
81                 error_msg = "directory entry across blocks";
82         else if (le32_to_cpu(de->inode) >
83                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
84                 error_msg = "inode out of bounds";
85
86         if (error_msg != NULL)
87                 ext4_error (dir->i_sb, function,
88                         "bad entry in directory #%lu: %s - "
89                         "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
90                         dir->i_ino, error_msg, offset,
91                         (unsigned long) le32_to_cpu(de->inode),
92                         rlen, de->name_len);
93         return error_msg == NULL ? 1 : 0;
94 }
95
96 static int ext4_readdir(struct file * filp,
97                          void * dirent, filldir_t filldir)
98 {
99         int error = 0;
100         unsigned long offset;
101         int i, stored;
102         struct ext4_dir_entry_2 *de;
103         struct super_block *sb;
104         int err;
105         struct inode *inode = filp->f_path.dentry->d_inode;
106         int ret = 0;
107
108         sb = inode->i_sb;
109
110 #ifdef CONFIG_EXT4_INDEX
111         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
112                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
113             ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
114              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
115                 err = ext4_dx_readdir(filp, dirent, filldir);
116                 if (err != ERR_BAD_DX_DIR) {
117                         ret = err;
118                         goto out;
119                 }
120                 /*
121                  * We don't set the inode dirty flag since it's not
122                  * critical that it get flushed back to the disk.
123                  */
124                 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
125         }
126 #endif
127         stored = 0;
128         offset = filp->f_pos & (sb->s_blocksize - 1);
129
130         while (!error && !stored && filp->f_pos < inode->i_size) {
131                 unsigned long blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
132                 struct buffer_head map_bh;
133                 struct buffer_head *bh = NULL;
134
135                 map_bh.b_state = 0;
136                 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0);
137                 if (err > 0) {
138                         page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
139                                 &filp->f_ra,
140                                 filp,
141                                 map_bh.b_blocknr >>
142                                         (PAGE_CACHE_SHIFT - inode->i_blkbits),
143                                 1);
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                         ext4_error (sb, "ext4_readdir",
153                                 "directory #%lu contains a hole at offset %lu",
154                                 inode->i_ino, (unsigned long)filp->f_pos);
155                         /* corrupt size?  Maybe no more blocks to read */
156                         if (filp->f_pos > inode->i_blocks << 9)
157                                 break;
158                         filp->f_pos += sb->s_blocksize - offset;
159                         continue;
160                 }
161
162 revalidate:
163                 /* If the dir block has changed since the last call to
164                  * readdir(2), then we might be pointing to an invalid
165                  * dirent right now.  Scan from the start of the block
166                  * to make sure. */
167                 if (filp->f_version != inode->i_version) {
168                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
169                                 de = (struct ext4_dir_entry_2 *)
170                                         (bh->b_data + i);
171                                 /* It's too expensive to do a full
172                                  * dirent test each time round this
173                                  * loop, but we do have to test at
174                                  * least that it is non-zero.  A
175                                  * failure will be detected in the
176                                  * dirent test below. */
177                                 if (le16_to_cpu(de->rec_len) <
178                                                 EXT4_DIR_REC_LEN(1))
179                                         break;
180                                 i += le16_to_cpu(de->rec_len);
181                         }
182                         offset = i;
183                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
184                                 | offset;
185                         filp->f_version = inode->i_version;
186                 }
187
188                 while (!error && filp->f_pos < inode->i_size
189                        && offset < sb->s_blocksize) {
190                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
191                         if (!ext4_check_dir_entry ("ext4_readdir", inode, de,
192                                                    bh, offset)) {
193                                 /*
194                                  * On error, skip the f_pos to the next block
195                                  */
196                                 filp->f_pos = (filp->f_pos |
197                                                 (sb->s_blocksize - 1)) + 1;
198                                 brelse (bh);
199                                 ret = stored;
200                                 goto out;
201                         }
202                         offset += le16_to_cpu(de->rec_len);
203                         if (le32_to_cpu(de->inode)) {
204                                 /* We might block in the next section
205                                  * if the data destination is
206                                  * currently swapped out.  So, use a
207                                  * version stamp to detect whether or
208                                  * not the directory has been modified
209                                  * during the copy operation.
210                                  */
211                                 unsigned long version = filp->f_version;
212
213                                 error = filldir(dirent, de->name,
214                                                 de->name_len,
215                                                 filp->f_pos,
216                                                 le32_to_cpu(de->inode),
217                                                 get_dtype(sb, de->file_type));
218                                 if (error)
219                                         break;
220                                 if (version != filp->f_version)
221                                         goto revalidate;
222                                 stored ++;
223                         }
224                         filp->f_pos += le16_to_cpu(de->rec_len);
225                 }
226                 offset = 0;
227                 brelse (bh);
228         }
229 out:
230         return ret;
231 }
232
233 #ifdef CONFIG_EXT4_INDEX
234 /*
235  * These functions convert from the major/minor hash to an f_pos
236  * value.
237  *
238  * Currently we only use major hash numer.  This is unfortunate, but
239  * on 32-bit machines, the same VFS interface is used for lseek and
240  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
241  * lseek/telldir/seekdir will blow out spectacularly, and from within
242  * the ext2 low-level routine, we don't know if we're being called by
243  * a 64-bit version of the system call or the 32-bit version of the
244  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
245  * cookie.  Sigh.
246  */
247 #define hash2pos(major, minor)  (major >> 1)
248 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
249 #define pos2min_hash(pos)       (0)
250
251 /*
252  * This structure holds the nodes of the red-black tree used to store
253  * the directory entry in hash order.
254  */
255 struct fname {
256         __u32           hash;
257         __u32           minor_hash;
258         struct rb_node  rb_hash;
259         struct fname    *next;
260         __u32           inode;
261         __u8            name_len;
262         __u8            file_type;
263         char            name[0];
264 };
265
266 /*
267  * This functoin implements a non-recursive way of freeing all of the
268  * nodes in the red-black tree.
269  */
270 static void free_rb_tree_fname(struct rb_root *root)
271 {
272         struct rb_node  *n = root->rb_node;
273         struct rb_node  *parent;
274         struct fname    *fname;
275
276         while (n) {
277                 /* Do the node's children first */
278                 if ((n)->rb_left) {
279                         n = n->rb_left;
280                         continue;
281                 }
282                 if (n->rb_right) {
283                         n = n->rb_right;
284                         continue;
285                 }
286                 /*
287                  * The node has no children; free it, and then zero
288                  * out parent's link to it.  Finally go to the
289                  * beginning of the loop and try to free the parent
290                  * node.
291                  */
292                 parent = rb_parent(n);
293                 fname = rb_entry(n, struct fname, rb_hash);
294                 while (fname) {
295                         struct fname * old = fname;
296                         fname = fname->next;
297                         kfree (old);
298                 }
299                 if (!parent)
300                         root->rb_node = NULL;
301                 else if (parent->rb_left == n)
302                         parent->rb_left = NULL;
303                 else if (parent->rb_right == n)
304                         parent->rb_right = NULL;
305                 n = parent;
306         }
307         root->rb_node = NULL;
308 }
309
310
311 static struct dir_private_info *create_dir_info(loff_t pos)
312 {
313         struct dir_private_info *p;
314
315         p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
316         if (!p)
317                 return NULL;
318         p->root.rb_node = NULL;
319         p->curr_node = NULL;
320         p->extra_fname = NULL;
321         p->last_pos = 0;
322         p->curr_hash = pos2maj_hash(pos);
323         p->curr_minor_hash = pos2min_hash(pos);
324         p->next_hash = 0;
325         return p;
326 }
327
328 void ext4_htree_free_dir_info(struct dir_private_info *p)
329 {
330         free_rb_tree_fname(&p->root);
331         kfree(p);
332 }
333
334 /*
335  * Given a directory entry, enter it into the fname rb tree.
336  */
337 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
338                              __u32 minor_hash,
339                              struct ext4_dir_entry_2 *dirent)
340 {
341         struct rb_node **p, *parent = NULL;
342         struct fname * fname, *new_fn;
343         struct dir_private_info *info;
344         int len;
345
346         info = (struct dir_private_info *) dir_file->private_data;
347         p = &info->root.rb_node;
348
349         /* Create and allocate the fname structure */
350         len = sizeof(struct fname) + dirent->name_len + 1;
351         new_fn = kzalloc(len, GFP_KERNEL);
352         if (!new_fn)
353                 return -ENOMEM;
354         new_fn->hash = hash;
355         new_fn->minor_hash = minor_hash;
356         new_fn->inode = le32_to_cpu(dirent->inode);
357         new_fn->name_len = dirent->name_len;
358         new_fn->file_type = dirent->file_type;
359         memcpy(new_fn->name, dirent->name, dirent->name_len);
360         new_fn->name[dirent->name_len] = 0;
361
362         while (*p) {
363                 parent = *p;
364                 fname = rb_entry(parent, struct fname, rb_hash);
365
366                 /*
367                  * If the hash and minor hash match up, then we put
368                  * them on a linked list.  This rarely happens...
369                  */
370                 if ((new_fn->hash == fname->hash) &&
371                     (new_fn->minor_hash == fname->minor_hash)) {
372                         new_fn->next = fname->next;
373                         fname->next = new_fn;
374                         return 0;
375                 }
376
377                 if (new_fn->hash < fname->hash)
378                         p = &(*p)->rb_left;
379                 else if (new_fn->hash > fname->hash)
380                         p = &(*p)->rb_right;
381                 else if (new_fn->minor_hash < fname->minor_hash)
382                         p = &(*p)->rb_left;
383                 else /* if (new_fn->minor_hash > fname->minor_hash) */
384                         p = &(*p)->rb_right;
385         }
386
387         rb_link_node(&new_fn->rb_hash, parent, p);
388         rb_insert_color(&new_fn->rb_hash, &info->root);
389         return 0;
390 }
391
392
393
394 /*
395  * This is a helper function for ext4_dx_readdir.  It calls filldir
396  * for all entres on the fname linked list.  (Normally there is only
397  * one entry on the linked list, unless there are 62 bit hash collisions.)
398  */
399 static int call_filldir(struct file * filp, void * dirent,
400                         filldir_t filldir, struct fname *fname)
401 {
402         struct dir_private_info *info = filp->private_data;
403         loff_t  curr_pos;
404         struct inode *inode = filp->f_path.dentry->d_inode;
405         struct super_block * sb;
406         int error;
407
408         sb = inode->i_sb;
409
410         if (!fname) {
411                 printk("call_filldir: called with null fname?!?\n");
412                 return 0;
413         }
414         curr_pos = hash2pos(fname->hash, fname->minor_hash);
415         while (fname) {
416                 error = filldir(dirent, fname->name,
417                                 fname->name_len, curr_pos,
418                                 fname->inode,
419                                 get_dtype(sb, fname->file_type));
420                 if (error) {
421                         filp->f_pos = curr_pos;
422                         info->extra_fname = fname->next;
423                         return error;
424                 }
425                 fname = fname->next;
426         }
427         return 0;
428 }
429
430 static int ext4_dx_readdir(struct file * filp,
431                          void * dirent, filldir_t filldir)
432 {
433         struct dir_private_info *info = filp->private_data;
434         struct inode *inode = filp->f_path.dentry->d_inode;
435         struct fname *fname;
436         int     ret;
437
438         if (!info) {
439                 info = create_dir_info(filp->f_pos);
440                 if (!info)
441                         return -ENOMEM;
442                 filp->private_data = info;
443         }
444
445         if (filp->f_pos == EXT4_HTREE_EOF)
446                 return 0;       /* EOF */
447
448         /* Some one has messed with f_pos; reset the world */
449         if (info->last_pos != filp->f_pos) {
450                 free_rb_tree_fname(&info->root);
451                 info->curr_node = NULL;
452                 info->extra_fname = NULL;
453                 info->curr_hash = pos2maj_hash(filp->f_pos);
454                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
455         }
456
457         /*
458          * If there are any leftover names on the hash collision
459          * chain, return them first.
460          */
461         if (info->extra_fname &&
462             call_filldir(filp, dirent, filldir, info->extra_fname))
463                 goto finished;
464
465         if (!info->curr_node)
466                 info->curr_node = rb_first(&info->root);
467
468         while (1) {
469                 /*
470                  * Fill the rbtree if we have no more entries,
471                  * or the inode has changed since we last read in the
472                  * cached entries.
473                  */
474                 if ((!info->curr_node) ||
475                     (filp->f_version != inode->i_version)) {
476                         info->curr_node = NULL;
477                         free_rb_tree_fname(&info->root);
478                         filp->f_version = inode->i_version;
479                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
480                                                    info->curr_minor_hash,
481                                                    &info->next_hash);
482                         if (ret < 0)
483                                 return ret;
484                         if (ret == 0) {
485                                 filp->f_pos = EXT4_HTREE_EOF;
486                                 break;
487                         }
488                         info->curr_node = rb_first(&info->root);
489                 }
490
491                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
492                 info->curr_hash = fname->hash;
493                 info->curr_minor_hash = fname->minor_hash;
494                 if (call_filldir(filp, dirent, filldir, fname))
495                         break;
496
497                 info->curr_node = rb_next(info->curr_node);
498                 if (!info->curr_node) {
499                         if (info->next_hash == ~0) {
500                                 filp->f_pos = EXT4_HTREE_EOF;
501                                 break;
502                         }
503                         info->curr_hash = info->next_hash;
504                         info->curr_minor_hash = 0;
505                 }
506         }
507 finished:
508         info->last_pos = filp->f_pos;
509         return 0;
510 }
511
512 static int ext4_release_dir (struct inode * inode, struct file * filp)
513 {
514         if (filp->private_data)
515                 ext4_htree_free_dir_info(filp->private_data);
516
517         return 0;
518 }
519
520 #endif