vfs: fix possible deadlock in ext2, ext3, ext4 when using xattrs
[sfrench/cifs-2.6.git] / fs / ext4 / xattr.c
1 /*
2  * linux/fs/ext4/xattr.c
3  *
4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5  *
6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
7  * Ext4 code with a lot of help from Eric Jarman <ejarman@acm.org>.
8  * Extended attributes for symlinks and special files added per
9  *  suggestion of Luka Renko <luka.renko@hermes.si>.
10  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
11  *  Red Hat Inc.
12  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
13  *  and Andreas Gruenbacher <agruen@suse.de>.
14  */
15
16 /*
17  * Extended attributes are stored directly in inodes (on file systems with
18  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
19  * field contains the block number if an inode uses an additional block. All
20  * attributes must fit in the inode and one additional block. Blocks that
21  * contain the identical set of attributes may be shared among several inodes.
22  * Identical blocks are detected by keeping a cache of blocks that have
23  * recently been accessed.
24  *
25  * The attributes in inodes and on blocks have a different header; the entries
26  * are stored in the same format:
27  *
28  *   +------------------+
29  *   | header           |
30  *   | entry 1          | |
31  *   | entry 2          | | growing downwards
32  *   | entry 3          | v
33  *   | four null bytes  |
34  *   | . . .            |
35  *   | value 1          | ^
36  *   | value 3          | | growing upwards
37  *   | value 2          | |
38  *   +------------------+
39  *
40  * The header is followed by multiple entry descriptors. In disk blocks, the
41  * entry descriptors are kept sorted. In inodes, they are unsorted. The
42  * attribute values are aligned to the end of the block in no specific order.
43  *
44  * Locking strategy
45  * ----------------
46  * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem.
47  * EA blocks are only changed if they are exclusive to an inode, so
48  * holding xattr_sem also means that nothing but the EA block's reference
49  * count can change. Multiple writers to the same block are synchronized
50  * by the buffer lock.
51  */
52
53 #include <linux/init.h>
54 #include <linux/fs.h>
55 #include <linux/slab.h>
56 #include <linux/ext4_jbd2.h>
57 #include <linux/ext4_fs.h>
58 #include <linux/mbcache.h>
59 #include <linux/quotaops.h>
60 #include <linux/rwsem.h>
61 #include "xattr.h"
62 #include "acl.h"
63
64 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
65 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
66 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
67 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
68
69 #ifdef EXT4_XATTR_DEBUG
70 # define ea_idebug(inode, f...) do { \
71                 printk(KERN_DEBUG "inode %s:%lu: ", \
72                         inode->i_sb->s_id, inode->i_ino); \
73                 printk(f); \
74                 printk("\n"); \
75         } while (0)
76 # define ea_bdebug(bh, f...) do { \
77                 char b[BDEVNAME_SIZE]; \
78                 printk(KERN_DEBUG "block %s:%lu: ", \
79                         bdevname(bh->b_bdev, b), \
80                         (unsigned long) bh->b_blocknr); \
81                 printk(f); \
82                 printk("\n"); \
83         } while (0)
84 #else
85 # define ea_idebug(f...)
86 # define ea_bdebug(f...)
87 #endif
88
89 static void ext4_xattr_cache_insert(struct buffer_head *);
90 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
91                                                  struct ext4_xattr_header *,
92                                                  struct mb_cache_entry **);
93 static void ext4_xattr_rehash(struct ext4_xattr_header *,
94                               struct ext4_xattr_entry *);
95
96 static struct mb_cache *ext4_xattr_cache;
97
98 static struct xattr_handler *ext4_xattr_handler_map[] = {
99         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
100 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
101         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
102         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,
103 #endif
104         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
105 #ifdef CONFIG_EXT4DEV_FS_SECURITY
106         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
107 #endif
108 };
109
110 struct xattr_handler *ext4_xattr_handlers[] = {
111         &ext4_xattr_user_handler,
112         &ext4_xattr_trusted_handler,
113 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
114         &ext4_xattr_acl_access_handler,
115         &ext4_xattr_acl_default_handler,
116 #endif
117 #ifdef CONFIG_EXT4DEV_FS_SECURITY
118         &ext4_xattr_security_handler,
119 #endif
120         NULL
121 };
122
123 static inline struct xattr_handler *
124 ext4_xattr_handler(int name_index)
125 {
126         struct xattr_handler *handler = NULL;
127
128         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
129                 handler = ext4_xattr_handler_map[name_index];
130         return handler;
131 }
132
133 /*
134  * Inode operation listxattr()
135  *
136  * dentry->d_inode->i_mutex: don't care
137  */
138 ssize_t
139 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
140 {
141         return ext4_xattr_list(dentry->d_inode, buffer, size);
142 }
143
144 static int
145 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
146 {
147         while (!IS_LAST_ENTRY(entry)) {
148                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
149                 if ((void *)next >= end)
150                         return -EIO;
151                 entry = next;
152         }
153         return 0;
154 }
155
156 static inline int
157 ext4_xattr_check_block(struct buffer_head *bh)
158 {
159         int error;
160
161         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
162             BHDR(bh)->h_blocks != cpu_to_le32(1))
163                 return -EIO;
164         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
165         return error;
166 }
167
168 static inline int
169 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
170 {
171         size_t value_size = le32_to_cpu(entry->e_value_size);
172
173         if (entry->e_value_block != 0 || value_size > size ||
174             le16_to_cpu(entry->e_value_offs) + value_size > size)
175                 return -EIO;
176         return 0;
177 }
178
179 static int
180 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
181                       const char *name, size_t size, int sorted)
182 {
183         struct ext4_xattr_entry *entry;
184         size_t name_len;
185         int cmp = 1;
186
187         if (name == NULL)
188                 return -EINVAL;
189         name_len = strlen(name);
190         entry = *pentry;
191         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
192                 cmp = name_index - entry->e_name_index;
193                 if (!cmp)
194                         cmp = name_len - entry->e_name_len;
195                 if (!cmp)
196                         cmp = memcmp(name, entry->e_name, name_len);
197                 if (cmp <= 0 && (sorted || cmp == 0))
198                         break;
199         }
200         *pentry = entry;
201         if (!cmp && ext4_xattr_check_entry(entry, size))
202                         return -EIO;
203         return cmp ? -ENODATA : 0;
204 }
205
206 static int
207 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
208                      void *buffer, size_t buffer_size)
209 {
210         struct buffer_head *bh = NULL;
211         struct ext4_xattr_entry *entry;
212         size_t size;
213         int error;
214
215         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
216                   name_index, name, buffer, (long)buffer_size);
217
218         error = -ENODATA;
219         if (!EXT4_I(inode)->i_file_acl)
220                 goto cleanup;
221         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
222         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
223         if (!bh)
224                 goto cleanup;
225         ea_bdebug(bh, "b_count=%d, refcount=%d",
226                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
227         if (ext4_xattr_check_block(bh)) {
228 bad_block:      ext4_error(inode->i_sb, __FUNCTION__,
229                            "inode %lu: bad block %llu", inode->i_ino,
230                            EXT4_I(inode)->i_file_acl);
231                 error = -EIO;
232                 goto cleanup;
233         }
234         ext4_xattr_cache_insert(bh);
235         entry = BFIRST(bh);
236         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
237         if (error == -EIO)
238                 goto bad_block;
239         if (error)
240                 goto cleanup;
241         size = le32_to_cpu(entry->e_value_size);
242         if (buffer) {
243                 error = -ERANGE;
244                 if (size > buffer_size)
245                         goto cleanup;
246                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
247                        size);
248         }
249         error = size;
250
251 cleanup:
252         brelse(bh);
253         return error;
254 }
255
256 static int
257 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
258                      void *buffer, size_t buffer_size)
259 {
260         struct ext4_xattr_ibody_header *header;
261         struct ext4_xattr_entry *entry;
262         struct ext4_inode *raw_inode;
263         struct ext4_iloc iloc;
264         size_t size;
265         void *end;
266         int error;
267
268         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
269                 return -ENODATA;
270         error = ext4_get_inode_loc(inode, &iloc);
271         if (error)
272                 return error;
273         raw_inode = ext4_raw_inode(&iloc);
274         header = IHDR(inode, raw_inode);
275         entry = IFIRST(header);
276         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
277         error = ext4_xattr_check_names(entry, end);
278         if (error)
279                 goto cleanup;
280         error = ext4_xattr_find_entry(&entry, name_index, name,
281                                       end - (void *)entry, 0);
282         if (error)
283                 goto cleanup;
284         size = le32_to_cpu(entry->e_value_size);
285         if (buffer) {
286                 error = -ERANGE;
287                 if (size > buffer_size)
288                         goto cleanup;
289                 memcpy(buffer, (void *)IFIRST(header) +
290                        le16_to_cpu(entry->e_value_offs), size);
291         }
292         error = size;
293
294 cleanup:
295         brelse(iloc.bh);
296         return error;
297 }
298
299 /*
300  * ext4_xattr_get()
301  *
302  * Copy an extended attribute into the buffer
303  * provided, or compute the buffer size required.
304  * Buffer is NULL to compute the size of the buffer required.
305  *
306  * Returns a negative error number on failure, or the number of bytes
307  * used / required on success.
308  */
309 int
310 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
311                void *buffer, size_t buffer_size)
312 {
313         int error;
314
315         down_read(&EXT4_I(inode)->xattr_sem);
316         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
317                                      buffer_size);
318         if (error == -ENODATA)
319                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
320                                              buffer_size);
321         up_read(&EXT4_I(inode)->xattr_sem);
322         return error;
323 }
324
325 static int
326 ext4_xattr_list_entries(struct inode *inode, struct ext4_xattr_entry *entry,
327                         char *buffer, size_t buffer_size)
328 {
329         size_t rest = buffer_size;
330
331         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
332                 struct xattr_handler *handler =
333                         ext4_xattr_handler(entry->e_name_index);
334
335                 if (handler) {
336                         size_t size = handler->list(inode, buffer, rest,
337                                                     entry->e_name,
338                                                     entry->e_name_len);
339                         if (buffer) {
340                                 if (size > rest)
341                                         return -ERANGE;
342                                 buffer += size;
343                         }
344                         rest -= size;
345                 }
346         }
347         return buffer_size - rest;
348 }
349
350 static int
351 ext4_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
352 {
353         struct buffer_head *bh = NULL;
354         int error;
355
356         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
357                   buffer, (long)buffer_size);
358
359         error = 0;
360         if (!EXT4_I(inode)->i_file_acl)
361                 goto cleanup;
362         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
363         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
364         error = -EIO;
365         if (!bh)
366                 goto cleanup;
367         ea_bdebug(bh, "b_count=%d, refcount=%d",
368                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
369         if (ext4_xattr_check_block(bh)) {
370                 ext4_error(inode->i_sb, __FUNCTION__,
371                            "inode %lu: bad block %llu", inode->i_ino,
372                            EXT4_I(inode)->i_file_acl);
373                 error = -EIO;
374                 goto cleanup;
375         }
376         ext4_xattr_cache_insert(bh);
377         error = ext4_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
378
379 cleanup:
380         brelse(bh);
381
382         return error;
383 }
384
385 static int
386 ext4_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
387 {
388         struct ext4_xattr_ibody_header *header;
389         struct ext4_inode *raw_inode;
390         struct ext4_iloc iloc;
391         void *end;
392         int error;
393
394         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
395                 return 0;
396         error = ext4_get_inode_loc(inode, &iloc);
397         if (error)
398                 return error;
399         raw_inode = ext4_raw_inode(&iloc);
400         header = IHDR(inode, raw_inode);
401         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
402         error = ext4_xattr_check_names(IFIRST(header), end);
403         if (error)
404                 goto cleanup;
405         error = ext4_xattr_list_entries(inode, IFIRST(header),
406                                         buffer, buffer_size);
407
408 cleanup:
409         brelse(iloc.bh);
410         return error;
411 }
412
413 /*
414  * ext4_xattr_list()
415  *
416  * Copy a list of attribute names into the buffer
417  * provided, or compute the buffer size required.
418  * Buffer is NULL to compute the size of the buffer required.
419  *
420  * Returns a negative error number on failure, or the number of bytes
421  * used / required on success.
422  */
423 int
424 ext4_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
425 {
426         int i_error, b_error;
427
428         down_read(&EXT4_I(inode)->xattr_sem);
429         i_error = ext4_xattr_ibody_list(inode, buffer, buffer_size);
430         if (i_error < 0) {
431                 b_error = 0;
432         } else {
433                 if (buffer) {
434                         buffer += i_error;
435                         buffer_size -= i_error;
436                 }
437                 b_error = ext4_xattr_block_list(inode, buffer, buffer_size);
438                 if (b_error < 0)
439                         i_error = 0;
440         }
441         up_read(&EXT4_I(inode)->xattr_sem);
442         return i_error + b_error;
443 }
444
445 /*
446  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
447  * not set, set it.
448  */
449 static void ext4_xattr_update_super_block(handle_t *handle,
450                                           struct super_block *sb)
451 {
452         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
453                 return;
454
455         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
456                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
457                 sb->s_dirt = 1;
458                 ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
459         }
460 }
461
462 /*
463  * Release the xattr block BH: If the reference count is > 1, decrement
464  * it; otherwise free the block.
465  */
466 static void
467 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
468                          struct buffer_head *bh)
469 {
470         struct mb_cache_entry *ce = NULL;
471         int error = 0;
472
473         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
474         error = ext4_journal_get_write_access(handle, bh);
475         if (error)
476                 goto out;
477
478         lock_buffer(bh);
479         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
480                 ea_bdebug(bh, "refcount now=0; freeing");
481                 if (ce)
482                         mb_cache_entry_free(ce);
483                 ext4_free_blocks(handle, inode, bh->b_blocknr, 1, 1);
484                 get_bh(bh);
485                 ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
486         } else {
487                 BHDR(bh)->h_refcount = cpu_to_le32(
488                                 le32_to_cpu(BHDR(bh)->h_refcount) - 1);
489                 error = ext4_journal_dirty_metadata(handle, bh);
490                 if (IS_SYNC(inode))
491                         handle->h_sync = 1;
492                 DQUOT_FREE_BLOCK(inode, 1);
493                 ea_bdebug(bh, "refcount now=%d; releasing",
494                           le32_to_cpu(BHDR(bh)->h_refcount));
495                 if (ce)
496                         mb_cache_entry_release(ce);
497         }
498         unlock_buffer(bh);
499 out:
500         ext4_std_error(inode->i_sb, error);
501         return;
502 }
503
504 /*
505  * Find the available free space for EAs. This also returns the total number of
506  * bytes used by EA entries.
507  */
508 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
509                                     size_t *min_offs, void *base, int *total)
510 {
511         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
512                 *total += EXT4_XATTR_LEN(last->e_name_len);
513                 if (!last->e_value_block && last->e_value_size) {
514                         size_t offs = le16_to_cpu(last->e_value_offs);
515                         if (offs < *min_offs)
516                                 *min_offs = offs;
517                 }
518         }
519         return (*min_offs - ((void *)last - base) - sizeof(__u32));
520 }
521
522 struct ext4_xattr_info {
523         int name_index;
524         const char *name;
525         const void *value;
526         size_t value_len;
527 };
528
529 struct ext4_xattr_search {
530         struct ext4_xattr_entry *first;
531         void *base;
532         void *end;
533         struct ext4_xattr_entry *here;
534         int not_found;
535 };
536
537 static int
538 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
539 {
540         struct ext4_xattr_entry *last;
541         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
542
543         /* Compute min_offs and last. */
544         last = s->first;
545         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
546                 if (!last->e_value_block && last->e_value_size) {
547                         size_t offs = le16_to_cpu(last->e_value_offs);
548                         if (offs < min_offs)
549                                 min_offs = offs;
550                 }
551         }
552         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
553         if (!s->not_found) {
554                 if (!s->here->e_value_block && s->here->e_value_size) {
555                         size_t size = le32_to_cpu(s->here->e_value_size);
556                         free += EXT4_XATTR_SIZE(size);
557                 }
558                 free += EXT4_XATTR_LEN(name_len);
559         }
560         if (i->value) {
561                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
562                     free < EXT4_XATTR_LEN(name_len) +
563                            EXT4_XATTR_SIZE(i->value_len))
564                         return -ENOSPC;
565         }
566
567         if (i->value && s->not_found) {
568                 /* Insert the new name. */
569                 size_t size = EXT4_XATTR_LEN(name_len);
570                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
571                 memmove((void *)s->here + size, s->here, rest);
572                 memset(s->here, 0, size);
573                 s->here->e_name_index = i->name_index;
574                 s->here->e_name_len = name_len;
575                 memcpy(s->here->e_name, i->name, name_len);
576         } else {
577                 if (!s->here->e_value_block && s->here->e_value_size) {
578                         void *first_val = s->base + min_offs;
579                         size_t offs = le16_to_cpu(s->here->e_value_offs);
580                         void *val = s->base + offs;
581                         size_t size = EXT4_XATTR_SIZE(
582                                 le32_to_cpu(s->here->e_value_size));
583
584                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
585                                 /* The old and the new value have the same
586                                    size. Just replace. */
587                                 s->here->e_value_size =
588                                         cpu_to_le32(i->value_len);
589                                 memset(val + size - EXT4_XATTR_PAD, 0,
590                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
591                                 memcpy(val, i->value, i->value_len);
592                                 return 0;
593                         }
594
595                         /* Remove the old value. */
596                         memmove(first_val + size, first_val, val - first_val);
597                         memset(first_val, 0, size);
598                         s->here->e_value_size = 0;
599                         s->here->e_value_offs = 0;
600                         min_offs += size;
601
602                         /* Adjust all value offsets. */
603                         last = s->first;
604                         while (!IS_LAST_ENTRY(last)) {
605                                 size_t o = le16_to_cpu(last->e_value_offs);
606                                 if (!last->e_value_block &&
607                                     last->e_value_size && o < offs)
608                                         last->e_value_offs =
609                                                 cpu_to_le16(o + size);
610                                 last = EXT4_XATTR_NEXT(last);
611                         }
612                 }
613                 if (!i->value) {
614                         /* Remove the old name. */
615                         size_t size = EXT4_XATTR_LEN(name_len);
616                         last = ENTRY((void *)last - size);
617                         memmove(s->here, (void *)s->here + size,
618                                 (void *)last - (void *)s->here + sizeof(__u32));
619                         memset(last, 0, size);
620                 }
621         }
622
623         if (i->value) {
624                 /* Insert the new value. */
625                 s->here->e_value_size = cpu_to_le32(i->value_len);
626                 if (i->value_len) {
627                         size_t size = EXT4_XATTR_SIZE(i->value_len);
628                         void *val = s->base + min_offs - size;
629                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
630                         memset(val + size - EXT4_XATTR_PAD, 0,
631                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
632                         memcpy(val, i->value, i->value_len);
633                 }
634         }
635         return 0;
636 }
637
638 struct ext4_xattr_block_find {
639         struct ext4_xattr_search s;
640         struct buffer_head *bh;
641 };
642
643 static int
644 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
645                       struct ext4_xattr_block_find *bs)
646 {
647         struct super_block *sb = inode->i_sb;
648         int error;
649
650         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
651                   i->name_index, i->name, i->value, (long)i->value_len);
652
653         if (EXT4_I(inode)->i_file_acl) {
654                 /* The inode already has an extended attribute block. */
655                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
656                 error = -EIO;
657                 if (!bs->bh)
658                         goto cleanup;
659                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
660                         atomic_read(&(bs->bh->b_count)),
661                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
662                 if (ext4_xattr_check_block(bs->bh)) {
663                         ext4_error(sb, __FUNCTION__,
664                                 "inode %lu: bad block %llu", inode->i_ino,
665                                 EXT4_I(inode)->i_file_acl);
666                         error = -EIO;
667                         goto cleanup;
668                 }
669                 /* Find the named attribute. */
670                 bs->s.base = BHDR(bs->bh);
671                 bs->s.first = BFIRST(bs->bh);
672                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
673                 bs->s.here = bs->s.first;
674                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
675                                               i->name, bs->bh->b_size, 1);
676                 if (error && error != -ENODATA)
677                         goto cleanup;
678                 bs->s.not_found = error;
679         }
680         error = 0;
681
682 cleanup:
683         return error;
684 }
685
686 static int
687 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
688                      struct ext4_xattr_info *i,
689                      struct ext4_xattr_block_find *bs)
690 {
691         struct super_block *sb = inode->i_sb;
692         struct buffer_head *new_bh = NULL;
693         struct ext4_xattr_search *s = &bs->s;
694         struct mb_cache_entry *ce = NULL;
695         int error = 0;
696
697 #define header(x) ((struct ext4_xattr_header *)(x))
698
699         if (i->value && i->value_len > sb->s_blocksize)
700                 return -ENOSPC;
701         if (s->base) {
702                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
703                                         bs->bh->b_blocknr);
704                 error = ext4_journal_get_write_access(handle, bs->bh);
705                 if (error)
706                         goto cleanup;
707                 lock_buffer(bs->bh);
708
709                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
710                         if (ce) {
711                                 mb_cache_entry_free(ce);
712                                 ce = NULL;
713                         }
714                         ea_bdebug(bs->bh, "modifying in-place");
715                         error = ext4_xattr_set_entry(i, s);
716                         if (!error) {
717                                 if (!IS_LAST_ENTRY(s->first))
718                                         ext4_xattr_rehash(header(s->base),
719                                                           s->here);
720                                 ext4_xattr_cache_insert(bs->bh);
721                         }
722                         unlock_buffer(bs->bh);
723                         if (error == -EIO)
724                                 goto bad_block;
725                         if (!error)
726                                 error = ext4_journal_dirty_metadata(handle,
727                                                                     bs->bh);
728                         if (error)
729                                 goto cleanup;
730                         goto inserted;
731                 } else {
732                         int offset = (char *)s->here - bs->bh->b_data;
733
734                         unlock_buffer(bs->bh);
735                         jbd2_journal_release_buffer(handle, bs->bh);
736                         if (ce) {
737                                 mb_cache_entry_release(ce);
738                                 ce = NULL;
739                         }
740                         ea_bdebug(bs->bh, "cloning");
741                         s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
742                         error = -ENOMEM;
743                         if (s->base == NULL)
744                                 goto cleanup;
745                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
746                         s->first = ENTRY(header(s->base)+1);
747                         header(s->base)->h_refcount = cpu_to_le32(1);
748                         s->here = ENTRY(s->base + offset);
749                         s->end = s->base + bs->bh->b_size;
750                 }
751         } else {
752                 /* Allocate a buffer where we construct the new block. */
753                 s->base = kzalloc(sb->s_blocksize, GFP_KERNEL);
754                 /* assert(header == s->base) */
755                 error = -ENOMEM;
756                 if (s->base == NULL)
757                         goto cleanup;
758                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
759                 header(s->base)->h_blocks = cpu_to_le32(1);
760                 header(s->base)->h_refcount = cpu_to_le32(1);
761                 s->first = ENTRY(header(s->base)+1);
762                 s->here = ENTRY(header(s->base)+1);
763                 s->end = s->base + sb->s_blocksize;
764         }
765
766         error = ext4_xattr_set_entry(i, s);
767         if (error == -EIO)
768                 goto bad_block;
769         if (error)
770                 goto cleanup;
771         if (!IS_LAST_ENTRY(s->first))
772                 ext4_xattr_rehash(header(s->base), s->here);
773
774 inserted:
775         if (!IS_LAST_ENTRY(s->first)) {
776                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
777                 if (new_bh) {
778                         /* We found an identical block in the cache. */
779                         if (new_bh == bs->bh)
780                                 ea_bdebug(new_bh, "keeping");
781                         else {
782                                 /* The old block is released after updating
783                                    the inode. */
784                                 error = -EDQUOT;
785                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
786                                         goto cleanup;
787                                 error = ext4_journal_get_write_access(handle,
788                                                                       new_bh);
789                                 if (error)
790                                         goto cleanup_dquot;
791                                 lock_buffer(new_bh);
792                                 BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
793                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
794                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
795                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
796                                 unlock_buffer(new_bh);
797                                 error = ext4_journal_dirty_metadata(handle,
798                                                                     new_bh);
799                                 if (error)
800                                         goto cleanup_dquot;
801                         }
802                         mb_cache_entry_release(ce);
803                         ce = NULL;
804                 } else if (bs->bh && s->base == bs->bh->b_data) {
805                         /* We were modifying this block in-place. */
806                         ea_bdebug(bs->bh, "keeping this block");
807                         new_bh = bs->bh;
808                         get_bh(new_bh);
809                 } else {
810                         /* We need to allocate a new block */
811                         ext4_fsblk_t goal = le32_to_cpu(
812                                         EXT4_SB(sb)->s_es->s_first_data_block) +
813                                 (ext4_fsblk_t)EXT4_I(inode)->i_block_group *
814                                 EXT4_BLOCKS_PER_GROUP(sb);
815                         ext4_fsblk_t block = ext4_new_block(handle, inode,
816                                                         goal, &error);
817                         if (error)
818                                 goto cleanup;
819                         ea_idebug(inode, "creating block %d", block);
820
821                         new_bh = sb_getblk(sb, block);
822                         if (!new_bh) {
823 getblk_failed:
824                                 ext4_free_blocks(handle, inode, block, 1, 1);
825                                 error = -EIO;
826                                 goto cleanup;
827                         }
828                         lock_buffer(new_bh);
829                         error = ext4_journal_get_create_access(handle, new_bh);
830                         if (error) {
831                                 unlock_buffer(new_bh);
832                                 goto getblk_failed;
833                         }
834                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
835                         set_buffer_uptodate(new_bh);
836                         unlock_buffer(new_bh);
837                         ext4_xattr_cache_insert(new_bh);
838                         error = ext4_journal_dirty_metadata(handle, new_bh);
839                         if (error)
840                                 goto cleanup;
841                 }
842         }
843
844         /* Update the inode. */
845         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
846
847         /* Drop the previous xattr block. */
848         if (bs->bh && bs->bh != new_bh)
849                 ext4_xattr_release_block(handle, inode, bs->bh);
850         error = 0;
851
852 cleanup:
853         if (ce)
854                 mb_cache_entry_release(ce);
855         brelse(new_bh);
856         if (!(bs->bh && s->base == bs->bh->b_data))
857                 kfree(s->base);
858
859         return error;
860
861 cleanup_dquot:
862         DQUOT_FREE_BLOCK(inode, 1);
863         goto cleanup;
864
865 bad_block:
866         ext4_error(inode->i_sb, __FUNCTION__,
867                    "inode %lu: bad block %llu", inode->i_ino,
868                    EXT4_I(inode)->i_file_acl);
869         goto cleanup;
870
871 #undef header
872 }
873
874 struct ext4_xattr_ibody_find {
875         struct ext4_xattr_search s;
876         struct ext4_iloc iloc;
877 };
878
879 static int
880 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
881                       struct ext4_xattr_ibody_find *is)
882 {
883         struct ext4_xattr_ibody_header *header;
884         struct ext4_inode *raw_inode;
885         int error;
886
887         if (EXT4_I(inode)->i_extra_isize == 0)
888                 return 0;
889         raw_inode = ext4_raw_inode(&is->iloc);
890         header = IHDR(inode, raw_inode);
891         is->s.base = is->s.first = IFIRST(header);
892         is->s.here = is->s.first;
893         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
894         if (EXT4_I(inode)->i_state & EXT4_STATE_XATTR) {
895                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
896                 if (error)
897                         return error;
898                 /* Find the named attribute. */
899                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
900                                               i->name, is->s.end -
901                                               (void *)is->s.base, 0);
902                 if (error && error != -ENODATA)
903                         return error;
904                 is->s.not_found = error;
905         }
906         return 0;
907 }
908
909 static int
910 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
911                      struct ext4_xattr_info *i,
912                      struct ext4_xattr_ibody_find *is)
913 {
914         struct ext4_xattr_ibody_header *header;
915         struct ext4_xattr_search *s = &is->s;
916         int error;
917
918         if (EXT4_I(inode)->i_extra_isize == 0)
919                 return -ENOSPC;
920         error = ext4_xattr_set_entry(i, s);
921         if (error)
922                 return error;
923         header = IHDR(inode, ext4_raw_inode(&is->iloc));
924         if (!IS_LAST_ENTRY(s->first)) {
925                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
926                 EXT4_I(inode)->i_state |= EXT4_STATE_XATTR;
927         } else {
928                 header->h_magic = cpu_to_le32(0);
929                 EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR;
930         }
931         return 0;
932 }
933
934 /*
935  * ext4_xattr_set_handle()
936  *
937  * Create, replace or remove an extended attribute for this inode. Buffer
938  * is NULL to remove an existing extended attribute, and non-NULL to
939  * either replace an existing extended attribute, or create a new extended
940  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
941  * specify that an extended attribute must exist and must not exist
942  * previous to the call, respectively.
943  *
944  * Returns 0, or a negative error number on failure.
945  */
946 int
947 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
948                       const char *name, const void *value, size_t value_len,
949                       int flags)
950 {
951         struct ext4_xattr_info i = {
952                 .name_index = name_index,
953                 .name = name,
954                 .value = value,
955                 .value_len = value_len,
956
957         };
958         struct ext4_xattr_ibody_find is = {
959                 .s = { .not_found = -ENODATA, },
960         };
961         struct ext4_xattr_block_find bs = {
962                 .s = { .not_found = -ENODATA, },
963         };
964         int error;
965
966         if (!name)
967                 return -EINVAL;
968         if (strlen(name) > 255)
969                 return -ERANGE;
970         down_write(&EXT4_I(inode)->xattr_sem);
971         error = ext4_get_inode_loc(inode, &is.iloc);
972         if (error)
973                 goto cleanup;
974
975         if (EXT4_I(inode)->i_state & EXT4_STATE_NEW) {
976                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
977                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
978                 EXT4_I(inode)->i_state &= ~EXT4_STATE_NEW;
979         }
980
981         error = ext4_xattr_ibody_find(inode, &i, &is);
982         if (error)
983                 goto cleanup;
984         if (is.s.not_found)
985                 error = ext4_xattr_block_find(inode, &i, &bs);
986         if (error)
987                 goto cleanup;
988         if (is.s.not_found && bs.s.not_found) {
989                 error = -ENODATA;
990                 if (flags & XATTR_REPLACE)
991                         goto cleanup;
992                 error = 0;
993                 if (!value)
994                         goto cleanup;
995         } else {
996                 error = -EEXIST;
997                 if (flags & XATTR_CREATE)
998                         goto cleanup;
999         }
1000         error = ext4_journal_get_write_access(handle, is.iloc.bh);
1001         if (error)
1002                 goto cleanup;
1003         if (!value) {
1004                 if (!is.s.not_found)
1005                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1006                 else if (!bs.s.not_found)
1007                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1008         } else {
1009                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1010                 if (!error && !bs.s.not_found) {
1011                         i.value = NULL;
1012                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1013                 } else if (error == -ENOSPC) {
1014                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1015                         if (error)
1016                                 goto cleanup;
1017                         if (!is.s.not_found) {
1018                                 i.value = NULL;
1019                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1020                                                              &is);
1021                         }
1022                 }
1023         }
1024         if (!error) {
1025                 ext4_xattr_update_super_block(handle, inode->i_sb);
1026                 inode->i_ctime = ext4_current_time(inode);
1027                 if (!value)
1028                         EXT4_I(inode)->i_state &= ~EXT4_STATE_NO_EXPAND;
1029                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1030                 /*
1031                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1032                  * error != 0.
1033                  */
1034                 is.iloc.bh = NULL;
1035                 if (IS_SYNC(inode))
1036                         handle->h_sync = 1;
1037         }
1038
1039 cleanup:
1040         brelse(is.iloc.bh);
1041         brelse(bs.bh);
1042         up_write(&EXT4_I(inode)->xattr_sem);
1043         return error;
1044 }
1045
1046 /*
1047  * ext4_xattr_set()
1048  *
1049  * Like ext4_xattr_set_handle, but start from an inode. This extended
1050  * attribute modification is a filesystem transaction by itself.
1051  *
1052  * Returns 0, or a negative error number on failure.
1053  */
1054 int
1055 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1056                const void *value, size_t value_len, int flags)
1057 {
1058         handle_t *handle;
1059         int error, retries = 0;
1060
1061 retry:
1062         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1063         if (IS_ERR(handle)) {
1064                 error = PTR_ERR(handle);
1065         } else {
1066                 int error2;
1067
1068                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1069                                               value, value_len, flags);
1070                 error2 = ext4_journal_stop(handle);
1071                 if (error == -ENOSPC &&
1072                     ext4_should_retry_alloc(inode->i_sb, &retries))
1073                         goto retry;
1074                 if (error == 0)
1075                         error = error2;
1076         }
1077
1078         return error;
1079 }
1080
1081 /*
1082  * Shift the EA entries in the inode to create space for the increased
1083  * i_extra_isize.
1084  */
1085 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1086                                      int value_offs_shift, void *to,
1087                                      void *from, size_t n, int blocksize)
1088 {
1089         struct ext4_xattr_entry *last = entry;
1090         int new_offs;
1091
1092         /* Adjust the value offsets of the entries */
1093         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1094                 if (!last->e_value_block && last->e_value_size) {
1095                         new_offs = le16_to_cpu(last->e_value_offs) +
1096                                                         value_offs_shift;
1097                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1098                                  > blocksize);
1099                         last->e_value_offs = cpu_to_le16(new_offs);
1100                 }
1101         }
1102         /* Shift the entries by n bytes */
1103         memmove(to, from, n);
1104 }
1105
1106 /*
1107  * Expand an inode by new_extra_isize bytes when EAs are present.
1108  * Returns 0 on success or negative error number on failure.
1109  */
1110 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1111                                struct ext4_inode *raw_inode, handle_t *handle)
1112 {
1113         struct ext4_xattr_ibody_header *header;
1114         struct ext4_xattr_entry *entry, *last, *first;
1115         struct buffer_head *bh = NULL;
1116         struct ext4_xattr_ibody_find *is = NULL;
1117         struct ext4_xattr_block_find *bs = NULL;
1118         char *buffer = NULL, *b_entry_name = NULL;
1119         size_t min_offs, free;
1120         int total_ino, total_blk;
1121         void *base, *start, *end;
1122         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1123         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1124
1125         down_write(&EXT4_I(inode)->xattr_sem);
1126 retry:
1127         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1128                 up_write(&EXT4_I(inode)->xattr_sem);
1129                 return 0;
1130         }
1131
1132         header = IHDR(inode, raw_inode);
1133         entry = IFIRST(header);
1134
1135         /*
1136          * Check if enough free space is available in the inode to shift the
1137          * entries ahead by new_extra_isize.
1138          */
1139
1140         base = start = entry;
1141         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1142         min_offs = end - base;
1143         last = entry;
1144         total_ino = sizeof(struct ext4_xattr_ibody_header);
1145
1146         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1147         if (free >= new_extra_isize) {
1148                 entry = IFIRST(header);
1149                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1150                                 - new_extra_isize, (void *)raw_inode +
1151                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1152                                 (void *)header, total_ino,
1153                                 inode->i_sb->s_blocksize);
1154                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1155                 error = 0;
1156                 goto cleanup;
1157         }
1158
1159         /*
1160          * Enough free space isn't available in the inode, check if
1161          * EA block can hold new_extra_isize bytes.
1162          */
1163         if (EXT4_I(inode)->i_file_acl) {
1164                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1165                 error = -EIO;
1166                 if (!bh)
1167                         goto cleanup;
1168                 if (ext4_xattr_check_block(bh)) {
1169                         ext4_error(inode->i_sb, __FUNCTION__,
1170                                 "inode %lu: bad block %llu", inode->i_ino,
1171                                 EXT4_I(inode)->i_file_acl);
1172                         error = -EIO;
1173                         goto cleanup;
1174                 }
1175                 base = BHDR(bh);
1176                 first = BFIRST(bh);
1177                 end = bh->b_data + bh->b_size;
1178                 min_offs = end - base;
1179                 free = ext4_xattr_free_space(first, &min_offs, base,
1180                                              &total_blk);
1181                 if (free < new_extra_isize) {
1182                         if (!tried_min_extra_isize && s_min_extra_isize) {
1183                                 tried_min_extra_isize++;
1184                                 new_extra_isize = s_min_extra_isize;
1185                                 brelse(bh);
1186                                 goto retry;
1187                         }
1188                         error = -1;
1189                         goto cleanup;
1190                 }
1191         } else {
1192                 free = inode->i_sb->s_blocksize;
1193         }
1194
1195         while (new_extra_isize > 0) {
1196                 size_t offs, size, entry_size;
1197                 struct ext4_xattr_entry *small_entry = NULL;
1198                 struct ext4_xattr_info i = {
1199                         .value = NULL,
1200                         .value_len = 0,
1201                 };
1202                 unsigned int total_size;  /* EA entry size + value size */
1203                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1204                 unsigned int min_total_size = ~0U;
1205
1206                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1207                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1208                 if (!is || !bs) {
1209                         error = -ENOMEM;
1210                         goto cleanup;
1211                 }
1212
1213                 is->s.not_found = -ENODATA;
1214                 bs->s.not_found = -ENODATA;
1215                 is->iloc.bh = NULL;
1216                 bs->bh = NULL;
1217
1218                 last = IFIRST(header);
1219                 /* Find the entry best suited to be pushed into EA block */
1220                 entry = NULL;
1221                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1222                         total_size =
1223                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1224                                         EXT4_XATTR_LEN(last->e_name_len);
1225                         if (total_size <= free && total_size < min_total_size) {
1226                                 if (total_size < new_extra_isize) {
1227                                         small_entry = last;
1228                                 } else {
1229                                         entry = last;
1230                                         min_total_size = total_size;
1231                                 }
1232                         }
1233                 }
1234
1235                 if (entry == NULL) {
1236                         if (small_entry) {
1237                                 entry = small_entry;
1238                         } else {
1239                                 if (!tried_min_extra_isize &&
1240                                     s_min_extra_isize) {
1241                                         tried_min_extra_isize++;
1242                                         new_extra_isize = s_min_extra_isize;
1243                                         goto retry;
1244                                 }
1245                                 error = -1;
1246                                 goto cleanup;
1247                         }
1248                 }
1249                 offs = le16_to_cpu(entry->e_value_offs);
1250                 size = le32_to_cpu(entry->e_value_size);
1251                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1252                 i.name_index = entry->e_name_index,
1253                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1254                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1255                 if (!buffer || !b_entry_name) {
1256                         error = -ENOMEM;
1257                         goto cleanup;
1258                 }
1259                 /* Save the entry name and the entry value */
1260                 memcpy(buffer, (void *)IFIRST(header) + offs,
1261                        EXT4_XATTR_SIZE(size));
1262                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1263                 b_entry_name[entry->e_name_len] = '\0';
1264                 i.name = b_entry_name;
1265
1266                 error = ext4_get_inode_loc(inode, &is->iloc);
1267                 if (error)
1268                         goto cleanup;
1269
1270                 error = ext4_xattr_ibody_find(inode, &i, is);
1271                 if (error)
1272                         goto cleanup;
1273
1274                 /* Remove the chosen entry from the inode */
1275                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1276
1277                 entry = IFIRST(header);
1278                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1279                         shift_bytes = new_extra_isize;
1280                 else
1281                         shift_bytes = entry_size + size;
1282                 /* Adjust the offsets and shift the remaining entries ahead */
1283                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1284                         shift_bytes, (void *)raw_inode +
1285                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1286                         (void *)header, total_ino - entry_size,
1287                         inode->i_sb->s_blocksize);
1288
1289                 extra_isize += shift_bytes;
1290                 new_extra_isize -= shift_bytes;
1291                 EXT4_I(inode)->i_extra_isize = extra_isize;
1292
1293                 i.name = b_entry_name;
1294                 i.value = buffer;
1295                 i.value_len = size;
1296                 error = ext4_xattr_block_find(inode, &i, bs);
1297                 if (error)
1298                         goto cleanup;
1299
1300                 /* Add entry which was removed from the inode into the block */
1301                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1302                 if (error)
1303                         goto cleanup;
1304                 kfree(b_entry_name);
1305                 kfree(buffer);
1306                 brelse(is->iloc.bh);
1307                 kfree(is);
1308                 kfree(bs);
1309         }
1310         brelse(bh);
1311         up_write(&EXT4_I(inode)->xattr_sem);
1312         return 0;
1313
1314 cleanup:
1315         kfree(b_entry_name);
1316         kfree(buffer);
1317         if (is)
1318                 brelse(is->iloc.bh);
1319         kfree(is);
1320         kfree(bs);
1321         brelse(bh);
1322         up_write(&EXT4_I(inode)->xattr_sem);
1323         return error;
1324 }
1325
1326
1327
1328 /*
1329  * ext4_xattr_delete_inode()
1330  *
1331  * Free extended attribute resources associated with this inode. This
1332  * is called immediately before an inode is freed. We have exclusive
1333  * access to the inode.
1334  */
1335 void
1336 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1337 {
1338         struct buffer_head *bh = NULL;
1339
1340         if (!EXT4_I(inode)->i_file_acl)
1341                 goto cleanup;
1342         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1343         if (!bh) {
1344                 ext4_error(inode->i_sb, __FUNCTION__,
1345                         "inode %lu: block %llu read error", inode->i_ino,
1346                         EXT4_I(inode)->i_file_acl);
1347                 goto cleanup;
1348         }
1349         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1350             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1351                 ext4_error(inode->i_sb, __FUNCTION__,
1352                         "inode %lu: bad block %llu", inode->i_ino,
1353                         EXT4_I(inode)->i_file_acl);
1354                 goto cleanup;
1355         }
1356         ext4_xattr_release_block(handle, inode, bh);
1357         EXT4_I(inode)->i_file_acl = 0;
1358
1359 cleanup:
1360         brelse(bh);
1361 }
1362
1363 /*
1364  * ext4_xattr_put_super()
1365  *
1366  * This is called when a file system is unmounted.
1367  */
1368 void
1369 ext4_xattr_put_super(struct super_block *sb)
1370 {
1371         mb_cache_shrink(sb->s_bdev);
1372 }
1373
1374 /*
1375  * ext4_xattr_cache_insert()
1376  *
1377  * Create a new entry in the extended attribute cache, and insert
1378  * it unless such an entry is already in the cache.
1379  *
1380  * Returns 0, or a negative error number on failure.
1381  */
1382 static void
1383 ext4_xattr_cache_insert(struct buffer_head *bh)
1384 {
1385         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1386         struct mb_cache_entry *ce;
1387         int error;
1388
1389         ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);
1390         if (!ce) {
1391                 ea_bdebug(bh, "out of memory");
1392                 return;
1393         }
1394         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1395         if (error) {
1396                 mb_cache_entry_free(ce);
1397                 if (error == -EBUSY) {
1398                         ea_bdebug(bh, "already in cache");
1399                         error = 0;
1400                 }
1401         } else {
1402                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1403                 mb_cache_entry_release(ce);
1404         }
1405 }
1406
1407 /*
1408  * ext4_xattr_cmp()
1409  *
1410  * Compare two extended attribute blocks for equality.
1411  *
1412  * Returns 0 if the blocks are equal, 1 if they differ, and
1413  * a negative error number on errors.
1414  */
1415 static int
1416 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1417                struct ext4_xattr_header *header2)
1418 {
1419         struct ext4_xattr_entry *entry1, *entry2;
1420
1421         entry1 = ENTRY(header1+1);
1422         entry2 = ENTRY(header2+1);
1423         while (!IS_LAST_ENTRY(entry1)) {
1424                 if (IS_LAST_ENTRY(entry2))
1425                         return 1;
1426                 if (entry1->e_hash != entry2->e_hash ||
1427                     entry1->e_name_index != entry2->e_name_index ||
1428                     entry1->e_name_len != entry2->e_name_len ||
1429                     entry1->e_value_size != entry2->e_value_size ||
1430                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1431                         return 1;
1432                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1433                         return -EIO;
1434                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1435                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1436                            le32_to_cpu(entry1->e_value_size)))
1437                         return 1;
1438
1439                 entry1 = EXT4_XATTR_NEXT(entry1);
1440                 entry2 = EXT4_XATTR_NEXT(entry2);
1441         }
1442         if (!IS_LAST_ENTRY(entry2))
1443                 return 1;
1444         return 0;
1445 }
1446
1447 /*
1448  * ext4_xattr_cache_find()
1449  *
1450  * Find an identical extended attribute block.
1451  *
1452  * Returns a pointer to the block found, or NULL if such a block was
1453  * not found or an error occurred.
1454  */
1455 static struct buffer_head *
1456 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1457                       struct mb_cache_entry **pce)
1458 {
1459         __u32 hash = le32_to_cpu(header->h_hash);
1460         struct mb_cache_entry *ce;
1461
1462         if (!header->h_hash)
1463                 return NULL;  /* never share */
1464         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1465 again:
1466         ce = mb_cache_entry_find_first(ext4_xattr_cache, 0,
1467                                        inode->i_sb->s_bdev, hash);
1468         while (ce) {
1469                 struct buffer_head *bh;
1470
1471                 if (IS_ERR(ce)) {
1472                         if (PTR_ERR(ce) == -EAGAIN)
1473                                 goto again;
1474                         break;
1475                 }
1476                 bh = sb_bread(inode->i_sb, ce->e_block);
1477                 if (!bh) {
1478                         ext4_error(inode->i_sb, __FUNCTION__,
1479                                 "inode %lu: block %lu read error",
1480                                 inode->i_ino, (unsigned long) ce->e_block);
1481                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1482                                 EXT4_XATTR_REFCOUNT_MAX) {
1483                         ea_idebug(inode, "block %lu refcount %d>=%d",
1484                                   (unsigned long) ce->e_block,
1485                                   le32_to_cpu(BHDR(bh)->h_refcount),
1486                                           EXT4_XATTR_REFCOUNT_MAX);
1487                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1488                         *pce = ce;
1489                         return bh;
1490                 }
1491                 brelse(bh);
1492                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1493         }
1494         return NULL;
1495 }
1496
1497 #define NAME_HASH_SHIFT 5
1498 #define VALUE_HASH_SHIFT 16
1499
1500 /*
1501  * ext4_xattr_hash_entry()
1502  *
1503  * Compute the hash of an extended attribute.
1504  */
1505 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1506                                          struct ext4_xattr_entry *entry)
1507 {
1508         __u32 hash = 0;
1509         char *name = entry->e_name;
1510         int n;
1511
1512         for (n=0; n < entry->e_name_len; n++) {
1513                 hash = (hash << NAME_HASH_SHIFT) ^
1514                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1515                        *name++;
1516         }
1517
1518         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1519                 __le32 *value = (__le32 *)((char *)header +
1520                         le16_to_cpu(entry->e_value_offs));
1521                 for (n = (le32_to_cpu(entry->e_value_size) +
1522                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1523                         hash = (hash << VALUE_HASH_SHIFT) ^
1524                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1525                                le32_to_cpu(*value++);
1526                 }
1527         }
1528         entry->e_hash = cpu_to_le32(hash);
1529 }
1530
1531 #undef NAME_HASH_SHIFT
1532 #undef VALUE_HASH_SHIFT
1533
1534 #define BLOCK_HASH_SHIFT 16
1535
1536 /*
1537  * ext4_xattr_rehash()
1538  *
1539  * Re-compute the extended attribute hash value after an entry has changed.
1540  */
1541 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1542                               struct ext4_xattr_entry *entry)
1543 {
1544         struct ext4_xattr_entry *here;
1545         __u32 hash = 0;
1546
1547         ext4_xattr_hash_entry(header, entry);
1548         here = ENTRY(header+1);
1549         while (!IS_LAST_ENTRY(here)) {
1550                 if (!here->e_hash) {
1551                         /* Block is not shared if an entry's hash value == 0 */
1552                         hash = 0;
1553                         break;
1554                 }
1555                 hash = (hash << BLOCK_HASH_SHIFT) ^
1556                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1557                        le32_to_cpu(here->e_hash);
1558                 here = EXT4_XATTR_NEXT(here);
1559         }
1560         header->h_hash = cpu_to_le32(hash);
1561 }
1562
1563 #undef BLOCK_HASH_SHIFT
1564
1565 int __init
1566 init_ext4_xattr(void)
1567 {
1568         ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL,
1569                 sizeof(struct mb_cache_entry) +
1570                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1571         if (!ext4_xattr_cache)
1572                 return -ENOMEM;
1573         return 0;
1574 }
1575
1576 void
1577 exit_ext4_xattr(void)
1578 {
1579         if (ext4_xattr_cache)
1580                 mb_cache_destroy(ext4_xattr_cache);
1581         ext4_xattr_cache = NULL;
1582 }