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TOMOYO Linux Cross Reference
Linux/fs/ext4/xattr.c

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  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/mbcache.h>
 57 #include <linux/quotaops.h>
 58 #include <linux/rwsem.h>
 59 #include "ext4_jbd2.h"
 60 #include "ext4.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 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
 96                            size_t buffer_size);
 97 
 98 static struct mb_cache *ext4_xattr_cache;
 99 
100 static const struct xattr_handler *ext4_xattr_handler_map[] = {
101         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
102 #ifdef CONFIG_EXT4_FS_POSIX_ACL
103         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
104         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,
105 #endif
106         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
107 #ifdef CONFIG_EXT4_FS_SECURITY
108         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
109 #endif
110 };
111 
112 const struct xattr_handler *ext4_xattr_handlers[] = {
113         &ext4_xattr_user_handler,
114         &ext4_xattr_trusted_handler,
115 #ifdef CONFIG_EXT4_FS_POSIX_ACL
116         &ext4_xattr_acl_access_handler,
117         &ext4_xattr_acl_default_handler,
118 #endif
119 #ifdef CONFIG_EXT4_FS_SECURITY
120         &ext4_xattr_security_handler,
121 #endif
122         NULL
123 };
124 
125 static inline const struct xattr_handler *
126 ext4_xattr_handler(int name_index)
127 {
128         const struct xattr_handler *handler = NULL;
129 
130         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
131                 handler = ext4_xattr_handler_map[name_index];
132         return handler;
133 }
134 
135 /*
136  * Inode operation listxattr()
137  *
138  * dentry->d_inode->i_mutex: don't care
139  */
140 ssize_t
141 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
142 {
143         return ext4_xattr_list(dentry, buffer, size);
144 }
145 
146 static int
147 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
148 {
149         while (!IS_LAST_ENTRY(entry)) {
150                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
151                 if ((void *)next >= end)
152                         return -EIO;
153                 entry = next;
154         }
155         return 0;
156 }
157 
158 static inline int
159 ext4_xattr_check_block(struct buffer_head *bh)
160 {
161         int error;
162 
163         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
164             BHDR(bh)->h_blocks != cpu_to_le32(1))
165                 return -EIO;
166         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
167         return error;
168 }
169 
170 static inline int
171 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
172 {
173         size_t value_size = le32_to_cpu(entry->e_value_size);
174 
175         if (entry->e_value_block != 0 || value_size > size ||
176             le16_to_cpu(entry->e_value_offs) + value_size > size)
177                 return -EIO;
178         return 0;
179 }
180 
181 static int
182 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
183                       const char *name, size_t size, int sorted)
184 {
185         struct ext4_xattr_entry *entry;
186         size_t name_len;
187         int cmp = 1;
188 
189         if (name == NULL)
190                 return -EINVAL;
191         name_len = strlen(name);
192         entry = *pentry;
193         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
194                 cmp = name_index - entry->e_name_index;
195                 if (!cmp)
196                         cmp = name_len - entry->e_name_len;
197                 if (!cmp)
198                         cmp = memcmp(name, entry->e_name, name_len);
199                 if (cmp <= 0 && (sorted || cmp == 0))
200                         break;
201         }
202         *pentry = entry;
203         if (!cmp && ext4_xattr_check_entry(entry, size))
204                         return -EIO;
205         return cmp ? -ENODATA : 0;
206 }
207 
208 static int
209 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
210                      void *buffer, size_t buffer_size)
211 {
212         struct buffer_head *bh = NULL;
213         struct ext4_xattr_entry *entry;
214         size_t size;
215         int error;
216 
217         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
218                   name_index, name, buffer, (long)buffer_size);
219 
220         error = -ENODATA;
221         if (!EXT4_I(inode)->i_file_acl)
222                 goto cleanup;
223         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
224         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
225         if (!bh)
226                 goto cleanup;
227         ea_bdebug(bh, "b_count=%d, refcount=%d",
228                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
229         if (ext4_xattr_check_block(bh)) {
230 bad_block:
231                 EXT4_ERROR_INODE(inode, "bad block %llu",
232                                  EXT4_I(inode)->i_file_acl);
233                 error = -EIO;
234                 goto cleanup;
235         }
236         ext4_xattr_cache_insert(bh);
237         entry = BFIRST(bh);
238         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
239         if (error == -EIO)
240                 goto bad_block;
241         if (error)
242                 goto cleanup;
243         size = le32_to_cpu(entry->e_value_size);
244         if (buffer) {
245                 error = -ERANGE;
246                 if (size > buffer_size)
247                         goto cleanup;
248                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
249                        size);
250         }
251         error = size;
252 
253 cleanup:
254         brelse(bh);
255         return error;
256 }
257 
258 static int
259 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
260                      void *buffer, size_t buffer_size)
261 {
262         struct ext4_xattr_ibody_header *header;
263         struct ext4_xattr_entry *entry;
264         struct ext4_inode *raw_inode;
265         struct ext4_iloc iloc;
266         size_t size;
267         void *end;
268         int error;
269 
270         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
271                 return -ENODATA;
272         error = ext4_get_inode_loc(inode, &iloc);
273         if (error)
274                 return error;
275         raw_inode = ext4_raw_inode(&iloc);
276         header = IHDR(inode, raw_inode);
277         entry = IFIRST(header);
278         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
279         error = ext4_xattr_check_names(entry, end);
280         if (error)
281                 goto cleanup;
282         error = ext4_xattr_find_entry(&entry, name_index, name,
283                                       end - (void *)entry, 0);
284         if (error)
285                 goto cleanup;
286         size = le32_to_cpu(entry->e_value_size);
287         if (buffer) {
288                 error = -ERANGE;
289                 if (size > buffer_size)
290                         goto cleanup;
291                 memcpy(buffer, (void *)IFIRST(header) +
292                        le16_to_cpu(entry->e_value_offs), size);
293         }
294         error = size;
295 
296 cleanup:
297         brelse(iloc.bh);
298         return error;
299 }
300 
301 /*
302  * ext4_xattr_get()
303  *
304  * Copy an extended attribute into the buffer
305  * provided, or compute the buffer size required.
306  * Buffer is NULL to compute the size of the buffer required.
307  *
308  * Returns a negative error number on failure, or the number of bytes
309  * used / required on success.
310  */
311 int
312 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
313                void *buffer, size_t buffer_size)
314 {
315         int error;
316 
317         down_read(&EXT4_I(inode)->xattr_sem);
318         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
319                                      buffer_size);
320         if (error == -ENODATA)
321                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
322                                              buffer_size);
323         up_read(&EXT4_I(inode)->xattr_sem);
324         return error;
325 }
326 
327 static int
328 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
329                         char *buffer, size_t buffer_size)
330 {
331         size_t rest = buffer_size;
332 
333         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
334                 const struct xattr_handler *handler =
335                         ext4_xattr_handler(entry->e_name_index);
336 
337                 if (handler) {
338                         size_t size = handler->list(dentry, buffer, rest,
339                                                     entry->e_name,
340                                                     entry->e_name_len,
341                                                     handler->flags);
342                         if (buffer) {
343                                 if (size > rest)
344                                         return -ERANGE;
345                                 buffer += size;
346                         }
347                         rest -= size;
348                 }
349         }
350         return buffer_size - rest;
351 }
352 
353 static int
354 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
355 {
356         struct inode *inode = dentry->d_inode;
357         struct buffer_head *bh = NULL;
358         int error;
359 
360         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
361                   buffer, (long)buffer_size);
362 
363         error = 0;
364         if (!EXT4_I(inode)->i_file_acl)
365                 goto cleanup;
366         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
367         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
368         error = -EIO;
369         if (!bh)
370                 goto cleanup;
371         ea_bdebug(bh, "b_count=%d, refcount=%d",
372                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
373         if (ext4_xattr_check_block(bh)) {
374                 EXT4_ERROR_INODE(inode, "bad block %llu",
375                                  EXT4_I(inode)->i_file_acl);
376                 error = -EIO;
377                 goto cleanup;
378         }
379         ext4_xattr_cache_insert(bh);
380         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
381 
382 cleanup:
383         brelse(bh);
384 
385         return error;
386 }
387 
388 static int
389 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
390 {
391         struct inode *inode = dentry->d_inode;
392         struct ext4_xattr_ibody_header *header;
393         struct ext4_inode *raw_inode;
394         struct ext4_iloc iloc;
395         void *end;
396         int error;
397 
398         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
399                 return 0;
400         error = ext4_get_inode_loc(inode, &iloc);
401         if (error)
402                 return error;
403         raw_inode = ext4_raw_inode(&iloc);
404         header = IHDR(inode, raw_inode);
405         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
406         error = ext4_xattr_check_names(IFIRST(header), end);
407         if (error)
408                 goto cleanup;
409         error = ext4_xattr_list_entries(dentry, IFIRST(header),
410                                         buffer, buffer_size);
411 
412 cleanup:
413         brelse(iloc.bh);
414         return error;
415 }
416 
417 /*
418  * ext4_xattr_list()
419  *
420  * Copy a list of attribute names into the buffer
421  * provided, or compute the buffer size required.
422  * Buffer is NULL to compute the size of the buffer required.
423  *
424  * Returns a negative error number on failure, or the number of bytes
425  * used / required on success.
426  */
427 static int
428 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
429 {
430         int ret, ret2;
431 
432         down_read(&EXT4_I(dentry->d_inode)->xattr_sem);
433         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
434         if (ret < 0)
435                 goto errout;
436         if (buffer) {
437                 buffer += ret;
438                 buffer_size -= ret;
439         }
440         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
441         if (ret < 0)
442                 goto errout;
443         ret += ret2;
444 errout:
445         up_read(&EXT4_I(dentry->d_inode)->xattr_sem);
446         return ret;
447 }
448 
449 /*
450  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
451  * not set, set it.
452  */
453 static void ext4_xattr_update_super_block(handle_t *handle,
454                                           struct super_block *sb)
455 {
456         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
457                 return;
458 
459         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
460                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
461                 ext4_handle_dirty_super(handle, sb);
462         }
463 }
464 
465 /*
466  * Release the xattr block BH: If the reference count is > 1, decrement
467  * it; otherwise free the block.
468  */
469 static void
470 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
471                          struct buffer_head *bh)
472 {
473         struct mb_cache_entry *ce = NULL;
474         int error = 0;
475 
476         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
477         error = ext4_journal_get_write_access(handle, bh);
478         if (error)
479                 goto out;
480 
481         lock_buffer(bh);
482         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
483                 ea_bdebug(bh, "refcount now=0; freeing");
484                 if (ce)
485                         mb_cache_entry_free(ce);
486                 get_bh(bh);
487                 ext4_free_blocks(handle, inode, bh, 0, 1,
488                                  EXT4_FREE_BLOCKS_METADATA |
489                                  EXT4_FREE_BLOCKS_FORGET);
490                 unlock_buffer(bh);
491         } else {
492                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
493                 if (ce)
494                         mb_cache_entry_release(ce);
495                 unlock_buffer(bh);
496                 error = ext4_handle_dirty_metadata(handle, inode, bh);
497                 if (IS_SYNC(inode))
498                         ext4_handle_sync(handle);
499                 dquot_free_block(inode, 1);
500                 ea_bdebug(bh, "refcount now=%d; releasing",
501                           le32_to_cpu(BHDR(bh)->h_refcount));
502         }
503 out:
504         ext4_std_error(inode->i_sb, error);
505         return;
506 }
507 
508 /*
509  * Find the available free space for EAs. This also returns the total number of
510  * bytes used by EA entries.
511  */
512 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
513                                     size_t *min_offs, void *base, int *total)
514 {
515         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
516                 *total += EXT4_XATTR_LEN(last->e_name_len);
517                 if (!last->e_value_block && last->e_value_size) {
518                         size_t offs = le16_to_cpu(last->e_value_offs);
519                         if (offs < *min_offs)
520                                 *min_offs = offs;
521                 }
522         }
523         return (*min_offs - ((void *)last - base) - sizeof(__u32));
524 }
525 
526 struct ext4_xattr_info {
527         int name_index;
528         const char *name;
529         const void *value;
530         size_t value_len;
531 };
532 
533 struct ext4_xattr_search {
534         struct ext4_xattr_entry *first;
535         void *base;
536         void *end;
537         struct ext4_xattr_entry *here;
538         int not_found;
539 };
540 
541 static int
542 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
543 {
544         struct ext4_xattr_entry *last;
545         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
546 
547         /* Compute min_offs and last. */
548         last = s->first;
549         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
550                 if (!last->e_value_block && last->e_value_size) {
551                         size_t offs = le16_to_cpu(last->e_value_offs);
552                         if (offs < min_offs)
553                                 min_offs = offs;
554                 }
555         }
556         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
557         if (!s->not_found) {
558                 if (!s->here->e_value_block && s->here->e_value_size) {
559                         size_t size = le32_to_cpu(s->here->e_value_size);
560                         free += EXT4_XATTR_SIZE(size);
561                 }
562                 free += EXT4_XATTR_LEN(name_len);
563         }
564         if (i->value) {
565                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
566                     free < EXT4_XATTR_LEN(name_len) +
567                            EXT4_XATTR_SIZE(i->value_len))
568                         return -ENOSPC;
569         }
570 
571         if (i->value && s->not_found) {
572                 /* Insert the new name. */
573                 size_t size = EXT4_XATTR_LEN(name_len);
574                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
575                 memmove((void *)s->here + size, s->here, rest);
576                 memset(s->here, 0, size);
577                 s->here->e_name_index = i->name_index;
578                 s->here->e_name_len = name_len;
579                 memcpy(s->here->e_name, i->name, name_len);
580         } else {
581                 if (!s->here->e_value_block && s->here->e_value_size) {
582                         void *first_val = s->base + min_offs;
583                         size_t offs = le16_to_cpu(s->here->e_value_offs);
584                         void *val = s->base + offs;
585                         size_t size = EXT4_XATTR_SIZE(
586                                 le32_to_cpu(s->here->e_value_size));
587 
588                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
589                                 /* The old and the new value have the same
590                                    size. Just replace. */
591                                 s->here->e_value_size =
592                                         cpu_to_le32(i->value_len);
593                                 memset(val + size - EXT4_XATTR_PAD, 0,
594                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
595                                 memcpy(val, i->value, i->value_len);
596                                 return 0;
597                         }
598 
599                         /* Remove the old value. */
600                         memmove(first_val + size, first_val, val - first_val);
601                         memset(first_val, 0, size);
602                         s->here->e_value_size = 0;
603                         s->here->e_value_offs = 0;
604                         min_offs += size;
605 
606                         /* Adjust all value offsets. */
607                         last = s->first;
608                         while (!IS_LAST_ENTRY(last)) {
609                                 size_t o = le16_to_cpu(last->e_value_offs);
610                                 if (!last->e_value_block &&
611                                     last->e_value_size && o < offs)
612                                         last->e_value_offs =
613                                                 cpu_to_le16(o + size);
614                                 last = EXT4_XATTR_NEXT(last);
615                         }
616                 }
617                 if (!i->value) {
618                         /* Remove the old name. */
619                         size_t size = EXT4_XATTR_LEN(name_len);
620                         last = ENTRY((void *)last - size);
621                         memmove(s->here, (void *)s->here + size,
622                                 (void *)last - (void *)s->here + sizeof(__u32));
623                         memset(last, 0, size);
624                 }
625         }
626 
627         if (i->value) {
628                 /* Insert the new value. */
629                 s->here->e_value_size = cpu_to_le32(i->value_len);
630                 if (i->value_len) {
631                         size_t size = EXT4_XATTR_SIZE(i->value_len);
632                         void *val = s->base + min_offs - size;
633                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
634                         memset(val + size - EXT4_XATTR_PAD, 0,
635                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
636                         memcpy(val, i->value, i->value_len);
637                 }
638         }
639         return 0;
640 }
641 
642 struct ext4_xattr_block_find {
643         struct ext4_xattr_search s;
644         struct buffer_head *bh;
645 };
646 
647 static int
648 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
649                       struct ext4_xattr_block_find *bs)
650 {
651         struct super_block *sb = inode->i_sb;
652         int error;
653 
654         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
655                   i->name_index, i->name, i->value, (long)i->value_len);
656 
657         if (EXT4_I(inode)->i_file_acl) {
658                 /* The inode already has an extended attribute block. */
659                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
660                 error = -EIO;
661                 if (!bs->bh)
662                         goto cleanup;
663                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
664                         atomic_read(&(bs->bh->b_count)),
665                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
666                 if (ext4_xattr_check_block(bs->bh)) {
667                         EXT4_ERROR_INODE(inode, "bad block %llu",
668                                          EXT4_I(inode)->i_file_acl);
669                         error = -EIO;
670                         goto cleanup;
671                 }
672                 /* Find the named attribute. */
673                 bs->s.base = BHDR(bs->bh);
674                 bs->s.first = BFIRST(bs->bh);
675                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
676                 bs->s.here = bs->s.first;
677                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
678                                               i->name, bs->bh->b_size, 1);
679                 if (error && error != -ENODATA)
680                         goto cleanup;
681                 bs->s.not_found = error;
682         }
683         error = 0;
684 
685 cleanup:
686         return error;
687 }
688 
689 static int
690 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
691                      struct ext4_xattr_info *i,
692                      struct ext4_xattr_block_find *bs)
693 {
694         struct super_block *sb = inode->i_sb;
695         struct buffer_head *new_bh = NULL;
696         struct ext4_xattr_search *s = &bs->s;
697         struct mb_cache_entry *ce = NULL;
698         int error = 0;
699 
700 #define header(x) ((struct ext4_xattr_header *)(x))
701 
702         if (i->value && i->value_len > sb->s_blocksize)
703                 return -ENOSPC;
704         if (s->base) {
705                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
706                                         bs->bh->b_blocknr);
707                 error = ext4_journal_get_write_access(handle, bs->bh);
708                 if (error)
709                         goto cleanup;
710                 lock_buffer(bs->bh);
711 
712                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
713                         if (ce) {
714                                 mb_cache_entry_free(ce);
715                                 ce = NULL;
716                         }
717                         ea_bdebug(bs->bh, "modifying in-place");
718                         error = ext4_xattr_set_entry(i, s);
719                         if (!error) {
720                                 if (!IS_LAST_ENTRY(s->first))
721                                         ext4_xattr_rehash(header(s->base),
722                                                           s->here);
723                                 ext4_xattr_cache_insert(bs->bh);
724                         }
725                         unlock_buffer(bs->bh);
726                         if (error == -EIO)
727                                 goto bad_block;
728                         if (!error)
729                                 error = ext4_handle_dirty_metadata(handle,
730                                                                    inode,
731                                                                    bs->bh);
732                         if (error)
733                                 goto cleanup;
734                         goto inserted;
735                 } else {
736                         int offset = (char *)s->here - bs->bh->b_data;
737 
738                         unlock_buffer(bs->bh);
739                         ext4_handle_release_buffer(handle, bs->bh);
740                         if (ce) {
741                                 mb_cache_entry_release(ce);
742                                 ce = NULL;
743                         }
744                         ea_bdebug(bs->bh, "cloning");
745                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
746                         error = -ENOMEM;
747                         if (s->base == NULL)
748                                 goto cleanup;
749                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
750                         s->first = ENTRY(header(s->base)+1);
751                         header(s->base)->h_refcount = cpu_to_le32(1);
752                         s->here = ENTRY(s->base + offset);
753                         s->end = s->base + bs->bh->b_size;
754                 }
755         } else {
756                 /* Allocate a buffer where we construct the new block. */
757                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
758                 /* assert(header == s->base) */
759                 error = -ENOMEM;
760                 if (s->base == NULL)
761                         goto cleanup;
762                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
763                 header(s->base)->h_blocks = cpu_to_le32(1);
764                 header(s->base)->h_refcount = cpu_to_le32(1);
765                 s->first = ENTRY(header(s->base)+1);
766                 s->here = ENTRY(header(s->base)+1);
767                 s->end = s->base + sb->s_blocksize;
768         }
769 
770         error = ext4_xattr_set_entry(i, s);
771         if (error == -EIO)
772                 goto bad_block;
773         if (error)
774                 goto cleanup;
775         if (!IS_LAST_ENTRY(s->first))
776                 ext4_xattr_rehash(header(s->base), s->here);
777 
778 inserted:
779         if (!IS_LAST_ENTRY(s->first)) {
780                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
781                 if (new_bh) {
782                         /* We found an identical block in the cache. */
783                         if (new_bh == bs->bh)
784                                 ea_bdebug(new_bh, "keeping");
785                         else {
786                                 /* The old block is released after updating
787                                    the inode. */
788                                 error = dquot_alloc_block(inode, 1);
789                                 if (error)
790                                         goto cleanup;
791                                 error = ext4_journal_get_write_access(handle,
792                                                                       new_bh);
793                                 if (error)
794                                         goto cleanup_dquot;
795                                 lock_buffer(new_bh);
796                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
797                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
798                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
799                                 unlock_buffer(new_bh);
800                                 error = ext4_handle_dirty_metadata(handle,
801                                                                    inode,
802                                                                    new_bh);
803                                 if (error)
804                                         goto cleanup_dquot;
805                         }
806                         mb_cache_entry_release(ce);
807                         ce = NULL;
808                 } else if (bs->bh && s->base == bs->bh->b_data) {
809                         /* We were modifying this block in-place. */
810                         ea_bdebug(bs->bh, "keeping this block");
811                         new_bh = bs->bh;
812                         get_bh(new_bh);
813                 } else {
814                         /* We need to allocate a new block */
815                         ext4_fsblk_t goal, block;
816 
817                         goal = ext4_group_first_block_no(sb,
818                                                 EXT4_I(inode)->i_block_group);
819 
820                         /* non-extent files can't have physical blocks past 2^32 */
821                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
822                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
823 
824                         /*
825                          * take i_data_sem because we will test
826                          * i_delalloc_reserved_flag in ext4_mb_new_blocks
827                          */
828                         down_read((&EXT4_I(inode)->i_data_sem));
829                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
830                                                      NULL, &error);
831                         up_read((&EXT4_I(inode)->i_data_sem));
832                         if (error)
833                                 goto cleanup;
834 
835                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
836                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
837 
838                         ea_idebug(inode, "creating block %d", block);
839 
840                         new_bh = sb_getblk(sb, block);
841                         if (!new_bh) {
842 getblk_failed:
843                                 ext4_free_blocks(handle, inode, NULL, block, 1,
844                                                  EXT4_FREE_BLOCKS_METADATA);
845                                 error = -EIO;
846                                 goto cleanup;
847                         }
848                         lock_buffer(new_bh);
849                         error = ext4_journal_get_create_access(handle, new_bh);
850                         if (error) {
851                                 unlock_buffer(new_bh);
852                                 goto getblk_failed;
853                         }
854                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
855                         set_buffer_uptodate(new_bh);
856                         unlock_buffer(new_bh);
857                         ext4_xattr_cache_insert(new_bh);
858                         error = ext4_handle_dirty_metadata(handle,
859                                                            inode, new_bh);
860                         if (error)
861                                 goto cleanup;
862                 }
863         }
864 
865         /* Update the inode. */
866         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
867 
868         /* Drop the previous xattr block. */
869         if (bs->bh && bs->bh != new_bh)
870                 ext4_xattr_release_block(handle, inode, bs->bh);
871         error = 0;
872 
873 cleanup:
874         if (ce)
875                 mb_cache_entry_release(ce);
876         brelse(new_bh);
877         if (!(bs->bh && s->base == bs->bh->b_data))
878                 kfree(s->base);
879 
880         return error;
881 
882 cleanup_dquot:
883         dquot_free_block(inode, 1);
884         goto cleanup;
885 
886 bad_block:
887         EXT4_ERROR_INODE(inode, "bad block %llu",
888                          EXT4_I(inode)->i_file_acl);
889         goto cleanup;
890 
891 #undef header
892 }
893 
894 struct ext4_xattr_ibody_find {
895         struct ext4_xattr_search s;
896         struct ext4_iloc iloc;
897 };
898 
899 static int
900 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
901                       struct ext4_xattr_ibody_find *is)
902 {
903         struct ext4_xattr_ibody_header *header;
904         struct ext4_inode *raw_inode;
905         int error;
906 
907         if (EXT4_I(inode)->i_extra_isize == 0)
908                 return 0;
909         raw_inode = ext4_raw_inode(&is->iloc);
910         header = IHDR(inode, raw_inode);
911         is->s.base = is->s.first = IFIRST(header);
912         is->s.here = is->s.first;
913         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
914         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
915                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
916                 if (error)
917                         return error;
918                 /* Find the named attribute. */
919                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
920                                               i->name, is->s.end -
921                                               (void *)is->s.base, 0);
922                 if (error && error != -ENODATA)
923                         return error;
924                 is->s.not_found = error;
925         }
926         return 0;
927 }
928 
929 static int
930 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
931                      struct ext4_xattr_info *i,
932                      struct ext4_xattr_ibody_find *is)
933 {
934         struct ext4_xattr_ibody_header *header;
935         struct ext4_xattr_search *s = &is->s;
936         int error;
937 
938         if (EXT4_I(inode)->i_extra_isize == 0)
939                 return -ENOSPC;
940         error = ext4_xattr_set_entry(i, s);
941         if (error)
942                 return error;
943         header = IHDR(inode, ext4_raw_inode(&is->iloc));
944         if (!IS_LAST_ENTRY(s->first)) {
945                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
946                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
947         } else {
948                 header->h_magic = cpu_to_le32(0);
949                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
950         }
951         return 0;
952 }
953 
954 /*
955  * ext4_xattr_set_handle()
956  *
957  * Create, replace or remove an extended attribute for this inode.  Value
958  * is NULL to remove an existing extended attribute, and non-NULL to
959  * either replace an existing extended attribute, or create a new extended
960  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
961  * specify that an extended attribute must exist and must not exist
962  * previous to the call, respectively.
963  *
964  * Returns 0, or a negative error number on failure.
965  */
966 int
967 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
968                       const char *name, const void *value, size_t value_len,
969                       int flags)
970 {
971         struct ext4_xattr_info i = {
972                 .name_index = name_index,
973                 .name = name,
974                 .value = value,
975                 .value_len = value_len,
976 
977         };
978         struct ext4_xattr_ibody_find is = {
979                 .s = { .not_found = -ENODATA, },
980         };
981         struct ext4_xattr_block_find bs = {
982                 .s = { .not_found = -ENODATA, },
983         };
984         unsigned long no_expand;
985         int error;
986 
987         if (!name)
988                 return -EINVAL;
989         if (strlen(name) > 255)
990                 return -ERANGE;
991         down_write(&EXT4_I(inode)->xattr_sem);
992         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
993         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
994 
995         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
996         if (error)
997                 goto cleanup;
998 
999         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1000                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1001                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1002                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1003         }
1004 
1005         error = ext4_xattr_ibody_find(inode, &i, &is);
1006         if (error)
1007                 goto cleanup;
1008         if (is.s.not_found)
1009                 error = ext4_xattr_block_find(inode, &i, &bs);
1010         if (error)
1011                 goto cleanup;
1012         if (is.s.not_found && bs.s.not_found) {
1013                 error = -ENODATA;
1014                 if (flags & XATTR_REPLACE)
1015                         goto cleanup;
1016                 error = 0;
1017                 if (!value)
1018                         goto cleanup;
1019         } else {
1020                 error = -EEXIST;
1021                 if (flags & XATTR_CREATE)
1022                         goto cleanup;
1023         }
1024         if (!value) {
1025                 if (!is.s.not_found)
1026                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1027                 else if (!bs.s.not_found)
1028                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1029         } else {
1030                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1031                 if (!error && !bs.s.not_found) {
1032                         i.value = NULL;
1033                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1034                 } else if (error == -ENOSPC) {
1035                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1036                                 error = ext4_xattr_block_find(inode, &i, &bs);
1037                                 if (error)
1038                                         goto cleanup;
1039                         }
1040                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1041                         if (error)
1042                                 goto cleanup;
1043                         if (!is.s.not_found) {
1044                                 i.value = NULL;
1045                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1046                                                              &is);
1047                         }
1048                 }
1049         }
1050         if (!error) {
1051                 ext4_xattr_update_super_block(handle, inode->i_sb);
1052                 inode->i_ctime = ext4_current_time(inode);
1053                 if (!value)
1054                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1055                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1056                 /*
1057                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1058                  * error != 0.
1059                  */
1060                 is.iloc.bh = NULL;
1061                 if (IS_SYNC(inode))
1062                         ext4_handle_sync(handle);
1063         }
1064 
1065 cleanup:
1066         brelse(is.iloc.bh);
1067         brelse(bs.bh);
1068         if (no_expand == 0)
1069                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1070         up_write(&EXT4_I(inode)->xattr_sem);
1071         return error;
1072 }
1073 
1074 /*
1075  * ext4_xattr_set()
1076  *
1077  * Like ext4_xattr_set_handle, but start from an inode. This extended
1078  * attribute modification is a filesystem transaction by itself.
1079  *
1080  * Returns 0, or a negative error number on failure.
1081  */
1082 int
1083 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1084                const void *value, size_t value_len, int flags)
1085 {
1086         handle_t *handle;
1087         int error, retries = 0;
1088 
1089 retry:
1090         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1091         if (IS_ERR(handle)) {
1092                 error = PTR_ERR(handle);
1093         } else {
1094                 int error2;
1095 
1096                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1097                                               value, value_len, flags);
1098                 error2 = ext4_journal_stop(handle);
1099                 if (error == -ENOSPC &&
1100                     ext4_should_retry_alloc(inode->i_sb, &retries))
1101                         goto retry;
1102                 if (error == 0)
1103                         error = error2;
1104         }
1105 
1106         return error;
1107 }
1108 
1109 /*
1110  * Shift the EA entries in the inode to create space for the increased
1111  * i_extra_isize.
1112  */
1113 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1114                                      int value_offs_shift, void *to,
1115                                      void *from, size_t n, int blocksize)
1116 {
1117         struct ext4_xattr_entry *last = entry;
1118         int new_offs;
1119 
1120         /* Adjust the value offsets of the entries */
1121         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1122                 if (!last->e_value_block && last->e_value_size) {
1123                         new_offs = le16_to_cpu(last->e_value_offs) +
1124                                                         value_offs_shift;
1125                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1126                                  > blocksize);
1127                         last->e_value_offs = cpu_to_le16(new_offs);
1128                 }
1129         }
1130         /* Shift the entries by n bytes */
1131         memmove(to, from, n);
1132 }
1133 
1134 /*
1135  * Expand an inode by new_extra_isize bytes when EAs are present.
1136  * Returns 0 on success or negative error number on failure.
1137  */
1138 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1139                                struct ext4_inode *raw_inode, handle_t *handle)
1140 {
1141         struct ext4_xattr_ibody_header *header;
1142         struct ext4_xattr_entry *entry, *last, *first;
1143         struct buffer_head *bh = NULL;
1144         struct ext4_xattr_ibody_find *is = NULL;
1145         struct ext4_xattr_block_find *bs = NULL;
1146         char *buffer = NULL, *b_entry_name = NULL;
1147         size_t min_offs, free;
1148         int total_ino, total_blk;
1149         void *base, *start, *end;
1150         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1151         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1152 
1153         down_write(&EXT4_I(inode)->xattr_sem);
1154 retry:
1155         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1156                 up_write(&EXT4_I(inode)->xattr_sem);
1157                 return 0;
1158         }
1159 
1160         header = IHDR(inode, raw_inode);
1161         entry = IFIRST(header);
1162 
1163         /*
1164          * Check if enough free space is available in the inode to shift the
1165          * entries ahead by new_extra_isize.
1166          */
1167 
1168         base = start = entry;
1169         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1170         min_offs = end - base;
1171         last = entry;
1172         total_ino = sizeof(struct ext4_xattr_ibody_header);
1173 
1174         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1175         if (free >= new_extra_isize) {
1176                 entry = IFIRST(header);
1177                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1178                                 - new_extra_isize, (void *)raw_inode +
1179                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1180                                 (void *)header, total_ino,
1181                                 inode->i_sb->s_blocksize);
1182                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1183                 error = 0;
1184                 goto cleanup;
1185         }
1186 
1187         /*
1188          * Enough free space isn't available in the inode, check if
1189          * EA block can hold new_extra_isize bytes.
1190          */
1191         if (EXT4_I(inode)->i_file_acl) {
1192                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1193                 error = -EIO;
1194                 if (!bh)
1195                         goto cleanup;
1196                 if (ext4_xattr_check_block(bh)) {
1197                         EXT4_ERROR_INODE(inode, "bad block %llu",
1198                                          EXT4_I(inode)->i_file_acl);
1199                         error = -EIO;
1200                         goto cleanup;
1201                 }
1202                 base = BHDR(bh);
1203                 first = BFIRST(bh);
1204                 end = bh->b_data + bh->b_size;
1205                 min_offs = end - base;
1206                 free = ext4_xattr_free_space(first, &min_offs, base,
1207                                              &total_blk);
1208                 if (free < new_extra_isize) {
1209                         if (!tried_min_extra_isize && s_min_extra_isize) {
1210                                 tried_min_extra_isize++;
1211                                 new_extra_isize = s_min_extra_isize;
1212                                 brelse(bh);
1213                                 goto retry;
1214                         }
1215                         error = -1;
1216                         goto cleanup;
1217                 }
1218         } else {
1219                 free = inode->i_sb->s_blocksize;
1220         }
1221 
1222         while (new_extra_isize > 0) {
1223                 size_t offs, size, entry_size;
1224                 struct ext4_xattr_entry *small_entry = NULL;
1225                 struct ext4_xattr_info i = {
1226                         .value = NULL,
1227                         .value_len = 0,
1228                 };
1229                 unsigned int total_size;  /* EA entry size + value size */
1230                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1231                 unsigned int min_total_size = ~0U;
1232 
1233                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1234                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1235                 if (!is || !bs) {
1236                         error = -ENOMEM;
1237                         goto cleanup;
1238                 }
1239 
1240                 is->s.not_found = -ENODATA;
1241                 bs->s.not_found = -ENODATA;
1242                 is->iloc.bh = NULL;
1243                 bs->bh = NULL;
1244 
1245                 last = IFIRST(header);
1246                 /* Find the entry best suited to be pushed into EA block */
1247                 entry = NULL;
1248                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1249                         total_size =
1250                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1251                                         EXT4_XATTR_LEN(last->e_name_len);
1252                         if (total_size <= free && total_size < min_total_size) {
1253                                 if (total_size < new_extra_isize) {
1254                                         small_entry = last;
1255                                 } else {
1256                                         entry = last;
1257                                         min_total_size = total_size;
1258                                 }
1259                         }
1260                 }
1261 
1262                 if (entry == NULL) {
1263                         if (small_entry) {
1264                                 entry = small_entry;
1265                         } else {
1266                                 if (!tried_min_extra_isize &&
1267                                     s_min_extra_isize) {
1268                                         tried_min_extra_isize++;
1269                                         new_extra_isize = s_min_extra_isize;
1270                                         goto retry;
1271                                 }
1272                                 error = -1;
1273                                 goto cleanup;
1274                         }
1275                 }
1276                 offs = le16_to_cpu(entry->e_value_offs);
1277                 size = le32_to_cpu(entry->e_value_size);
1278                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1279                 i.name_index = entry->e_name_index,
1280                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1281                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1282                 if (!buffer || !b_entry_name) {
1283                         error = -ENOMEM;
1284                         goto cleanup;
1285                 }
1286                 /* Save the entry name and the entry value */
1287                 memcpy(buffer, (void *)IFIRST(header) + offs,
1288                        EXT4_XATTR_SIZE(size));
1289                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1290                 b_entry_name[entry->e_name_len] = '\0';
1291                 i.name = b_entry_name;
1292 
1293                 error = ext4_get_inode_loc(inode, &is->iloc);
1294                 if (error)
1295                         goto cleanup;
1296 
1297                 error = ext4_xattr_ibody_find(inode, &i, is);
1298                 if (error)
1299                         goto cleanup;
1300 
1301                 /* Remove the chosen entry from the inode */
1302                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1303                 if (error)
1304                         goto cleanup;
1305 
1306                 entry = IFIRST(header);
1307                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1308                         shift_bytes = new_extra_isize;
1309                 else
1310                         shift_bytes = entry_size + size;
1311                 /* Adjust the offsets and shift the remaining entries ahead */
1312                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1313                         shift_bytes, (void *)raw_inode +
1314                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1315                         (void *)header, total_ino - entry_size,
1316                         inode->i_sb->s_blocksize);
1317 
1318                 extra_isize += shift_bytes;
1319                 new_extra_isize -= shift_bytes;
1320                 EXT4_I(inode)->i_extra_isize = extra_isize;
1321 
1322                 i.name = b_entry_name;
1323                 i.value = buffer;
1324                 i.value_len = size;
1325                 error = ext4_xattr_block_find(inode, &i, bs);
1326                 if (error)
1327                         goto cleanup;
1328 
1329                 /* Add entry which was removed from the inode into the block */
1330                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1331                 if (error)
1332                         goto cleanup;
1333                 kfree(b_entry_name);
1334                 kfree(buffer);
1335                 b_entry_name = NULL;
1336                 buffer = NULL;
1337                 brelse(is->iloc.bh);
1338                 kfree(is);
1339                 kfree(bs);
1340         }
1341         brelse(bh);
1342         up_write(&EXT4_I(inode)->xattr_sem);
1343         return 0;
1344 
1345 cleanup:
1346         kfree(b_entry_name);
1347         kfree(buffer);
1348         if (is)
1349                 brelse(is->iloc.bh);
1350         kfree(is);
1351         kfree(bs);
1352         brelse(bh);
1353         up_write(&EXT4_I(inode)->xattr_sem);
1354         return error;
1355 }
1356 
1357 
1358 
1359 /*
1360  * ext4_xattr_delete_inode()
1361  *
1362  * Free extended attribute resources associated with this inode. This
1363  * is called immediately before an inode is freed. We have exclusive
1364  * access to the inode.
1365  */
1366 void
1367 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1368 {
1369         struct buffer_head *bh = NULL;
1370 
1371         if (!EXT4_I(inode)->i_file_acl)
1372                 goto cleanup;
1373         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1374         if (!bh) {
1375                 EXT4_ERROR_INODE(inode, "block %llu read error",
1376                                  EXT4_I(inode)->i_file_acl);
1377                 goto cleanup;
1378         }
1379         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1380             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1381                 EXT4_ERROR_INODE(inode, "bad block %llu",
1382                                  EXT4_I(inode)->i_file_acl);
1383                 goto cleanup;
1384         }
1385         ext4_xattr_release_block(handle, inode, bh);
1386         EXT4_I(inode)->i_file_acl = 0;
1387 
1388 cleanup:
1389         brelse(bh);
1390 }
1391 
1392 /*
1393  * ext4_xattr_put_super()
1394  *
1395  * This is called when a file system is unmounted.
1396  */
1397 void
1398 ext4_xattr_put_super(struct super_block *sb)
1399 {
1400         mb_cache_shrink(sb->s_bdev);
1401 }
1402 
1403 /*
1404  * ext4_xattr_cache_insert()
1405  *
1406  * Create a new entry in the extended attribute cache, and insert
1407  * it unless such an entry is already in the cache.
1408  *
1409  * Returns 0, or a negative error number on failure.
1410  */
1411 static void
1412 ext4_xattr_cache_insert(struct buffer_head *bh)
1413 {
1414         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1415         struct mb_cache_entry *ce;
1416         int error;
1417 
1418         ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);
1419         if (!ce) {
1420                 ea_bdebug(bh, "out of memory");
1421                 return;
1422         }
1423         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1424         if (error) {
1425                 mb_cache_entry_free(ce);
1426                 if (error == -EBUSY) {
1427                         ea_bdebug(bh, "already in cache");
1428                         error = 0;
1429                 }
1430         } else {
1431                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1432                 mb_cache_entry_release(ce);
1433         }
1434 }
1435 
1436 /*
1437  * ext4_xattr_cmp()
1438  *
1439  * Compare two extended attribute blocks for equality.
1440  *
1441  * Returns 0 if the blocks are equal, 1 if they differ, and
1442  * a negative error number on errors.
1443  */
1444 static int
1445 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1446                struct ext4_xattr_header *header2)
1447 {
1448         struct ext4_xattr_entry *entry1, *entry2;
1449 
1450         entry1 = ENTRY(header1+1);
1451         entry2 = ENTRY(header2+1);
1452         while (!IS_LAST_ENTRY(entry1)) {
1453                 if (IS_LAST_ENTRY(entry2))
1454                         return 1;
1455                 if (entry1->e_hash != entry2->e_hash ||
1456                     entry1->e_name_index != entry2->e_name_index ||
1457                     entry1->e_name_len != entry2->e_name_len ||
1458                     entry1->e_value_size != entry2->e_value_size ||
1459                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1460                         return 1;
1461                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1462                         return -EIO;
1463                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1464                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1465                            le32_to_cpu(entry1->e_value_size)))
1466                         return 1;
1467 
1468                 entry1 = EXT4_XATTR_NEXT(entry1);
1469                 entry2 = EXT4_XATTR_NEXT(entry2);
1470         }
1471         if (!IS_LAST_ENTRY(entry2))
1472                 return 1;
1473         return 0;
1474 }
1475 
1476 /*
1477  * ext4_xattr_cache_find()
1478  *
1479  * Find an identical extended attribute block.
1480  *
1481  * Returns a pointer to the block found, or NULL if such a block was
1482  * not found or an error occurred.
1483  */
1484 static struct buffer_head *
1485 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1486                       struct mb_cache_entry **pce)
1487 {
1488         __u32 hash = le32_to_cpu(header->h_hash);
1489         struct mb_cache_entry *ce;
1490 
1491         if (!header->h_hash)
1492                 return NULL;  /* never share */
1493         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1494 again:
1495         ce = mb_cache_entry_find_first(ext4_xattr_cache, inode->i_sb->s_bdev,
1496                                        hash);
1497         while (ce) {
1498                 struct buffer_head *bh;
1499 
1500                 if (IS_ERR(ce)) {
1501                         if (PTR_ERR(ce) == -EAGAIN)
1502                                 goto again;
1503                         break;
1504                 }
1505                 bh = sb_bread(inode->i_sb, ce->e_block);
1506                 if (!bh) {
1507                         EXT4_ERROR_INODE(inode, "block %lu read error",
1508                                          (unsigned long) ce->e_block);
1509                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1510                                 EXT4_XATTR_REFCOUNT_MAX) {
1511                         ea_idebug(inode, "block %lu refcount %d>=%d",
1512                                   (unsigned long) ce->e_block,
1513                                   le32_to_cpu(BHDR(bh)->h_refcount),
1514                                           EXT4_XATTR_REFCOUNT_MAX);
1515                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1516                         *pce = ce;
1517                         return bh;
1518                 }
1519                 brelse(bh);
1520                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1521         }
1522         return NULL;
1523 }
1524 
1525 #define NAME_HASH_SHIFT 5
1526 #define VALUE_HASH_SHIFT 16
1527 
1528 /*
1529  * ext4_xattr_hash_entry()
1530  *
1531  * Compute the hash of an extended attribute.
1532  */
1533 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1534                                          struct ext4_xattr_entry *entry)
1535 {
1536         __u32 hash = 0;
1537         char *name = entry->e_name;
1538         int n;
1539 
1540         for (n = 0; n < entry->e_name_len; n++) {
1541                 hash = (hash << NAME_HASH_SHIFT) ^
1542                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1543                        *name++;
1544         }
1545 
1546         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1547                 __le32 *value = (__le32 *)((char *)header +
1548                         le16_to_cpu(entry->e_value_offs));
1549                 for (n = (le32_to_cpu(entry->e_value_size) +
1550                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1551                         hash = (hash << VALUE_HASH_SHIFT) ^
1552                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1553                                le32_to_cpu(*value++);
1554                 }
1555         }
1556         entry->e_hash = cpu_to_le32(hash);
1557 }
1558 
1559 #undef NAME_HASH_SHIFT
1560 #undef VALUE_HASH_SHIFT
1561 
1562 #define BLOCK_HASH_SHIFT 16
1563 
1564 /*
1565  * ext4_xattr_rehash()
1566  *
1567  * Re-compute the extended attribute hash value after an entry has changed.
1568  */
1569 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1570                               struct ext4_xattr_entry *entry)
1571 {
1572         struct ext4_xattr_entry *here;
1573         __u32 hash = 0;
1574 
1575         ext4_xattr_hash_entry(header, entry);
1576         here = ENTRY(header+1);
1577         while (!IS_LAST_ENTRY(here)) {
1578                 if (!here->e_hash) {
1579                         /* Block is not shared if an entry's hash value == 0 */
1580                         hash = 0;
1581                         break;
1582                 }
1583                 hash = (hash << BLOCK_HASH_SHIFT) ^
1584                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1585                        le32_to_cpu(here->e_hash);
1586                 here = EXT4_XATTR_NEXT(here);
1587         }
1588         header->h_hash = cpu_to_le32(hash);
1589 }
1590 
1591 #undef BLOCK_HASH_SHIFT
1592 
1593 int __init
1594 ext4_init_xattr(void)
1595 {
1596         ext4_xattr_cache = mb_cache_create("ext4_xattr", 6);
1597         if (!ext4_xattr_cache)
1598                 return -ENOMEM;
1599         return 0;
1600 }
1601 
1602 void
1603 ext4_exit_xattr(void)
1604 {
1605         if (ext4_xattr_cache)
1606                 mb_cache_destroy(ext4_xattr_cache);
1607         ext4_xattr_cache = NULL;
1608 }
1609 

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