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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 "ext4_jbd2.h"
 59 #include "ext4.h"
 60 #include "xattr.h"
 61 #include "acl.h"
 62 
 63 #ifdef EXT4_XATTR_DEBUG
 64 # define ea_idebug(inode, f...) do { \
 65                 printk(KERN_DEBUG "inode %s:%lu: ", \
 66                         inode->i_sb->s_id, inode->i_ino); \
 67                 printk(f); \
 68                 printk("\n"); \
 69         } while (0)
 70 # define ea_bdebug(bh, f...) do { \
 71                 char b[BDEVNAME_SIZE]; \
 72                 printk(KERN_DEBUG "block %s:%lu: ", \
 73                         bdevname(bh->b_bdev, b), \
 74                         (unsigned long) bh->b_blocknr); \
 75                 printk(f); \
 76                 printk("\n"); \
 77         } while (0)
 78 #else
 79 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
 80 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
 81 #endif
 82 
 83 static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
 84 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
 85                                                  struct ext4_xattr_header *,
 86                                                  struct mb_cache_entry **);
 87 static void ext4_xattr_rehash(struct ext4_xattr_header *,
 88                               struct ext4_xattr_entry *);
 89 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
 90                            size_t buffer_size);
 91 
 92 static const struct xattr_handler *ext4_xattr_handler_map[] = {
 93         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
 94 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 95         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
 96         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
 97 #endif
 98         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
 99 #ifdef CONFIG_EXT4_FS_SECURITY
100         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
101 #endif
102 };
103 
104 const struct xattr_handler *ext4_xattr_handlers[] = {
105         &ext4_xattr_user_handler,
106         &ext4_xattr_trusted_handler,
107 #ifdef CONFIG_EXT4_FS_POSIX_ACL
108         &posix_acl_access_xattr_handler,
109         &posix_acl_default_xattr_handler,
110 #endif
111 #ifdef CONFIG_EXT4_FS_SECURITY
112         &ext4_xattr_security_handler,
113 #endif
114         NULL
115 };
116 
117 #define EXT4_GET_MB_CACHE(inode)        (((struct ext4_sb_info *) \
118                                 inode->i_sb->s_fs_info)->s_mb_cache)
119 
120 static __le32 ext4_xattr_block_csum(struct inode *inode,
121                                     sector_t block_nr,
122                                     struct ext4_xattr_header *hdr)
123 {
124         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
125         __u32 csum;
126         __le32 save_csum;
127         __le64 dsk_block_nr = cpu_to_le64(block_nr);
128 
129         save_csum = hdr->h_checksum;
130         hdr->h_checksum = 0;
131         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
132                            sizeof(dsk_block_nr));
133         csum = ext4_chksum(sbi, csum, (__u8 *)hdr,
134                            EXT4_BLOCK_SIZE(inode->i_sb));
135 
136         hdr->h_checksum = save_csum;
137         return cpu_to_le32(csum);
138 }
139 
140 static int ext4_xattr_block_csum_verify(struct inode *inode,
141                                         sector_t block_nr,
142                                         struct ext4_xattr_header *hdr)
143 {
144         if (ext4_has_metadata_csum(inode->i_sb) &&
145             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
146                 return 0;
147         return 1;
148 }
149 
150 static void ext4_xattr_block_csum_set(struct inode *inode,
151                                       sector_t block_nr,
152                                       struct ext4_xattr_header *hdr)
153 {
154         if (!ext4_has_metadata_csum(inode->i_sb))
155                 return;
156 
157         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
158 }
159 
160 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
161                                                 struct inode *inode,
162                                                 struct buffer_head *bh)
163 {
164         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
165         return ext4_handle_dirty_metadata(handle, inode, bh);
166 }
167 
168 static inline const struct xattr_handler *
169 ext4_xattr_handler(int name_index)
170 {
171         const struct xattr_handler *handler = NULL;
172 
173         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
174                 handler = ext4_xattr_handler_map[name_index];
175         return handler;
176 }
177 
178 /*
179  * Inode operation listxattr()
180  *
181  * d_inode(dentry)->i_mutex: don't care
182  */
183 ssize_t
184 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
185 {
186         return ext4_xattr_list(dentry, buffer, size);
187 }
188 
189 static int
190 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
191                        void *value_start)
192 {
193         struct ext4_xattr_entry *e = entry;
194 
195         while (!IS_LAST_ENTRY(e)) {
196                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
197                 if ((void *)next >= end)
198                         return -EIO;
199                 e = next;
200         }
201 
202         while (!IS_LAST_ENTRY(entry)) {
203                 if (entry->e_value_size != 0 &&
204                     (value_start + le16_to_cpu(entry->e_value_offs) <
205                      (void *)e + sizeof(__u32) ||
206                      value_start + le16_to_cpu(entry->e_value_offs) +
207                     le32_to_cpu(entry->e_value_size) > end))
208                         return -EIO;
209                 entry = EXT4_XATTR_NEXT(entry);
210         }
211 
212         return 0;
213 }
214 
215 static inline int
216 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
217 {
218         int error;
219 
220         if (buffer_verified(bh))
221                 return 0;
222 
223         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
224             BHDR(bh)->h_blocks != cpu_to_le32(1))
225                 return -EIO;
226         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
227                 return -EIO;
228         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
229                                        bh->b_data);
230         if (!error)
231                 set_buffer_verified(bh);
232         return error;
233 }
234 
235 static inline int
236 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
237 {
238         size_t value_size = le32_to_cpu(entry->e_value_size);
239 
240         if (entry->e_value_block != 0 || value_size > size ||
241             le16_to_cpu(entry->e_value_offs) + value_size > size)
242                 return -EIO;
243         return 0;
244 }
245 
246 static int
247 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
248                       const char *name, size_t size, int sorted)
249 {
250         struct ext4_xattr_entry *entry;
251         size_t name_len;
252         int cmp = 1;
253 
254         if (name == NULL)
255                 return -EINVAL;
256         name_len = strlen(name);
257         entry = *pentry;
258         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
259                 cmp = name_index - entry->e_name_index;
260                 if (!cmp)
261                         cmp = name_len - entry->e_name_len;
262                 if (!cmp)
263                         cmp = memcmp(name, entry->e_name, name_len);
264                 if (cmp <= 0 && (sorted || cmp == 0))
265                         break;
266         }
267         *pentry = entry;
268         if (!cmp && ext4_xattr_check_entry(entry, size))
269                         return -EIO;
270         return cmp ? -ENODATA : 0;
271 }
272 
273 static int
274 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
275                      void *buffer, size_t buffer_size)
276 {
277         struct buffer_head *bh = NULL;
278         struct ext4_xattr_entry *entry;
279         size_t size;
280         int error;
281         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
282 
283         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
284                   name_index, name, buffer, (long)buffer_size);
285 
286         error = -ENODATA;
287         if (!EXT4_I(inode)->i_file_acl)
288                 goto cleanup;
289         ea_idebug(inode, "reading block %llu",
290                   (unsigned long long)EXT4_I(inode)->i_file_acl);
291         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
292         if (!bh)
293                 goto cleanup;
294         ea_bdebug(bh, "b_count=%d, refcount=%d",
295                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
296         if (ext4_xattr_check_block(inode, bh)) {
297 bad_block:
298                 EXT4_ERROR_INODE(inode, "bad block %llu",
299                                  EXT4_I(inode)->i_file_acl);
300                 error = -EIO;
301                 goto cleanup;
302         }
303         ext4_xattr_cache_insert(ext4_mb_cache, bh);
304         entry = BFIRST(bh);
305         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
306         if (error == -EIO)
307                 goto bad_block;
308         if (error)
309                 goto cleanup;
310         size = le32_to_cpu(entry->e_value_size);
311         if (buffer) {
312                 error = -ERANGE;
313                 if (size > buffer_size)
314                         goto cleanup;
315                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
316                        size);
317         }
318         error = size;
319 
320 cleanup:
321         brelse(bh);
322         return error;
323 }
324 
325 int
326 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
327                      void *buffer, size_t buffer_size)
328 {
329         struct ext4_xattr_ibody_header *header;
330         struct ext4_xattr_entry *entry;
331         struct ext4_inode *raw_inode;
332         struct ext4_iloc iloc;
333         size_t size;
334         void *end;
335         int error;
336 
337         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
338                 return -ENODATA;
339         error = ext4_get_inode_loc(inode, &iloc);
340         if (error)
341                 return error;
342         raw_inode = ext4_raw_inode(&iloc);
343         header = IHDR(inode, raw_inode);
344         entry = IFIRST(header);
345         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
346         error = ext4_xattr_check_names(entry, end, entry);
347         if (error)
348                 goto cleanup;
349         error = ext4_xattr_find_entry(&entry, name_index, name,
350                                       end - (void *)entry, 0);
351         if (error)
352                 goto cleanup;
353         size = le32_to_cpu(entry->e_value_size);
354         if (buffer) {
355                 error = -ERANGE;
356                 if (size > buffer_size)
357                         goto cleanup;
358                 memcpy(buffer, (void *)IFIRST(header) +
359                        le16_to_cpu(entry->e_value_offs), size);
360         }
361         error = size;
362 
363 cleanup:
364         brelse(iloc.bh);
365         return error;
366 }
367 
368 /*
369  * ext4_xattr_get()
370  *
371  * Copy an extended attribute into the buffer
372  * provided, or compute the buffer size required.
373  * Buffer is NULL to compute the size of the buffer required.
374  *
375  * Returns a negative error number on failure, or the number of bytes
376  * used / required on success.
377  */
378 int
379 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
380                void *buffer, size_t buffer_size)
381 {
382         int error;
383 
384         if (strlen(name) > 255)
385                 return -ERANGE;
386 
387         down_read(&EXT4_I(inode)->xattr_sem);
388         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
389                                      buffer_size);
390         if (error == -ENODATA)
391                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
392                                              buffer_size);
393         up_read(&EXT4_I(inode)->xattr_sem);
394         return error;
395 }
396 
397 static int
398 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
399                         char *buffer, size_t buffer_size)
400 {
401         size_t rest = buffer_size;
402 
403         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
404                 const struct xattr_handler *handler =
405                         ext4_xattr_handler(entry->e_name_index);
406 
407                 if (handler) {
408                         size_t size = handler->list(dentry, buffer, rest,
409                                                     entry->e_name,
410                                                     entry->e_name_len,
411                                                     handler->flags);
412                         if (buffer) {
413                                 if (size > rest)
414                                         return -ERANGE;
415                                 buffer += size;
416                         }
417                         rest -= size;
418                 }
419         }
420         return buffer_size - rest;
421 }
422 
423 static int
424 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
425 {
426         struct inode *inode = d_inode(dentry);
427         struct buffer_head *bh = NULL;
428         int error;
429         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
430 
431         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
432                   buffer, (long)buffer_size);
433 
434         error = 0;
435         if (!EXT4_I(inode)->i_file_acl)
436                 goto cleanup;
437         ea_idebug(inode, "reading block %llu",
438                   (unsigned long long)EXT4_I(inode)->i_file_acl);
439         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
440         error = -EIO;
441         if (!bh)
442                 goto cleanup;
443         ea_bdebug(bh, "b_count=%d, refcount=%d",
444                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
445         if (ext4_xattr_check_block(inode, bh)) {
446                 EXT4_ERROR_INODE(inode, "bad block %llu",
447                                  EXT4_I(inode)->i_file_acl);
448                 error = -EIO;
449                 goto cleanup;
450         }
451         ext4_xattr_cache_insert(ext4_mb_cache, bh);
452         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
453 
454 cleanup:
455         brelse(bh);
456 
457         return error;
458 }
459 
460 static int
461 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
462 {
463         struct inode *inode = d_inode(dentry);
464         struct ext4_xattr_ibody_header *header;
465         struct ext4_inode *raw_inode;
466         struct ext4_iloc iloc;
467         void *end;
468         int error;
469 
470         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
471                 return 0;
472         error = ext4_get_inode_loc(inode, &iloc);
473         if (error)
474                 return error;
475         raw_inode = ext4_raw_inode(&iloc);
476         header = IHDR(inode, raw_inode);
477         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
478         error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
479         if (error)
480                 goto cleanup;
481         error = ext4_xattr_list_entries(dentry, IFIRST(header),
482                                         buffer, buffer_size);
483 
484 cleanup:
485         brelse(iloc.bh);
486         return error;
487 }
488 
489 /*
490  * ext4_xattr_list()
491  *
492  * Copy a list of attribute names into the buffer
493  * provided, or compute the buffer size required.
494  * Buffer is NULL to compute the size of the buffer required.
495  *
496  * Returns a negative error number on failure, or the number of bytes
497  * used / required on success.
498  */
499 static int
500 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
501 {
502         int ret, ret2;
503 
504         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
505         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
506         if (ret < 0)
507                 goto errout;
508         if (buffer) {
509                 buffer += ret;
510                 buffer_size -= ret;
511         }
512         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
513         if (ret < 0)
514                 goto errout;
515         ret += ret2;
516 errout:
517         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
518         return ret;
519 }
520 
521 /*
522  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
523  * not set, set it.
524  */
525 static void ext4_xattr_update_super_block(handle_t *handle,
526                                           struct super_block *sb)
527 {
528         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
529                 return;
530 
531         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
532         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
533                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
534                 ext4_handle_dirty_super(handle, sb);
535         }
536 }
537 
538 /*
539  * Release the xattr block BH: If the reference count is > 1, decrement it;
540  * otherwise free the block.
541  */
542 static void
543 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
544                          struct buffer_head *bh)
545 {
546         struct mb_cache_entry *ce = NULL;
547         int error = 0;
548         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
549 
550         ce = mb_cache_entry_get(ext4_mb_cache, bh->b_bdev, bh->b_blocknr);
551         BUFFER_TRACE(bh, "get_write_access");
552         error = ext4_journal_get_write_access(handle, bh);
553         if (error)
554                 goto out;
555 
556         lock_buffer(bh);
557         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
558                 ea_bdebug(bh, "refcount now=0; freeing");
559                 if (ce)
560                         mb_cache_entry_free(ce);
561                 get_bh(bh);
562                 unlock_buffer(bh);
563                 ext4_free_blocks(handle, inode, bh, 0, 1,
564                                  EXT4_FREE_BLOCKS_METADATA |
565                                  EXT4_FREE_BLOCKS_FORGET);
566         } else {
567                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
568                 if (ce)
569                         mb_cache_entry_release(ce);
570                 /*
571                  * Beware of this ugliness: Releasing of xattr block references
572                  * from different inodes can race and so we have to protect
573                  * from a race where someone else frees the block (and releases
574                  * its journal_head) before we are done dirtying the buffer. In
575                  * nojournal mode this race is harmless and we actually cannot
576                  * call ext4_handle_dirty_xattr_block() with locked buffer as
577                  * that function can call sync_dirty_buffer() so for that case
578                  * we handle the dirtying after unlocking the buffer.
579                  */
580                 if (ext4_handle_valid(handle))
581                         error = ext4_handle_dirty_xattr_block(handle, inode,
582                                                               bh);
583                 unlock_buffer(bh);
584                 if (!ext4_handle_valid(handle))
585                         error = ext4_handle_dirty_xattr_block(handle, inode,
586                                                               bh);
587                 if (IS_SYNC(inode))
588                         ext4_handle_sync(handle);
589                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
590                 ea_bdebug(bh, "refcount now=%d; releasing",
591                           le32_to_cpu(BHDR(bh)->h_refcount));
592         }
593 out:
594         ext4_std_error(inode->i_sb, error);
595         return;
596 }
597 
598 /*
599  * Find the available free space for EAs. This also returns the total number of
600  * bytes used by EA entries.
601  */
602 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
603                                     size_t *min_offs, void *base, int *total)
604 {
605         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
606                 if (!last->e_value_block && last->e_value_size) {
607                         size_t offs = le16_to_cpu(last->e_value_offs);
608                         if (offs < *min_offs)
609                                 *min_offs = offs;
610                 }
611                 if (total)
612                         *total += EXT4_XATTR_LEN(last->e_name_len);
613         }
614         return (*min_offs - ((void *)last - base) - sizeof(__u32));
615 }
616 
617 static int
618 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
619 {
620         struct ext4_xattr_entry *last;
621         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
622 
623         /* Compute min_offs and last. */
624         last = s->first;
625         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
626                 if (!last->e_value_block && last->e_value_size) {
627                         size_t offs = le16_to_cpu(last->e_value_offs);
628                         if (offs < min_offs)
629                                 min_offs = offs;
630                 }
631         }
632         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
633         if (!s->not_found) {
634                 if (!s->here->e_value_block && s->here->e_value_size) {
635                         size_t size = le32_to_cpu(s->here->e_value_size);
636                         free += EXT4_XATTR_SIZE(size);
637                 }
638                 free += EXT4_XATTR_LEN(name_len);
639         }
640         if (i->value) {
641                 if (free < EXT4_XATTR_LEN(name_len) +
642                            EXT4_XATTR_SIZE(i->value_len))
643                         return -ENOSPC;
644         }
645 
646         if (i->value && s->not_found) {
647                 /* Insert the new name. */
648                 size_t size = EXT4_XATTR_LEN(name_len);
649                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
650                 memmove((void *)s->here + size, s->here, rest);
651                 memset(s->here, 0, size);
652                 s->here->e_name_index = i->name_index;
653                 s->here->e_name_len = name_len;
654                 memcpy(s->here->e_name, i->name, name_len);
655         } else {
656                 if (!s->here->e_value_block && s->here->e_value_size) {
657                         void *first_val = s->base + min_offs;
658                         size_t offs = le16_to_cpu(s->here->e_value_offs);
659                         void *val = s->base + offs;
660                         size_t size = EXT4_XATTR_SIZE(
661                                 le32_to_cpu(s->here->e_value_size));
662 
663                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
664                                 /* The old and the new value have the same
665                                    size. Just replace. */
666                                 s->here->e_value_size =
667                                         cpu_to_le32(i->value_len);
668                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
669                                         memset(val, 0, size);
670                                 } else {
671                                         /* Clear pad bytes first. */
672                                         memset(val + size - EXT4_XATTR_PAD, 0,
673                                                EXT4_XATTR_PAD);
674                                         memcpy(val, i->value, i->value_len);
675                                 }
676                                 return 0;
677                         }
678 
679                         /* Remove the old value. */
680                         memmove(first_val + size, first_val, val - first_val);
681                         memset(first_val, 0, size);
682                         s->here->e_value_size = 0;
683                         s->here->e_value_offs = 0;
684                         min_offs += size;
685 
686                         /* Adjust all value offsets. */
687                         last = s->first;
688                         while (!IS_LAST_ENTRY(last)) {
689                                 size_t o = le16_to_cpu(last->e_value_offs);
690                                 if (!last->e_value_block &&
691                                     last->e_value_size && o < offs)
692                                         last->e_value_offs =
693                                                 cpu_to_le16(o + size);
694                                 last = EXT4_XATTR_NEXT(last);
695                         }
696                 }
697                 if (!i->value) {
698                         /* Remove the old name. */
699                         size_t size = EXT4_XATTR_LEN(name_len);
700                         last = ENTRY((void *)last - size);
701                         memmove(s->here, (void *)s->here + size,
702                                 (void *)last - (void *)s->here + sizeof(__u32));
703                         memset(last, 0, size);
704                 }
705         }
706 
707         if (i->value) {
708                 /* Insert the new value. */
709                 s->here->e_value_size = cpu_to_le32(i->value_len);
710                 if (i->value_len) {
711                         size_t size = EXT4_XATTR_SIZE(i->value_len);
712                         void *val = s->base + min_offs - size;
713                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
714                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
715                                 memset(val, 0, size);
716                         } else {
717                                 /* Clear the pad bytes first. */
718                                 memset(val + size - EXT4_XATTR_PAD, 0,
719                                        EXT4_XATTR_PAD);
720                                 memcpy(val, i->value, i->value_len);
721                         }
722                 }
723         }
724         return 0;
725 }
726 
727 struct ext4_xattr_block_find {
728         struct ext4_xattr_search s;
729         struct buffer_head *bh;
730 };
731 
732 static int
733 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
734                       struct ext4_xattr_block_find *bs)
735 {
736         struct super_block *sb = inode->i_sb;
737         int error;
738 
739         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
740                   i->name_index, i->name, i->value, (long)i->value_len);
741 
742         if (EXT4_I(inode)->i_file_acl) {
743                 /* The inode already has an extended attribute block. */
744                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
745                 error = -EIO;
746                 if (!bs->bh)
747                         goto cleanup;
748                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
749                         atomic_read(&(bs->bh->b_count)),
750                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
751                 if (ext4_xattr_check_block(inode, bs->bh)) {
752                         EXT4_ERROR_INODE(inode, "bad block %llu",
753                                          EXT4_I(inode)->i_file_acl);
754                         error = -EIO;
755                         goto cleanup;
756                 }
757                 /* Find the named attribute. */
758                 bs->s.base = BHDR(bs->bh);
759                 bs->s.first = BFIRST(bs->bh);
760                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
761                 bs->s.here = bs->s.first;
762                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
763                                               i->name, bs->bh->b_size, 1);
764                 if (error && error != -ENODATA)
765                         goto cleanup;
766                 bs->s.not_found = error;
767         }
768         error = 0;
769 
770 cleanup:
771         return error;
772 }
773 
774 static int
775 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
776                      struct ext4_xattr_info *i,
777                      struct ext4_xattr_block_find *bs)
778 {
779         struct super_block *sb = inode->i_sb;
780         struct buffer_head *new_bh = NULL;
781         struct ext4_xattr_search *s = &bs->s;
782         struct mb_cache_entry *ce = NULL;
783         int error = 0;
784         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
785 
786 #define header(x) ((struct ext4_xattr_header *)(x))
787 
788         if (i->value && i->value_len > sb->s_blocksize)
789                 return -ENOSPC;
790         if (s->base) {
791                 ce = mb_cache_entry_get(ext4_mb_cache, bs->bh->b_bdev,
792                                         bs->bh->b_blocknr);
793                 BUFFER_TRACE(bs->bh, "get_write_access");
794                 error = ext4_journal_get_write_access(handle, bs->bh);
795                 if (error)
796                         goto cleanup;
797                 lock_buffer(bs->bh);
798 
799                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
800                         if (ce) {
801                                 mb_cache_entry_free(ce);
802                                 ce = NULL;
803                         }
804                         ea_bdebug(bs->bh, "modifying in-place");
805                         error = ext4_xattr_set_entry(i, s);
806                         if (!error) {
807                                 if (!IS_LAST_ENTRY(s->first))
808                                         ext4_xattr_rehash(header(s->base),
809                                                           s->here);
810                                 ext4_xattr_cache_insert(ext4_mb_cache,
811                                         bs->bh);
812                         }
813                         unlock_buffer(bs->bh);
814                         if (error == -EIO)
815                                 goto bad_block;
816                         if (!error)
817                                 error = ext4_handle_dirty_xattr_block(handle,
818                                                                       inode,
819                                                                       bs->bh);
820                         if (error)
821                                 goto cleanup;
822                         goto inserted;
823                 } else {
824                         int offset = (char *)s->here - bs->bh->b_data;
825 
826                         unlock_buffer(bs->bh);
827                         if (ce) {
828                                 mb_cache_entry_release(ce);
829                                 ce = NULL;
830                         }
831                         ea_bdebug(bs->bh, "cloning");
832                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
833                         error = -ENOMEM;
834                         if (s->base == NULL)
835                                 goto cleanup;
836                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
837                         s->first = ENTRY(header(s->base)+1);
838                         header(s->base)->h_refcount = cpu_to_le32(1);
839                         s->here = ENTRY(s->base + offset);
840                         s->end = s->base + bs->bh->b_size;
841                 }
842         } else {
843                 /* Allocate a buffer where we construct the new block. */
844                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
845                 /* assert(header == s->base) */
846                 error = -ENOMEM;
847                 if (s->base == NULL)
848                         goto cleanup;
849                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
850                 header(s->base)->h_blocks = cpu_to_le32(1);
851                 header(s->base)->h_refcount = cpu_to_le32(1);
852                 s->first = ENTRY(header(s->base)+1);
853                 s->here = ENTRY(header(s->base)+1);
854                 s->end = s->base + sb->s_blocksize;
855         }
856 
857         error = ext4_xattr_set_entry(i, s);
858         if (error == -EIO)
859                 goto bad_block;
860         if (error)
861                 goto cleanup;
862         if (!IS_LAST_ENTRY(s->first))
863                 ext4_xattr_rehash(header(s->base), s->here);
864 
865 inserted:
866         if (!IS_LAST_ENTRY(s->first)) {
867                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
868                 if (new_bh) {
869                         /* We found an identical block in the cache. */
870                         if (new_bh == bs->bh)
871                                 ea_bdebug(new_bh, "keeping");
872                         else {
873                                 /* The old block is released after updating
874                                    the inode. */
875                                 error = dquot_alloc_block(inode,
876                                                 EXT4_C2B(EXT4_SB(sb), 1));
877                                 if (error)
878                                         goto cleanup;
879                                 BUFFER_TRACE(new_bh, "get_write_access");
880                                 error = ext4_journal_get_write_access(handle,
881                                                                       new_bh);
882                                 if (error)
883                                         goto cleanup_dquot;
884                                 lock_buffer(new_bh);
885                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
886                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
887                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
888                                 unlock_buffer(new_bh);
889                                 error = ext4_handle_dirty_xattr_block(handle,
890                                                                       inode,
891                                                                       new_bh);
892                                 if (error)
893                                         goto cleanup_dquot;
894                         }
895                         mb_cache_entry_release(ce);
896                         ce = NULL;
897                 } else if (bs->bh && s->base == bs->bh->b_data) {
898                         /* We were modifying this block in-place. */
899                         ea_bdebug(bs->bh, "keeping this block");
900                         new_bh = bs->bh;
901                         get_bh(new_bh);
902                 } else {
903                         /* We need to allocate a new block */
904                         ext4_fsblk_t goal, block;
905 
906                         goal = ext4_group_first_block_no(sb,
907                                                 EXT4_I(inode)->i_block_group);
908 
909                         /* non-extent files can't have physical blocks past 2^32 */
910                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
911                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
912 
913                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
914                                                      NULL, &error);
915                         if (error)
916                                 goto cleanup;
917 
918                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
919                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
920 
921                         ea_idebug(inode, "creating block %llu",
922                                   (unsigned long long)block);
923 
924                         new_bh = sb_getblk(sb, block);
925                         if (unlikely(!new_bh)) {
926                                 error = -ENOMEM;
927 getblk_failed:
928                                 ext4_free_blocks(handle, inode, NULL, block, 1,
929                                                  EXT4_FREE_BLOCKS_METADATA);
930                                 goto cleanup;
931                         }
932                         lock_buffer(new_bh);
933                         error = ext4_journal_get_create_access(handle, new_bh);
934                         if (error) {
935                                 unlock_buffer(new_bh);
936                                 error = -EIO;
937                                 goto getblk_failed;
938                         }
939                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
940                         set_buffer_uptodate(new_bh);
941                         unlock_buffer(new_bh);
942                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
943                         error = ext4_handle_dirty_xattr_block(handle,
944                                                               inode, new_bh);
945                         if (error)
946                                 goto cleanup;
947                 }
948         }
949 
950         /* Update the inode. */
951         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
952 
953         /* Drop the previous xattr block. */
954         if (bs->bh && bs->bh != new_bh)
955                 ext4_xattr_release_block(handle, inode, bs->bh);
956         error = 0;
957 
958 cleanup:
959         if (ce)
960                 mb_cache_entry_release(ce);
961         brelse(new_bh);
962         if (!(bs->bh && s->base == bs->bh->b_data))
963                 kfree(s->base);
964 
965         return error;
966 
967 cleanup_dquot:
968         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
969         goto cleanup;
970 
971 bad_block:
972         EXT4_ERROR_INODE(inode, "bad block %llu",
973                          EXT4_I(inode)->i_file_acl);
974         goto cleanup;
975 
976 #undef header
977 }
978 
979 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
980                           struct ext4_xattr_ibody_find *is)
981 {
982         struct ext4_xattr_ibody_header *header;
983         struct ext4_inode *raw_inode;
984         int error;
985 
986         if (EXT4_I(inode)->i_extra_isize == 0)
987                 return 0;
988         raw_inode = ext4_raw_inode(&is->iloc);
989         header = IHDR(inode, raw_inode);
990         is->s.base = is->s.first = IFIRST(header);
991         is->s.here = is->s.first;
992         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
993         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
994                 error = ext4_xattr_check_names(IFIRST(header), is->s.end,
995                                                IFIRST(header));
996                 if (error)
997                         return error;
998                 /* Find the named attribute. */
999                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
1000                                               i->name, is->s.end -
1001                                               (void *)is->s.base, 0);
1002                 if (error && error != -ENODATA)
1003                         return error;
1004                 is->s.not_found = error;
1005         }
1006         return 0;
1007 }
1008 
1009 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1010                                 struct ext4_xattr_info *i,
1011                                 struct ext4_xattr_ibody_find *is)
1012 {
1013         struct ext4_xattr_ibody_header *header;
1014         struct ext4_xattr_search *s = &is->s;
1015         int error;
1016 
1017         if (EXT4_I(inode)->i_extra_isize == 0)
1018                 return -ENOSPC;
1019         error = ext4_xattr_set_entry(i, s);
1020         if (error) {
1021                 if (error == -ENOSPC &&
1022                     ext4_has_inline_data(inode)) {
1023                         error = ext4_try_to_evict_inline_data(handle, inode,
1024                                         EXT4_XATTR_LEN(strlen(i->name) +
1025                                         EXT4_XATTR_SIZE(i->value_len)));
1026                         if (error)
1027                                 return error;
1028                         error = ext4_xattr_ibody_find(inode, i, is);
1029                         if (error)
1030                                 return error;
1031                         error = ext4_xattr_set_entry(i, s);
1032                 }
1033                 if (error)
1034                         return error;
1035         }
1036         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1037         if (!IS_LAST_ENTRY(s->first)) {
1038                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1039                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1040         } else {
1041                 header->h_magic = cpu_to_le32(0);
1042                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1043         }
1044         return 0;
1045 }
1046 
1047 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
1048                                 struct ext4_xattr_info *i,
1049                                 struct ext4_xattr_ibody_find *is)
1050 {
1051         struct ext4_xattr_ibody_header *header;
1052         struct ext4_xattr_search *s = &is->s;
1053         int error;
1054 
1055         if (EXT4_I(inode)->i_extra_isize == 0)
1056                 return -ENOSPC;
1057         error = ext4_xattr_set_entry(i, s);
1058         if (error)
1059                 return error;
1060         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1061         if (!IS_LAST_ENTRY(s->first)) {
1062                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1063                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1064         } else {
1065                 header->h_magic = cpu_to_le32(0);
1066                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1067         }
1068         return 0;
1069 }
1070 
1071 /*
1072  * ext4_xattr_set_handle()
1073  *
1074  * Create, replace or remove an extended attribute for this inode.  Value
1075  * is NULL to remove an existing extended attribute, and non-NULL to
1076  * either replace an existing extended attribute, or create a new extended
1077  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1078  * specify that an extended attribute must exist and must not exist
1079  * previous to the call, respectively.
1080  *
1081  * Returns 0, or a negative error number on failure.
1082  */
1083 int
1084 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1085                       const char *name, const void *value, size_t value_len,
1086                       int flags)
1087 {
1088         struct ext4_xattr_info i = {
1089                 .name_index = name_index,
1090                 .name = name,
1091                 .value = value,
1092                 .value_len = value_len,
1093 
1094         };
1095         struct ext4_xattr_ibody_find is = {
1096                 .s = { .not_found = -ENODATA, },
1097         };
1098         struct ext4_xattr_block_find bs = {
1099                 .s = { .not_found = -ENODATA, },
1100         };
1101         unsigned long no_expand;
1102         int error;
1103 
1104         if (!name)
1105                 return -EINVAL;
1106         if (strlen(name) > 255)
1107                 return -ERANGE;
1108         down_write(&EXT4_I(inode)->xattr_sem);
1109         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1110         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1111 
1112         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1113         if (error)
1114                 goto cleanup;
1115 
1116         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1117                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1118                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1119                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1120         }
1121 
1122         error = ext4_xattr_ibody_find(inode, &i, &is);
1123         if (error)
1124                 goto cleanup;
1125         if (is.s.not_found)
1126                 error = ext4_xattr_block_find(inode, &i, &bs);
1127         if (error)
1128                 goto cleanup;
1129         if (is.s.not_found && bs.s.not_found) {
1130                 error = -ENODATA;
1131                 if (flags & XATTR_REPLACE)
1132                         goto cleanup;
1133                 error = 0;
1134                 if (!value)
1135                         goto cleanup;
1136         } else {
1137                 error = -EEXIST;
1138                 if (flags & XATTR_CREATE)
1139                         goto cleanup;
1140         }
1141         if (!value) {
1142                 if (!is.s.not_found)
1143                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1144                 else if (!bs.s.not_found)
1145                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1146         } else {
1147                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1148                 if (!error && !bs.s.not_found) {
1149                         i.value = NULL;
1150                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1151                 } else if (error == -ENOSPC) {
1152                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1153                                 error = ext4_xattr_block_find(inode, &i, &bs);
1154                                 if (error)
1155                                         goto cleanup;
1156                         }
1157                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1158                         if (error)
1159                                 goto cleanup;
1160                         if (!is.s.not_found) {
1161                                 i.value = NULL;
1162                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1163                                                              &is);
1164                         }
1165                 }
1166         }
1167         if (!error) {
1168                 ext4_xattr_update_super_block(handle, inode->i_sb);
1169                 inode->i_ctime = ext4_current_time(inode);
1170                 if (!value)
1171                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1172                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1173                 /*
1174                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1175                  * error != 0.
1176                  */
1177                 is.iloc.bh = NULL;
1178                 if (IS_SYNC(inode))
1179                         ext4_handle_sync(handle);
1180         }
1181 
1182 cleanup:
1183         brelse(is.iloc.bh);
1184         brelse(bs.bh);
1185         if (no_expand == 0)
1186                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1187         up_write(&EXT4_I(inode)->xattr_sem);
1188         return error;
1189 }
1190 
1191 /*
1192  * ext4_xattr_set()
1193  *
1194  * Like ext4_xattr_set_handle, but start from an inode. This extended
1195  * attribute modification is a filesystem transaction by itself.
1196  *
1197  * Returns 0, or a negative error number on failure.
1198  */
1199 int
1200 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1201                const void *value, size_t value_len, int flags)
1202 {
1203         handle_t *handle;
1204         int error, retries = 0;
1205         int credits = ext4_jbd2_credits_xattr(inode);
1206 
1207 retry:
1208         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1209         if (IS_ERR(handle)) {
1210                 error = PTR_ERR(handle);
1211         } else {
1212                 int error2;
1213 
1214                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1215                                               value, value_len, flags);
1216                 error2 = ext4_journal_stop(handle);
1217                 if (error == -ENOSPC &&
1218                     ext4_should_retry_alloc(inode->i_sb, &retries))
1219                         goto retry;
1220                 if (error == 0)
1221                         error = error2;
1222         }
1223 
1224         return error;
1225 }
1226 
1227 /*
1228  * Shift the EA entries in the inode to create space for the increased
1229  * i_extra_isize.
1230  */
1231 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1232                                      int value_offs_shift, void *to,
1233                                      void *from, size_t n, int blocksize)
1234 {
1235         struct ext4_xattr_entry *last = entry;
1236         int new_offs;
1237 
1238         /* Adjust the value offsets of the entries */
1239         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1240                 if (!last->e_value_block && last->e_value_size) {
1241                         new_offs = le16_to_cpu(last->e_value_offs) +
1242                                                         value_offs_shift;
1243                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1244                                  > blocksize);
1245                         last->e_value_offs = cpu_to_le16(new_offs);
1246                 }
1247         }
1248         /* Shift the entries by n bytes */
1249         memmove(to, from, n);
1250 }
1251 
1252 /*
1253  * Expand an inode by new_extra_isize bytes when EAs are present.
1254  * Returns 0 on success or negative error number on failure.
1255  */
1256 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1257                                struct ext4_inode *raw_inode, handle_t *handle)
1258 {
1259         struct ext4_xattr_ibody_header *header;
1260         struct ext4_xattr_entry *entry, *last, *first;
1261         struct buffer_head *bh = NULL;
1262         struct ext4_xattr_ibody_find *is = NULL;
1263         struct ext4_xattr_block_find *bs = NULL;
1264         char *buffer = NULL, *b_entry_name = NULL;
1265         size_t min_offs, free;
1266         int total_ino;
1267         void *base, *start, *end;
1268         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1269         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1270 
1271         down_write(&EXT4_I(inode)->xattr_sem);
1272 retry:
1273         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1274                 up_write(&EXT4_I(inode)->xattr_sem);
1275                 return 0;
1276         }
1277 
1278         header = IHDR(inode, raw_inode);
1279         entry = IFIRST(header);
1280 
1281         /*
1282          * Check if enough free space is available in the inode to shift the
1283          * entries ahead by new_extra_isize.
1284          */
1285 
1286         base = start = entry;
1287         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1288         min_offs = end - base;
1289         last = entry;
1290         total_ino = sizeof(struct ext4_xattr_ibody_header);
1291 
1292         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1293         if (free >= new_extra_isize) {
1294                 entry = IFIRST(header);
1295                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1296                                 - new_extra_isize, (void *)raw_inode +
1297                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1298                                 (void *)header, total_ino,
1299                                 inode->i_sb->s_blocksize);
1300                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1301                 error = 0;
1302                 goto cleanup;
1303         }
1304 
1305         /*
1306          * Enough free space isn't available in the inode, check if
1307          * EA block can hold new_extra_isize bytes.
1308          */
1309         if (EXT4_I(inode)->i_file_acl) {
1310                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1311                 error = -EIO;
1312                 if (!bh)
1313                         goto cleanup;
1314                 if (ext4_xattr_check_block(inode, bh)) {
1315                         EXT4_ERROR_INODE(inode, "bad block %llu",
1316                                          EXT4_I(inode)->i_file_acl);
1317                         error = -EIO;
1318                         goto cleanup;
1319                 }
1320                 base = BHDR(bh);
1321                 first = BFIRST(bh);
1322                 end = bh->b_data + bh->b_size;
1323                 min_offs = end - base;
1324                 free = ext4_xattr_free_space(first, &min_offs, base, NULL);
1325                 if (free < new_extra_isize) {
1326                         if (!tried_min_extra_isize && s_min_extra_isize) {
1327                                 tried_min_extra_isize++;
1328                                 new_extra_isize = s_min_extra_isize;
1329                                 brelse(bh);
1330                                 goto retry;
1331                         }
1332                         error = -1;
1333                         goto cleanup;
1334                 }
1335         } else {
1336                 free = inode->i_sb->s_blocksize;
1337         }
1338 
1339         while (new_extra_isize > 0) {
1340                 size_t offs, size, entry_size;
1341                 struct ext4_xattr_entry *small_entry = NULL;
1342                 struct ext4_xattr_info i = {
1343                         .value = NULL,
1344                         .value_len = 0,
1345                 };
1346                 unsigned int total_size;  /* EA entry size + value size */
1347                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1348                 unsigned int min_total_size = ~0U;
1349 
1350                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1351                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1352                 if (!is || !bs) {
1353                         error = -ENOMEM;
1354                         goto cleanup;
1355                 }
1356 
1357                 is->s.not_found = -ENODATA;
1358                 bs->s.not_found = -ENODATA;
1359                 is->iloc.bh = NULL;
1360                 bs->bh = NULL;
1361 
1362                 last = IFIRST(header);
1363                 /* Find the entry best suited to be pushed into EA block */
1364                 entry = NULL;
1365                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1366                         total_size =
1367                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1368                                         EXT4_XATTR_LEN(last->e_name_len);
1369                         if (total_size <= free && total_size < min_total_size) {
1370                                 if (total_size < new_extra_isize) {
1371                                         small_entry = last;
1372                                 } else {
1373                                         entry = last;
1374                                         min_total_size = total_size;
1375                                 }
1376                         }
1377                 }
1378 
1379                 if (entry == NULL) {
1380                         if (small_entry) {
1381                                 entry = small_entry;
1382                         } else {
1383                                 if (!tried_min_extra_isize &&
1384                                     s_min_extra_isize) {
1385                                         tried_min_extra_isize++;
1386                                         new_extra_isize = s_min_extra_isize;
1387                                         kfree(is); is = NULL;
1388                                         kfree(bs); bs = NULL;
1389                                         brelse(bh);
1390                                         goto retry;
1391                                 }
1392                                 error = -1;
1393                                 goto cleanup;
1394                         }
1395                 }
1396                 offs = le16_to_cpu(entry->e_value_offs);
1397                 size = le32_to_cpu(entry->e_value_size);
1398                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1399                 i.name_index = entry->e_name_index,
1400                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1401                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1402                 if (!buffer || !b_entry_name) {
1403                         error = -ENOMEM;
1404                         goto cleanup;
1405                 }
1406                 /* Save the entry name and the entry value */
1407                 memcpy(buffer, (void *)IFIRST(header) + offs,
1408                        EXT4_XATTR_SIZE(size));
1409                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1410                 b_entry_name[entry->e_name_len] = '\0';
1411                 i.name = b_entry_name;
1412 
1413                 error = ext4_get_inode_loc(inode, &is->iloc);
1414                 if (error)
1415                         goto cleanup;
1416 
1417                 error = ext4_xattr_ibody_find(inode, &i, is);
1418                 if (error)
1419                         goto cleanup;
1420 
1421                 /* Remove the chosen entry from the inode */
1422                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1423                 if (error)
1424                         goto cleanup;
1425 
1426                 entry = IFIRST(header);
1427                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1428                         shift_bytes = new_extra_isize;
1429                 else
1430                         shift_bytes = entry_size + size;
1431                 /* Adjust the offsets and shift the remaining entries ahead */
1432                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1433                         shift_bytes, (void *)raw_inode +
1434                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1435                         (void *)header, total_ino - entry_size,
1436                         inode->i_sb->s_blocksize);
1437 
1438                 extra_isize += shift_bytes;
1439                 new_extra_isize -= shift_bytes;
1440                 EXT4_I(inode)->i_extra_isize = extra_isize;
1441 
1442                 i.name = b_entry_name;
1443                 i.value = buffer;
1444                 i.value_len = size;
1445                 error = ext4_xattr_block_find(inode, &i, bs);
1446                 if (error)
1447                         goto cleanup;
1448 
1449                 /* Add entry which was removed from the inode into the block */
1450                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1451                 if (error)
1452                         goto cleanup;
1453                 kfree(b_entry_name);
1454                 kfree(buffer);
1455                 b_entry_name = NULL;
1456                 buffer = NULL;
1457                 brelse(is->iloc.bh);
1458                 kfree(is);
1459                 kfree(bs);
1460         }
1461         brelse(bh);
1462         up_write(&EXT4_I(inode)->xattr_sem);
1463         return 0;
1464 
1465 cleanup:
1466         kfree(b_entry_name);
1467         kfree(buffer);
1468         if (is)
1469                 brelse(is->iloc.bh);
1470         kfree(is);
1471         kfree(bs);
1472         brelse(bh);
1473         up_write(&EXT4_I(inode)->xattr_sem);
1474         return error;
1475 }
1476 
1477 
1478 
1479 /*
1480  * ext4_xattr_delete_inode()
1481  *
1482  * Free extended attribute resources associated with this inode. This
1483  * is called immediately before an inode is freed. We have exclusive
1484  * access to the inode.
1485  */
1486 void
1487 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1488 {
1489         struct buffer_head *bh = NULL;
1490 
1491         if (!EXT4_I(inode)->i_file_acl)
1492                 goto cleanup;
1493         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1494         if (!bh) {
1495                 EXT4_ERROR_INODE(inode, "block %llu read error",
1496                                  EXT4_I(inode)->i_file_acl);
1497                 goto cleanup;
1498         }
1499         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1500             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1501                 EXT4_ERROR_INODE(inode, "bad block %llu",
1502                                  EXT4_I(inode)->i_file_acl);
1503                 goto cleanup;
1504         }
1505         ext4_xattr_release_block(handle, inode, bh);
1506         EXT4_I(inode)->i_file_acl = 0;
1507 
1508 cleanup:
1509         brelse(bh);
1510 }
1511 
1512 /*
1513  * ext4_xattr_put_super()
1514  *
1515  * This is called when a file system is unmounted.
1516  */
1517 void
1518 ext4_xattr_put_super(struct super_block *sb)
1519 {
1520         mb_cache_shrink(sb->s_bdev);
1521 }
1522 
1523 /*
1524  * ext4_xattr_cache_insert()
1525  *
1526  * Create a new entry in the extended attribute cache, and insert
1527  * it unless such an entry is already in the cache.
1528  *
1529  * Returns 0, or a negative error number on failure.
1530  */
1531 static void
1532 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1533 {
1534         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1535         struct mb_cache_entry *ce;
1536         int error;
1537 
1538         ce = mb_cache_entry_alloc(ext4_mb_cache, GFP_NOFS);
1539         if (!ce) {
1540                 ea_bdebug(bh, "out of memory");
1541                 return;
1542         }
1543         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1544         if (error) {
1545                 mb_cache_entry_free(ce);
1546                 if (error == -EBUSY) {
1547                         ea_bdebug(bh, "already in cache");
1548                         error = 0;
1549                 }
1550         } else {
1551                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1552                 mb_cache_entry_release(ce);
1553         }
1554 }
1555 
1556 /*
1557  * ext4_xattr_cmp()
1558  *
1559  * Compare two extended attribute blocks for equality.
1560  *
1561  * Returns 0 if the blocks are equal, 1 if they differ, and
1562  * a negative error number on errors.
1563  */
1564 static int
1565 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1566                struct ext4_xattr_header *header2)
1567 {
1568         struct ext4_xattr_entry *entry1, *entry2;
1569 
1570         entry1 = ENTRY(header1+1);
1571         entry2 = ENTRY(header2+1);
1572         while (!IS_LAST_ENTRY(entry1)) {
1573                 if (IS_LAST_ENTRY(entry2))
1574                         return 1;
1575                 if (entry1->e_hash != entry2->e_hash ||
1576                     entry1->e_name_index != entry2->e_name_index ||
1577                     entry1->e_name_len != entry2->e_name_len ||
1578                     entry1->e_value_size != entry2->e_value_size ||
1579                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1580                         return 1;
1581                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1582                         return -EIO;
1583                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1584                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1585                            le32_to_cpu(entry1->e_value_size)))
1586                         return 1;
1587 
1588                 entry1 = EXT4_XATTR_NEXT(entry1);
1589                 entry2 = EXT4_XATTR_NEXT(entry2);
1590         }
1591         if (!IS_LAST_ENTRY(entry2))
1592                 return 1;
1593         return 0;
1594 }
1595 
1596 /*
1597  * ext4_xattr_cache_find()
1598  *
1599  * Find an identical extended attribute block.
1600  *
1601  * Returns a pointer to the block found, or NULL if such a block was
1602  * not found or an error occurred.
1603  */
1604 static struct buffer_head *
1605 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1606                       struct mb_cache_entry **pce)
1607 {
1608         __u32 hash = le32_to_cpu(header->h_hash);
1609         struct mb_cache_entry *ce;
1610         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1611 
1612         if (!header->h_hash)
1613                 return NULL;  /* never share */
1614         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1615 again:
1616         ce = mb_cache_entry_find_first(ext4_mb_cache, inode->i_sb->s_bdev,
1617                                        hash);
1618         while (ce) {
1619                 struct buffer_head *bh;
1620 
1621                 if (IS_ERR(ce)) {
1622                         if (PTR_ERR(ce) == -EAGAIN)
1623                                 goto again;
1624                         break;
1625                 }
1626                 bh = sb_bread(inode->i_sb, ce->e_block);
1627                 if (!bh) {
1628                         EXT4_ERROR_INODE(inode, "block %lu read error",
1629                                          (unsigned long) ce->e_block);
1630                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1631                                 EXT4_XATTR_REFCOUNT_MAX) {
1632                         ea_idebug(inode, "block %lu refcount %d>=%d",
1633                                   (unsigned long) ce->e_block,
1634                                   le32_to_cpu(BHDR(bh)->h_refcount),
1635                                           EXT4_XATTR_REFCOUNT_MAX);
1636                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1637                         *pce = ce;
1638                         return bh;
1639                 }
1640                 brelse(bh);
1641                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1642         }
1643         return NULL;
1644 }
1645 
1646 #define NAME_HASH_SHIFT 5
1647 #define VALUE_HASH_SHIFT 16
1648 
1649 /*
1650  * ext4_xattr_hash_entry()
1651  *
1652  * Compute the hash of an extended attribute.
1653  */
1654 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1655                                          struct ext4_xattr_entry *entry)
1656 {
1657         __u32 hash = 0;
1658         char *name = entry->e_name;
1659         int n;
1660 
1661         for (n = 0; n < entry->e_name_len; n++) {
1662                 hash = (hash << NAME_HASH_SHIFT) ^
1663                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1664                        *name++;
1665         }
1666 
1667         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1668                 __le32 *value = (__le32 *)((char *)header +
1669                         le16_to_cpu(entry->e_value_offs));
1670                 for (n = (le32_to_cpu(entry->e_value_size) +
1671                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1672                         hash = (hash << VALUE_HASH_SHIFT) ^
1673                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1674                                le32_to_cpu(*value++);
1675                 }
1676         }
1677         entry->e_hash = cpu_to_le32(hash);
1678 }
1679 
1680 #undef NAME_HASH_SHIFT
1681 #undef VALUE_HASH_SHIFT
1682 
1683 #define BLOCK_HASH_SHIFT 16
1684 
1685 /*
1686  * ext4_xattr_rehash()
1687  *
1688  * Re-compute the extended attribute hash value after an entry has changed.
1689  */
1690 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1691                               struct ext4_xattr_entry *entry)
1692 {
1693         struct ext4_xattr_entry *here;
1694         __u32 hash = 0;
1695 
1696         ext4_xattr_hash_entry(header, entry);
1697         here = ENTRY(header+1);
1698         while (!IS_LAST_ENTRY(here)) {
1699                 if (!here->e_hash) {
1700                         /* Block is not shared if an entry's hash value == 0 */
1701                         hash = 0;
1702                         break;
1703                 }
1704                 hash = (hash << BLOCK_HASH_SHIFT) ^
1705                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1706                        le32_to_cpu(here->e_hash);
1707                 here = EXT4_XATTR_NEXT(here);
1708         }
1709         header->h_hash = cpu_to_le32(hash);
1710 }
1711 
1712 #undef BLOCK_HASH_SHIFT
1713 
1714 #define HASH_BUCKET_BITS        10
1715 
1716 struct mb_cache *
1717 ext4_xattr_create_cache(char *name)
1718 {
1719         return mb_cache_create(name, HASH_BUCKET_BITS);
1720 }
1721 
1722 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1723 {
1724         if (cache)
1725                 mb_cache_destroy(cache);
1726 }
1727 
1728 

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