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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                 printk(KERN_DEBUG "block %pg:%lu: ",               \
 72                        bh->b_bdev, (unsigned long) bh->b_blocknr); \
 73                 printk(f); \
 74                 printk("\n"); \
 75         } while (0)
 76 #else
 77 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
 78 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
 79 #endif
 80 
 81 static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
 82 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
 83                                                  struct ext4_xattr_header *,
 84                                                  struct mb_cache_entry **);
 85 static void ext4_xattr_rehash(struct ext4_xattr_header *,
 86                               struct ext4_xattr_entry *);
 87 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
 88                            size_t buffer_size);
 89 
 90 static const struct xattr_handler *ext4_xattr_handler_map[] = {
 91         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
 92 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 93         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
 94         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
 95 #endif
 96         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
 97 #ifdef CONFIG_EXT4_FS_SECURITY
 98         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 99 #endif
100 };
101 
102 const struct xattr_handler *ext4_xattr_handlers[] = {
103         &ext4_xattr_user_handler,
104         &ext4_xattr_trusted_handler,
105 #ifdef CONFIG_EXT4_FS_POSIX_ACL
106         &posix_acl_access_xattr_handler,
107         &posix_acl_default_xattr_handler,
108 #endif
109 #ifdef CONFIG_EXT4_FS_SECURITY
110         &ext4_xattr_security_handler,
111 #endif
112         NULL
113 };
114 
115 #define EXT4_GET_MB_CACHE(inode)        (((struct ext4_sb_info *) \
116                                 inode->i_sb->s_fs_info)->s_mb_cache)
117 
118 static __le32 ext4_xattr_block_csum(struct inode *inode,
119                                     sector_t block_nr,
120                                     struct ext4_xattr_header *hdr)
121 {
122         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
123         __u32 csum;
124         __le64 dsk_block_nr = cpu_to_le64(block_nr);
125         __u32 dummy_csum = 0;
126         int offset = offsetof(struct ext4_xattr_header, h_checksum);
127 
128         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
129                            sizeof(dsk_block_nr));
130         csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset);
131         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
132         offset += sizeof(dummy_csum);
133         csum = ext4_chksum(sbi, csum, (__u8 *)hdr + offset,
134                            EXT4_BLOCK_SIZE(inode->i_sb) - offset);
135 
136         return cpu_to_le32(csum);
137 }
138 
139 static int ext4_xattr_block_csum_verify(struct inode *inode,
140                                         sector_t block_nr,
141                                         struct ext4_xattr_header *hdr)
142 {
143         if (ext4_has_metadata_csum(inode->i_sb) &&
144             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
145                 return 0;
146         return 1;
147 }
148 
149 static void ext4_xattr_block_csum_set(struct inode *inode,
150                                       sector_t block_nr,
151                                       struct ext4_xattr_header *hdr)
152 {
153         if (!ext4_has_metadata_csum(inode->i_sb))
154                 return;
155 
156         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
157 }
158 
159 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
160                                                 struct inode *inode,
161                                                 struct buffer_head *bh)
162 {
163         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
164         return ext4_handle_dirty_metadata(handle, inode, bh);
165 }
166 
167 static inline const struct xattr_handler *
168 ext4_xattr_handler(int name_index)
169 {
170         const struct xattr_handler *handler = NULL;
171 
172         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
173                 handler = ext4_xattr_handler_map[name_index];
174         return handler;
175 }
176 
177 /*
178  * Inode operation listxattr()
179  *
180  * d_inode(dentry)->i_mutex: don't care
181  */
182 ssize_t
183 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
184 {
185         return ext4_xattr_list(dentry, buffer, size);
186 }
187 
188 static int
189 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
190                        void *value_start)
191 {
192         struct ext4_xattr_entry *e = entry;
193 
194         while (!IS_LAST_ENTRY(e)) {
195                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
196                 if ((void *)next >= end)
197                         return -EFSCORRUPTED;
198                 e = next;
199         }
200 
201         while (!IS_LAST_ENTRY(entry)) {
202                 if (entry->e_value_size != 0 &&
203                     (value_start + le16_to_cpu(entry->e_value_offs) <
204                      (void *)e + sizeof(__u32) ||
205                      value_start + le16_to_cpu(entry->e_value_offs) +
206                     le32_to_cpu(entry->e_value_size) > end))
207                         return -EFSCORRUPTED;
208                 entry = EXT4_XATTR_NEXT(entry);
209         }
210 
211         return 0;
212 }
213 
214 static inline int
215 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
216 {
217         int error;
218 
219         if (buffer_verified(bh))
220                 return 0;
221 
222         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
223             BHDR(bh)->h_blocks != cpu_to_le32(1))
224                 return -EFSCORRUPTED;
225         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
226                 return -EFSBADCRC;
227         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
228                                        bh->b_data);
229         if (!error)
230                 set_buffer_verified(bh);
231         return error;
232 }
233 
234 static int
235 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
236                          void *end, const char *function, unsigned int line)
237 {
238         struct ext4_xattr_entry *entry = IFIRST(header);
239         int error = -EFSCORRUPTED;
240 
241         if (((void *) header >= end) ||
242             (header->h_magic != le32_to_cpu(EXT4_XATTR_MAGIC)))
243                 goto errout;
244         error = ext4_xattr_check_names(entry, end, entry);
245 errout:
246         if (error)
247                 __ext4_error_inode(inode, function, line, 0,
248                                    "corrupted in-inode xattr");
249         return error;
250 }
251 
252 #define xattr_check_inode(inode, header, end) \
253         __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
254 
255 static inline int
256 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
257 {
258         size_t value_size = le32_to_cpu(entry->e_value_size);
259 
260         if (entry->e_value_block != 0 || value_size > size ||
261             le16_to_cpu(entry->e_value_offs) + value_size > size)
262                 return -EFSCORRUPTED;
263         return 0;
264 }
265 
266 static int
267 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
268                       const char *name, size_t size, int sorted)
269 {
270         struct ext4_xattr_entry *entry;
271         size_t name_len;
272         int cmp = 1;
273 
274         if (name == NULL)
275                 return -EINVAL;
276         name_len = strlen(name);
277         entry = *pentry;
278         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
279                 cmp = name_index - entry->e_name_index;
280                 if (!cmp)
281                         cmp = name_len - entry->e_name_len;
282                 if (!cmp)
283                         cmp = memcmp(name, entry->e_name, name_len);
284                 if (cmp <= 0 && (sorted || cmp == 0))
285                         break;
286         }
287         *pentry = entry;
288         if (!cmp && ext4_xattr_check_entry(entry, size))
289                 return -EFSCORRUPTED;
290         return cmp ? -ENODATA : 0;
291 }
292 
293 static int
294 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
295                      void *buffer, size_t buffer_size)
296 {
297         struct buffer_head *bh = NULL;
298         struct ext4_xattr_entry *entry;
299         size_t size;
300         int error;
301         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
302 
303         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
304                   name_index, name, buffer, (long)buffer_size);
305 
306         error = -ENODATA;
307         if (!EXT4_I(inode)->i_file_acl)
308                 goto cleanup;
309         ea_idebug(inode, "reading block %llu",
310                   (unsigned long long)EXT4_I(inode)->i_file_acl);
311         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
312         if (!bh)
313                 goto cleanup;
314         ea_bdebug(bh, "b_count=%d, refcount=%d",
315                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
316         if (ext4_xattr_check_block(inode, bh)) {
317 bad_block:
318                 EXT4_ERROR_INODE(inode, "bad block %llu",
319                                  EXT4_I(inode)->i_file_acl);
320                 error = -EFSCORRUPTED;
321                 goto cleanup;
322         }
323         ext4_xattr_cache_insert(ext4_mb_cache, bh);
324         entry = BFIRST(bh);
325         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
326         if (error == -EFSCORRUPTED)
327                 goto bad_block;
328         if (error)
329                 goto cleanup;
330         size = le32_to_cpu(entry->e_value_size);
331         if (buffer) {
332                 error = -ERANGE;
333                 if (size > buffer_size)
334                         goto cleanup;
335                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
336                        size);
337         }
338         error = size;
339 
340 cleanup:
341         brelse(bh);
342         return error;
343 }
344 
345 int
346 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
347                      void *buffer, size_t buffer_size)
348 {
349         struct ext4_xattr_ibody_header *header;
350         struct ext4_xattr_entry *entry;
351         struct ext4_inode *raw_inode;
352         struct ext4_iloc iloc;
353         size_t size;
354         void *end;
355         int error;
356 
357         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
358                 return -ENODATA;
359         error = ext4_get_inode_loc(inode, &iloc);
360         if (error)
361                 return error;
362         raw_inode = ext4_raw_inode(&iloc);
363         header = IHDR(inode, raw_inode);
364         entry = IFIRST(header);
365         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
366         error = xattr_check_inode(inode, header, end);
367         if (error)
368                 goto cleanup;
369         error = ext4_xattr_find_entry(&entry, name_index, name,
370                                       end - (void *)entry, 0);
371         if (error)
372                 goto cleanup;
373         size = le32_to_cpu(entry->e_value_size);
374         if (buffer) {
375                 error = -ERANGE;
376                 if (size > buffer_size)
377                         goto cleanup;
378                 memcpy(buffer, (void *)IFIRST(header) +
379                        le16_to_cpu(entry->e_value_offs), size);
380         }
381         error = size;
382 
383 cleanup:
384         brelse(iloc.bh);
385         return error;
386 }
387 
388 /*
389  * ext4_xattr_get()
390  *
391  * Copy an extended attribute into the buffer
392  * provided, or compute the buffer size required.
393  * Buffer is NULL to compute the size of the buffer required.
394  *
395  * Returns a negative error number on failure, or the number of bytes
396  * used / required on success.
397  */
398 int
399 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
400                void *buffer, size_t buffer_size)
401 {
402         int error;
403 
404         if (strlen(name) > 255)
405                 return -ERANGE;
406 
407         down_read(&EXT4_I(inode)->xattr_sem);
408         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
409                                      buffer_size);
410         if (error == -ENODATA)
411                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
412                                              buffer_size);
413         up_read(&EXT4_I(inode)->xattr_sem);
414         return error;
415 }
416 
417 static int
418 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
419                         char *buffer, size_t buffer_size)
420 {
421         size_t rest = buffer_size;
422 
423         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
424                 const struct xattr_handler *handler =
425                         ext4_xattr_handler(entry->e_name_index);
426 
427                 if (handler && (!handler->list || handler->list(dentry))) {
428                         const char *prefix = handler->prefix ?: handler->name;
429                         size_t prefix_len = strlen(prefix);
430                         size_t size = prefix_len + entry->e_name_len + 1;
431 
432                         if (buffer) {
433                                 if (size > rest)
434                                         return -ERANGE;
435                                 memcpy(buffer, prefix, prefix_len);
436                                 buffer += prefix_len;
437                                 memcpy(buffer, entry->e_name, entry->e_name_len);
438                                 buffer += entry->e_name_len;
439                                 *buffer++ = 0;
440                         }
441                         rest -= size;
442                 }
443         }
444         return buffer_size - rest;  /* total size */
445 }
446 
447 static int
448 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
449 {
450         struct inode *inode = d_inode(dentry);
451         struct buffer_head *bh = NULL;
452         int error;
453         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
454 
455         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
456                   buffer, (long)buffer_size);
457 
458         error = 0;
459         if (!EXT4_I(inode)->i_file_acl)
460                 goto cleanup;
461         ea_idebug(inode, "reading block %llu",
462                   (unsigned long long)EXT4_I(inode)->i_file_acl);
463         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
464         error = -EIO;
465         if (!bh)
466                 goto cleanup;
467         ea_bdebug(bh, "b_count=%d, refcount=%d",
468                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
469         if (ext4_xattr_check_block(inode, bh)) {
470                 EXT4_ERROR_INODE(inode, "bad block %llu",
471                                  EXT4_I(inode)->i_file_acl);
472                 error = -EFSCORRUPTED;
473                 goto cleanup;
474         }
475         ext4_xattr_cache_insert(ext4_mb_cache, bh);
476         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
477 
478 cleanup:
479         brelse(bh);
480 
481         return error;
482 }
483 
484 static int
485 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
486 {
487         struct inode *inode = d_inode(dentry);
488         struct ext4_xattr_ibody_header *header;
489         struct ext4_inode *raw_inode;
490         struct ext4_iloc iloc;
491         void *end;
492         int error;
493 
494         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
495                 return 0;
496         error = ext4_get_inode_loc(inode, &iloc);
497         if (error)
498                 return error;
499         raw_inode = ext4_raw_inode(&iloc);
500         header = IHDR(inode, raw_inode);
501         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
502         error = xattr_check_inode(inode, header, end);
503         if (error)
504                 goto cleanup;
505         error = ext4_xattr_list_entries(dentry, IFIRST(header),
506                                         buffer, buffer_size);
507 
508 cleanup:
509         brelse(iloc.bh);
510         return error;
511 }
512 
513 /*
514  * ext4_xattr_list()
515  *
516  * Copy a list of attribute names into the buffer
517  * provided, or compute the buffer size required.
518  * Buffer is NULL to compute the size of the buffer required.
519  *
520  * Returns a negative error number on failure, or the number of bytes
521  * used / required on success.
522  */
523 static int
524 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
525 {
526         int ret, ret2;
527 
528         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
529         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
530         if (ret < 0)
531                 goto errout;
532         if (buffer) {
533                 buffer += ret;
534                 buffer_size -= ret;
535         }
536         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
537         if (ret < 0)
538                 goto errout;
539         ret += ret2;
540 errout:
541         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
542         return ret;
543 }
544 
545 /*
546  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
547  * not set, set it.
548  */
549 static void ext4_xattr_update_super_block(handle_t *handle,
550                                           struct super_block *sb)
551 {
552         if (ext4_has_feature_xattr(sb))
553                 return;
554 
555         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
556         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
557                 ext4_set_feature_xattr(sb);
558                 ext4_handle_dirty_super(handle, sb);
559         }
560 }
561 
562 /*
563  * Release the xattr block BH: If the reference count is > 1, decrement it;
564  * otherwise free the block.
565  */
566 static void
567 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
568                          struct buffer_head *bh)
569 {
570         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
571         u32 hash, ref;
572         int error = 0;
573 
574         BUFFER_TRACE(bh, "get_write_access");
575         error = ext4_journal_get_write_access(handle, bh);
576         if (error)
577                 goto out;
578 
579         lock_buffer(bh);
580         hash = le32_to_cpu(BHDR(bh)->h_hash);
581         ref = le32_to_cpu(BHDR(bh)->h_refcount);
582         if (ref == 1) {
583                 ea_bdebug(bh, "refcount now=0; freeing");
584                 /*
585                  * This must happen under buffer lock for
586                  * ext4_xattr_block_set() to reliably detect freed block
587                  */
588                 mb_cache_entry_delete_block(ext4_mb_cache, hash, bh->b_blocknr);
589                 get_bh(bh);
590                 unlock_buffer(bh);
591                 ext4_free_blocks(handle, inode, bh, 0, 1,
592                                  EXT4_FREE_BLOCKS_METADATA |
593                                  EXT4_FREE_BLOCKS_FORGET);
594         } else {
595                 ref--;
596                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
597                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
598                         struct mb_cache_entry *ce;
599 
600                         ce = mb_cache_entry_get(ext4_mb_cache, hash,
601                                                 bh->b_blocknr);
602                         if (ce) {
603                                 ce->e_reusable = 1;
604                                 mb_cache_entry_put(ext4_mb_cache, ce);
605                         }
606                 }
607 
608                 /*
609                  * Beware of this ugliness: Releasing of xattr block references
610                  * from different inodes can race and so we have to protect
611                  * from a race where someone else frees the block (and releases
612                  * its journal_head) before we are done dirtying the buffer. In
613                  * nojournal mode this race is harmless and we actually cannot
614                  * call ext4_handle_dirty_xattr_block() with locked buffer as
615                  * that function can call sync_dirty_buffer() so for that case
616                  * we handle the dirtying after unlocking the buffer.
617                  */
618                 if (ext4_handle_valid(handle))
619                         error = ext4_handle_dirty_xattr_block(handle, inode,
620                                                               bh);
621                 unlock_buffer(bh);
622                 if (!ext4_handle_valid(handle))
623                         error = ext4_handle_dirty_xattr_block(handle, inode,
624                                                               bh);
625                 if (IS_SYNC(inode))
626                         ext4_handle_sync(handle);
627                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
628                 ea_bdebug(bh, "refcount now=%d; releasing",
629                           le32_to_cpu(BHDR(bh)->h_refcount));
630         }
631 out:
632         ext4_std_error(inode->i_sb, error);
633         return;
634 }
635 
636 /*
637  * Find the available free space for EAs. This also returns the total number of
638  * bytes used by EA entries.
639  */
640 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
641                                     size_t *min_offs, void *base, int *total)
642 {
643         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
644                 if (!last->e_value_block && last->e_value_size) {
645                         size_t offs = le16_to_cpu(last->e_value_offs);
646                         if (offs < *min_offs)
647                                 *min_offs = offs;
648                 }
649                 if (total)
650                         *total += EXT4_XATTR_LEN(last->e_name_len);
651         }
652         return (*min_offs - ((void *)last - base) - sizeof(__u32));
653 }
654 
655 static int
656 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
657 {
658         struct ext4_xattr_entry *last;
659         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
660 
661         /* Compute min_offs and last. */
662         last = s->first;
663         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
664                 if (!last->e_value_block && last->e_value_size) {
665                         size_t offs = le16_to_cpu(last->e_value_offs);
666                         if (offs < min_offs)
667                                 min_offs = offs;
668                 }
669         }
670         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
671         if (!s->not_found) {
672                 if (!s->here->e_value_block && s->here->e_value_size) {
673                         size_t size = le32_to_cpu(s->here->e_value_size);
674                         free += EXT4_XATTR_SIZE(size);
675                 }
676                 free += EXT4_XATTR_LEN(name_len);
677         }
678         if (i->value) {
679                 if (free < EXT4_XATTR_LEN(name_len) +
680                            EXT4_XATTR_SIZE(i->value_len))
681                         return -ENOSPC;
682         }
683 
684         if (i->value && s->not_found) {
685                 /* Insert the new name. */
686                 size_t size = EXT4_XATTR_LEN(name_len);
687                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
688                 memmove((void *)s->here + size, s->here, rest);
689                 memset(s->here, 0, size);
690                 s->here->e_name_index = i->name_index;
691                 s->here->e_name_len = name_len;
692                 memcpy(s->here->e_name, i->name, name_len);
693         } else {
694                 if (!s->here->e_value_block && s->here->e_value_size) {
695                         void *first_val = s->base + min_offs;
696                         size_t offs = le16_to_cpu(s->here->e_value_offs);
697                         void *val = s->base + offs;
698                         size_t size = EXT4_XATTR_SIZE(
699                                 le32_to_cpu(s->here->e_value_size));
700 
701                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
702                                 /* The old and the new value have the same
703                                    size. Just replace. */
704                                 s->here->e_value_size =
705                                         cpu_to_le32(i->value_len);
706                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
707                                         memset(val, 0, size);
708                                 } else {
709                                         /* Clear pad bytes first. */
710                                         memset(val + size - EXT4_XATTR_PAD, 0,
711                                                EXT4_XATTR_PAD);
712                                         memcpy(val, i->value, i->value_len);
713                                 }
714                                 return 0;
715                         }
716 
717                         /* Remove the old value. */
718                         memmove(first_val + size, first_val, val - first_val);
719                         memset(first_val, 0, size);
720                         s->here->e_value_size = 0;
721                         s->here->e_value_offs = 0;
722                         min_offs += size;
723 
724                         /* Adjust all value offsets. */
725                         last = s->first;
726                         while (!IS_LAST_ENTRY(last)) {
727                                 size_t o = le16_to_cpu(last->e_value_offs);
728                                 if (!last->e_value_block &&
729                                     last->e_value_size && o < offs)
730                                         last->e_value_offs =
731                                                 cpu_to_le16(o + size);
732                                 last = EXT4_XATTR_NEXT(last);
733                         }
734                 }
735                 if (!i->value) {
736                         /* Remove the old name. */
737                         size_t size = EXT4_XATTR_LEN(name_len);
738                         last = ENTRY((void *)last - size);
739                         memmove(s->here, (void *)s->here + size,
740                                 (void *)last - (void *)s->here + sizeof(__u32));
741                         memset(last, 0, size);
742                 }
743         }
744 
745         if (i->value) {
746                 /* Insert the new value. */
747                 s->here->e_value_size = cpu_to_le32(i->value_len);
748                 if (i->value_len) {
749                         size_t size = EXT4_XATTR_SIZE(i->value_len);
750                         void *val = s->base + min_offs - size;
751                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
752                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
753                                 memset(val, 0, size);
754                         } else {
755                                 /* Clear the pad bytes first. */
756                                 memset(val + size - EXT4_XATTR_PAD, 0,
757                                        EXT4_XATTR_PAD);
758                                 memcpy(val, i->value, i->value_len);
759                         }
760                 }
761         }
762         return 0;
763 }
764 
765 struct ext4_xattr_block_find {
766         struct ext4_xattr_search s;
767         struct buffer_head *bh;
768 };
769 
770 static int
771 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
772                       struct ext4_xattr_block_find *bs)
773 {
774         struct super_block *sb = inode->i_sb;
775         int error;
776 
777         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
778                   i->name_index, i->name, i->value, (long)i->value_len);
779 
780         if (EXT4_I(inode)->i_file_acl) {
781                 /* The inode already has an extended attribute block. */
782                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
783                 error = -EIO;
784                 if (!bs->bh)
785                         goto cleanup;
786                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
787                         atomic_read(&(bs->bh->b_count)),
788                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
789                 if (ext4_xattr_check_block(inode, bs->bh)) {
790                         EXT4_ERROR_INODE(inode, "bad block %llu",
791                                          EXT4_I(inode)->i_file_acl);
792                         error = -EFSCORRUPTED;
793                         goto cleanup;
794                 }
795                 /* Find the named attribute. */
796                 bs->s.base = BHDR(bs->bh);
797                 bs->s.first = BFIRST(bs->bh);
798                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
799                 bs->s.here = bs->s.first;
800                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
801                                               i->name, bs->bh->b_size, 1);
802                 if (error && error != -ENODATA)
803                         goto cleanup;
804                 bs->s.not_found = error;
805         }
806         error = 0;
807 
808 cleanup:
809         return error;
810 }
811 
812 static int
813 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
814                      struct ext4_xattr_info *i,
815                      struct ext4_xattr_block_find *bs)
816 {
817         struct super_block *sb = inode->i_sb;
818         struct buffer_head *new_bh = NULL;
819         struct ext4_xattr_search *s = &bs->s;
820         struct mb_cache_entry *ce = NULL;
821         int error = 0;
822         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
823 
824 #define header(x) ((struct ext4_xattr_header *)(x))
825 
826         if (i->value && i->value_len > sb->s_blocksize)
827                 return -ENOSPC;
828         if (s->base) {
829                 BUFFER_TRACE(bs->bh, "get_write_access");
830                 error = ext4_journal_get_write_access(handle, bs->bh);
831                 if (error)
832                         goto cleanup;
833                 lock_buffer(bs->bh);
834 
835                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
836                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
837 
838                         /*
839                          * This must happen under buffer lock for
840                          * ext4_xattr_block_set() to reliably detect modified
841                          * block
842                          */
843                         mb_cache_entry_delete_block(ext4_mb_cache, hash,
844                                                     bs->bh->b_blocknr);
845                         ea_bdebug(bs->bh, "modifying in-place");
846                         error = ext4_xattr_set_entry(i, s);
847                         if (!error) {
848                                 if (!IS_LAST_ENTRY(s->first))
849                                         ext4_xattr_rehash(header(s->base),
850                                                           s->here);
851                                 ext4_xattr_cache_insert(ext4_mb_cache,
852                                         bs->bh);
853                         }
854                         unlock_buffer(bs->bh);
855                         if (error == -EFSCORRUPTED)
856                                 goto bad_block;
857                         if (!error)
858                                 error = ext4_handle_dirty_xattr_block(handle,
859                                                                       inode,
860                                                                       bs->bh);
861                         if (error)
862                                 goto cleanup;
863                         goto inserted;
864                 } else {
865                         int offset = (char *)s->here - bs->bh->b_data;
866 
867                         unlock_buffer(bs->bh);
868                         ea_bdebug(bs->bh, "cloning");
869                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
870                         error = -ENOMEM;
871                         if (s->base == NULL)
872                                 goto cleanup;
873                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
874                         s->first = ENTRY(header(s->base)+1);
875                         header(s->base)->h_refcount = cpu_to_le32(1);
876                         s->here = ENTRY(s->base + offset);
877                         s->end = s->base + bs->bh->b_size;
878                 }
879         } else {
880                 /* Allocate a buffer where we construct the new block. */
881                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
882                 /* assert(header == s->base) */
883                 error = -ENOMEM;
884                 if (s->base == NULL)
885                         goto cleanup;
886                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
887                 header(s->base)->h_blocks = cpu_to_le32(1);
888                 header(s->base)->h_refcount = cpu_to_le32(1);
889                 s->first = ENTRY(header(s->base)+1);
890                 s->here = ENTRY(header(s->base)+1);
891                 s->end = s->base + sb->s_blocksize;
892         }
893 
894         error = ext4_xattr_set_entry(i, s);
895         if (error == -EFSCORRUPTED)
896                 goto bad_block;
897         if (error)
898                 goto cleanup;
899         if (!IS_LAST_ENTRY(s->first))
900                 ext4_xattr_rehash(header(s->base), s->here);
901 
902 inserted:
903         if (!IS_LAST_ENTRY(s->first)) {
904                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
905                 if (new_bh) {
906                         /* We found an identical block in the cache. */
907                         if (new_bh == bs->bh)
908                                 ea_bdebug(new_bh, "keeping");
909                         else {
910                                 u32 ref;
911 
912                                 /* The old block is released after updating
913                                    the inode. */
914                                 error = dquot_alloc_block(inode,
915                                                 EXT4_C2B(EXT4_SB(sb), 1));
916                                 if (error)
917                                         goto cleanup;
918                                 BUFFER_TRACE(new_bh, "get_write_access");
919                                 error = ext4_journal_get_write_access(handle,
920                                                                       new_bh);
921                                 if (error)
922                                         goto cleanup_dquot;
923                                 lock_buffer(new_bh);
924                                 /*
925                                  * We have to be careful about races with
926                                  * freeing, rehashing or adding references to
927                                  * xattr block. Once we hold buffer lock xattr
928                                  * block's state is stable so we can check
929                                  * whether the block got freed / rehashed or
930                                  * not.  Since we unhash mbcache entry under
931                                  * buffer lock when freeing / rehashing xattr
932                                  * block, checking whether entry is still
933                                  * hashed is reliable. Same rules hold for
934                                  * e_reusable handling.
935                                  */
936                                 if (hlist_bl_unhashed(&ce->e_hash_list) ||
937                                     !ce->e_reusable) {
938                                         /*
939                                          * Undo everything and check mbcache
940                                          * again.
941                                          */
942                                         unlock_buffer(new_bh);
943                                         dquot_free_block(inode,
944                                                          EXT4_C2B(EXT4_SB(sb),
945                                                                   1));
946                                         brelse(new_bh);
947                                         mb_cache_entry_put(ext4_mb_cache, ce);
948                                         ce = NULL;
949                                         new_bh = NULL;
950                                         goto inserted;
951                                 }
952                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
953                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
954                                 if (ref >= EXT4_XATTR_REFCOUNT_MAX)
955                                         ce->e_reusable = 0;
956                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
957                                           ref);
958                                 unlock_buffer(new_bh);
959                                 error = ext4_handle_dirty_xattr_block(handle,
960                                                                       inode,
961                                                                       new_bh);
962                                 if (error)
963                                         goto cleanup_dquot;
964                         }
965                         mb_cache_entry_touch(ext4_mb_cache, ce);
966                         mb_cache_entry_put(ext4_mb_cache, ce);
967                         ce = NULL;
968                 } else if (bs->bh && s->base == bs->bh->b_data) {
969                         /* We were modifying this block in-place. */
970                         ea_bdebug(bs->bh, "keeping this block");
971                         new_bh = bs->bh;
972                         get_bh(new_bh);
973                 } else {
974                         /* We need to allocate a new block */
975                         ext4_fsblk_t goal, block;
976 
977                         goal = ext4_group_first_block_no(sb,
978                                                 EXT4_I(inode)->i_block_group);
979 
980                         /* non-extent files can't have physical blocks past 2^32 */
981                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
982                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
983 
984                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
985                                                      NULL, &error);
986                         if (error)
987                                 goto cleanup;
988 
989                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
990                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
991 
992                         ea_idebug(inode, "creating block %llu",
993                                   (unsigned long long)block);
994 
995                         new_bh = sb_getblk(sb, block);
996                         if (unlikely(!new_bh)) {
997                                 error = -ENOMEM;
998 getblk_failed:
999                                 ext4_free_blocks(handle, inode, NULL, block, 1,
1000                                                  EXT4_FREE_BLOCKS_METADATA);
1001                                 goto cleanup;
1002                         }
1003                         lock_buffer(new_bh);
1004                         error = ext4_journal_get_create_access(handle, new_bh);
1005                         if (error) {
1006                                 unlock_buffer(new_bh);
1007                                 error = -EIO;
1008                                 goto getblk_failed;
1009                         }
1010                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
1011                         set_buffer_uptodate(new_bh);
1012                         unlock_buffer(new_bh);
1013                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
1014                         error = ext4_handle_dirty_xattr_block(handle,
1015                                                               inode, new_bh);
1016                         if (error)
1017                                 goto cleanup;
1018                 }
1019         }
1020 
1021         /* Update the inode. */
1022         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
1023 
1024         /* Drop the previous xattr block. */
1025         if (bs->bh && bs->bh != new_bh)
1026                 ext4_xattr_release_block(handle, inode, bs->bh);
1027         error = 0;
1028 
1029 cleanup:
1030         if (ce)
1031                 mb_cache_entry_put(ext4_mb_cache, ce);
1032         brelse(new_bh);
1033         if (!(bs->bh && s->base == bs->bh->b_data))
1034                 kfree(s->base);
1035 
1036         return error;
1037 
1038 cleanup_dquot:
1039         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
1040         goto cleanup;
1041 
1042 bad_block:
1043         EXT4_ERROR_INODE(inode, "bad block %llu",
1044                          EXT4_I(inode)->i_file_acl);
1045         goto cleanup;
1046 
1047 #undef header
1048 }
1049 
1050 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
1051                           struct ext4_xattr_ibody_find *is)
1052 {
1053         struct ext4_xattr_ibody_header *header;
1054         struct ext4_inode *raw_inode;
1055         int error;
1056 
1057         if (EXT4_I(inode)->i_extra_isize == 0)
1058                 return 0;
1059         raw_inode = ext4_raw_inode(&is->iloc);
1060         header = IHDR(inode, raw_inode);
1061         is->s.base = is->s.first = IFIRST(header);
1062         is->s.here = is->s.first;
1063         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1064         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
1065                 error = xattr_check_inode(inode, header, is->s.end);
1066                 if (error)
1067                         return error;
1068                 /* Find the named attribute. */
1069                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
1070                                               i->name, is->s.end -
1071                                               (void *)is->s.base, 0);
1072                 if (error && error != -ENODATA)
1073                         return error;
1074                 is->s.not_found = error;
1075         }
1076         return 0;
1077 }
1078 
1079 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1080                                 struct ext4_xattr_info *i,
1081                                 struct ext4_xattr_ibody_find *is)
1082 {
1083         struct ext4_xattr_ibody_header *header;
1084         struct ext4_xattr_search *s = &is->s;
1085         int error;
1086 
1087         if (EXT4_I(inode)->i_extra_isize == 0)
1088                 return -ENOSPC;
1089         error = ext4_xattr_set_entry(i, s);
1090         if (error) {
1091                 if (error == -ENOSPC &&
1092                     ext4_has_inline_data(inode)) {
1093                         error = ext4_try_to_evict_inline_data(handle, inode,
1094                                         EXT4_XATTR_LEN(strlen(i->name) +
1095                                         EXT4_XATTR_SIZE(i->value_len)));
1096                         if (error)
1097                                 return error;
1098                         error = ext4_xattr_ibody_find(inode, i, is);
1099                         if (error)
1100                                 return error;
1101                         error = ext4_xattr_set_entry(i, s);
1102                 }
1103                 if (error)
1104                         return error;
1105         }
1106         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1107         if (!IS_LAST_ENTRY(s->first)) {
1108                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1109                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1110         } else {
1111                 header->h_magic = cpu_to_le32(0);
1112                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1113         }
1114         return 0;
1115 }
1116 
1117 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
1118                                 struct ext4_xattr_info *i,
1119                                 struct ext4_xattr_ibody_find *is)
1120 {
1121         struct ext4_xattr_ibody_header *header;
1122         struct ext4_xattr_search *s = &is->s;
1123         int error;
1124 
1125         if (EXT4_I(inode)->i_extra_isize == 0)
1126                 return -ENOSPC;
1127         error = ext4_xattr_set_entry(i, s);
1128         if (error)
1129                 return error;
1130         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1131         if (!IS_LAST_ENTRY(s->first)) {
1132                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1133                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1134         } else {
1135                 header->h_magic = cpu_to_le32(0);
1136                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1137         }
1138         return 0;
1139 }
1140 
1141 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
1142                                  struct ext4_xattr_info *i)
1143 {
1144         void *value;
1145 
1146         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
1147                 return 0;
1148         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
1149         return !memcmp(value, i->value, i->value_len);
1150 }
1151 
1152 /*
1153  * ext4_xattr_set_handle()
1154  *
1155  * Create, replace or remove an extended attribute for this inode.  Value
1156  * is NULL to remove an existing extended attribute, and non-NULL to
1157  * either replace an existing extended attribute, or create a new extended
1158  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1159  * specify that an extended attribute must exist and must not exist
1160  * previous to the call, respectively.
1161  *
1162  * Returns 0, or a negative error number on failure.
1163  */
1164 int
1165 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1166                       const char *name, const void *value, size_t value_len,
1167                       int flags)
1168 {
1169         struct ext4_xattr_info i = {
1170                 .name_index = name_index,
1171                 .name = name,
1172                 .value = value,
1173                 .value_len = value_len,
1174 
1175         };
1176         struct ext4_xattr_ibody_find is = {
1177                 .s = { .not_found = -ENODATA, },
1178         };
1179         struct ext4_xattr_block_find bs = {
1180                 .s = { .not_found = -ENODATA, },
1181         };
1182         unsigned long no_expand;
1183         int error;
1184 
1185         if (!name)
1186                 return -EINVAL;
1187         if (strlen(name) > 255)
1188                 return -ERANGE;
1189         down_write(&EXT4_I(inode)->xattr_sem);
1190         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1191         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1192 
1193         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1194         if (error)
1195                 goto cleanup;
1196 
1197         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1198                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1199                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1200                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1201         }
1202 
1203         error = ext4_xattr_ibody_find(inode, &i, &is);
1204         if (error)
1205                 goto cleanup;
1206         if (is.s.not_found)
1207                 error = ext4_xattr_block_find(inode, &i, &bs);
1208         if (error)
1209                 goto cleanup;
1210         if (is.s.not_found && bs.s.not_found) {
1211                 error = -ENODATA;
1212                 if (flags & XATTR_REPLACE)
1213                         goto cleanup;
1214                 error = 0;
1215                 if (!value)
1216                         goto cleanup;
1217         } else {
1218                 error = -EEXIST;
1219                 if (flags & XATTR_CREATE)
1220                         goto cleanup;
1221         }
1222         if (!value) {
1223                 if (!is.s.not_found)
1224                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1225                 else if (!bs.s.not_found)
1226                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1227         } else {
1228                 error = 0;
1229                 /* Xattr value did not change? Save us some work and bail out */
1230                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
1231                         goto cleanup;
1232                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
1233                         goto cleanup;
1234 
1235                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1236                 if (!error && !bs.s.not_found) {
1237                         i.value = NULL;
1238                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1239                 } else if (error == -ENOSPC) {
1240                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1241                                 error = ext4_xattr_block_find(inode, &i, &bs);
1242                                 if (error)
1243                                         goto cleanup;
1244                         }
1245                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1246                         if (error)
1247                                 goto cleanup;
1248                         if (!is.s.not_found) {
1249                                 i.value = NULL;
1250                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1251                                                              &is);
1252                         }
1253                 }
1254         }
1255         if (!error) {
1256                 ext4_xattr_update_super_block(handle, inode->i_sb);
1257                 inode->i_ctime = ext4_current_time(inode);
1258                 if (!value)
1259                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1260                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1261                 /*
1262                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1263                  * error != 0.
1264                  */
1265                 is.iloc.bh = NULL;
1266                 if (IS_SYNC(inode))
1267                         ext4_handle_sync(handle);
1268         }
1269 
1270 cleanup:
1271         brelse(is.iloc.bh);
1272         brelse(bs.bh);
1273         if (no_expand == 0)
1274                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1275         up_write(&EXT4_I(inode)->xattr_sem);
1276         return error;
1277 }
1278 
1279 /*
1280  * ext4_xattr_set()
1281  *
1282  * Like ext4_xattr_set_handle, but start from an inode. This extended
1283  * attribute modification is a filesystem transaction by itself.
1284  *
1285  * Returns 0, or a negative error number on failure.
1286  */
1287 int
1288 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1289                const void *value, size_t value_len, int flags)
1290 {
1291         handle_t *handle;
1292         int error, retries = 0;
1293         int credits = ext4_jbd2_credits_xattr(inode);
1294 
1295 retry:
1296         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1297         if (IS_ERR(handle)) {
1298                 error = PTR_ERR(handle);
1299         } else {
1300                 int error2;
1301 
1302                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1303                                               value, value_len, flags);
1304                 error2 = ext4_journal_stop(handle);
1305                 if (error == -ENOSPC &&
1306                     ext4_should_retry_alloc(inode->i_sb, &retries))
1307                         goto retry;
1308                 if (error == 0)
1309                         error = error2;
1310         }
1311 
1312         return error;
1313 }
1314 
1315 /*
1316  * Shift the EA entries in the inode to create space for the increased
1317  * i_extra_isize.
1318  */
1319 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1320                                      int value_offs_shift, void *to,
1321                                      void *from, size_t n, int blocksize)
1322 {
1323         struct ext4_xattr_entry *last = entry;
1324         int new_offs;
1325 
1326         /* Adjust the value offsets of the entries */
1327         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1328                 if (!last->e_value_block && last->e_value_size) {
1329                         new_offs = le16_to_cpu(last->e_value_offs) +
1330                                                         value_offs_shift;
1331                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1332                                  > blocksize);
1333                         last->e_value_offs = cpu_to_le16(new_offs);
1334                 }
1335         }
1336         /* Shift the entries by n bytes */
1337         memmove(to, from, n);
1338 }
1339 
1340 /*
1341  * Expand an inode by new_extra_isize bytes when EAs are present.
1342  * Returns 0 on success or negative error number on failure.
1343  */
1344 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1345                                struct ext4_inode *raw_inode, handle_t *handle)
1346 {
1347         struct ext4_xattr_ibody_header *header;
1348         struct ext4_xattr_entry *entry, *last, *first;
1349         struct buffer_head *bh = NULL;
1350         struct ext4_xattr_ibody_find *is = NULL;
1351         struct ext4_xattr_block_find *bs = NULL;
1352         char *buffer = NULL, *b_entry_name = NULL;
1353         size_t min_offs, free;
1354         int total_ino;
1355         void *base, *start, *end;
1356         int error = 0, tried_min_extra_isize = 0;
1357         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1358         int isize_diff; /* How much do we need to grow i_extra_isize */
1359 
1360         down_write(&EXT4_I(inode)->xattr_sem);
1361         /*
1362          * Set EXT4_STATE_NO_EXPAND to avoid recursion when marking inode dirty
1363          */
1364         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1365 retry:
1366         isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
1367         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
1368                 goto out;
1369 
1370         header = IHDR(inode, raw_inode);
1371         entry = IFIRST(header);
1372 
1373         /*
1374          * Check if enough free space is available in the inode to shift the
1375          * entries ahead by new_extra_isize.
1376          */
1377 
1378         base = start = entry;
1379         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1380         min_offs = end - base;
1381         last = entry;
1382         total_ino = sizeof(struct ext4_xattr_ibody_header);
1383 
1384         error = xattr_check_inode(inode, header, end);
1385         if (error)
1386                 goto cleanup;
1387 
1388         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1389         if (free >= isize_diff) {
1390                 entry = IFIRST(header);
1391                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1392                                 - new_extra_isize, (void *)raw_inode +
1393                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1394                                 (void *)header, total_ino,
1395                                 inode->i_sb->s_blocksize);
1396                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1397                 goto out;
1398         }
1399 
1400         /*
1401          * Enough free space isn't available in the inode, check if
1402          * EA block can hold new_extra_isize bytes.
1403          */
1404         if (EXT4_I(inode)->i_file_acl) {
1405                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1406                 error = -EIO;
1407                 if (!bh)
1408                         goto cleanup;
1409                 if (ext4_xattr_check_block(inode, bh)) {
1410                         EXT4_ERROR_INODE(inode, "bad block %llu",
1411                                          EXT4_I(inode)->i_file_acl);
1412                         error = -EFSCORRUPTED;
1413                         goto cleanup;
1414                 }
1415                 base = BHDR(bh);
1416                 first = BFIRST(bh);
1417                 end = bh->b_data + bh->b_size;
1418                 min_offs = end - base;
1419                 free = ext4_xattr_free_space(first, &min_offs, base, NULL);
1420                 if (free < isize_diff) {
1421                         if (!tried_min_extra_isize && s_min_extra_isize) {
1422                                 tried_min_extra_isize++;
1423                                 new_extra_isize = s_min_extra_isize;
1424                                 brelse(bh);
1425                                 goto retry;
1426                         }
1427                         error = -1;
1428                         goto cleanup;
1429                 }
1430         } else {
1431                 free = inode->i_sb->s_blocksize;
1432         }
1433 
1434         while (isize_diff > 0) {
1435                 size_t offs, size, entry_size;
1436                 struct ext4_xattr_entry *small_entry = NULL;
1437                 struct ext4_xattr_info i = {
1438                         .value = NULL,
1439                         .value_len = 0,
1440                 };
1441                 unsigned int total_size;  /* EA entry size + value size */
1442                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1443                 unsigned int min_total_size = ~0U;
1444 
1445                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1446                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1447                 if (!is || !bs) {
1448                         error = -ENOMEM;
1449                         goto cleanup;
1450                 }
1451 
1452                 is->s.not_found = -ENODATA;
1453                 bs->s.not_found = -ENODATA;
1454                 is->iloc.bh = NULL;
1455                 bs->bh = NULL;
1456 
1457                 last = IFIRST(header);
1458                 /* Find the entry best suited to be pushed into EA block */
1459                 entry = NULL;
1460                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1461                         total_size =
1462                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1463                                         EXT4_XATTR_LEN(last->e_name_len);
1464                         if (total_size <= free && total_size < min_total_size) {
1465                                 if (total_size < isize_diff) {
1466                                         small_entry = last;
1467                                 } else {
1468                                         entry = last;
1469                                         min_total_size = total_size;
1470                                 }
1471                         }
1472                 }
1473 
1474                 if (entry == NULL) {
1475                         if (small_entry) {
1476                                 entry = small_entry;
1477                         } else {
1478                                 if (!tried_min_extra_isize &&
1479                                     s_min_extra_isize) {
1480                                         tried_min_extra_isize++;
1481                                         new_extra_isize = s_min_extra_isize;
1482                                         kfree(is); is = NULL;
1483                                         kfree(bs); bs = NULL;
1484                                         brelse(bh);
1485                                         goto retry;
1486                                 }
1487                                 error = -1;
1488                                 goto cleanup;
1489                         }
1490                 }
1491                 offs = le16_to_cpu(entry->e_value_offs);
1492                 size = le32_to_cpu(entry->e_value_size);
1493                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1494                 i.name_index = entry->e_name_index,
1495                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1496                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1497                 if (!buffer || !b_entry_name) {
1498                         error = -ENOMEM;
1499                         goto cleanup;
1500                 }
1501                 /* Save the entry name and the entry value */
1502                 memcpy(buffer, (void *)IFIRST(header) + offs,
1503                        EXT4_XATTR_SIZE(size));
1504                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1505                 b_entry_name[entry->e_name_len] = '\0';
1506                 i.name = b_entry_name;
1507 
1508                 error = ext4_get_inode_loc(inode, &is->iloc);
1509                 if (error)
1510                         goto cleanup;
1511 
1512                 error = ext4_xattr_ibody_find(inode, &i, is);
1513                 if (error)
1514                         goto cleanup;
1515 
1516                 /* Remove the chosen entry from the inode */
1517                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1518                 if (error)
1519                         goto cleanup;
1520                 total_ino -= entry_size;
1521 
1522                 entry = IFIRST(header);
1523                 if (entry_size + EXT4_XATTR_SIZE(size) >= isize_diff)
1524                         shift_bytes = isize_diff;
1525                 else
1526                         shift_bytes = entry_size + EXT4_XATTR_SIZE(size);
1527                 /* Adjust the offsets and shift the remaining entries ahead */
1528                 ext4_xattr_shift_entries(entry, -shift_bytes,
1529                         (void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
1530                         EXT4_I(inode)->i_extra_isize + shift_bytes,
1531                         (void *)header, total_ino, inode->i_sb->s_blocksize);
1532 
1533                 isize_diff -= shift_bytes;
1534                 EXT4_I(inode)->i_extra_isize += shift_bytes;
1535                 header = IHDR(inode, raw_inode);
1536 
1537                 i.name = b_entry_name;
1538                 i.value = buffer;
1539                 i.value_len = size;
1540                 error = ext4_xattr_block_find(inode, &i, bs);
1541                 if (error)
1542                         goto cleanup;
1543 
1544                 /* Add entry which was removed from the inode into the block */
1545                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1546                 if (error)
1547                         goto cleanup;
1548                 kfree(b_entry_name);
1549                 kfree(buffer);
1550                 b_entry_name = NULL;
1551                 buffer = NULL;
1552                 brelse(is->iloc.bh);
1553                 kfree(is);
1554                 kfree(bs);
1555         }
1556         brelse(bh);
1557 out:
1558         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1559         up_write(&EXT4_I(inode)->xattr_sem);
1560         return 0;
1561 
1562 cleanup:
1563         kfree(b_entry_name);
1564         kfree(buffer);
1565         if (is)
1566                 brelse(is->iloc.bh);
1567         kfree(is);
1568         kfree(bs);
1569         brelse(bh);
1570         /*
1571          * We deliberately leave EXT4_STATE_NO_EXPAND set here since inode
1572          * size expansion failed.
1573          */
1574         up_write(&EXT4_I(inode)->xattr_sem);
1575         return error;
1576 }
1577 
1578 
1579 
1580 /*
1581  * ext4_xattr_delete_inode()
1582  *
1583  * Free extended attribute resources associated with this inode. This
1584  * is called immediately before an inode is freed. We have exclusive
1585  * access to the inode.
1586  */
1587 void
1588 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1589 {
1590         struct buffer_head *bh = NULL;
1591 
1592         if (!EXT4_I(inode)->i_file_acl)
1593                 goto cleanup;
1594         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1595         if (!bh) {
1596                 EXT4_ERROR_INODE(inode, "block %llu read error",
1597                                  EXT4_I(inode)->i_file_acl);
1598                 goto cleanup;
1599         }
1600         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1601             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1602                 EXT4_ERROR_INODE(inode, "bad block %llu",
1603                                  EXT4_I(inode)->i_file_acl);
1604                 goto cleanup;
1605         }
1606         ext4_xattr_release_block(handle, inode, bh);
1607         EXT4_I(inode)->i_file_acl = 0;
1608 
1609 cleanup:
1610         brelse(bh);
1611 }
1612 
1613 /*
1614  * ext4_xattr_cache_insert()
1615  *
1616  * Create a new entry in the extended attribute cache, and insert
1617  * it unless such an entry is already in the cache.
1618  *
1619  * Returns 0, or a negative error number on failure.
1620  */
1621 static void
1622 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1623 {
1624         struct ext4_xattr_header *header = BHDR(bh);
1625         __u32 hash = le32_to_cpu(header->h_hash);
1626         int reusable = le32_to_cpu(header->h_refcount) <
1627                        EXT4_XATTR_REFCOUNT_MAX;
1628         int error;
1629 
1630         error = mb_cache_entry_create(ext4_mb_cache, GFP_NOFS, hash,
1631                                       bh->b_blocknr, reusable);
1632         if (error) {
1633                 if (error == -EBUSY)
1634                         ea_bdebug(bh, "already in cache");
1635         } else
1636                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1637 }
1638 
1639 /*
1640  * ext4_xattr_cmp()
1641  *
1642  * Compare two extended attribute blocks for equality.
1643  *
1644  * Returns 0 if the blocks are equal, 1 if they differ, and
1645  * a negative error number on errors.
1646  */
1647 static int
1648 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1649                struct ext4_xattr_header *header2)
1650 {
1651         struct ext4_xattr_entry *entry1, *entry2;
1652 
1653         entry1 = ENTRY(header1+1);
1654         entry2 = ENTRY(header2+1);
1655         while (!IS_LAST_ENTRY(entry1)) {
1656                 if (IS_LAST_ENTRY(entry2))
1657                         return 1;
1658                 if (entry1->e_hash != entry2->e_hash ||
1659                     entry1->e_name_index != entry2->e_name_index ||
1660                     entry1->e_name_len != entry2->e_name_len ||
1661                     entry1->e_value_size != entry2->e_value_size ||
1662                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1663                         return 1;
1664                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1665                         return -EFSCORRUPTED;
1666                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1667                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1668                            le32_to_cpu(entry1->e_value_size)))
1669                         return 1;
1670 
1671                 entry1 = EXT4_XATTR_NEXT(entry1);
1672                 entry2 = EXT4_XATTR_NEXT(entry2);
1673         }
1674         if (!IS_LAST_ENTRY(entry2))
1675                 return 1;
1676         return 0;
1677 }
1678 
1679 /*
1680  * ext4_xattr_cache_find()
1681  *
1682  * Find an identical extended attribute block.
1683  *
1684  * Returns a pointer to the block found, or NULL if such a block was
1685  * not found or an error occurred.
1686  */
1687 static struct buffer_head *
1688 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1689                       struct mb_cache_entry **pce)
1690 {
1691         __u32 hash = le32_to_cpu(header->h_hash);
1692         struct mb_cache_entry *ce;
1693         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1694 
1695         if (!header->h_hash)
1696                 return NULL;  /* never share */
1697         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1698         ce = mb_cache_entry_find_first(ext4_mb_cache, hash);
1699         while (ce) {
1700                 struct buffer_head *bh;
1701 
1702                 bh = sb_bread(inode->i_sb, ce->e_block);
1703                 if (!bh) {
1704                         EXT4_ERROR_INODE(inode, "block %lu read error",
1705                                          (unsigned long) ce->e_block);
1706                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1707                         *pce = ce;
1708                         return bh;
1709                 }
1710                 brelse(bh);
1711                 ce = mb_cache_entry_find_next(ext4_mb_cache, ce);
1712         }
1713         return NULL;
1714 }
1715 
1716 #define NAME_HASH_SHIFT 5
1717 #define VALUE_HASH_SHIFT 16
1718 
1719 /*
1720  * ext4_xattr_hash_entry()
1721  *
1722  * Compute the hash of an extended attribute.
1723  */
1724 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1725                                          struct ext4_xattr_entry *entry)
1726 {
1727         __u32 hash = 0;
1728         char *name = entry->e_name;
1729         int n;
1730 
1731         for (n = 0; n < entry->e_name_len; n++) {
1732                 hash = (hash << NAME_HASH_SHIFT) ^
1733                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1734                        *name++;
1735         }
1736 
1737         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1738                 __le32 *value = (__le32 *)((char *)header +
1739                         le16_to_cpu(entry->e_value_offs));
1740                 for (n = (le32_to_cpu(entry->e_value_size) +
1741                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1742                         hash = (hash << VALUE_HASH_SHIFT) ^
1743                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1744                                le32_to_cpu(*value++);
1745                 }
1746         }
1747         entry->e_hash = cpu_to_le32(hash);
1748 }
1749 
1750 #undef NAME_HASH_SHIFT
1751 #undef VALUE_HASH_SHIFT
1752 
1753 #define BLOCK_HASH_SHIFT 16
1754 
1755 /*
1756  * ext4_xattr_rehash()
1757  *
1758  * Re-compute the extended attribute hash value after an entry has changed.
1759  */
1760 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1761                               struct ext4_xattr_entry *entry)
1762 {
1763         struct ext4_xattr_entry *here;
1764         __u32 hash = 0;
1765 
1766         ext4_xattr_hash_entry(header, entry);
1767         here = ENTRY(header+1);
1768         while (!IS_LAST_ENTRY(here)) {
1769                 if (!here->e_hash) {
1770                         /* Block is not shared if an entry's hash value == 0 */
1771                         hash = 0;
1772                         break;
1773                 }
1774                 hash = (hash << BLOCK_HASH_SHIFT) ^
1775                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1776                        le32_to_cpu(here->e_hash);
1777                 here = EXT4_XATTR_NEXT(here);
1778         }
1779         header->h_hash = cpu_to_le32(hash);
1780 }
1781 
1782 #undef BLOCK_HASH_SHIFT
1783 
1784 #define HASH_BUCKET_BITS        10
1785 
1786 struct mb_cache *
1787 ext4_xattr_create_cache(void)
1788 {
1789         return mb_cache_create(HASH_BUCKET_BITS);
1790 }
1791 
1792 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1793 {
1794         if (cache)
1795                 mb_cache_destroy(cache);
1796 }
1797 
1798 

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