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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/fs/ext2/xattr.c | |
4 | * | |
5 | * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de> | |
6 | * | |
7 | * Fix by Harrison Xing <harrison@mountainviewdata.com>. | |
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 | * | |
13 | */ | |
14 | ||
15 | /* | |
16 | * Extended attributes are stored on disk blocks allocated outside of | |
17 | * any inode. The i_file_acl field is then made to point to this allocated | |
18 | * block. If all extended attributes of an inode are identical, these | |
19 | * inodes may share the same extended attribute block. Such situations | |
20 | * are automatically detected by keeping a cache of recent attribute block | |
21 | * numbers and hashes over the block's contents in memory. | |
22 | * | |
23 | * | |
24 | * Extended attribute block layout: | |
25 | * | |
26 | * +------------------+ | |
27 | * | header | | |
28 | * | entry 1 | | | |
29 | * | entry 2 | | growing downwards | |
30 | * | entry 3 | v | |
31 | * | four null bytes | | |
32 | * | . . . | | |
33 | * | value 1 | ^ | |
34 | * | value 3 | | growing upwards | |
35 | * | value 2 | | | |
36 | * +------------------+ | |
37 | * | |
38 | * The block header is followed by multiple entry descriptors. These entry | |
25985edc | 39 | * descriptors are variable in size, and aligned to EXT2_XATTR_PAD |
1da177e4 LT |
40 | * byte boundaries. The entry descriptors are sorted by attribute name, |
41 | * so that two extended attribute blocks can be compared efficiently. | |
42 | * | |
43 | * Attribute values are aligned to the end of the block, stored in | |
44 | * no specific order. They are also padded to EXT2_XATTR_PAD byte | |
45 | * boundaries. No additional gaps are left between them. | |
46 | * | |
47 | * Locking strategy | |
48 | * ---------------- | |
49 | * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem. | |
50 | * EA blocks are only changed if they are exclusive to an inode, so | |
51 | * holding xattr_sem also means that nothing but the EA block's reference | |
52 | * count will change. Multiple writers to an EA block are synchronized | |
53 | * by the bh lock. No more than a single bh lock is held at any time | |
54 | * to avoid deadlocks. | |
55 | */ | |
56 | ||
57 | #include <linux/buffer_head.h> | |
1da177e4 | 58 | #include <linux/init.h> |
44a52022 | 59 | #include <linux/printk.h> |
1da177e4 | 60 | #include <linux/slab.h> |
7a2508e1 | 61 | #include <linux/mbcache.h> |
1da177e4 LT |
62 | #include <linux/quotaops.h> |
63 | #include <linux/rwsem.h> | |
431547b3 | 64 | #include <linux/security.h> |
1da177e4 LT |
65 | #include "ext2.h" |
66 | #include "xattr.h" | |
67 | #include "acl.h" | |
68 | ||
69 | #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) | |
70 | #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) | |
71 | #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) | |
72 | #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) | |
73 | ||
74 | #ifdef EXT2_XATTR_DEBUG | |
75 | # define ea_idebug(inode, f...) do { \ | |
76 | printk(KERN_DEBUG "inode %s:%ld: ", \ | |
77 | inode->i_sb->s_id, inode->i_ino); \ | |
78 | printk(f); \ | |
79 | printk("\n"); \ | |
80 | } while (0) | |
81 | # define ea_bdebug(bh, f...) do { \ | |
a1c6f057 DM |
82 | printk(KERN_DEBUG "block %pg:%lu: ", \ |
83 | bh->b_bdev, (unsigned long) bh->b_blocknr); \ | |
1da177e4 LT |
84 | printk(f); \ |
85 | printk("\n"); \ | |
86 | } while (0) | |
87 | #else | |
44a52022 RD |
88 | # define ea_idebug(inode, f...) no_printk(f) |
89 | # define ea_bdebug(bh, f...) no_printk(f) | |
1da177e4 LT |
90 | #endif |
91 | ||
92 | static int ext2_xattr_set2(struct inode *, struct buffer_head *, | |
93 | struct ext2_xattr_header *); | |
94 | ||
7a2508e1 | 95 | static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *); |
1da177e4 LT |
96 | static struct buffer_head *ext2_xattr_cache_find(struct inode *, |
97 | struct ext2_xattr_header *); | |
98 | static void ext2_xattr_rehash(struct ext2_xattr_header *, | |
99 | struct ext2_xattr_entry *); | |
100 | ||
749c72ef | 101 | static const struct xattr_handler *ext2_xattr_handler_map[] = { |
1da177e4 LT |
102 | [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, |
103 | #ifdef CONFIG_EXT2_FS_POSIX_ACL | |
64e178a7 CH |
104 | [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, |
105 | [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, | |
1da177e4 LT |
106 | #endif |
107 | [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, | |
108 | #ifdef CONFIG_EXT2_FS_SECURITY | |
109 | [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, | |
110 | #endif | |
111 | }; | |
112 | ||
749c72ef | 113 | const struct xattr_handler *ext2_xattr_handlers[] = { |
1da177e4 LT |
114 | &ext2_xattr_user_handler, |
115 | &ext2_xattr_trusted_handler, | |
116 | #ifdef CONFIG_EXT2_FS_POSIX_ACL | |
64e178a7 CH |
117 | &posix_acl_access_xattr_handler, |
118 | &posix_acl_default_xattr_handler, | |
1da177e4 LT |
119 | #endif |
120 | #ifdef CONFIG_EXT2_FS_SECURITY | |
121 | &ext2_xattr_security_handler, | |
122 | #endif | |
123 | NULL | |
124 | }; | |
125 | ||
47387409 TE |
126 | #define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache) |
127 | ||
749c72ef | 128 | static inline const struct xattr_handler * |
1da177e4 LT |
129 | ext2_xattr_handler(int name_index) |
130 | { | |
749c72ef | 131 | const struct xattr_handler *handler = NULL; |
1da177e4 LT |
132 | |
133 | if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) | |
134 | handler = ext2_xattr_handler_map[name_index]; | |
135 | return handler; | |
136 | } | |
137 | ||
02475de9 CX |
138 | static bool |
139 | ext2_xattr_header_valid(struct ext2_xattr_header *header) | |
140 | { | |
141 | if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || | |
142 | header->h_blocks != cpu_to_le32(1)) | |
143 | return false; | |
144 | ||
145 | return true; | |
146 | } | |
147 | ||
f4c3fb8c | 148 | static bool |
9bb1d7a6 CX |
149 | ext2_xattr_entry_valid(struct ext2_xattr_entry *entry, |
150 | char *end, size_t end_offs) | |
f4c3fb8c | 151 | { |
9bb1d7a6 | 152 | struct ext2_xattr_entry *next; |
f4c3fb8c CX |
153 | size_t size; |
154 | ||
9bb1d7a6 CX |
155 | next = EXT2_XATTR_NEXT(entry); |
156 | if ((char *)next >= end) | |
157 | return false; | |
158 | ||
f4c3fb8c CX |
159 | if (entry->e_value_block != 0) |
160 | return false; | |
161 | ||
162 | size = le32_to_cpu(entry->e_value_size); | |
163 | if (size > end_offs || | |
164 | le16_to_cpu(entry->e_value_offs) + size > end_offs) | |
165 | return false; | |
166 | ||
167 | return true; | |
168 | } | |
169 | ||
d561d4dd CX |
170 | static int |
171 | ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name, | |
172 | struct ext2_xattr_entry *entry) | |
173 | { | |
174 | int cmp; | |
175 | ||
176 | cmp = name_index - entry->e_name_index; | |
177 | if (!cmp) | |
178 | cmp = name_len - entry->e_name_len; | |
179 | if (!cmp) | |
180 | cmp = memcmp(name, entry->e_name, name_len); | |
181 | ||
182 | return cmp; | |
183 | } | |
184 | ||
1da177e4 LT |
185 | /* |
186 | * ext2_xattr_get() | |
187 | * | |
188 | * Copy an extended attribute into the buffer | |
189 | * provided, or compute the buffer size required. | |
190 | * Buffer is NULL to compute the size of the buffer required. | |
191 | * | |
192 | * Returns a negative error number on failure, or the number of bytes | |
193 | * used / required on success. | |
194 | */ | |
195 | int | |
196 | ext2_xattr_get(struct inode *inode, int name_index, const char *name, | |
197 | void *buffer, size_t buffer_size) | |
198 | { | |
199 | struct buffer_head *bh = NULL; | |
200 | struct ext2_xattr_entry *entry; | |
201 | size_t name_len, size; | |
202 | char *end; | |
1eaf5faa | 203 | int error, not_found; |
47387409 | 204 | struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); |
1da177e4 LT |
205 | |
206 | ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", | |
207 | name_index, name, buffer, (long)buffer_size); | |
208 | ||
209 | if (name == NULL) | |
210 | return -EINVAL; | |
03b5bb34 WSH |
211 | name_len = strlen(name); |
212 | if (name_len > 255) | |
213 | return -ERANGE; | |
214 | ||
1da177e4 LT |
215 | down_read(&EXT2_I(inode)->xattr_sem); |
216 | error = -ENODATA; | |
217 | if (!EXT2_I(inode)->i_file_acl) | |
218 | goto cleanup; | |
219 | ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); | |
220 | bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); | |
221 | error = -EIO; | |
222 | if (!bh) | |
223 | goto cleanup; | |
224 | ea_bdebug(bh, "b_count=%d, refcount=%d", | |
225 | atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); | |
226 | end = bh->b_data + bh->b_size; | |
02475de9 CX |
227 | if (!ext2_xattr_header_valid(HDR(bh))) { |
228 | bad_block: | |
229 | ext2_error(inode->i_sb, "ext2_xattr_get", | |
1da177e4 LT |
230 | "inode %ld: bad block %d", inode->i_ino, |
231 | EXT2_I(inode)->i_file_acl); | |
232 | error = -EIO; | |
233 | goto cleanup; | |
234 | } | |
1da177e4 | 235 | |
03b5bb34 | 236 | /* find named attribute */ |
1da177e4 LT |
237 | entry = FIRST_ENTRY(bh); |
238 | while (!IS_LAST_ENTRY(entry)) { | |
9bb1d7a6 CX |
239 | if (!ext2_xattr_entry_valid(entry, end, |
240 | inode->i_sb->s_blocksize)) | |
6c71b489 | 241 | goto bad_block; |
1eaf5faa CX |
242 | |
243 | not_found = ext2_xattr_cmp_entry(name_index, name_len, name, | |
244 | entry); | |
245 | if (!not_found) | |
1da177e4 | 246 | goto found; |
1eaf5faa CX |
247 | if (not_found < 0) |
248 | break; | |
249 | ||
9bb1d7a6 | 250 | entry = EXT2_XATTR_NEXT(entry); |
1da177e4 | 251 | } |
47387409 | 252 | if (ext2_xattr_cache_insert(ea_block_cache, bh)) |
1da177e4 LT |
253 | ea_idebug(inode, "cache insert failed"); |
254 | error = -ENODATA; | |
255 | goto cleanup; | |
256 | found: | |
f4c3fb8c | 257 | size = le32_to_cpu(entry->e_value_size); |
47387409 | 258 | if (ext2_xattr_cache_insert(ea_block_cache, bh)) |
1da177e4 LT |
259 | ea_idebug(inode, "cache insert failed"); |
260 | if (buffer) { | |
261 | error = -ERANGE; | |
262 | if (size > buffer_size) | |
263 | goto cleanup; | |
264 | /* return value of attribute */ | |
265 | memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), | |
266 | size); | |
267 | } | |
268 | error = size; | |
269 | ||
270 | cleanup: | |
271 | brelse(bh); | |
272 | up_read(&EXT2_I(inode)->xattr_sem); | |
273 | ||
274 | return error; | |
275 | } | |
276 | ||
277 | /* | |
278 | * ext2_xattr_list() | |
279 | * | |
280 | * Copy a list of attribute names into the buffer | |
281 | * provided, or compute the buffer size required. | |
282 | * Buffer is NULL to compute the size of the buffer required. | |
283 | * | |
284 | * Returns a negative error number on failure, or the number of bytes | |
285 | * used / required on success. | |
286 | */ | |
287 | static int | |
431547b3 | 288 | ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) |
1da177e4 | 289 | { |
2b0143b5 | 290 | struct inode *inode = d_inode(dentry); |
1da177e4 LT |
291 | struct buffer_head *bh = NULL; |
292 | struct ext2_xattr_entry *entry; | |
293 | char *end; | |
294 | size_t rest = buffer_size; | |
295 | int error; | |
47387409 | 296 | struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); |
1da177e4 LT |
297 | |
298 | ea_idebug(inode, "buffer=%p, buffer_size=%ld", | |
299 | buffer, (long)buffer_size); | |
300 | ||
301 | down_read(&EXT2_I(inode)->xattr_sem); | |
302 | error = 0; | |
303 | if (!EXT2_I(inode)->i_file_acl) | |
304 | goto cleanup; | |
305 | ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); | |
306 | bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); | |
307 | error = -EIO; | |
308 | if (!bh) | |
309 | goto cleanup; | |
310 | ea_bdebug(bh, "b_count=%d, refcount=%d", | |
311 | atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); | |
312 | end = bh->b_data + bh->b_size; | |
02475de9 CX |
313 | if (!ext2_xattr_header_valid(HDR(bh))) { |
314 | bad_block: | |
315 | ext2_error(inode->i_sb, "ext2_xattr_list", | |
1da177e4 LT |
316 | "inode %ld: bad block %d", inode->i_ino, |
317 | EXT2_I(inode)->i_file_acl); | |
318 | error = -EIO; | |
319 | goto cleanup; | |
320 | } | |
321 | ||
322 | /* check the on-disk data structure */ | |
323 | entry = FIRST_ENTRY(bh); | |
324 | while (!IS_LAST_ENTRY(entry)) { | |
9bb1d7a6 CX |
325 | if (!ext2_xattr_entry_valid(entry, end, |
326 | inode->i_sb->s_blocksize)) | |
6c71b489 | 327 | goto bad_block; |
9bb1d7a6 | 328 | entry = EXT2_XATTR_NEXT(entry); |
1da177e4 | 329 | } |
47387409 | 330 | if (ext2_xattr_cache_insert(ea_block_cache, bh)) |
1da177e4 LT |
331 | ea_idebug(inode, "cache insert failed"); |
332 | ||
333 | /* list the attribute names */ | |
334 | for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); | |
335 | entry = EXT2_XATTR_NEXT(entry)) { | |
749c72ef | 336 | const struct xattr_handler *handler = |
1da177e4 LT |
337 | ext2_xattr_handler(entry->e_name_index); |
338 | ||
764a5c6b AG |
339 | if (handler && (!handler->list || handler->list(dentry))) { |
340 | const char *prefix = handler->prefix ?: handler->name; | |
341 | size_t prefix_len = strlen(prefix); | |
342 | size_t size = prefix_len + entry->e_name_len + 1; | |
343 | ||
1da177e4 LT |
344 | if (buffer) { |
345 | if (size > rest) { | |
346 | error = -ERANGE; | |
347 | goto cleanup; | |
348 | } | |
764a5c6b AG |
349 | memcpy(buffer, prefix, prefix_len); |
350 | buffer += prefix_len; | |
351 | memcpy(buffer, entry->e_name, entry->e_name_len); | |
352 | buffer += entry->e_name_len; | |
353 | *buffer++ = 0; | |
1da177e4 LT |
354 | } |
355 | rest -= size; | |
356 | } | |
357 | } | |
358 | error = buffer_size - rest; /* total size */ | |
359 | ||
360 | cleanup: | |
361 | brelse(bh); | |
362 | up_read(&EXT2_I(inode)->xattr_sem); | |
363 | ||
364 | return error; | |
365 | } | |
366 | ||
367 | /* | |
368 | * Inode operation listxattr() | |
369 | * | |
2b0143b5 | 370 | * d_inode(dentry)->i_mutex: don't care |
1da177e4 LT |
371 | */ |
372 | ssize_t | |
373 | ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) | |
374 | { | |
431547b3 | 375 | return ext2_xattr_list(dentry, buffer, size); |
1da177e4 LT |
376 | } |
377 | ||
378 | /* | |
379 | * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is | |
380 | * not set, set it. | |
381 | */ | |
382 | static void ext2_xattr_update_super_block(struct super_block *sb) | |
383 | { | |
384 | if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) | |
385 | return; | |
386 | ||
c15271f4 | 387 | spin_lock(&EXT2_SB(sb)->s_lock); |
032cdc39 | 388 | ext2_update_dynamic_rev(sb); |
ed2908f3 | 389 | EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); |
c15271f4 | 390 | spin_unlock(&EXT2_SB(sb)->s_lock); |
1da177e4 | 391 | mark_buffer_dirty(EXT2_SB(sb)->s_sbh); |
1da177e4 LT |
392 | } |
393 | ||
394 | /* | |
395 | * ext2_xattr_set() | |
396 | * | |
6e9510b0 | 397 | * Create, replace or remove an extended attribute for this inode. Value |
1da177e4 LT |
398 | * is NULL to remove an existing extended attribute, and non-NULL to |
399 | * either replace an existing extended attribute, or create a new extended | |
400 | * attribute. The flags XATTR_REPLACE and XATTR_CREATE | |
401 | * specify that an extended attribute must exist and must not exist | |
402 | * previous to the call, respectively. | |
403 | * | |
404 | * Returns 0, or a negative error number on failure. | |
405 | */ | |
406 | int | |
407 | ext2_xattr_set(struct inode *inode, int name_index, const char *name, | |
408 | const void *value, size_t value_len, int flags) | |
409 | { | |
410 | struct super_block *sb = inode->i_sb; | |
411 | struct buffer_head *bh = NULL; | |
412 | struct ext2_xattr_header *header = NULL; | |
9bb1d7a6 | 413 | struct ext2_xattr_entry *here = NULL, *last = NULL; |
1da177e4 LT |
414 | size_t name_len, free, min_offs = sb->s_blocksize; |
415 | int not_found = 1, error; | |
416 | char *end; | |
417 | ||
418 | /* | |
419 | * header -- Points either into bh, or to a temporarily | |
420 | * allocated buffer. | |
421 | * here -- The named entry found, or the place for inserting, within | |
422 | * the block pointed to by header. | |
423 | * last -- Points right after the last named entry within the block | |
424 | * pointed to by header. | |
425 | * min_offs -- The offset of the first value (values are aligned | |
426 | * towards the end of the block). | |
427 | * end -- Points right after the block pointed to by header. | |
428 | */ | |
429 | ||
430 | ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", | |
431 | name_index, name, value, (long)value_len); | |
432 | ||
1da177e4 LT |
433 | if (value == NULL) |
434 | value_len = 0; | |
435 | if (name == NULL) | |
436 | return -EINVAL; | |
437 | name_len = strlen(name); | |
438 | if (name_len > 255 || value_len > sb->s_blocksize) | |
439 | return -ERANGE; | |
1197d04f CX |
440 | error = dquot_initialize(inode); |
441 | if (error) | |
442 | return error; | |
1da177e4 LT |
443 | down_write(&EXT2_I(inode)->xattr_sem); |
444 | if (EXT2_I(inode)->i_file_acl) { | |
445 | /* The inode already has an extended attribute block. */ | |
446 | bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); | |
447 | error = -EIO; | |
448 | if (!bh) | |
449 | goto cleanup; | |
450 | ea_bdebug(bh, "b_count=%d, refcount=%d", | |
451 | atomic_read(&(bh->b_count)), | |
452 | le32_to_cpu(HDR(bh)->h_refcount)); | |
453 | header = HDR(bh); | |
454 | end = bh->b_data + bh->b_size; | |
02475de9 CX |
455 | if (!ext2_xattr_header_valid(header)) { |
456 | bad_block: | |
457 | ext2_error(sb, "ext2_xattr_set", | |
1da177e4 LT |
458 | "inode %ld: bad block %d", inode->i_ino, |
459 | EXT2_I(inode)->i_file_acl); | |
460 | error = -EIO; | |
461 | goto cleanup; | |
462 | } | |
8cd0f2ba JK |
463 | /* |
464 | * Find the named attribute. If not found, 'here' will point | |
465 | * to entry where the new attribute should be inserted to | |
466 | * maintain sorting. | |
467 | */ | |
468 | last = FIRST_ENTRY(bh); | |
1da177e4 | 469 | while (!IS_LAST_ENTRY(last)) { |
9bb1d7a6 | 470 | if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize)) |
6c71b489 JK |
471 | goto bad_block; |
472 | if (last->e_value_size) { | |
1da177e4 LT |
473 | size_t offs = le16_to_cpu(last->e_value_offs); |
474 | if (offs < min_offs) | |
475 | min_offs = offs; | |
476 | } | |
8cd0f2ba | 477 | if (not_found > 0) { |
d561d4dd CX |
478 | not_found = ext2_xattr_cmp_entry(name_index, |
479 | name_len, | |
480 | name, last); | |
8cd0f2ba JK |
481 | if (not_found <= 0) |
482 | here = last; | |
483 | } | |
9bb1d7a6 | 484 | last = EXT2_XATTR_NEXT(last); |
1da177e4 | 485 | } |
8cd0f2ba JK |
486 | if (not_found > 0) |
487 | here = last; | |
1da177e4 LT |
488 | |
489 | /* Check whether we have enough space left. */ | |
490 | free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); | |
491 | } else { | |
492 | /* We will use a new extended attribute block. */ | |
493 | free = sb->s_blocksize - | |
494 | sizeof(struct ext2_xattr_header) - sizeof(__u32); | |
1da177e4 LT |
495 | } |
496 | ||
497 | if (not_found) { | |
498 | /* Request to remove a nonexistent attribute? */ | |
499 | error = -ENODATA; | |
500 | if (flags & XATTR_REPLACE) | |
501 | goto cleanup; | |
502 | error = 0; | |
503 | if (value == NULL) | |
504 | goto cleanup; | |
505 | } else { | |
506 | /* Request to create an existing attribute? */ | |
507 | error = -EEXIST; | |
508 | if (flags & XATTR_CREATE) | |
509 | goto cleanup; | |
6c71b489 | 510 | free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size)); |
1da177e4 LT |
511 | free += EXT2_XATTR_LEN(name_len); |
512 | } | |
513 | error = -ENOSPC; | |
514 | if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) | |
515 | goto cleanup; | |
516 | ||
517 | /* Here we know that we can set the new attribute. */ | |
518 | ||
519 | if (header) { | |
1da177e4 | 520 | /* assert(header == HDR(bh)); */ |
1da177e4 LT |
521 | lock_buffer(bh); |
522 | if (header->h_refcount == cpu_to_le32(1)) { | |
be0726d3 JK |
523 | __u32 hash = le32_to_cpu(header->h_hash); |
524 | ||
1da177e4 | 525 | ea_bdebug(bh, "modifying in-place"); |
be0726d3 JK |
526 | /* |
527 | * This must happen under buffer lock for | |
528 | * ext2_xattr_set2() to reliably detect modified block | |
529 | */ | |
47387409 | 530 | mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, |
c07dfcb4 | 531 | bh->b_blocknr); |
be0726d3 | 532 | |
1da177e4 LT |
533 | /* keep the buffer locked while modifying it. */ |
534 | } else { | |
535 | int offset; | |
536 | ||
1da177e4 LT |
537 | unlock_buffer(bh); |
538 | ea_bdebug(bh, "cloning"); | |
90f15ac9 | 539 | header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL); |
1da177e4 LT |
540 | error = -ENOMEM; |
541 | if (header == NULL) | |
542 | goto cleanup; | |
1da177e4 LT |
543 | header->h_refcount = cpu_to_le32(1); |
544 | ||
545 | offset = (char *)here - bh->b_data; | |
546 | here = ENTRY((char *)header + offset); | |
547 | offset = (char *)last - bh->b_data; | |
548 | last = ENTRY((char *)header + offset); | |
549 | } | |
550 | } else { | |
551 | /* Allocate a buffer where we construct the new block. */ | |
f8314dc6 | 552 | header = kzalloc(sb->s_blocksize, GFP_KERNEL); |
1da177e4 LT |
553 | error = -ENOMEM; |
554 | if (header == NULL) | |
555 | goto cleanup; | |
1da177e4 LT |
556 | end = (char *)header + sb->s_blocksize; |
557 | header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); | |
558 | header->h_blocks = header->h_refcount = cpu_to_le32(1); | |
559 | last = here = ENTRY(header+1); | |
560 | } | |
561 | ||
562 | /* Iff we are modifying the block in-place, bh is locked here. */ | |
563 | ||
564 | if (not_found) { | |
565 | /* Insert the new name. */ | |
566 | size_t size = EXT2_XATTR_LEN(name_len); | |
567 | size_t rest = (char *)last - (char *)here; | |
568 | memmove((char *)here + size, here, rest); | |
569 | memset(here, 0, size); | |
570 | here->e_name_index = name_index; | |
571 | here->e_name_len = name_len; | |
572 | memcpy(here->e_name, name, name_len); | |
573 | } else { | |
6c71b489 | 574 | if (here->e_value_size) { |
1da177e4 LT |
575 | char *first_val = (char *)header + min_offs; |
576 | size_t offs = le16_to_cpu(here->e_value_offs); | |
577 | char *val = (char *)header + offs; | |
578 | size_t size = EXT2_XATTR_SIZE( | |
579 | le32_to_cpu(here->e_value_size)); | |
580 | ||
581 | if (size == EXT2_XATTR_SIZE(value_len)) { | |
582 | /* The old and the new value have the same | |
583 | size. Just replace. */ | |
584 | here->e_value_size = cpu_to_le32(value_len); | |
585 | memset(val + size - EXT2_XATTR_PAD, 0, | |
586 | EXT2_XATTR_PAD); /* Clear pad bytes. */ | |
587 | memcpy(val, value, value_len); | |
588 | goto skip_replace; | |
589 | } | |
590 | ||
591 | /* Remove the old value. */ | |
592 | memmove(first_val + size, first_val, val - first_val); | |
593 | memset(first_val, 0, size); | |
1da177e4 LT |
594 | min_offs += size; |
595 | ||
596 | /* Adjust all value offsets. */ | |
597 | last = ENTRY(header+1); | |
598 | while (!IS_LAST_ENTRY(last)) { | |
599 | size_t o = le16_to_cpu(last->e_value_offs); | |
6c71b489 | 600 | if (o < offs) |
1da177e4 LT |
601 | last->e_value_offs = |
602 | cpu_to_le16(o + size); | |
603 | last = EXT2_XATTR_NEXT(last); | |
604 | } | |
1fcbcf06 CX |
605 | |
606 | here->e_value_offs = 0; | |
1da177e4 LT |
607 | } |
608 | if (value == NULL) { | |
609 | /* Remove the old name. */ | |
610 | size_t size = EXT2_XATTR_LEN(name_len); | |
611 | last = ENTRY((char *)last - size); | |
612 | memmove(here, (char*)here + size, | |
613 | (char*)last - (char*)here); | |
614 | memset(last, 0, size); | |
615 | } | |
616 | } | |
617 | ||
618 | if (value != NULL) { | |
619 | /* Insert the new value. */ | |
620 | here->e_value_size = cpu_to_le32(value_len); | |
621 | if (value_len) { | |
622 | size_t size = EXT2_XATTR_SIZE(value_len); | |
623 | char *val = (char *)header + min_offs - size; | |
624 | here->e_value_offs = | |
625 | cpu_to_le16((char *)val - (char *)header); | |
626 | memset(val + size - EXT2_XATTR_PAD, 0, | |
627 | EXT2_XATTR_PAD); /* Clear the pad bytes. */ | |
628 | memcpy(val, value, value_len); | |
629 | } | |
630 | } | |
631 | ||
632 | skip_replace: | |
633 | if (IS_LAST_ENTRY(ENTRY(header+1))) { | |
634 | /* This block is now empty. */ | |
635 | if (bh && header == HDR(bh)) | |
636 | unlock_buffer(bh); /* we were modifying in-place. */ | |
637 | error = ext2_xattr_set2(inode, bh, NULL); | |
638 | } else { | |
639 | ext2_xattr_rehash(header, here); | |
640 | if (bh && header == HDR(bh)) | |
641 | unlock_buffer(bh); /* we were modifying in-place. */ | |
642 | error = ext2_xattr_set2(inode, bh, header); | |
643 | } | |
644 | ||
645 | cleanup: | |
1da177e4 LT |
646 | if (!(bh && header == HDR(bh))) |
647 | kfree(header); | |
ecebf55d | 648 | brelse(bh); |
1da177e4 LT |
649 | up_write(&EXT2_I(inode)->xattr_sem); |
650 | ||
651 | return error; | |
652 | } | |
653 | ||
654 | /* | |
655 | * Second half of ext2_xattr_set(): Update the file system. | |
656 | */ | |
657 | static int | |
658 | ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, | |
659 | struct ext2_xattr_header *header) | |
660 | { | |
661 | struct super_block *sb = inode->i_sb; | |
662 | struct buffer_head *new_bh = NULL; | |
663 | int error; | |
47387409 | 664 | struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); |
1da177e4 LT |
665 | |
666 | if (header) { | |
667 | new_bh = ext2_xattr_cache_find(inode, header); | |
668 | if (new_bh) { | |
669 | /* We found an identical block in the cache. */ | |
670 | if (new_bh == old_bh) { | |
671 | ea_bdebug(new_bh, "keeping this block"); | |
672 | } else { | |
673 | /* The old block is released after updating | |
674 | the inode. */ | |
675 | ea_bdebug(new_bh, "reusing block"); | |
676 | ||
5dd4056d CH |
677 | error = dquot_alloc_block(inode, 1); |
678 | if (error) { | |
1da177e4 LT |
679 | unlock_buffer(new_bh); |
680 | goto cleanup; | |
681 | } | |
fba4d399 | 682 | le32_add_cpu(&HDR(new_bh)->h_refcount, 1); |
1da177e4 LT |
683 | ea_bdebug(new_bh, "refcount now=%d", |
684 | le32_to_cpu(HDR(new_bh)->h_refcount)); | |
685 | } | |
686 | unlock_buffer(new_bh); | |
687 | } else if (old_bh && header == HDR(old_bh)) { | |
688 | /* Keep this block. No need to lock the block as we | |
689 | don't need to change the reference count. */ | |
690 | new_bh = old_bh; | |
691 | get_bh(new_bh); | |
47387409 | 692 | ext2_xattr_cache_insert(ea_block_cache, new_bh); |
1da177e4 LT |
693 | } else { |
694 | /* We need to allocate a new block */ | |
24097d12 AM |
695 | ext2_fsblk_t goal = ext2_group_first_block_no(sb, |
696 | EXT2_I(inode)->i_block_group); | |
a686cd89 | 697 | int block = ext2_new_block(inode, goal, &error); |
1da177e4 LT |
698 | if (error) |
699 | goto cleanup; | |
700 | ea_idebug(inode, "creating block %d", block); | |
701 | ||
702 | new_bh = sb_getblk(sb, block); | |
2b0542a4 | 703 | if (unlikely(!new_bh)) { |
1da177e4 | 704 | ext2_free_blocks(inode, block, 1); |
addacc7d | 705 | mark_inode_dirty(inode); |
ab6a773d | 706 | error = -ENOMEM; |
1da177e4 LT |
707 | goto cleanup; |
708 | } | |
709 | lock_buffer(new_bh); | |
710 | memcpy(new_bh->b_data, header, new_bh->b_size); | |
711 | set_buffer_uptodate(new_bh); | |
712 | unlock_buffer(new_bh); | |
47387409 | 713 | ext2_xattr_cache_insert(ea_block_cache, new_bh); |
1da177e4 LT |
714 | |
715 | ext2_xattr_update_super_block(sb); | |
716 | } | |
717 | mark_buffer_dirty(new_bh); | |
718 | if (IS_SYNC(inode)) { | |
719 | sync_dirty_buffer(new_bh); | |
720 | error = -EIO; | |
721 | if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) | |
722 | goto cleanup; | |
723 | } | |
724 | } | |
725 | ||
726 | /* Update the inode. */ | |
727 | EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; | |
02027d42 | 728 | inode->i_ctime = current_time(inode); |
1da177e4 | 729 | if (IS_SYNC(inode)) { |
c3765016 | 730 | error = sync_inode_metadata(inode, 1); |
1da177e4 LT |
731 | /* In case sync failed due to ENOSPC the inode was actually |
732 | * written (only some dirty data were not) so we just proceed | |
733 | * as if nothing happened and cleanup the unused block */ | |
734 | if (error && error != -ENOSPC) { | |
3889717d AV |
735 | if (new_bh && new_bh != old_bh) { |
736 | dquot_free_block_nodirty(inode, 1); | |
737 | mark_inode_dirty(inode); | |
738 | } | |
1da177e4 LT |
739 | goto cleanup; |
740 | } | |
741 | } else | |
742 | mark_inode_dirty(inode); | |
743 | ||
744 | error = 0; | |
745 | if (old_bh && old_bh != new_bh) { | |
1da177e4 LT |
746 | /* |
747 | * If there was an old block and we are no longer using it, | |
748 | * release the old block. | |
749 | */ | |
1da177e4 LT |
750 | lock_buffer(old_bh); |
751 | if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { | |
be0726d3 JK |
752 | __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash); |
753 | ||
754 | /* | |
755 | * This must happen under buffer lock for | |
756 | * ext2_xattr_set2() to reliably detect freed block | |
757 | */ | |
47387409 | 758 | mb_cache_entry_delete(ea_block_cache, hash, |
c07dfcb4 | 759 | old_bh->b_blocknr); |
1da177e4 | 760 | /* Free the old block. */ |
1da177e4 LT |
761 | ea_bdebug(old_bh, "freeing"); |
762 | ext2_free_blocks(inode, old_bh->b_blocknr, 1); | |
addacc7d | 763 | mark_inode_dirty(inode); |
1da177e4 LT |
764 | /* We let our caller release old_bh, so we |
765 | * need to duplicate the buffer before. */ | |
766 | get_bh(old_bh); | |
767 | bforget(old_bh); | |
768 | } else { | |
769 | /* Decrement the refcount only. */ | |
fba4d399 | 770 | le32_add_cpu(&HDR(old_bh)->h_refcount, -1); |
3889717d AV |
771 | dquot_free_block_nodirty(inode, 1); |
772 | mark_inode_dirty(inode); | |
1da177e4 LT |
773 | mark_buffer_dirty(old_bh); |
774 | ea_bdebug(old_bh, "refcount now=%d", | |
775 | le32_to_cpu(HDR(old_bh)->h_refcount)); | |
776 | } | |
777 | unlock_buffer(old_bh); | |
778 | } | |
779 | ||
780 | cleanup: | |
781 | brelse(new_bh); | |
782 | ||
783 | return error; | |
784 | } | |
785 | ||
786 | /* | |
787 | * ext2_xattr_delete_inode() | |
788 | * | |
789 | * Free extended attribute resources associated with this inode. This | |
790 | * is called immediately before an inode is freed. | |
791 | */ | |
792 | void | |
793 | ext2_xattr_delete_inode(struct inode *inode) | |
794 | { | |
795 | struct buffer_head *bh = NULL; | |
ff0031d8 | 796 | struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb); |
1da177e4 | 797 | |
bc36dfff JK |
798 | /* |
799 | * We are the only ones holding inode reference. The xattr_sem should | |
800 | * better be unlocked! We could as well just not acquire xattr_sem at | |
801 | * all but this makes the code more futureproof. OTOH we need trylock | |
802 | * here to avoid false-positive warning from lockdep about reclaim | |
803 | * circular dependency. | |
804 | */ | |
805 | if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem))) | |
806 | return; | |
1da177e4 LT |
807 | if (!EXT2_I(inode)->i_file_acl) |
808 | goto cleanup; | |
ff0031d8 | 809 | |
e5d39597 | 810 | if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) { |
ff0031d8 CM |
811 | ext2_error(inode->i_sb, "ext2_xattr_delete_inode", |
812 | "inode %ld: xattr block %d is out of data blocks range", | |
813 | inode->i_ino, EXT2_I(inode)->i_file_acl); | |
814 | goto cleanup; | |
815 | } | |
816 | ||
1da177e4 LT |
817 | bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); |
818 | if (!bh) { | |
819 | ext2_error(inode->i_sb, "ext2_xattr_delete_inode", | |
820 | "inode %ld: block %d read error", inode->i_ino, | |
821 | EXT2_I(inode)->i_file_acl); | |
822 | goto cleanup; | |
823 | } | |
824 | ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); | |
02475de9 | 825 | if (!ext2_xattr_header_valid(HDR(bh))) { |
1da177e4 LT |
826 | ext2_error(inode->i_sb, "ext2_xattr_delete_inode", |
827 | "inode %ld: bad block %d", inode->i_ino, | |
828 | EXT2_I(inode)->i_file_acl); | |
829 | goto cleanup; | |
830 | } | |
1da177e4 LT |
831 | lock_buffer(bh); |
832 | if (HDR(bh)->h_refcount == cpu_to_le32(1)) { | |
be0726d3 JK |
833 | __u32 hash = le32_to_cpu(HDR(bh)->h_hash); |
834 | ||
835 | /* | |
836 | * This must happen under buffer lock for ext2_xattr_set2() to | |
837 | * reliably detect freed block | |
838 | */ | |
47387409 | 839 | mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, |
c07dfcb4 | 840 | bh->b_blocknr); |
1da177e4 LT |
841 | ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); |
842 | get_bh(bh); | |
843 | bforget(bh); | |
b2f49033 | 844 | unlock_buffer(bh); |
1da177e4 | 845 | } else { |
fba4d399 | 846 | le32_add_cpu(&HDR(bh)->h_refcount, -1); |
b2f49033 PS |
847 | ea_bdebug(bh, "refcount now=%d", |
848 | le32_to_cpu(HDR(bh)->h_refcount)); | |
849 | unlock_buffer(bh); | |
1da177e4 LT |
850 | mark_buffer_dirty(bh); |
851 | if (IS_SYNC(inode)) | |
852 | sync_dirty_buffer(bh); | |
3889717d | 853 | dquot_free_block_nodirty(inode, 1); |
1da177e4 | 854 | } |
1da177e4 LT |
855 | EXT2_I(inode)->i_file_acl = 0; |
856 | ||
857 | cleanup: | |
858 | brelse(bh); | |
859 | up_write(&EXT2_I(inode)->xattr_sem); | |
860 | } | |
861 | ||
1da177e4 LT |
862 | /* |
863 | * ext2_xattr_cache_insert() | |
864 | * | |
865 | * Create a new entry in the extended attribute cache, and insert | |
866 | * it unless such an entry is already in the cache. | |
867 | * | |
868 | * Returns 0, or a negative error number on failure. | |
869 | */ | |
870 | static int | |
7a2508e1 | 871 | ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) |
1da177e4 LT |
872 | { |
873 | __u32 hash = le32_to_cpu(HDR(bh)->h_hash); | |
1da177e4 LT |
874 | int error; |
875 | ||
3e159b95 CX |
876 | error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, |
877 | true); | |
1da177e4 | 878 | if (error) { |
1da177e4 | 879 | if (error == -EBUSY) { |
32302085 | 880 | ea_bdebug(bh, "already in cache"); |
1da177e4 LT |
881 | error = 0; |
882 | } | |
be0726d3 JK |
883 | } else |
884 | ea_bdebug(bh, "inserting [%x]", (int)hash); | |
1da177e4 LT |
885 | return error; |
886 | } | |
887 | ||
888 | /* | |
889 | * ext2_xattr_cmp() | |
890 | * | |
891 | * Compare two extended attribute blocks for equality. | |
892 | * | |
893 | * Returns 0 if the blocks are equal, 1 if they differ, and | |
894 | * a negative error number on errors. | |
895 | */ | |
896 | static int | |
897 | ext2_xattr_cmp(struct ext2_xattr_header *header1, | |
898 | struct ext2_xattr_header *header2) | |
899 | { | |
900 | struct ext2_xattr_entry *entry1, *entry2; | |
901 | ||
902 | entry1 = ENTRY(header1+1); | |
903 | entry2 = ENTRY(header2+1); | |
904 | while (!IS_LAST_ENTRY(entry1)) { | |
905 | if (IS_LAST_ENTRY(entry2)) | |
906 | return 1; | |
907 | if (entry1->e_hash != entry2->e_hash || | |
908 | entry1->e_name_index != entry2->e_name_index || | |
909 | entry1->e_name_len != entry2->e_name_len || | |
910 | entry1->e_value_size != entry2->e_value_size || | |
911 | memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) | |
912 | return 1; | |
913 | if (entry1->e_value_block != 0 || entry2->e_value_block != 0) | |
914 | return -EIO; | |
915 | if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), | |
916 | (char *)header2 + le16_to_cpu(entry2->e_value_offs), | |
917 | le32_to_cpu(entry1->e_value_size))) | |
918 | return 1; | |
919 | ||
920 | entry1 = EXT2_XATTR_NEXT(entry1); | |
921 | entry2 = EXT2_XATTR_NEXT(entry2); | |
922 | } | |
923 | if (!IS_LAST_ENTRY(entry2)) | |
924 | return 1; | |
925 | return 0; | |
926 | } | |
927 | ||
928 | /* | |
929 | * ext2_xattr_cache_find() | |
930 | * | |
931 | * Find an identical extended attribute block. | |
932 | * | |
933 | * Returns a locked buffer head to the block found, or NULL if such | |
934 | * a block was not found or an error occurred. | |
935 | */ | |
936 | static struct buffer_head * | |
937 | ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) | |
938 | { | |
939 | __u32 hash = le32_to_cpu(header->h_hash); | |
7a2508e1 | 940 | struct mb_cache_entry *ce; |
47387409 | 941 | struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); |
1da177e4 LT |
942 | |
943 | if (!header->h_hash) | |
944 | return NULL; /* never share */ | |
945 | ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); | |
946 | again: | |
47387409 | 947 | ce = mb_cache_entry_find_first(ea_block_cache, hash); |
1da177e4 LT |
948 | while (ce) { |
949 | struct buffer_head *bh; | |
950 | ||
c07dfcb4 | 951 | bh = sb_bread(inode->i_sb, ce->e_value); |
1da177e4 LT |
952 | if (!bh) { |
953 | ext2_error(inode->i_sb, "ext2_xattr_cache_find", | |
954 | "inode %ld: block %ld read error", | |
c07dfcb4 | 955 | inode->i_ino, (unsigned long) ce->e_value); |
1da177e4 LT |
956 | } else { |
957 | lock_buffer(bh); | |
be0726d3 JK |
958 | /* |
959 | * We have to be careful about races with freeing or | |
960 | * rehashing of xattr block. Once we hold buffer lock | |
961 | * xattr block's state is stable so we can check | |
962 | * whether the block got freed / rehashed or not. | |
963 | * Since we unhash mbcache entry under buffer lock when | |
964 | * freeing / rehashing xattr block, checking whether | |
965 | * entry is still hashed is reliable. | |
966 | */ | |
967 | if (hlist_bl_unhashed(&ce->e_hash_list)) { | |
47387409 | 968 | mb_cache_entry_put(ea_block_cache, ce); |
be0726d3 JK |
969 | unlock_buffer(bh); |
970 | brelse(bh); | |
971 | goto again; | |
972 | } else if (le32_to_cpu(HDR(bh)->h_refcount) > | |
1da177e4 LT |
973 | EXT2_XATTR_REFCOUNT_MAX) { |
974 | ea_idebug(inode, "block %ld refcount %d>%d", | |
c07dfcb4 | 975 | (unsigned long) ce->e_value, |
1da177e4 LT |
976 | le32_to_cpu(HDR(bh)->h_refcount), |
977 | EXT2_XATTR_REFCOUNT_MAX); | |
978 | } else if (!ext2_xattr_cmp(header, HDR(bh))) { | |
979 | ea_bdebug(bh, "b_count=%d", | |
980 | atomic_read(&(bh->b_count))); | |
47387409 TE |
981 | mb_cache_entry_touch(ea_block_cache, ce); |
982 | mb_cache_entry_put(ea_block_cache, ce); | |
1da177e4 LT |
983 | return bh; |
984 | } | |
985 | unlock_buffer(bh); | |
986 | brelse(bh); | |
987 | } | |
47387409 | 988 | ce = mb_cache_entry_find_next(ea_block_cache, ce); |
1da177e4 LT |
989 | } |
990 | return NULL; | |
991 | } | |
992 | ||
993 | #define NAME_HASH_SHIFT 5 | |
994 | #define VALUE_HASH_SHIFT 16 | |
995 | ||
996 | /* | |
997 | * ext2_xattr_hash_entry() | |
998 | * | |
999 | * Compute the hash of an extended attribute. | |
1000 | */ | |
1001 | static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, | |
1002 | struct ext2_xattr_entry *entry) | |
1003 | { | |
1004 | __u32 hash = 0; | |
1005 | char *name = entry->e_name; | |
1006 | int n; | |
1007 | ||
1008 | for (n=0; n < entry->e_name_len; n++) { | |
1009 | hash = (hash << NAME_HASH_SHIFT) ^ | |
1010 | (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ | |
1011 | *name++; | |
1012 | } | |
1013 | ||
1014 | if (entry->e_value_block == 0 && entry->e_value_size != 0) { | |
1015 | __le32 *value = (__le32 *)((char *)header + | |
1016 | le16_to_cpu(entry->e_value_offs)); | |
1017 | for (n = (le32_to_cpu(entry->e_value_size) + | |
1018 | EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { | |
1019 | hash = (hash << VALUE_HASH_SHIFT) ^ | |
1020 | (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ | |
1021 | le32_to_cpu(*value++); | |
1022 | } | |
1023 | } | |
1024 | entry->e_hash = cpu_to_le32(hash); | |
1025 | } | |
1026 | ||
1027 | #undef NAME_HASH_SHIFT | |
1028 | #undef VALUE_HASH_SHIFT | |
1029 | ||
1030 | #define BLOCK_HASH_SHIFT 16 | |
1031 | ||
1032 | /* | |
1033 | * ext2_xattr_rehash() | |
1034 | * | |
1035 | * Re-compute the extended attribute hash value after an entry has changed. | |
1036 | */ | |
1037 | static void ext2_xattr_rehash(struct ext2_xattr_header *header, | |
1038 | struct ext2_xattr_entry *entry) | |
1039 | { | |
1040 | struct ext2_xattr_entry *here; | |
1041 | __u32 hash = 0; | |
1042 | ||
1043 | ext2_xattr_hash_entry(header, entry); | |
1044 | here = ENTRY(header+1); | |
1045 | while (!IS_LAST_ENTRY(here)) { | |
1046 | if (!here->e_hash) { | |
1047 | /* Block is not shared if an entry's hash value == 0 */ | |
1048 | hash = 0; | |
1049 | break; | |
1050 | } | |
1051 | hash = (hash << BLOCK_HASH_SHIFT) ^ | |
1052 | (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ | |
1053 | le32_to_cpu(here->e_hash); | |
1054 | here = EXT2_XATTR_NEXT(here); | |
1055 | } | |
1056 | header->h_hash = cpu_to_le32(hash); | |
1057 | } | |
1058 | ||
1059 | #undef BLOCK_HASH_SHIFT | |
1060 | ||
be0726d3 JK |
1061 | #define HASH_BUCKET_BITS 10 |
1062 | ||
7a2508e1 | 1063 | struct mb_cache *ext2_xattr_create_cache(void) |
1da177e4 | 1064 | { |
7a2508e1 | 1065 | return mb_cache_create(HASH_BUCKET_BITS); |
1da177e4 LT |
1066 | } |
1067 | ||
7a2508e1 | 1068 | void ext2_xattr_destroy_cache(struct mb_cache *cache) |
1da177e4 | 1069 | { |
be0726d3 | 1070 | if (cache) |
7a2508e1 | 1071 | mb_cache_destroy(cache); |
1da177e4 | 1072 | } |