blob: 6dcafc7efdfdb26c989f802c646a8b943adb93a3 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/ext2/xattr.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
5 *
6 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
7 * Extended attributes for symlinks and special files added per
8 * suggestion of Luka Renko <luka.renko@hermes.si>.
9 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
10 * Red Hat Inc.
11 *
12 */
13
14/*
15 * Extended attributes are stored on disk blocks allocated outside of
16 * any inode. The i_file_acl field is then made to point to this allocated
17 * block. If all extended attributes of an inode are identical, these
18 * inodes may share the same extended attribute block. Such situations
19 * are automatically detected by keeping a cache of recent attribute block
20 * numbers and hashes over the block's contents in memory.
21 *
22 *
23 * Extended attribute block layout:
24 *
25 * +------------------+
26 * | header |
27 * | entry 1 | |
28 * | entry 2 | | growing downwards
29 * | entry 3 | v
30 * | four null bytes |
31 * | . . . |
32 * | value 1 | ^
33 * | value 3 | | growing upwards
34 * | value 2 | |
35 * +------------------+
36 *
37 * The block header is followed by multiple entry descriptors. These entry
Lucas De Marchi25985ed2011-03-30 22:57:33 -030038 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 * byte boundaries. The entry descriptors are sorted by attribute name,
40 * so that two extended attribute blocks can be compared efficiently.
41 *
42 * Attribute values are aligned to the end of the block, stored in
43 * no specific order. They are also padded to EXT2_XATTR_PAD byte
44 * boundaries. No additional gaps are left between them.
45 *
46 * Locking strategy
47 * ----------------
48 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.
49 * EA blocks are only changed if they are exclusive to an inode, so
50 * holding xattr_sem also means that nothing but the EA block's reference
51 * count will change. Multiple writers to an EA block are synchronized
52 * by the bh lock. No more than a single bh lock is held at any time
53 * to avoid deadlocks.
54 */
55
56#include <linux/buffer_head.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070057#include <linux/init.h>
58#include <linux/slab.h>
59#include <linux/mbcache.h>
60#include <linux/quotaops.h>
61#include <linux/rwsem.h>
Christoph Hellwig431547b2009-11-13 09:52:56 +000062#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070063#include "ext2.h"
64#include "xattr.h"
65#include "acl.h"
66
67#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
68#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
69#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
70#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
71
72#ifdef EXT2_XATTR_DEBUG
73# define ea_idebug(inode, f...) do { \
74 printk(KERN_DEBUG "inode %s:%ld: ", \
75 inode->i_sb->s_id, inode->i_ino); \
76 printk(f); \
77 printk("\n"); \
78 } while (0)
79# define ea_bdebug(bh, f...) do { \
80 char b[BDEVNAME_SIZE]; \
81 printk(KERN_DEBUG "block %s:%lu: ", \
82 bdevname(bh->b_bdev, b), \
83 (unsigned long) bh->b_blocknr); \
84 printk(f); \
85 printk("\n"); \
86 } while (0)
87#else
88# define ea_idebug(f...)
89# define ea_bdebug(f...)
90#endif
91
92static int ext2_xattr_set2(struct inode *, struct buffer_head *,
93 struct ext2_xattr_header *);
94
95static int ext2_xattr_cache_insert(struct buffer_head *);
96static struct buffer_head *ext2_xattr_cache_find(struct inode *,
97 struct ext2_xattr_header *);
98static void ext2_xattr_rehash(struct ext2_xattr_header *,
99 struct ext2_xattr_entry *);
100
101static struct mb_cache *ext2_xattr_cache;
102
Stephen Hemminger749c72e2010-05-13 17:53:16 -0700103static const struct xattr_handler *ext2_xattr_handler_map[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
105#ifdef CONFIG_EXT2_FS_POSIX_ACL
106 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
107 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
108#endif
109 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
110#ifdef CONFIG_EXT2_FS_SECURITY
111 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
112#endif
113};
114
Stephen Hemminger749c72e2010-05-13 17:53:16 -0700115const struct xattr_handler *ext2_xattr_handlers[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 &ext2_xattr_user_handler,
117 &ext2_xattr_trusted_handler,
118#ifdef CONFIG_EXT2_FS_POSIX_ACL
119 &ext2_xattr_acl_access_handler,
120 &ext2_xattr_acl_default_handler,
121#endif
122#ifdef CONFIG_EXT2_FS_SECURITY
123 &ext2_xattr_security_handler,
124#endif
125 NULL
126};
127
Stephen Hemminger749c72e2010-05-13 17:53:16 -0700128static inline const struct xattr_handler *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129ext2_xattr_handler(int name_index)
130{
Stephen Hemminger749c72e2010-05-13 17:53:16 -0700131 const struct xattr_handler *handler = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
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
138/*
139 * ext2_xattr_get()
140 *
141 * Copy an extended attribute into the buffer
142 * provided, or compute the buffer size required.
143 * Buffer is NULL to compute the size of the buffer required.
144 *
145 * Returns a negative error number on failure, or the number of bytes
146 * used / required on success.
147 */
148int
149ext2_xattr_get(struct inode *inode, int name_index, const char *name,
150 void *buffer, size_t buffer_size)
151{
152 struct buffer_head *bh = NULL;
153 struct ext2_xattr_entry *entry;
154 size_t name_len, size;
155 char *end;
156 int error;
157
158 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
159 name_index, name, buffer, (long)buffer_size);
160
161 if (name == NULL)
162 return -EINVAL;
Wang Sheng-Hui03b5bb32011-07-22 08:50:13 -0500163 name_len = strlen(name);
164 if (name_len > 255)
165 return -ERANGE;
166
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 down_read(&EXT2_I(inode)->xattr_sem);
168 error = -ENODATA;
169 if (!EXT2_I(inode)->i_file_acl)
170 goto cleanup;
171 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
172 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
173 error = -EIO;
174 if (!bh)
175 goto cleanup;
176 ea_bdebug(bh, "b_count=%d, refcount=%d",
177 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
178 end = bh->b_data + bh->b_size;
179 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
180 HDR(bh)->h_blocks != cpu_to_le32(1)) {
181bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
182 "inode %ld: bad block %d", inode->i_ino,
183 EXT2_I(inode)->i_file_acl);
184 error = -EIO;
185 goto cleanup;
186 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Wang Sheng-Hui03b5bb32011-07-22 08:50:13 -0500188 /* find named attribute */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 entry = FIRST_ENTRY(bh);
190 while (!IS_LAST_ENTRY(entry)) {
191 struct ext2_xattr_entry *next =
192 EXT2_XATTR_NEXT(entry);
193 if ((char *)next >= end)
194 goto bad_block;
195 if (name_index == entry->e_name_index &&
196 name_len == entry->e_name_len &&
197 memcmp(name, entry->e_name, name_len) == 0)
198 goto found;
199 entry = next;
200 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 if (ext2_xattr_cache_insert(bh))
202 ea_idebug(inode, "cache insert failed");
203 error = -ENODATA;
204 goto cleanup;
205found:
206 /* check the buffer size */
207 if (entry->e_value_block != 0)
208 goto bad_block;
209 size = le32_to_cpu(entry->e_value_size);
210 if (size > inode->i_sb->s_blocksize ||
211 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
212 goto bad_block;
213
214 if (ext2_xattr_cache_insert(bh))
215 ea_idebug(inode, "cache insert failed");
216 if (buffer) {
217 error = -ERANGE;
218 if (size > buffer_size)
219 goto cleanup;
220 /* return value of attribute */
221 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
222 size);
223 }
224 error = size;
225
226cleanup:
227 brelse(bh);
228 up_read(&EXT2_I(inode)->xattr_sem);
229
230 return error;
231}
232
233/*
234 * ext2_xattr_list()
235 *
236 * Copy a list of attribute names into the buffer
237 * provided, or compute the buffer size required.
238 * Buffer is NULL to compute the size of the buffer required.
239 *
240 * Returns a negative error number on failure, or the number of bytes
241 * used / required on success.
242 */
243static int
Christoph Hellwig431547b2009-11-13 09:52:56 +0000244ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245{
Christoph Hellwig431547b2009-11-13 09:52:56 +0000246 struct inode *inode = dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 struct buffer_head *bh = NULL;
248 struct ext2_xattr_entry *entry;
249 char *end;
250 size_t rest = buffer_size;
251 int error;
252
253 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
254 buffer, (long)buffer_size);
255
256 down_read(&EXT2_I(inode)->xattr_sem);
257 error = 0;
258 if (!EXT2_I(inode)->i_file_acl)
259 goto cleanup;
260 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
261 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
262 error = -EIO;
263 if (!bh)
264 goto cleanup;
265 ea_bdebug(bh, "b_count=%d, refcount=%d",
266 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
267 end = bh->b_data + bh->b_size;
268 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
269 HDR(bh)->h_blocks != cpu_to_le32(1)) {
270bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
271 "inode %ld: bad block %d", inode->i_ino,
272 EXT2_I(inode)->i_file_acl);
273 error = -EIO;
274 goto cleanup;
275 }
276
277 /* check the on-disk data structure */
278 entry = FIRST_ENTRY(bh);
279 while (!IS_LAST_ENTRY(entry)) {
280 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
281
282 if ((char *)next >= end)
283 goto bad_block;
284 entry = next;
285 }
286 if (ext2_xattr_cache_insert(bh))
287 ea_idebug(inode, "cache insert failed");
288
289 /* list the attribute names */
290 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
291 entry = EXT2_XATTR_NEXT(entry)) {
Stephen Hemminger749c72e2010-05-13 17:53:16 -0700292 const struct xattr_handler *handler =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 ext2_xattr_handler(entry->e_name_index);
294
295 if (handler) {
Christoph Hellwig431547b2009-11-13 09:52:56 +0000296 size_t size = handler->list(dentry, buffer, rest,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 entry->e_name,
Christoph Hellwig431547b2009-11-13 09:52:56 +0000298 entry->e_name_len,
299 handler->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 if (buffer) {
301 if (size > rest) {
302 error = -ERANGE;
303 goto cleanup;
304 }
305 buffer += size;
306 }
307 rest -= size;
308 }
309 }
310 error = buffer_size - rest; /* total size */
311
312cleanup:
313 brelse(bh);
314 up_read(&EXT2_I(inode)->xattr_sem);
315
316 return error;
317}
318
319/*
320 * Inode operation listxattr()
321 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800322 * dentry->d_inode->i_mutex: don't care
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 */
324ssize_t
325ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
326{
Christoph Hellwig431547b2009-11-13 09:52:56 +0000327 return ext2_xattr_list(dentry, buffer, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328}
329
330/*
331 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
332 * not set, set it.
333 */
334static void ext2_xattr_update_super_block(struct super_block *sb)
335{
336 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
337 return;
338
Jan Blunckc15271f2010-04-14 14:38:38 +0200339 spin_lock(&EXT2_SB(sb)->s_lock);
Andreas Gruenbachered2908f2006-12-06 20:36:16 -0800340 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
Jan Blunckc15271f2010-04-14 14:38:38 +0200341 spin_unlock(&EXT2_SB(sb)->s_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 sb->s_dirt = 1;
343 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344}
345
346/*
347 * ext2_xattr_set()
348 *
Wang Sheng-Hui6e9510b2011-01-10 12:10:30 -0500349 * Create, replace or remove an extended attribute for this inode. Value
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 * is NULL to remove an existing extended attribute, and non-NULL to
351 * either replace an existing extended attribute, or create a new extended
352 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
353 * specify that an extended attribute must exist and must not exist
354 * previous to the call, respectively.
355 *
356 * Returns 0, or a negative error number on failure.
357 */
358int
359ext2_xattr_set(struct inode *inode, int name_index, const char *name,
360 const void *value, size_t value_len, int flags)
361{
362 struct super_block *sb = inode->i_sb;
363 struct buffer_head *bh = NULL;
364 struct ext2_xattr_header *header = NULL;
365 struct ext2_xattr_entry *here, *last;
366 size_t name_len, free, min_offs = sb->s_blocksize;
367 int not_found = 1, error;
368 char *end;
369
370 /*
371 * header -- Points either into bh, or to a temporarily
372 * allocated buffer.
373 * here -- The named entry found, or the place for inserting, within
374 * the block pointed to by header.
375 * last -- Points right after the last named entry within the block
376 * pointed to by header.
377 * min_offs -- The offset of the first value (values are aligned
378 * towards the end of the block).
379 * end -- Points right after the block pointed to by header.
380 */
381
382 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
383 name_index, name, value, (long)value_len);
384
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 if (value == NULL)
386 value_len = 0;
387 if (name == NULL)
388 return -EINVAL;
389 name_len = strlen(name);
390 if (name_len > 255 || value_len > sb->s_blocksize)
391 return -ERANGE;
392 down_write(&EXT2_I(inode)->xattr_sem);
393 if (EXT2_I(inode)->i_file_acl) {
394 /* The inode already has an extended attribute block. */
395 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
396 error = -EIO;
397 if (!bh)
398 goto cleanup;
399 ea_bdebug(bh, "b_count=%d, refcount=%d",
400 atomic_read(&(bh->b_count)),
401 le32_to_cpu(HDR(bh)->h_refcount));
402 header = HDR(bh);
403 end = bh->b_data + bh->b_size;
404 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
405 header->h_blocks != cpu_to_le32(1)) {
406bad_block: ext2_error(sb, "ext2_xattr_set",
407 "inode %ld: bad block %d", inode->i_ino,
408 EXT2_I(inode)->i_file_acl);
409 error = -EIO;
410 goto cleanup;
411 }
412 /* Find the named attribute. */
413 here = FIRST_ENTRY(bh);
414 while (!IS_LAST_ENTRY(here)) {
415 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
416 if ((char *)next >= end)
417 goto bad_block;
418 if (!here->e_value_block && here->e_value_size) {
419 size_t offs = le16_to_cpu(here->e_value_offs);
420 if (offs < min_offs)
421 min_offs = offs;
422 }
423 not_found = name_index - here->e_name_index;
424 if (!not_found)
425 not_found = name_len - here->e_name_len;
426 if (!not_found)
427 not_found = memcmp(name, here->e_name,name_len);
428 if (not_found <= 0)
429 break;
430 here = next;
431 }
432 last = here;
433 /* We still need to compute min_offs and last. */
434 while (!IS_LAST_ENTRY(last)) {
435 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
436 if ((char *)next >= end)
437 goto bad_block;
438 if (!last->e_value_block && last->e_value_size) {
439 size_t offs = le16_to_cpu(last->e_value_offs);
440 if (offs < min_offs)
441 min_offs = offs;
442 }
443 last = next;
444 }
445
446 /* Check whether we have enough space left. */
447 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
448 } else {
449 /* We will use a new extended attribute block. */
450 free = sb->s_blocksize -
451 sizeof(struct ext2_xattr_header) - sizeof(__u32);
452 here = last = NULL; /* avoid gcc uninitialized warning. */
453 }
454
455 if (not_found) {
456 /* Request to remove a nonexistent attribute? */
457 error = -ENODATA;
458 if (flags & XATTR_REPLACE)
459 goto cleanup;
460 error = 0;
461 if (value == NULL)
462 goto cleanup;
463 } else {
464 /* Request to create an existing attribute? */
465 error = -EEXIST;
466 if (flags & XATTR_CREATE)
467 goto cleanup;
468 if (!here->e_value_block && here->e_value_size) {
469 size_t size = le32_to_cpu(here->e_value_size);
470
471 if (le16_to_cpu(here->e_value_offs) + size >
472 sb->s_blocksize || size > sb->s_blocksize)
473 goto bad_block;
474 free += EXT2_XATTR_SIZE(size);
475 }
476 free += EXT2_XATTR_LEN(name_len);
477 }
478 error = -ENOSPC;
479 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
480 goto cleanup;
481
482 /* Here we know that we can set the new attribute. */
483
484 if (header) {
485 struct mb_cache_entry *ce;
486
487 /* assert(header == HDR(bh)); */
488 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
489 bh->b_blocknr);
490 lock_buffer(bh);
491 if (header->h_refcount == cpu_to_le32(1)) {
492 ea_bdebug(bh, "modifying in-place");
493 if (ce)
494 mb_cache_entry_free(ce);
495 /* keep the buffer locked while modifying it. */
496 } else {
497 int offset;
498
499 if (ce)
500 mb_cache_entry_release(ce);
501 unlock_buffer(bh);
502 ea_bdebug(bh, "cloning");
503 header = kmalloc(bh->b_size, GFP_KERNEL);
504 error = -ENOMEM;
505 if (header == NULL)
506 goto cleanup;
507 memcpy(header, HDR(bh), bh->b_size);
508 header->h_refcount = cpu_to_le32(1);
509
510 offset = (char *)here - bh->b_data;
511 here = ENTRY((char *)header + offset);
512 offset = (char *)last - bh->b_data;
513 last = ENTRY((char *)header + offset);
514 }
515 } else {
516 /* Allocate a buffer where we construct the new block. */
Panagiotis Issarisf8314dc2006-09-27 01:49:37 -0700517 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 error = -ENOMEM;
519 if (header == NULL)
520 goto cleanup;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 end = (char *)header + sb->s_blocksize;
522 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
523 header->h_blocks = header->h_refcount = cpu_to_le32(1);
524 last = here = ENTRY(header+1);
525 }
526
527 /* Iff we are modifying the block in-place, bh is locked here. */
528
529 if (not_found) {
530 /* Insert the new name. */
531 size_t size = EXT2_XATTR_LEN(name_len);
532 size_t rest = (char *)last - (char *)here;
533 memmove((char *)here + size, here, rest);
534 memset(here, 0, size);
535 here->e_name_index = name_index;
536 here->e_name_len = name_len;
537 memcpy(here->e_name, name, name_len);
538 } else {
539 if (!here->e_value_block && here->e_value_size) {
540 char *first_val = (char *)header + min_offs;
541 size_t offs = le16_to_cpu(here->e_value_offs);
542 char *val = (char *)header + offs;
543 size_t size = EXT2_XATTR_SIZE(
544 le32_to_cpu(here->e_value_size));
545
546 if (size == EXT2_XATTR_SIZE(value_len)) {
547 /* The old and the new value have the same
548 size. Just replace. */
549 here->e_value_size = cpu_to_le32(value_len);
550 memset(val + size - EXT2_XATTR_PAD, 0,
551 EXT2_XATTR_PAD); /* Clear pad bytes. */
552 memcpy(val, value, value_len);
553 goto skip_replace;
554 }
555
556 /* Remove the old value. */
557 memmove(first_val + size, first_val, val - first_val);
558 memset(first_val, 0, size);
559 here->e_value_offs = 0;
560 min_offs += size;
561
562 /* Adjust all value offsets. */
563 last = ENTRY(header+1);
564 while (!IS_LAST_ENTRY(last)) {
565 size_t o = le16_to_cpu(last->e_value_offs);
566 if (!last->e_value_block && o < offs)
567 last->e_value_offs =
568 cpu_to_le16(o + size);
569 last = EXT2_XATTR_NEXT(last);
570 }
571 }
572 if (value == NULL) {
573 /* Remove the old name. */
574 size_t size = EXT2_XATTR_LEN(name_len);
575 last = ENTRY((char *)last - size);
576 memmove(here, (char*)here + size,
577 (char*)last - (char*)here);
578 memset(last, 0, size);
579 }
580 }
581
582 if (value != NULL) {
583 /* Insert the new value. */
584 here->e_value_size = cpu_to_le32(value_len);
585 if (value_len) {
586 size_t size = EXT2_XATTR_SIZE(value_len);
587 char *val = (char *)header + min_offs - size;
588 here->e_value_offs =
589 cpu_to_le16((char *)val - (char *)header);
590 memset(val + size - EXT2_XATTR_PAD, 0,
591 EXT2_XATTR_PAD); /* Clear the pad bytes. */
592 memcpy(val, value, value_len);
593 }
594 }
595
596skip_replace:
597 if (IS_LAST_ENTRY(ENTRY(header+1))) {
598 /* This block is now empty. */
599 if (bh && header == HDR(bh))
600 unlock_buffer(bh); /* we were modifying in-place. */
601 error = ext2_xattr_set2(inode, bh, NULL);
602 } else {
603 ext2_xattr_rehash(header, here);
604 if (bh && header == HDR(bh))
605 unlock_buffer(bh); /* we were modifying in-place. */
606 error = ext2_xattr_set2(inode, bh, header);
607 }
608
609cleanup:
610 brelse(bh);
611 if (!(bh && header == HDR(bh)))
612 kfree(header);
613 up_write(&EXT2_I(inode)->xattr_sem);
614
615 return error;
616}
617
618/*
619 * Second half of ext2_xattr_set(): Update the file system.
620 */
621static int
622ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
623 struct ext2_xattr_header *header)
624{
625 struct super_block *sb = inode->i_sb;
626 struct buffer_head *new_bh = NULL;
627 int error;
628
629 if (header) {
630 new_bh = ext2_xattr_cache_find(inode, header);
631 if (new_bh) {
632 /* We found an identical block in the cache. */
633 if (new_bh == old_bh) {
634 ea_bdebug(new_bh, "keeping this block");
635 } else {
636 /* The old block is released after updating
637 the inode. */
638 ea_bdebug(new_bh, "reusing block");
639
Christoph Hellwig5dd40562010-03-03 09:05:00 -0500640 error = dquot_alloc_block(inode, 1);
641 if (error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 unlock_buffer(new_bh);
643 goto cleanup;
644 }
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700645 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646 ea_bdebug(new_bh, "refcount now=%d",
647 le32_to_cpu(HDR(new_bh)->h_refcount));
648 }
649 unlock_buffer(new_bh);
650 } else if (old_bh && header == HDR(old_bh)) {
651 /* Keep this block. No need to lock the block as we
652 don't need to change the reference count. */
653 new_bh = old_bh;
654 get_bh(new_bh);
655 ext2_xattr_cache_insert(new_bh);
656 } else {
657 /* We need to allocate a new block */
Akinobu Mita24097d12008-04-28 02:16:01 -0700658 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
659 EXT2_I(inode)->i_block_group);
Martin J. Bligha686cd82007-10-16 23:30:46 -0700660 int block = ext2_new_block(inode, goal, &error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 if (error)
662 goto cleanup;
663 ea_idebug(inode, "creating block %d", block);
664
665 new_bh = sb_getblk(sb, block);
666 if (!new_bh) {
667 ext2_free_blocks(inode, block, 1);
Al Viroaddacc72010-07-22 01:19:42 +0400668 mark_inode_dirty(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 error = -EIO;
670 goto cleanup;
671 }
672 lock_buffer(new_bh);
673 memcpy(new_bh->b_data, header, new_bh->b_size);
674 set_buffer_uptodate(new_bh);
675 unlock_buffer(new_bh);
676 ext2_xattr_cache_insert(new_bh);
677
678 ext2_xattr_update_super_block(sb);
679 }
680 mark_buffer_dirty(new_bh);
681 if (IS_SYNC(inode)) {
682 sync_dirty_buffer(new_bh);
683 error = -EIO;
684 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
685 goto cleanup;
686 }
687 }
688
689 /* Update the inode. */
690 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
691 inode->i_ctime = CURRENT_TIME_SEC;
692 if (IS_SYNC(inode)) {
Christoph Hellwigc3765012010-10-06 10:48:20 +0200693 error = sync_inode_metadata(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 /* In case sync failed due to ENOSPC the inode was actually
695 * written (only some dirty data were not) so we just proceed
696 * as if nothing happened and cleanup the unused block */
697 if (error && error != -ENOSPC) {
Al Viro38897172010-07-22 01:13:36 +0400698 if (new_bh && new_bh != old_bh) {
699 dquot_free_block_nodirty(inode, 1);
700 mark_inode_dirty(inode);
701 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 goto cleanup;
703 }
704 } else
705 mark_inode_dirty(inode);
706
707 error = 0;
708 if (old_bh && old_bh != new_bh) {
709 struct mb_cache_entry *ce;
710
711 /*
712 * If there was an old block and we are no longer using it,
713 * release the old block.
714 */
715 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
716 old_bh->b_blocknr);
717 lock_buffer(old_bh);
718 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
719 /* Free the old block. */
720 if (ce)
721 mb_cache_entry_free(ce);
722 ea_bdebug(old_bh, "freeing");
723 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
Al Viroaddacc72010-07-22 01:19:42 +0400724 mark_inode_dirty(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 /* We let our caller release old_bh, so we
726 * need to duplicate the buffer before. */
727 get_bh(old_bh);
728 bforget(old_bh);
729 } else {
730 /* Decrement the refcount only. */
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700731 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 if (ce)
733 mb_cache_entry_release(ce);
Al Viro38897172010-07-22 01:13:36 +0400734 dquot_free_block_nodirty(inode, 1);
735 mark_inode_dirty(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 mark_buffer_dirty(old_bh);
737 ea_bdebug(old_bh, "refcount now=%d",
738 le32_to_cpu(HDR(old_bh)->h_refcount));
739 }
740 unlock_buffer(old_bh);
741 }
742
743cleanup:
744 brelse(new_bh);
745
746 return error;
747}
748
749/*
750 * ext2_xattr_delete_inode()
751 *
752 * Free extended attribute resources associated with this inode. This
753 * is called immediately before an inode is freed.
754 */
755void
756ext2_xattr_delete_inode(struct inode *inode)
757{
758 struct buffer_head *bh = NULL;
759 struct mb_cache_entry *ce;
760
761 down_write(&EXT2_I(inode)->xattr_sem);
762 if (!EXT2_I(inode)->i_file_acl)
763 goto cleanup;
764 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
765 if (!bh) {
766 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
767 "inode %ld: block %d read error", inode->i_ino,
768 EXT2_I(inode)->i_file_acl);
769 goto cleanup;
770 }
771 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
772 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
773 HDR(bh)->h_blocks != cpu_to_le32(1)) {
774 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
775 "inode %ld: bad block %d", inode->i_ino,
776 EXT2_I(inode)->i_file_acl);
777 goto cleanup;
778 }
779 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
780 lock_buffer(bh);
781 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
782 if (ce)
783 mb_cache_entry_free(ce);
784 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
785 get_bh(bh);
786 bforget(bh);
Peter Staubachb2f49032006-02-17 13:52:36 -0800787 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 } else {
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700789 le32_add_cpu(&HDR(bh)->h_refcount, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 if (ce)
791 mb_cache_entry_release(ce);
Peter Staubachb2f49032006-02-17 13:52:36 -0800792 ea_bdebug(bh, "refcount now=%d",
793 le32_to_cpu(HDR(bh)->h_refcount));
794 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 mark_buffer_dirty(bh);
796 if (IS_SYNC(inode))
797 sync_dirty_buffer(bh);
Al Viro38897172010-07-22 01:13:36 +0400798 dquot_free_block_nodirty(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 EXT2_I(inode)->i_file_acl = 0;
801
802cleanup:
803 brelse(bh);
804 up_write(&EXT2_I(inode)->xattr_sem);
805}
806
807/*
808 * ext2_xattr_put_super()
809 *
810 * This is called when a file system is unmounted.
811 */
812void
813ext2_xattr_put_super(struct super_block *sb)
814{
Andreas Gruenbacher8c52ab42005-07-27 11:45:15 -0700815 mb_cache_shrink(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816}
817
818
819/*
820 * ext2_xattr_cache_insert()
821 *
822 * Create a new entry in the extended attribute cache, and insert
823 * it unless such an entry is already in the cache.
824 *
825 * Returns 0, or a negative error number on failure.
826 */
827static int
828ext2_xattr_cache_insert(struct buffer_head *bh)
829{
830 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
831 struct mb_cache_entry *ce;
832 int error;
833
Jan Kara335e92e2008-04-15 14:34:43 -0700834 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 if (!ce)
836 return -ENOMEM;
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +0200837 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 if (error) {
839 mb_cache_entry_free(ce);
840 if (error == -EBUSY) {
841 ea_bdebug(bh, "already in cache (%d cache entries)",
842 atomic_read(&ext2_xattr_cache->c_entry_count));
843 error = 0;
844 }
845 } else {
846 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
847 atomic_read(&ext2_xattr_cache->c_entry_count));
848 mb_cache_entry_release(ce);
849 }
850 return error;
851}
852
853/*
854 * ext2_xattr_cmp()
855 *
856 * Compare two extended attribute blocks for equality.
857 *
858 * Returns 0 if the blocks are equal, 1 if they differ, and
859 * a negative error number on errors.
860 */
861static int
862ext2_xattr_cmp(struct ext2_xattr_header *header1,
863 struct ext2_xattr_header *header2)
864{
865 struct ext2_xattr_entry *entry1, *entry2;
866
867 entry1 = ENTRY(header1+1);
868 entry2 = ENTRY(header2+1);
869 while (!IS_LAST_ENTRY(entry1)) {
870 if (IS_LAST_ENTRY(entry2))
871 return 1;
872 if (entry1->e_hash != entry2->e_hash ||
873 entry1->e_name_index != entry2->e_name_index ||
874 entry1->e_name_len != entry2->e_name_len ||
875 entry1->e_value_size != entry2->e_value_size ||
876 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
877 return 1;
878 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
879 return -EIO;
880 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
881 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
882 le32_to_cpu(entry1->e_value_size)))
883 return 1;
884
885 entry1 = EXT2_XATTR_NEXT(entry1);
886 entry2 = EXT2_XATTR_NEXT(entry2);
887 }
888 if (!IS_LAST_ENTRY(entry2))
889 return 1;
890 return 0;
891}
892
893/*
894 * ext2_xattr_cache_find()
895 *
896 * Find an identical extended attribute block.
897 *
898 * Returns a locked buffer head to the block found, or NULL if such
899 * a block was not found or an error occurred.
900 */
901static struct buffer_head *
902ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
903{
904 __u32 hash = le32_to_cpu(header->h_hash);
905 struct mb_cache_entry *ce;
906
907 if (!header->h_hash)
908 return NULL; /* never share */
909 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
910again:
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +0200911 ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
912 hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 while (ce) {
914 struct buffer_head *bh;
915
916 if (IS_ERR(ce)) {
917 if (PTR_ERR(ce) == -EAGAIN)
918 goto again;
919 break;
920 }
921
922 bh = sb_bread(inode->i_sb, ce->e_block);
923 if (!bh) {
924 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
925 "inode %ld: block %ld read error",
926 inode->i_ino, (unsigned long) ce->e_block);
927 } else {
928 lock_buffer(bh);
929 if (le32_to_cpu(HDR(bh)->h_refcount) >
930 EXT2_XATTR_REFCOUNT_MAX) {
931 ea_idebug(inode, "block %ld refcount %d>%d",
932 (unsigned long) ce->e_block,
933 le32_to_cpu(HDR(bh)->h_refcount),
934 EXT2_XATTR_REFCOUNT_MAX);
935 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
936 ea_bdebug(bh, "b_count=%d",
937 atomic_read(&(bh->b_count)));
938 mb_cache_entry_release(ce);
939 return bh;
940 }
941 unlock_buffer(bh);
942 brelse(bh);
943 }
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +0200944 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 }
946 return NULL;
947}
948
949#define NAME_HASH_SHIFT 5
950#define VALUE_HASH_SHIFT 16
951
952/*
953 * ext2_xattr_hash_entry()
954 *
955 * Compute the hash of an extended attribute.
956 */
957static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
958 struct ext2_xattr_entry *entry)
959{
960 __u32 hash = 0;
961 char *name = entry->e_name;
962 int n;
963
964 for (n=0; n < entry->e_name_len; n++) {
965 hash = (hash << NAME_HASH_SHIFT) ^
966 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
967 *name++;
968 }
969
970 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
971 __le32 *value = (__le32 *)((char *)header +
972 le16_to_cpu(entry->e_value_offs));
973 for (n = (le32_to_cpu(entry->e_value_size) +
974 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
975 hash = (hash << VALUE_HASH_SHIFT) ^
976 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
977 le32_to_cpu(*value++);
978 }
979 }
980 entry->e_hash = cpu_to_le32(hash);
981}
982
983#undef NAME_HASH_SHIFT
984#undef VALUE_HASH_SHIFT
985
986#define BLOCK_HASH_SHIFT 16
987
988/*
989 * ext2_xattr_rehash()
990 *
991 * Re-compute the extended attribute hash value after an entry has changed.
992 */
993static void ext2_xattr_rehash(struct ext2_xattr_header *header,
994 struct ext2_xattr_entry *entry)
995{
996 struct ext2_xattr_entry *here;
997 __u32 hash = 0;
998
999 ext2_xattr_hash_entry(header, entry);
1000 here = ENTRY(header+1);
1001 while (!IS_LAST_ENTRY(here)) {
1002 if (!here->e_hash) {
1003 /* Block is not shared if an entry's hash value == 0 */
1004 hash = 0;
1005 break;
1006 }
1007 hash = (hash << BLOCK_HASH_SHIFT) ^
1008 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1009 le32_to_cpu(here->e_hash);
1010 here = EXT2_XATTR_NEXT(here);
1011 }
1012 header->h_hash = cpu_to_le32(hash);
1013}
1014
1015#undef BLOCK_HASH_SHIFT
1016
1017int __init
1018init_ext2_xattr(void)
1019{
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +02001020 ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021 if (!ext2_xattr_cache)
1022 return -ENOMEM;
1023 return 0;
1024}
1025
1026void
1027exit_ext2_xattr(void)
1028{
1029 mb_cache_destroy(ext2_xattr_cache);
1030}