blob: e44dc92609be86eff6638fe6aaae3bf6ecf1e779 [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
38 * descriptors are variable in size, and alligned to EXT2_XATTR_PAD
39 * 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>
57#include <linux/module.h>
58#include <linux/init.h>
59#include <linux/slab.h>
60#include <linux/mbcache.h>
61#include <linux/quotaops.h>
62#include <linux/rwsem.h>
Christoph Hellwig431547b2009-11-13 09:52:56 +000063#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070064#include "ext2.h"
65#include "xattr.h"
66#include "acl.h"
67
68#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
69#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
70#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
71#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
72
73#ifdef EXT2_XATTR_DEBUG
74# define ea_idebug(inode, f...) do { \
75 printk(KERN_DEBUG "inode %s:%ld: ", \
76 inode->i_sb->s_id, inode->i_ino); \
77 printk(f); \
78 printk("\n"); \
79 } while (0)
80# define ea_bdebug(bh, f...) do { \
81 char b[BDEVNAME_SIZE]; \
82 printk(KERN_DEBUG "block %s:%lu: ", \
83 bdevname(bh->b_bdev, b), \
84 (unsigned long) bh->b_blocknr); \
85 printk(f); \
86 printk("\n"); \
87 } while (0)
88#else
89# define ea_idebug(f...)
90# define ea_bdebug(f...)
91#endif
92
93static int ext2_xattr_set2(struct inode *, struct buffer_head *,
94 struct ext2_xattr_header *);
95
96static int ext2_xattr_cache_insert(struct buffer_head *);
97static struct buffer_head *ext2_xattr_cache_find(struct inode *,
98 struct ext2_xattr_header *);
99static void ext2_xattr_rehash(struct ext2_xattr_header *,
100 struct ext2_xattr_entry *);
101
102static struct mb_cache *ext2_xattr_cache;
103
104static struct xattr_handler *ext2_xattr_handler_map[] = {
105 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
106#ifdef CONFIG_EXT2_FS_POSIX_ACL
107 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
108 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
109#endif
110 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
111#ifdef CONFIG_EXT2_FS_SECURITY
112 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
113#endif
114};
115
116struct xattr_handler *ext2_xattr_handlers[] = {
117 &ext2_xattr_user_handler,
118 &ext2_xattr_trusted_handler,
119#ifdef CONFIG_EXT2_FS_POSIX_ACL
120 &ext2_xattr_acl_access_handler,
121 &ext2_xattr_acl_default_handler,
122#endif
123#ifdef CONFIG_EXT2_FS_SECURITY
124 &ext2_xattr_security_handler,
125#endif
126 NULL
127};
128
129static inline struct xattr_handler *
130ext2_xattr_handler(int name_index)
131{
132 struct xattr_handler *handler = NULL;
133
134 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
135 handler = ext2_xattr_handler_map[name_index];
136 return handler;
137}
138
139/*
140 * ext2_xattr_get()
141 *
142 * Copy an extended attribute into the buffer
143 * provided, or compute the buffer size required.
144 * Buffer is NULL to compute the size of the buffer required.
145 *
146 * Returns a negative error number on failure, or the number of bytes
147 * used / required on success.
148 */
149int
150ext2_xattr_get(struct inode *inode, int name_index, const char *name,
151 void *buffer, size_t buffer_size)
152{
153 struct buffer_head *bh = NULL;
154 struct ext2_xattr_entry *entry;
155 size_t name_len, size;
156 char *end;
157 int error;
158
159 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
160 name_index, name, buffer, (long)buffer_size);
161
162 if (name == NULL)
163 return -EINVAL;
164 down_read(&EXT2_I(inode)->xattr_sem);
165 error = -ENODATA;
166 if (!EXT2_I(inode)->i_file_acl)
167 goto cleanup;
168 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
169 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
170 error = -EIO;
171 if (!bh)
172 goto cleanup;
173 ea_bdebug(bh, "b_count=%d, refcount=%d",
174 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
175 end = bh->b_data + bh->b_size;
176 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
177 HDR(bh)->h_blocks != cpu_to_le32(1)) {
178bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
179 "inode %ld: bad block %d", inode->i_ino,
180 EXT2_I(inode)->i_file_acl);
181 error = -EIO;
182 goto cleanup;
183 }
184 /* find named attribute */
185 name_len = strlen(name);
186
187 error = -ERANGE;
188 if (name_len > 255)
189 goto cleanup;
190 entry = FIRST_ENTRY(bh);
191 while (!IS_LAST_ENTRY(entry)) {
192 struct ext2_xattr_entry *next =
193 EXT2_XATTR_NEXT(entry);
194 if ((char *)next >= end)
195 goto bad_block;
196 if (name_index == entry->e_name_index &&
197 name_len == entry->e_name_len &&
198 memcmp(name, entry->e_name, name_len) == 0)
199 goto found;
200 entry = next;
201 }
202 /* Check the remaining name entries */
203 while (!IS_LAST_ENTRY(entry)) {
204 struct ext2_xattr_entry *next =
205 EXT2_XATTR_NEXT(entry);
206 if ((char *)next >= end)
207 goto bad_block;
208 entry = next;
209 }
210 if (ext2_xattr_cache_insert(bh))
211 ea_idebug(inode, "cache insert failed");
212 error = -ENODATA;
213 goto cleanup;
214found:
215 /* check the buffer size */
216 if (entry->e_value_block != 0)
217 goto bad_block;
218 size = le32_to_cpu(entry->e_value_size);
219 if (size > inode->i_sb->s_blocksize ||
220 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
221 goto bad_block;
222
223 if (ext2_xattr_cache_insert(bh))
224 ea_idebug(inode, "cache insert failed");
225 if (buffer) {
226 error = -ERANGE;
227 if (size > buffer_size)
228 goto cleanup;
229 /* return value of attribute */
230 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
231 size);
232 }
233 error = size;
234
235cleanup:
236 brelse(bh);
237 up_read(&EXT2_I(inode)->xattr_sem);
238
239 return error;
240}
241
242/*
243 * ext2_xattr_list()
244 *
245 * Copy a list of attribute names into the buffer
246 * provided, or compute the buffer size required.
247 * Buffer is NULL to compute the size of the buffer required.
248 *
249 * Returns a negative error number on failure, or the number of bytes
250 * used / required on success.
251 */
252static int
Christoph Hellwig431547b2009-11-13 09:52:56 +0000253ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254{
Christoph Hellwig431547b2009-11-13 09:52:56 +0000255 struct inode *inode = dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 struct buffer_head *bh = NULL;
257 struct ext2_xattr_entry *entry;
258 char *end;
259 size_t rest = buffer_size;
260 int error;
261
262 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
263 buffer, (long)buffer_size);
264
265 down_read(&EXT2_I(inode)->xattr_sem);
266 error = 0;
267 if (!EXT2_I(inode)->i_file_acl)
268 goto cleanup;
269 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
270 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
271 error = -EIO;
272 if (!bh)
273 goto cleanup;
274 ea_bdebug(bh, "b_count=%d, refcount=%d",
275 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
276 end = bh->b_data + bh->b_size;
277 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
278 HDR(bh)->h_blocks != cpu_to_le32(1)) {
279bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
280 "inode %ld: bad block %d", inode->i_ino,
281 EXT2_I(inode)->i_file_acl);
282 error = -EIO;
283 goto cleanup;
284 }
285
286 /* check the on-disk data structure */
287 entry = FIRST_ENTRY(bh);
288 while (!IS_LAST_ENTRY(entry)) {
289 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
290
291 if ((char *)next >= end)
292 goto bad_block;
293 entry = next;
294 }
295 if (ext2_xattr_cache_insert(bh))
296 ea_idebug(inode, "cache insert failed");
297
298 /* list the attribute names */
299 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
300 entry = EXT2_XATTR_NEXT(entry)) {
301 struct xattr_handler *handler =
302 ext2_xattr_handler(entry->e_name_index);
303
304 if (handler) {
Christoph Hellwig431547b2009-11-13 09:52:56 +0000305 size_t size = handler->list(dentry, buffer, rest,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 entry->e_name,
Christoph Hellwig431547b2009-11-13 09:52:56 +0000307 entry->e_name_len,
308 handler->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 if (buffer) {
310 if (size > rest) {
311 error = -ERANGE;
312 goto cleanup;
313 }
314 buffer += size;
315 }
316 rest -= size;
317 }
318 }
319 error = buffer_size - rest; /* total size */
320
321cleanup:
322 brelse(bh);
323 up_read(&EXT2_I(inode)->xattr_sem);
324
325 return error;
326}
327
328/*
329 * Inode operation listxattr()
330 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800331 * dentry->d_inode->i_mutex: don't care
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 */
333ssize_t
334ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
335{
Christoph Hellwig431547b2009-11-13 09:52:56 +0000336 return ext2_xattr_list(dentry, buffer, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337}
338
339/*
340 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
341 * not set, set it.
342 */
343static void ext2_xattr_update_super_block(struct super_block *sb)
344{
345 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
346 return;
347
Andreas Gruenbachered2908f2006-12-06 20:36:16 -0800348 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 sb->s_dirt = 1;
350 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351}
352
353/*
354 * ext2_xattr_set()
355 *
356 * Create, replace or remove an extended attribute for this inode. Buffer
357 * is NULL to remove an existing extended attribute, and non-NULL to
358 * either replace an existing extended attribute, or create a new extended
359 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
360 * specify that an extended attribute must exist and must not exist
361 * previous to the call, respectively.
362 *
363 * Returns 0, or a negative error number on failure.
364 */
365int
366ext2_xattr_set(struct inode *inode, int name_index, const char *name,
367 const void *value, size_t value_len, int flags)
368{
369 struct super_block *sb = inode->i_sb;
370 struct buffer_head *bh = NULL;
371 struct ext2_xattr_header *header = NULL;
372 struct ext2_xattr_entry *here, *last;
373 size_t name_len, free, min_offs = sb->s_blocksize;
374 int not_found = 1, error;
375 char *end;
376
377 /*
378 * header -- Points either into bh, or to a temporarily
379 * allocated buffer.
380 * here -- The named entry found, or the place for inserting, within
381 * the block pointed to by header.
382 * last -- Points right after the last named entry within the block
383 * pointed to by header.
384 * min_offs -- The offset of the first value (values are aligned
385 * towards the end of the block).
386 * end -- Points right after the block pointed to by header.
387 */
388
389 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
390 name_index, name, value, (long)value_len);
391
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 if (value == NULL)
393 value_len = 0;
394 if (name == NULL)
395 return -EINVAL;
396 name_len = strlen(name);
397 if (name_len > 255 || value_len > sb->s_blocksize)
398 return -ERANGE;
399 down_write(&EXT2_I(inode)->xattr_sem);
400 if (EXT2_I(inode)->i_file_acl) {
401 /* The inode already has an extended attribute block. */
402 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
403 error = -EIO;
404 if (!bh)
405 goto cleanup;
406 ea_bdebug(bh, "b_count=%d, refcount=%d",
407 atomic_read(&(bh->b_count)),
408 le32_to_cpu(HDR(bh)->h_refcount));
409 header = HDR(bh);
410 end = bh->b_data + bh->b_size;
411 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
412 header->h_blocks != cpu_to_le32(1)) {
413bad_block: ext2_error(sb, "ext2_xattr_set",
414 "inode %ld: bad block %d", inode->i_ino,
415 EXT2_I(inode)->i_file_acl);
416 error = -EIO;
417 goto cleanup;
418 }
419 /* Find the named attribute. */
420 here = FIRST_ENTRY(bh);
421 while (!IS_LAST_ENTRY(here)) {
422 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
423 if ((char *)next >= end)
424 goto bad_block;
425 if (!here->e_value_block && here->e_value_size) {
426 size_t offs = le16_to_cpu(here->e_value_offs);
427 if (offs < min_offs)
428 min_offs = offs;
429 }
430 not_found = name_index - here->e_name_index;
431 if (!not_found)
432 not_found = name_len - here->e_name_len;
433 if (!not_found)
434 not_found = memcmp(name, here->e_name,name_len);
435 if (not_found <= 0)
436 break;
437 here = next;
438 }
439 last = here;
440 /* We still need to compute min_offs and last. */
441 while (!IS_LAST_ENTRY(last)) {
442 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
443 if ((char *)next >= end)
444 goto bad_block;
445 if (!last->e_value_block && last->e_value_size) {
446 size_t offs = le16_to_cpu(last->e_value_offs);
447 if (offs < min_offs)
448 min_offs = offs;
449 }
450 last = next;
451 }
452
453 /* Check whether we have enough space left. */
454 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
455 } else {
456 /* We will use a new extended attribute block. */
457 free = sb->s_blocksize -
458 sizeof(struct ext2_xattr_header) - sizeof(__u32);
459 here = last = NULL; /* avoid gcc uninitialized warning. */
460 }
461
462 if (not_found) {
463 /* Request to remove a nonexistent attribute? */
464 error = -ENODATA;
465 if (flags & XATTR_REPLACE)
466 goto cleanup;
467 error = 0;
468 if (value == NULL)
469 goto cleanup;
470 } else {
471 /* Request to create an existing attribute? */
472 error = -EEXIST;
473 if (flags & XATTR_CREATE)
474 goto cleanup;
475 if (!here->e_value_block && here->e_value_size) {
476 size_t size = le32_to_cpu(here->e_value_size);
477
478 if (le16_to_cpu(here->e_value_offs) + size >
479 sb->s_blocksize || size > sb->s_blocksize)
480 goto bad_block;
481 free += EXT2_XATTR_SIZE(size);
482 }
483 free += EXT2_XATTR_LEN(name_len);
484 }
485 error = -ENOSPC;
486 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
487 goto cleanup;
488
489 /* Here we know that we can set the new attribute. */
490
491 if (header) {
492 struct mb_cache_entry *ce;
493
494 /* assert(header == HDR(bh)); */
495 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
496 bh->b_blocknr);
497 lock_buffer(bh);
498 if (header->h_refcount == cpu_to_le32(1)) {
499 ea_bdebug(bh, "modifying in-place");
500 if (ce)
501 mb_cache_entry_free(ce);
502 /* keep the buffer locked while modifying it. */
503 } else {
504 int offset;
505
506 if (ce)
507 mb_cache_entry_release(ce);
508 unlock_buffer(bh);
509 ea_bdebug(bh, "cloning");
510 header = kmalloc(bh->b_size, GFP_KERNEL);
511 error = -ENOMEM;
512 if (header == NULL)
513 goto cleanup;
514 memcpy(header, HDR(bh), bh->b_size);
515 header->h_refcount = cpu_to_le32(1);
516
517 offset = (char *)here - bh->b_data;
518 here = ENTRY((char *)header + offset);
519 offset = (char *)last - bh->b_data;
520 last = ENTRY((char *)header + offset);
521 }
522 } else {
523 /* Allocate a buffer where we construct the new block. */
Panagiotis Issarisf8314dc2006-09-27 01:49:37 -0700524 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 error = -ENOMEM;
526 if (header == NULL)
527 goto cleanup;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 end = (char *)header + sb->s_blocksize;
529 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
530 header->h_blocks = header->h_refcount = cpu_to_le32(1);
531 last = here = ENTRY(header+1);
532 }
533
534 /* Iff we are modifying the block in-place, bh is locked here. */
535
536 if (not_found) {
537 /* Insert the new name. */
538 size_t size = EXT2_XATTR_LEN(name_len);
539 size_t rest = (char *)last - (char *)here;
540 memmove((char *)here + size, here, rest);
541 memset(here, 0, size);
542 here->e_name_index = name_index;
543 here->e_name_len = name_len;
544 memcpy(here->e_name, name, name_len);
545 } else {
546 if (!here->e_value_block && here->e_value_size) {
547 char *first_val = (char *)header + min_offs;
548 size_t offs = le16_to_cpu(here->e_value_offs);
549 char *val = (char *)header + offs;
550 size_t size = EXT2_XATTR_SIZE(
551 le32_to_cpu(here->e_value_size));
552
553 if (size == EXT2_XATTR_SIZE(value_len)) {
554 /* The old and the new value have the same
555 size. Just replace. */
556 here->e_value_size = cpu_to_le32(value_len);
557 memset(val + size - EXT2_XATTR_PAD, 0,
558 EXT2_XATTR_PAD); /* Clear pad bytes. */
559 memcpy(val, value, value_len);
560 goto skip_replace;
561 }
562
563 /* Remove the old value. */
564 memmove(first_val + size, first_val, val - first_val);
565 memset(first_val, 0, size);
566 here->e_value_offs = 0;
567 min_offs += size;
568
569 /* Adjust all value offsets. */
570 last = ENTRY(header+1);
571 while (!IS_LAST_ENTRY(last)) {
572 size_t o = le16_to_cpu(last->e_value_offs);
573 if (!last->e_value_block && o < offs)
574 last->e_value_offs =
575 cpu_to_le16(o + size);
576 last = EXT2_XATTR_NEXT(last);
577 }
578 }
579 if (value == NULL) {
580 /* Remove the old name. */
581 size_t size = EXT2_XATTR_LEN(name_len);
582 last = ENTRY((char *)last - size);
583 memmove(here, (char*)here + size,
584 (char*)last - (char*)here);
585 memset(last, 0, size);
586 }
587 }
588
589 if (value != NULL) {
590 /* Insert the new value. */
591 here->e_value_size = cpu_to_le32(value_len);
592 if (value_len) {
593 size_t size = EXT2_XATTR_SIZE(value_len);
594 char *val = (char *)header + min_offs - size;
595 here->e_value_offs =
596 cpu_to_le16((char *)val - (char *)header);
597 memset(val + size - EXT2_XATTR_PAD, 0,
598 EXT2_XATTR_PAD); /* Clear the pad bytes. */
599 memcpy(val, value, value_len);
600 }
601 }
602
603skip_replace:
604 if (IS_LAST_ENTRY(ENTRY(header+1))) {
605 /* This block is now empty. */
606 if (bh && header == HDR(bh))
607 unlock_buffer(bh); /* we were modifying in-place. */
608 error = ext2_xattr_set2(inode, bh, NULL);
609 } else {
610 ext2_xattr_rehash(header, here);
611 if (bh && header == HDR(bh))
612 unlock_buffer(bh); /* we were modifying in-place. */
613 error = ext2_xattr_set2(inode, bh, header);
614 }
615
616cleanup:
617 brelse(bh);
618 if (!(bh && header == HDR(bh)))
619 kfree(header);
620 up_write(&EXT2_I(inode)->xattr_sem);
621
622 return error;
623}
624
625/*
626 * Second half of ext2_xattr_set(): Update the file system.
627 */
628static int
629ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
630 struct ext2_xattr_header *header)
631{
632 struct super_block *sb = inode->i_sb;
633 struct buffer_head *new_bh = NULL;
634 int error;
635
636 if (header) {
637 new_bh = ext2_xattr_cache_find(inode, header);
638 if (new_bh) {
639 /* We found an identical block in the cache. */
640 if (new_bh == old_bh) {
641 ea_bdebug(new_bh, "keeping this block");
642 } else {
643 /* The old block is released after updating
644 the inode. */
645 ea_bdebug(new_bh, "reusing block");
646
Christoph Hellwig5dd40562010-03-03 09:05:00 -0500647 error = dquot_alloc_block(inode, 1);
648 if (error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649 unlock_buffer(new_bh);
650 goto cleanup;
651 }
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700652 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 ea_bdebug(new_bh, "refcount now=%d",
654 le32_to_cpu(HDR(new_bh)->h_refcount));
655 }
656 unlock_buffer(new_bh);
657 } else if (old_bh && header == HDR(old_bh)) {
658 /* Keep this block. No need to lock the block as we
659 don't need to change the reference count. */
660 new_bh = old_bh;
661 get_bh(new_bh);
662 ext2_xattr_cache_insert(new_bh);
663 } else {
664 /* We need to allocate a new block */
Akinobu Mita24097d12008-04-28 02:16:01 -0700665 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
666 EXT2_I(inode)->i_block_group);
Martin J. Bligha686cd82007-10-16 23:30:46 -0700667 int block = ext2_new_block(inode, goal, &error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 if (error)
669 goto cleanup;
670 ea_idebug(inode, "creating block %d", block);
671
672 new_bh = sb_getblk(sb, block);
673 if (!new_bh) {
674 ext2_free_blocks(inode, block, 1);
675 error = -EIO;
676 goto cleanup;
677 }
678 lock_buffer(new_bh);
679 memcpy(new_bh->b_data, header, new_bh->b_size);
680 set_buffer_uptodate(new_bh);
681 unlock_buffer(new_bh);
682 ext2_xattr_cache_insert(new_bh);
683
684 ext2_xattr_update_super_block(sb);
685 }
686 mark_buffer_dirty(new_bh);
687 if (IS_SYNC(inode)) {
688 sync_dirty_buffer(new_bh);
689 error = -EIO;
690 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
691 goto cleanup;
692 }
693 }
694
695 /* Update the inode. */
696 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
697 inode->i_ctime = CURRENT_TIME_SEC;
698 if (IS_SYNC(inode)) {
699 error = ext2_sync_inode (inode);
700 /* In case sync failed due to ENOSPC the inode was actually
701 * written (only some dirty data were not) so we just proceed
702 * as if nothing happened and cleanup the unused block */
703 if (error && error != -ENOSPC) {
704 if (new_bh && new_bh != old_bh)
Christoph Hellwig5dd40562010-03-03 09:05:00 -0500705 dquot_free_block(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706 goto cleanup;
707 }
708 } else
709 mark_inode_dirty(inode);
710
711 error = 0;
712 if (old_bh && old_bh != new_bh) {
713 struct mb_cache_entry *ce;
714
715 /*
716 * If there was an old block and we are no longer using it,
717 * release the old block.
718 */
719 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
720 old_bh->b_blocknr);
721 lock_buffer(old_bh);
722 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
723 /* Free the old block. */
724 if (ce)
725 mb_cache_entry_free(ce);
726 ea_bdebug(old_bh, "freeing");
727 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
728 /* We let our caller release old_bh, so we
729 * need to duplicate the buffer before. */
730 get_bh(old_bh);
731 bforget(old_bh);
732 } else {
733 /* Decrement the refcount only. */
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700734 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 if (ce)
736 mb_cache_entry_release(ce);
Christoph Hellwig5dd40562010-03-03 09:05:00 -0500737 dquot_free_block(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 mark_buffer_dirty(old_bh);
739 ea_bdebug(old_bh, "refcount now=%d",
740 le32_to_cpu(HDR(old_bh)->h_refcount));
741 }
742 unlock_buffer(old_bh);
743 }
744
745cleanup:
746 brelse(new_bh);
747
748 return error;
749}
750
751/*
752 * ext2_xattr_delete_inode()
753 *
754 * Free extended attribute resources associated with this inode. This
755 * is called immediately before an inode is freed.
756 */
757void
758ext2_xattr_delete_inode(struct inode *inode)
759{
760 struct buffer_head *bh = NULL;
761 struct mb_cache_entry *ce;
762
763 down_write(&EXT2_I(inode)->xattr_sem);
764 if (!EXT2_I(inode)->i_file_acl)
765 goto cleanup;
766 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
767 if (!bh) {
768 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
769 "inode %ld: block %d read error", inode->i_ino,
770 EXT2_I(inode)->i_file_acl);
771 goto cleanup;
772 }
773 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
774 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
775 HDR(bh)->h_blocks != cpu_to_le32(1)) {
776 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
777 "inode %ld: bad block %d", inode->i_ino,
778 EXT2_I(inode)->i_file_acl);
779 goto cleanup;
780 }
781 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
782 lock_buffer(bh);
783 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
784 if (ce)
785 mb_cache_entry_free(ce);
786 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
787 get_bh(bh);
788 bforget(bh);
Peter Staubachb2f49032006-02-17 13:52:36 -0800789 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 } else {
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700791 le32_add_cpu(&HDR(bh)->h_refcount, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 if (ce)
793 mb_cache_entry_release(ce);
Peter Staubachb2f49032006-02-17 13:52:36 -0800794 ea_bdebug(bh, "refcount now=%d",
795 le32_to_cpu(HDR(bh)->h_refcount));
796 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 mark_buffer_dirty(bh);
798 if (IS_SYNC(inode))
799 sync_dirty_buffer(bh);
Christoph Hellwig5dd40562010-03-03 09:05:00 -0500800 dquot_free_block(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 EXT2_I(inode)->i_file_acl = 0;
803
804cleanup:
805 brelse(bh);
806 up_write(&EXT2_I(inode)->xattr_sem);
807}
808
809/*
810 * ext2_xattr_put_super()
811 *
812 * This is called when a file system is unmounted.
813 */
814void
815ext2_xattr_put_super(struct super_block *sb)
816{
Andreas Gruenbacher8c52ab42005-07-27 11:45:15 -0700817 mb_cache_shrink(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818}
819
820
821/*
822 * ext2_xattr_cache_insert()
823 *
824 * Create a new entry in the extended attribute cache, and insert
825 * it unless such an entry is already in the cache.
826 *
827 * Returns 0, or a negative error number on failure.
828 */
829static int
830ext2_xattr_cache_insert(struct buffer_head *bh)
831{
832 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
833 struct mb_cache_entry *ce;
834 int error;
835
Jan Kara335e92e2008-04-15 14:34:43 -0700836 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 if (!ce)
838 return -ENOMEM;
839 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
840 if (error) {
841 mb_cache_entry_free(ce);
842 if (error == -EBUSY) {
843 ea_bdebug(bh, "already in cache (%d cache entries)",
844 atomic_read(&ext2_xattr_cache->c_entry_count));
845 error = 0;
846 }
847 } else {
848 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
849 atomic_read(&ext2_xattr_cache->c_entry_count));
850 mb_cache_entry_release(ce);
851 }
852 return error;
853}
854
855/*
856 * ext2_xattr_cmp()
857 *
858 * Compare two extended attribute blocks for equality.
859 *
860 * Returns 0 if the blocks are equal, 1 if they differ, and
861 * a negative error number on errors.
862 */
863static int
864ext2_xattr_cmp(struct ext2_xattr_header *header1,
865 struct ext2_xattr_header *header2)
866{
867 struct ext2_xattr_entry *entry1, *entry2;
868
869 entry1 = ENTRY(header1+1);
870 entry2 = ENTRY(header2+1);
871 while (!IS_LAST_ENTRY(entry1)) {
872 if (IS_LAST_ENTRY(entry2))
873 return 1;
874 if (entry1->e_hash != entry2->e_hash ||
875 entry1->e_name_index != entry2->e_name_index ||
876 entry1->e_name_len != entry2->e_name_len ||
877 entry1->e_value_size != entry2->e_value_size ||
878 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
879 return 1;
880 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
881 return -EIO;
882 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
883 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
884 le32_to_cpu(entry1->e_value_size)))
885 return 1;
886
887 entry1 = EXT2_XATTR_NEXT(entry1);
888 entry2 = EXT2_XATTR_NEXT(entry2);
889 }
890 if (!IS_LAST_ENTRY(entry2))
891 return 1;
892 return 0;
893}
894
895/*
896 * ext2_xattr_cache_find()
897 *
898 * Find an identical extended attribute block.
899 *
900 * Returns a locked buffer head to the block found, or NULL if such
901 * a block was not found or an error occurred.
902 */
903static struct buffer_head *
904ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
905{
906 __u32 hash = le32_to_cpu(header->h_hash);
907 struct mb_cache_entry *ce;
908
909 if (!header->h_hash)
910 return NULL; /* never share */
911 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
912again:
913 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0,
914 inode->i_sb->s_bdev, hash);
915 while (ce) {
916 struct buffer_head *bh;
917
918 if (IS_ERR(ce)) {
919 if (PTR_ERR(ce) == -EAGAIN)
920 goto again;
921 break;
922 }
923
924 bh = sb_bread(inode->i_sb, ce->e_block);
925 if (!bh) {
926 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
927 "inode %ld: block %ld read error",
928 inode->i_ino, (unsigned long) ce->e_block);
929 } else {
930 lock_buffer(bh);
931 if (le32_to_cpu(HDR(bh)->h_refcount) >
932 EXT2_XATTR_REFCOUNT_MAX) {
933 ea_idebug(inode, "block %ld refcount %d>%d",
934 (unsigned long) ce->e_block,
935 le32_to_cpu(HDR(bh)->h_refcount),
936 EXT2_XATTR_REFCOUNT_MAX);
937 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
938 ea_bdebug(bh, "b_count=%d",
939 atomic_read(&(bh->b_count)));
940 mb_cache_entry_release(ce);
941 return bh;
942 }
943 unlock_buffer(bh);
944 brelse(bh);
945 }
946 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
947 }
948 return NULL;
949}
950
951#define NAME_HASH_SHIFT 5
952#define VALUE_HASH_SHIFT 16
953
954/*
955 * ext2_xattr_hash_entry()
956 *
957 * Compute the hash of an extended attribute.
958 */
959static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
960 struct ext2_xattr_entry *entry)
961{
962 __u32 hash = 0;
963 char *name = entry->e_name;
964 int n;
965
966 for (n=0; n < entry->e_name_len; n++) {
967 hash = (hash << NAME_HASH_SHIFT) ^
968 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
969 *name++;
970 }
971
972 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
973 __le32 *value = (__le32 *)((char *)header +
974 le16_to_cpu(entry->e_value_offs));
975 for (n = (le32_to_cpu(entry->e_value_size) +
976 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
977 hash = (hash << VALUE_HASH_SHIFT) ^
978 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
979 le32_to_cpu(*value++);
980 }
981 }
982 entry->e_hash = cpu_to_le32(hash);
983}
984
985#undef NAME_HASH_SHIFT
986#undef VALUE_HASH_SHIFT
987
988#define BLOCK_HASH_SHIFT 16
989
990/*
991 * ext2_xattr_rehash()
992 *
993 * Re-compute the extended attribute hash value after an entry has changed.
994 */
995static void ext2_xattr_rehash(struct ext2_xattr_header *header,
996 struct ext2_xattr_entry *entry)
997{
998 struct ext2_xattr_entry *here;
999 __u32 hash = 0;
1000
1001 ext2_xattr_hash_entry(header, entry);
1002 here = ENTRY(header+1);
1003 while (!IS_LAST_ENTRY(here)) {
1004 if (!here->e_hash) {
1005 /* Block is not shared if an entry's hash value == 0 */
1006 hash = 0;
1007 break;
1008 }
1009 hash = (hash << BLOCK_HASH_SHIFT) ^
1010 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1011 le32_to_cpu(here->e_hash);
1012 here = EXT2_XATTR_NEXT(here);
1013 }
1014 header->h_hash = cpu_to_le32(hash);
1015}
1016
1017#undef BLOCK_HASH_SHIFT
1018
1019int __init
1020init_ext2_xattr(void)
1021{
1022 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL,
1023 sizeof(struct mb_cache_entry) +
1024 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1025 if (!ext2_xattr_cache)
1026 return -ENOMEM;
1027 return 0;
1028}
1029
1030void
1031exit_ext2_xattr(void)
1032{
1033 mb_cache_destroy(ext2_xattr_cache);
1034}