blob: 86ae8e93adb9d84dadbace346c65f0c5b09952fa [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>
63#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
103static struct xattr_handler *ext2_xattr_handler_map[] = {
104 [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
115struct xattr_handler *ext2_xattr_handlers[] = {
116 &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
128static inline struct xattr_handler *
129ext2_xattr_handler(int name_index)
130{
131 struct xattr_handler *handler = NULL;
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
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;
163 down_read(&EXT2_I(inode)->xattr_sem);
164 error = -ENODATA;
165 if (!EXT2_I(inode)->i_file_acl)
166 goto cleanup;
167 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
168 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
169 error = -EIO;
170 if (!bh)
171 goto cleanup;
172 ea_bdebug(bh, "b_count=%d, refcount=%d",
173 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
174 end = bh->b_data + bh->b_size;
175 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
176 HDR(bh)->h_blocks != cpu_to_le32(1)) {
177bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
178 "inode %ld: bad block %d", inode->i_ino,
179 EXT2_I(inode)->i_file_acl);
180 error = -EIO;
181 goto cleanup;
182 }
183 /* find named attribute */
184 name_len = strlen(name);
185
186 error = -ERANGE;
187 if (name_len > 255)
188 goto cleanup;
189 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 }
201 /* Check the remaining name entries */
202 while (!IS_LAST_ENTRY(entry)) {
203 struct ext2_xattr_entry *next =
204 EXT2_XATTR_NEXT(entry);
205 if ((char *)next >= end)
206 goto bad_block;
207 entry = next;
208 }
209 if (ext2_xattr_cache_insert(bh))
210 ea_idebug(inode, "cache insert failed");
211 error = -ENODATA;
212 goto cleanup;
213found:
214 /* check the buffer size */
215 if (entry->e_value_block != 0)
216 goto bad_block;
217 size = le32_to_cpu(entry->e_value_size);
218 if (size > inode->i_sb->s_blocksize ||
219 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
220 goto bad_block;
221
222 if (ext2_xattr_cache_insert(bh))
223 ea_idebug(inode, "cache insert failed");
224 if (buffer) {
225 error = -ERANGE;
226 if (size > buffer_size)
227 goto cleanup;
228 /* return value of attribute */
229 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
230 size);
231 }
232 error = size;
233
234cleanup:
235 brelse(bh);
236 up_read(&EXT2_I(inode)->xattr_sem);
237
238 return error;
239}
240
241/*
242 * ext2_xattr_list()
243 *
244 * Copy a list of attribute names into the buffer
245 * provided, or compute the buffer size required.
246 * Buffer is NULL to compute the size of the buffer required.
247 *
248 * Returns a negative error number on failure, or the number of bytes
249 * used / required on success.
250 */
251static int
252ext2_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
253{
254 struct buffer_head *bh = NULL;
255 struct ext2_xattr_entry *entry;
256 char *end;
257 size_t rest = buffer_size;
258 int error;
259
260 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
261 buffer, (long)buffer_size);
262
263 down_read(&EXT2_I(inode)->xattr_sem);
264 error = 0;
265 if (!EXT2_I(inode)->i_file_acl)
266 goto cleanup;
267 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
268 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
269 error = -EIO;
270 if (!bh)
271 goto cleanup;
272 ea_bdebug(bh, "b_count=%d, refcount=%d",
273 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
274 end = bh->b_data + bh->b_size;
275 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
276 HDR(bh)->h_blocks != cpu_to_le32(1)) {
277bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
278 "inode %ld: bad block %d", inode->i_ino,
279 EXT2_I(inode)->i_file_acl);
280 error = -EIO;
281 goto cleanup;
282 }
283
284 /* check the on-disk data structure */
285 entry = FIRST_ENTRY(bh);
286 while (!IS_LAST_ENTRY(entry)) {
287 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
288
289 if ((char *)next >= end)
290 goto bad_block;
291 entry = next;
292 }
293 if (ext2_xattr_cache_insert(bh))
294 ea_idebug(inode, "cache insert failed");
295
296 /* list the attribute names */
297 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
298 entry = EXT2_XATTR_NEXT(entry)) {
299 struct xattr_handler *handler =
300 ext2_xattr_handler(entry->e_name_index);
301
302 if (handler) {
303 size_t size = handler->list(inode, buffer, rest,
304 entry->e_name,
305 entry->e_name_len);
306 if (buffer) {
307 if (size > rest) {
308 error = -ERANGE;
309 goto cleanup;
310 }
311 buffer += size;
312 }
313 rest -= size;
314 }
315 }
316 error = buffer_size - rest; /* total size */
317
318cleanup:
319 brelse(bh);
320 up_read(&EXT2_I(inode)->xattr_sem);
321
322 return error;
323}
324
325/*
326 * Inode operation listxattr()
327 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800328 * dentry->d_inode->i_mutex: don't care
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 */
330ssize_t
331ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
332{
333 return ext2_xattr_list(dentry->d_inode, buffer, size);
334}
335
336/*
337 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
338 * not set, set it.
339 */
340static void ext2_xattr_update_super_block(struct super_block *sb)
341{
342 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
343 return;
344
345 lock_super(sb);
346 EXT2_SB(sb)->s_es->s_feature_compat |=
347 cpu_to_le32(EXT2_FEATURE_COMPAT_EXT_ATTR);
348 sb->s_dirt = 1;
349 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
350 unlock_super(sb);
351}
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. */
524 header = kmalloc(sb->s_blocksize, GFP_KERNEL);
525 error = -ENOMEM;
526 if (header == NULL)
527 goto cleanup;
528 memset(header, 0, sb->s_blocksize);
529 end = (char *)header + sb->s_blocksize;
530 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
531 header->h_blocks = header->h_refcount = cpu_to_le32(1);
532 last = here = ENTRY(header+1);
533 }
534
535 /* Iff we are modifying the block in-place, bh is locked here. */
536
537 if (not_found) {
538 /* Insert the new name. */
539 size_t size = EXT2_XATTR_LEN(name_len);
540 size_t rest = (char *)last - (char *)here;
541 memmove((char *)here + size, here, rest);
542 memset(here, 0, size);
543 here->e_name_index = name_index;
544 here->e_name_len = name_len;
545 memcpy(here->e_name, name, name_len);
546 } else {
547 if (!here->e_value_block && here->e_value_size) {
548 char *first_val = (char *)header + min_offs;
549 size_t offs = le16_to_cpu(here->e_value_offs);
550 char *val = (char *)header + offs;
551 size_t size = EXT2_XATTR_SIZE(
552 le32_to_cpu(here->e_value_size));
553
554 if (size == EXT2_XATTR_SIZE(value_len)) {
555 /* The old and the new value have the same
556 size. Just replace. */
557 here->e_value_size = cpu_to_le32(value_len);
558 memset(val + size - EXT2_XATTR_PAD, 0,
559 EXT2_XATTR_PAD); /* Clear pad bytes. */
560 memcpy(val, value, value_len);
561 goto skip_replace;
562 }
563
564 /* Remove the old value. */
565 memmove(first_val + size, first_val, val - first_val);
566 memset(first_val, 0, size);
567 here->e_value_offs = 0;
568 min_offs += size;
569
570 /* Adjust all value offsets. */
571 last = ENTRY(header+1);
572 while (!IS_LAST_ENTRY(last)) {
573 size_t o = le16_to_cpu(last->e_value_offs);
574 if (!last->e_value_block && o < offs)
575 last->e_value_offs =
576 cpu_to_le16(o + size);
577 last = EXT2_XATTR_NEXT(last);
578 }
579 }
580 if (value == NULL) {
581 /* Remove the old name. */
582 size_t size = EXT2_XATTR_LEN(name_len);
583 last = ENTRY((char *)last - size);
584 memmove(here, (char*)here + size,
585 (char*)last - (char*)here);
586 memset(last, 0, size);
587 }
588 }
589
590 if (value != NULL) {
591 /* Insert the new value. */
592 here->e_value_size = cpu_to_le32(value_len);
593 if (value_len) {
594 size_t size = EXT2_XATTR_SIZE(value_len);
595 char *val = (char *)header + min_offs - size;
596 here->e_value_offs =
597 cpu_to_le16((char *)val - (char *)header);
598 memset(val + size - EXT2_XATTR_PAD, 0,
599 EXT2_XATTR_PAD); /* Clear the pad bytes. */
600 memcpy(val, value, value_len);
601 }
602 }
603
604skip_replace:
605 if (IS_LAST_ENTRY(ENTRY(header+1))) {
606 /* This block is now empty. */
607 if (bh && header == HDR(bh))
608 unlock_buffer(bh); /* we were modifying in-place. */
609 error = ext2_xattr_set2(inode, bh, NULL);
610 } else {
611 ext2_xattr_rehash(header, here);
612 if (bh && header == HDR(bh))
613 unlock_buffer(bh); /* we were modifying in-place. */
614 error = ext2_xattr_set2(inode, bh, header);
615 }
616
617cleanup:
618 brelse(bh);
619 if (!(bh && header == HDR(bh)))
620 kfree(header);
621 up_write(&EXT2_I(inode)->xattr_sem);
622
623 return error;
624}
625
626/*
627 * Second half of ext2_xattr_set(): Update the file system.
628 */
629static int
630ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
631 struct ext2_xattr_header *header)
632{
633 struct super_block *sb = inode->i_sb;
634 struct buffer_head *new_bh = NULL;
635 int error;
636
637 if (header) {
638 new_bh = ext2_xattr_cache_find(inode, header);
639 if (new_bh) {
640 /* We found an identical block in the cache. */
641 if (new_bh == old_bh) {
642 ea_bdebug(new_bh, "keeping this block");
643 } else {
644 /* The old block is released after updating
645 the inode. */
646 ea_bdebug(new_bh, "reusing block");
647
648 error = -EDQUOT;
649 if (DQUOT_ALLOC_BLOCK(inode, 1)) {
650 unlock_buffer(new_bh);
651 goto cleanup;
652 }
653 HDR(new_bh)->h_refcount = cpu_to_le32(1 +
654 le32_to_cpu(HDR(new_bh)->h_refcount));
655 ea_bdebug(new_bh, "refcount now=%d",
656 le32_to_cpu(HDR(new_bh)->h_refcount));
657 }
658 unlock_buffer(new_bh);
659 } else if (old_bh && header == HDR(old_bh)) {
660 /* Keep this block. No need to lock the block as we
661 don't need to change the reference count. */
662 new_bh = old_bh;
663 get_bh(new_bh);
664 ext2_xattr_cache_insert(new_bh);
665 } else {
666 /* We need to allocate a new block */
667 int goal = le32_to_cpu(EXT2_SB(sb)->s_es->
668 s_first_data_block) +
669 EXT2_I(inode)->i_block_group *
670 EXT2_BLOCKS_PER_GROUP(sb);
671 int block = ext2_new_block(inode, goal,
672 NULL, NULL, &error);
673 if (error)
674 goto cleanup;
675 ea_idebug(inode, "creating block %d", block);
676
677 new_bh = sb_getblk(sb, block);
678 if (!new_bh) {
679 ext2_free_blocks(inode, block, 1);
680 error = -EIO;
681 goto cleanup;
682 }
683 lock_buffer(new_bh);
684 memcpy(new_bh->b_data, header, new_bh->b_size);
685 set_buffer_uptodate(new_bh);
686 unlock_buffer(new_bh);
687 ext2_xattr_cache_insert(new_bh);
688
689 ext2_xattr_update_super_block(sb);
690 }
691 mark_buffer_dirty(new_bh);
692 if (IS_SYNC(inode)) {
693 sync_dirty_buffer(new_bh);
694 error = -EIO;
695 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
696 goto cleanup;
697 }
698 }
699
700 /* Update the inode. */
701 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
702 inode->i_ctime = CURRENT_TIME_SEC;
703 if (IS_SYNC(inode)) {
704 error = ext2_sync_inode (inode);
705 /* In case sync failed due to ENOSPC the inode was actually
706 * written (only some dirty data were not) so we just proceed
707 * as if nothing happened and cleanup the unused block */
708 if (error && error != -ENOSPC) {
709 if (new_bh && new_bh != old_bh)
710 DQUOT_FREE_BLOCK(inode, 1);
711 goto cleanup;
712 }
713 } else
714 mark_inode_dirty(inode);
715
716 error = 0;
717 if (old_bh && old_bh != new_bh) {
718 struct mb_cache_entry *ce;
719
720 /*
721 * If there was an old block and we are no longer using it,
722 * release the old block.
723 */
724 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
725 old_bh->b_blocknr);
726 lock_buffer(old_bh);
727 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
728 /* Free the old block. */
729 if (ce)
730 mb_cache_entry_free(ce);
731 ea_bdebug(old_bh, "freeing");
732 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
733 /* We let our caller release old_bh, so we
734 * need to duplicate the buffer before. */
735 get_bh(old_bh);
736 bforget(old_bh);
737 } else {
738 /* Decrement the refcount only. */
739 HDR(old_bh)->h_refcount = cpu_to_le32(
740 le32_to_cpu(HDR(old_bh)->h_refcount) - 1);
741 if (ce)
742 mb_cache_entry_release(ce);
743 DQUOT_FREE_BLOCK(inode, 1);
744 mark_buffer_dirty(old_bh);
745 ea_bdebug(old_bh, "refcount now=%d",
746 le32_to_cpu(HDR(old_bh)->h_refcount));
747 }
748 unlock_buffer(old_bh);
749 }
750
751cleanup:
752 brelse(new_bh);
753
754 return error;
755}
756
757/*
758 * ext2_xattr_delete_inode()
759 *
760 * Free extended attribute resources associated with this inode. This
761 * is called immediately before an inode is freed.
762 */
763void
764ext2_xattr_delete_inode(struct inode *inode)
765{
766 struct buffer_head *bh = NULL;
767 struct mb_cache_entry *ce;
768
769 down_write(&EXT2_I(inode)->xattr_sem);
770 if (!EXT2_I(inode)->i_file_acl)
771 goto cleanup;
772 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
773 if (!bh) {
774 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
775 "inode %ld: block %d read error", inode->i_ino,
776 EXT2_I(inode)->i_file_acl);
777 goto cleanup;
778 }
779 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
780 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
781 HDR(bh)->h_blocks != cpu_to_le32(1)) {
782 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
783 "inode %ld: bad block %d", inode->i_ino,
784 EXT2_I(inode)->i_file_acl);
785 goto cleanup;
786 }
787 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
788 lock_buffer(bh);
789 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
790 if (ce)
791 mb_cache_entry_free(ce);
792 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
793 get_bh(bh);
794 bforget(bh);
Peter Staubachb2f49032006-02-17 13:52:36 -0800795 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 } else {
797 HDR(bh)->h_refcount = cpu_to_le32(
798 le32_to_cpu(HDR(bh)->h_refcount) - 1);
799 if (ce)
800 mb_cache_entry_release(ce);
Peter Staubachb2f49032006-02-17 13:52:36 -0800801 ea_bdebug(bh, "refcount now=%d",
802 le32_to_cpu(HDR(bh)->h_refcount));
803 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 mark_buffer_dirty(bh);
805 if (IS_SYNC(inode))
806 sync_dirty_buffer(bh);
807 DQUOT_FREE_BLOCK(inode, 1);
808 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 EXT2_I(inode)->i_file_acl = 0;
810
811cleanup:
812 brelse(bh);
813 up_write(&EXT2_I(inode)->xattr_sem);
814}
815
816/*
817 * ext2_xattr_put_super()
818 *
819 * This is called when a file system is unmounted.
820 */
821void
822ext2_xattr_put_super(struct super_block *sb)
823{
Andreas Gruenbacher8c52ab42005-07-27 11:45:15 -0700824 mb_cache_shrink(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825}
826
827
828/*
829 * ext2_xattr_cache_insert()
830 *
831 * Create a new entry in the extended attribute cache, and insert
832 * it unless such an entry is already in the cache.
833 *
834 * Returns 0, or a negative error number on failure.
835 */
836static int
837ext2_xattr_cache_insert(struct buffer_head *bh)
838{
839 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
840 struct mb_cache_entry *ce;
841 int error;
842
843 ce = mb_cache_entry_alloc(ext2_xattr_cache);
844 if (!ce)
845 return -ENOMEM;
846 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
847 if (error) {
848 mb_cache_entry_free(ce);
849 if (error == -EBUSY) {
850 ea_bdebug(bh, "already in cache (%d cache entries)",
851 atomic_read(&ext2_xattr_cache->c_entry_count));
852 error = 0;
853 }
854 } else {
855 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
856 atomic_read(&ext2_xattr_cache->c_entry_count));
857 mb_cache_entry_release(ce);
858 }
859 return error;
860}
861
862/*
863 * ext2_xattr_cmp()
864 *
865 * Compare two extended attribute blocks for equality.
866 *
867 * Returns 0 if the blocks are equal, 1 if they differ, and
868 * a negative error number on errors.
869 */
870static int
871ext2_xattr_cmp(struct ext2_xattr_header *header1,
872 struct ext2_xattr_header *header2)
873{
874 struct ext2_xattr_entry *entry1, *entry2;
875
876 entry1 = ENTRY(header1+1);
877 entry2 = ENTRY(header2+1);
878 while (!IS_LAST_ENTRY(entry1)) {
879 if (IS_LAST_ENTRY(entry2))
880 return 1;
881 if (entry1->e_hash != entry2->e_hash ||
882 entry1->e_name_index != entry2->e_name_index ||
883 entry1->e_name_len != entry2->e_name_len ||
884 entry1->e_value_size != entry2->e_value_size ||
885 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
886 return 1;
887 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
888 return -EIO;
889 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
890 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
891 le32_to_cpu(entry1->e_value_size)))
892 return 1;
893
894 entry1 = EXT2_XATTR_NEXT(entry1);
895 entry2 = EXT2_XATTR_NEXT(entry2);
896 }
897 if (!IS_LAST_ENTRY(entry2))
898 return 1;
899 return 0;
900}
901
902/*
903 * ext2_xattr_cache_find()
904 *
905 * Find an identical extended attribute block.
906 *
907 * Returns a locked buffer head to the block found, or NULL if such
908 * a block was not found or an error occurred.
909 */
910static struct buffer_head *
911ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
912{
913 __u32 hash = le32_to_cpu(header->h_hash);
914 struct mb_cache_entry *ce;
915
916 if (!header->h_hash)
917 return NULL; /* never share */
918 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
919again:
920 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0,
921 inode->i_sb->s_bdev, hash);
922 while (ce) {
923 struct buffer_head *bh;
924
925 if (IS_ERR(ce)) {
926 if (PTR_ERR(ce) == -EAGAIN)
927 goto again;
928 break;
929 }
930
931 bh = sb_bread(inode->i_sb, ce->e_block);
932 if (!bh) {
933 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
934 "inode %ld: block %ld read error",
935 inode->i_ino, (unsigned long) ce->e_block);
936 } else {
937 lock_buffer(bh);
938 if (le32_to_cpu(HDR(bh)->h_refcount) >
939 EXT2_XATTR_REFCOUNT_MAX) {
940 ea_idebug(inode, "block %ld refcount %d>%d",
941 (unsigned long) ce->e_block,
942 le32_to_cpu(HDR(bh)->h_refcount),
943 EXT2_XATTR_REFCOUNT_MAX);
944 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
945 ea_bdebug(bh, "b_count=%d",
946 atomic_read(&(bh->b_count)));
947 mb_cache_entry_release(ce);
948 return bh;
949 }
950 unlock_buffer(bh);
951 brelse(bh);
952 }
953 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
954 }
955 return NULL;
956}
957
958#define NAME_HASH_SHIFT 5
959#define VALUE_HASH_SHIFT 16
960
961/*
962 * ext2_xattr_hash_entry()
963 *
964 * Compute the hash of an extended attribute.
965 */
966static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
967 struct ext2_xattr_entry *entry)
968{
969 __u32 hash = 0;
970 char *name = entry->e_name;
971 int n;
972
973 for (n=0; n < entry->e_name_len; n++) {
974 hash = (hash << NAME_HASH_SHIFT) ^
975 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
976 *name++;
977 }
978
979 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
980 __le32 *value = (__le32 *)((char *)header +
981 le16_to_cpu(entry->e_value_offs));
982 for (n = (le32_to_cpu(entry->e_value_size) +
983 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
984 hash = (hash << VALUE_HASH_SHIFT) ^
985 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
986 le32_to_cpu(*value++);
987 }
988 }
989 entry->e_hash = cpu_to_le32(hash);
990}
991
992#undef NAME_HASH_SHIFT
993#undef VALUE_HASH_SHIFT
994
995#define BLOCK_HASH_SHIFT 16
996
997/*
998 * ext2_xattr_rehash()
999 *
1000 * Re-compute the extended attribute hash value after an entry has changed.
1001 */
1002static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1003 struct ext2_xattr_entry *entry)
1004{
1005 struct ext2_xattr_entry *here;
1006 __u32 hash = 0;
1007
1008 ext2_xattr_hash_entry(header, entry);
1009 here = ENTRY(header+1);
1010 while (!IS_LAST_ENTRY(here)) {
1011 if (!here->e_hash) {
1012 /* Block is not shared if an entry's hash value == 0 */
1013 hash = 0;
1014 break;
1015 }
1016 hash = (hash << BLOCK_HASH_SHIFT) ^
1017 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1018 le32_to_cpu(here->e_hash);
1019 here = EXT2_XATTR_NEXT(here);
1020 }
1021 header->h_hash = cpu_to_le32(hash);
1022}
1023
1024#undef BLOCK_HASH_SHIFT
1025
1026int __init
1027init_ext2_xattr(void)
1028{
1029 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL,
1030 sizeof(struct mb_cache_entry) +
1031 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1032 if (!ext2_xattr_cache)
1033 return -ENOMEM;
1034 return 0;
1035}
1036
1037void
1038exit_ext2_xattr(void)
1039{
1040 mb_cache_destroy(ext2_xattr_cache);
1041}