blob: f84700be3274292808c9cfa2b9517274d9b17fc1 [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
Stephen Hemminger749c72ef2010-05-13 17:53:16 -0700104static const struct xattr_handler *ext2_xattr_handler_map[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 [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
Stephen Hemminger749c72ef2010-05-13 17:53:16 -0700116const struct xattr_handler *ext2_xattr_handlers[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 &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
Stephen Hemminger749c72ef2010-05-13 17:53:16 -0700129static inline const struct xattr_handler *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130ext2_xattr_handler(int name_index)
131{
Stephen Hemminger749c72ef2010-05-13 17:53:16 -0700132 const struct xattr_handler *handler = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
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)) {
Stephen Hemminger749c72ef2010-05-13 17:53:16 -0700301 const struct xattr_handler *handler =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 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
Jan Blunckc15271f2010-04-14 14:38:38 +0200348 spin_lock(&EXT2_SB(sb)->s_lock);
Andreas Gruenbachered2908f2006-12-06 20:36:16 -0800349 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
Jan Blunckc15271f2010-04-14 14:38:38 +0200350 spin_unlock(&EXT2_SB(sb)->s_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 sb->s_dirt = 1;
352 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353}
354
355/*
356 * ext2_xattr_set()
357 *
358 * Create, replace or remove an extended attribute for this inode. Buffer
359 * is NULL to remove an existing extended attribute, and non-NULL to
360 * either replace an existing extended attribute, or create a new extended
361 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
362 * specify that an extended attribute must exist and must not exist
363 * previous to the call, respectively.
364 *
365 * Returns 0, or a negative error number on failure.
366 */
367int
368ext2_xattr_set(struct inode *inode, int name_index, const char *name,
369 const void *value, size_t value_len, int flags)
370{
371 struct super_block *sb = inode->i_sb;
372 struct buffer_head *bh = NULL;
373 struct ext2_xattr_header *header = NULL;
374 struct ext2_xattr_entry *here, *last;
375 size_t name_len, free, min_offs = sb->s_blocksize;
376 int not_found = 1, error;
377 char *end;
378
379 /*
380 * header -- Points either into bh, or to a temporarily
381 * allocated buffer.
382 * here -- The named entry found, or the place for inserting, within
383 * the block pointed to by header.
384 * last -- Points right after the last named entry within the block
385 * pointed to by header.
386 * min_offs -- The offset of the first value (values are aligned
387 * towards the end of the block).
388 * end -- Points right after the block pointed to by header.
389 */
390
391 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
392 name_index, name, value, (long)value_len);
393
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 if (value == NULL)
395 value_len = 0;
396 if (name == NULL)
397 return -EINVAL;
398 name_len = strlen(name);
399 if (name_len > 255 || value_len > sb->s_blocksize)
400 return -ERANGE;
401 down_write(&EXT2_I(inode)->xattr_sem);
402 if (EXT2_I(inode)->i_file_acl) {
403 /* The inode already has an extended attribute block. */
404 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
405 error = -EIO;
406 if (!bh)
407 goto cleanup;
408 ea_bdebug(bh, "b_count=%d, refcount=%d",
409 atomic_read(&(bh->b_count)),
410 le32_to_cpu(HDR(bh)->h_refcount));
411 header = HDR(bh);
412 end = bh->b_data + bh->b_size;
413 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
414 header->h_blocks != cpu_to_le32(1)) {
415bad_block: ext2_error(sb, "ext2_xattr_set",
416 "inode %ld: bad block %d", inode->i_ino,
417 EXT2_I(inode)->i_file_acl);
418 error = -EIO;
419 goto cleanup;
420 }
421 /* Find the named attribute. */
422 here = FIRST_ENTRY(bh);
423 while (!IS_LAST_ENTRY(here)) {
424 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
425 if ((char *)next >= end)
426 goto bad_block;
427 if (!here->e_value_block && here->e_value_size) {
428 size_t offs = le16_to_cpu(here->e_value_offs);
429 if (offs < min_offs)
430 min_offs = offs;
431 }
432 not_found = name_index - here->e_name_index;
433 if (!not_found)
434 not_found = name_len - here->e_name_len;
435 if (!not_found)
436 not_found = memcmp(name, here->e_name,name_len);
437 if (not_found <= 0)
438 break;
439 here = next;
440 }
441 last = here;
442 /* We still need to compute min_offs and last. */
443 while (!IS_LAST_ENTRY(last)) {
444 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
445 if ((char *)next >= end)
446 goto bad_block;
447 if (!last->e_value_block && last->e_value_size) {
448 size_t offs = le16_to_cpu(last->e_value_offs);
449 if (offs < min_offs)
450 min_offs = offs;
451 }
452 last = next;
453 }
454
455 /* Check whether we have enough space left. */
456 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
457 } else {
458 /* We will use a new extended attribute block. */
459 free = sb->s_blocksize -
460 sizeof(struct ext2_xattr_header) - sizeof(__u32);
461 here = last = NULL; /* avoid gcc uninitialized warning. */
462 }
463
464 if (not_found) {
465 /* Request to remove a nonexistent attribute? */
466 error = -ENODATA;
467 if (flags & XATTR_REPLACE)
468 goto cleanup;
469 error = 0;
470 if (value == NULL)
471 goto cleanup;
472 } else {
473 /* Request to create an existing attribute? */
474 error = -EEXIST;
475 if (flags & XATTR_CREATE)
476 goto cleanup;
477 if (!here->e_value_block && here->e_value_size) {
478 size_t size = le32_to_cpu(here->e_value_size);
479
480 if (le16_to_cpu(here->e_value_offs) + size >
481 sb->s_blocksize || size > sb->s_blocksize)
482 goto bad_block;
483 free += EXT2_XATTR_SIZE(size);
484 }
485 free += EXT2_XATTR_LEN(name_len);
486 }
487 error = -ENOSPC;
488 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
489 goto cleanup;
490
491 /* Here we know that we can set the new attribute. */
492
493 if (header) {
494 struct mb_cache_entry *ce;
495
496 /* assert(header == HDR(bh)); */
497 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
498 bh->b_blocknr);
499 lock_buffer(bh);
500 if (header->h_refcount == cpu_to_le32(1)) {
501 ea_bdebug(bh, "modifying in-place");
502 if (ce)
503 mb_cache_entry_free(ce);
504 /* keep the buffer locked while modifying it. */
505 } else {
506 int offset;
507
508 if (ce)
509 mb_cache_entry_release(ce);
510 unlock_buffer(bh);
511 ea_bdebug(bh, "cloning");
512 header = kmalloc(bh->b_size, GFP_KERNEL);
513 error = -ENOMEM;
514 if (header == NULL)
515 goto cleanup;
516 memcpy(header, HDR(bh), bh->b_size);
517 header->h_refcount = cpu_to_le32(1);
518
519 offset = (char *)here - bh->b_data;
520 here = ENTRY((char *)header + offset);
521 offset = (char *)last - bh->b_data;
522 last = ENTRY((char *)header + offset);
523 }
524 } else {
525 /* Allocate a buffer where we construct the new block. */
Panagiotis Issarisf8314dc2006-09-27 01:49:37 -0700526 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 error = -ENOMEM;
528 if (header == NULL)
529 goto cleanup;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 end = (char *)header + sb->s_blocksize;
531 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
532 header->h_blocks = header->h_refcount = cpu_to_le32(1);
533 last = here = ENTRY(header+1);
534 }
535
536 /* Iff we are modifying the block in-place, bh is locked here. */
537
538 if (not_found) {
539 /* Insert the new name. */
540 size_t size = EXT2_XATTR_LEN(name_len);
541 size_t rest = (char *)last - (char *)here;
542 memmove((char *)here + size, here, rest);
543 memset(here, 0, size);
544 here->e_name_index = name_index;
545 here->e_name_len = name_len;
546 memcpy(here->e_name, name, name_len);
547 } else {
548 if (!here->e_value_block && here->e_value_size) {
549 char *first_val = (char *)header + min_offs;
550 size_t offs = le16_to_cpu(here->e_value_offs);
551 char *val = (char *)header + offs;
552 size_t size = EXT2_XATTR_SIZE(
553 le32_to_cpu(here->e_value_size));
554
555 if (size == EXT2_XATTR_SIZE(value_len)) {
556 /* The old and the new value have the same
557 size. Just replace. */
558 here->e_value_size = cpu_to_le32(value_len);
559 memset(val + size - EXT2_XATTR_PAD, 0,
560 EXT2_XATTR_PAD); /* Clear pad bytes. */
561 memcpy(val, value, value_len);
562 goto skip_replace;
563 }
564
565 /* Remove the old value. */
566 memmove(first_val + size, first_val, val - first_val);
567 memset(first_val, 0, size);
568 here->e_value_offs = 0;
569 min_offs += size;
570
571 /* Adjust all value offsets. */
572 last = ENTRY(header+1);
573 while (!IS_LAST_ENTRY(last)) {
574 size_t o = le16_to_cpu(last->e_value_offs);
575 if (!last->e_value_block && o < offs)
576 last->e_value_offs =
577 cpu_to_le16(o + size);
578 last = EXT2_XATTR_NEXT(last);
579 }
580 }
581 if (value == NULL) {
582 /* Remove the old name. */
583 size_t size = EXT2_XATTR_LEN(name_len);
584 last = ENTRY((char *)last - size);
585 memmove(here, (char*)here + size,
586 (char*)last - (char*)here);
587 memset(last, 0, size);
588 }
589 }
590
591 if (value != NULL) {
592 /* Insert the new value. */
593 here->e_value_size = cpu_to_le32(value_len);
594 if (value_len) {
595 size_t size = EXT2_XATTR_SIZE(value_len);
596 char *val = (char *)header + min_offs - size;
597 here->e_value_offs =
598 cpu_to_le16((char *)val - (char *)header);
599 memset(val + size - EXT2_XATTR_PAD, 0,
600 EXT2_XATTR_PAD); /* Clear the pad bytes. */
601 memcpy(val, value, value_len);
602 }
603 }
604
605skip_replace:
606 if (IS_LAST_ENTRY(ENTRY(header+1))) {
607 /* This block is now empty. */
608 if (bh && header == HDR(bh))
609 unlock_buffer(bh); /* we were modifying in-place. */
610 error = ext2_xattr_set2(inode, bh, NULL);
611 } else {
612 ext2_xattr_rehash(header, here);
613 if (bh && header == HDR(bh))
614 unlock_buffer(bh); /* we were modifying in-place. */
615 error = ext2_xattr_set2(inode, bh, header);
616 }
617
618cleanup:
619 brelse(bh);
620 if (!(bh && header == HDR(bh)))
621 kfree(header);
622 up_write(&EXT2_I(inode)->xattr_sem);
623
624 return error;
625}
626
627/*
628 * Second half of ext2_xattr_set(): Update the file system.
629 */
630static int
631ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
632 struct ext2_xattr_header *header)
633{
634 struct super_block *sb = inode->i_sb;
635 struct buffer_head *new_bh = NULL;
636 int error;
637
638 if (header) {
639 new_bh = ext2_xattr_cache_find(inode, header);
640 if (new_bh) {
641 /* We found an identical block in the cache. */
642 if (new_bh == old_bh) {
643 ea_bdebug(new_bh, "keeping this block");
644 } else {
645 /* The old block is released after updating
646 the inode. */
647 ea_bdebug(new_bh, "reusing block");
648
Christoph Hellwig5dd40562010-03-03 09:05:00 -0500649 error = dquot_alloc_block(inode, 1);
650 if (error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 unlock_buffer(new_bh);
652 goto cleanup;
653 }
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700654 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 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 */
Akinobu Mita24097d12008-04-28 02:16:01 -0700667 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
668 EXT2_I(inode)->i_block_group);
Martin J. Bligha686cd82007-10-16 23:30:46 -0700669 int block = ext2_new_block(inode, goal, &error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 if (error)
671 goto cleanup;
672 ea_idebug(inode, "creating block %d", block);
673
674 new_bh = sb_getblk(sb, block);
675 if (!new_bh) {
676 ext2_free_blocks(inode, block, 1);
Al Viroaddacc72010-07-22 01:19:42 +0400677 mark_inode_dirty(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 error = -EIO;
679 goto cleanup;
680 }
681 lock_buffer(new_bh);
682 memcpy(new_bh->b_data, header, new_bh->b_size);
683 set_buffer_uptodate(new_bh);
684 unlock_buffer(new_bh);
685 ext2_xattr_cache_insert(new_bh);
686
687 ext2_xattr_update_super_block(sb);
688 }
689 mark_buffer_dirty(new_bh);
690 if (IS_SYNC(inode)) {
691 sync_dirty_buffer(new_bh);
692 error = -EIO;
693 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
694 goto cleanup;
695 }
696 }
697
698 /* Update the inode. */
699 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
700 inode->i_ctime = CURRENT_TIME_SEC;
701 if (IS_SYNC(inode)) {
Christoph Hellwigc37650162010-10-06 10:48:20 +0200702 error = sync_inode_metadata(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 /* In case sync failed due to ENOSPC the inode was actually
704 * written (only some dirty data were not) so we just proceed
705 * as if nothing happened and cleanup the unused block */
706 if (error && error != -ENOSPC) {
Al Viro38897172010-07-22 01:13:36 +0400707 if (new_bh && new_bh != old_bh) {
708 dquot_free_block_nodirty(inode, 1);
709 mark_inode_dirty(inode);
710 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 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);
Al Viroaddacc72010-07-22 01:19:42 +0400733 mark_inode_dirty(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 /* We let our caller release old_bh, so we
735 * need to duplicate the buffer before. */
736 get_bh(old_bh);
737 bforget(old_bh);
738 } else {
739 /* Decrement the refcount only. */
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700740 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 if (ce)
742 mb_cache_entry_release(ce);
Al Viro38897172010-07-22 01:13:36 +0400743 dquot_free_block_nodirty(inode, 1);
744 mark_inode_dirty(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 mark_buffer_dirty(old_bh);
746 ea_bdebug(old_bh, "refcount now=%d",
747 le32_to_cpu(HDR(old_bh)->h_refcount));
748 }
749 unlock_buffer(old_bh);
750 }
751
752cleanup:
753 brelse(new_bh);
754
755 return error;
756}
757
758/*
759 * ext2_xattr_delete_inode()
760 *
761 * Free extended attribute resources associated with this inode. This
762 * is called immediately before an inode is freed.
763 */
764void
765ext2_xattr_delete_inode(struct inode *inode)
766{
767 struct buffer_head *bh = NULL;
768 struct mb_cache_entry *ce;
769
770 down_write(&EXT2_I(inode)->xattr_sem);
771 if (!EXT2_I(inode)->i_file_acl)
772 goto cleanup;
773 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
774 if (!bh) {
775 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
776 "inode %ld: block %d read error", inode->i_ino,
777 EXT2_I(inode)->i_file_acl);
778 goto cleanup;
779 }
780 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
781 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
782 HDR(bh)->h_blocks != cpu_to_le32(1)) {
783 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
784 "inode %ld: bad block %d", inode->i_ino,
785 EXT2_I(inode)->i_file_acl);
786 goto cleanup;
787 }
788 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
789 lock_buffer(bh);
790 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
791 if (ce)
792 mb_cache_entry_free(ce);
793 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
794 get_bh(bh);
795 bforget(bh);
Peter Staubachb2f49032006-02-17 13:52:36 -0800796 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 } else {
Marcin Slusarzfba4d392008-04-28 02:15:59 -0700798 le32_add_cpu(&HDR(bh)->h_refcount, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 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);
Al Viro38897172010-07-22 01:13:36 +0400807 dquot_free_block_nodirty(inode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 }
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
Jan Kara335e92e2008-04-15 14:34:43 -0700843 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 if (!ce)
845 return -ENOMEM;
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +0200846 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847 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:
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +0200920 ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
921 hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 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 }
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +0200953 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 }
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{
Andreas Gruenbacher2aec7c52010-07-19 18:19:41 +02001029 ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 if (!ext2_xattr_cache)
1031 return -ENOMEM;
1032 return 0;
1033}
1034
1035void
1036exit_ext2_xattr(void)
1037{
1038 mb_cache_destroy(ext2_xattr_cache);
1039}