Root/fs/ext3/xattr.c

1/*
2 * linux/fs/ext3/xattr.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 *
6 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
7 * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
8 * Extended attributes for symlinks and special files added per
9 * suggestion of Luka Renko <luka.renko@hermes.si>.
10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
11 * Red Hat Inc.
12 * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
13 * and Andreas Gruenbacher <agruen@suse.de>.
14 */
15
16/*
17 * Extended attributes are stored directly in inodes (on file systems with
18 * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
19 * field contains the block number if an inode uses an additional block. All
20 * attributes must fit in the inode and one additional block. Blocks that
21 * contain the identical set of attributes may be shared among several inodes.
22 * Identical blocks are detected by keeping a cache of blocks that have
23 * recently been accessed.
24 *
25 * The attributes in inodes and on blocks have a different header; the entries
26 * are stored in the same format:
27 *
28 * +------------------+
29 * | header |
30 * | entry 1 | |
31 * | entry 2 | | growing downwards
32 * | entry 3 | v
33 * | four null bytes |
34 * | . . . |
35 * | value 1 | ^
36 * | value 3 | | growing upwards
37 * | value 2 | |
38 * +------------------+
39 *
40 * The header is followed by multiple entry descriptors. In disk blocks, the
41 * entry descriptors are kept sorted. In inodes, they are unsorted. The
42 * attribute values are aligned to the end of the block in no specific order.
43 *
44 * Locking strategy
45 * ----------------
46 * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
47 * EA blocks are only changed if they are exclusive to an inode, so
48 * holding xattr_sem also means that nothing but the EA block's reference
49 * count can change. Multiple writers to the same block are synchronized
50 * by the buffer lock.
51 */
52
53#include <linux/init.h>
54#include <linux/fs.h>
55#include <linux/slab.h>
56#include <linux/ext3_jbd.h>
57#include <linux/ext3_fs.h>
58#include <linux/mbcache.h>
59#include <linux/quotaops.h>
60#include <linux/rwsem.h>
61#include "xattr.h"
62#include "acl.h"
63
64#define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
65#define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
66#define BFIRST(bh) ENTRY(BHDR(bh)+1)
67#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
68
69#define IHDR(inode, raw_inode) \
70    ((struct ext3_xattr_ibody_header *) \
71        ((void *)raw_inode + \
72         EXT3_GOOD_OLD_INODE_SIZE + \
73         EXT3_I(inode)->i_extra_isize))
74#define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
75
76#ifdef EXT3_XATTR_DEBUG
77# define ea_idebug(inode, f...) do { \
78        printk(KERN_DEBUG "inode %s:%lu: ", \
79            inode->i_sb->s_id, inode->i_ino); \
80        printk(f); \
81        printk("\n"); \
82    } while (0)
83# define ea_bdebug(bh, f...) do { \
84        char b[BDEVNAME_SIZE]; \
85        printk(KERN_DEBUG "block %s:%lu: ", \
86            bdevname(bh->b_bdev, b), \
87            (unsigned long) bh->b_blocknr); \
88        printk(f); \
89        printk("\n"); \
90    } while (0)
91#else
92# define ea_idebug(f...)
93# define ea_bdebug(f...)
94#endif
95
96static void ext3_xattr_cache_insert(struct buffer_head *);
97static struct buffer_head *ext3_xattr_cache_find(struct inode *,
98                         struct ext3_xattr_header *,
99                         struct mb_cache_entry **);
100static void ext3_xattr_rehash(struct ext3_xattr_header *,
101                  struct ext3_xattr_entry *);
102static int ext3_xattr_list(struct dentry *dentry, char *buffer,
103               size_t buffer_size);
104
105static struct mb_cache *ext3_xattr_cache;
106
107static const struct xattr_handler *ext3_xattr_handler_map[] = {
108    [EXT3_XATTR_INDEX_USER] = &ext3_xattr_user_handler,
109#ifdef CONFIG_EXT3_FS_POSIX_ACL
110    [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext3_xattr_acl_access_handler,
111    [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
112#endif
113    [EXT3_XATTR_INDEX_TRUSTED] = &ext3_xattr_trusted_handler,
114#ifdef CONFIG_EXT3_FS_SECURITY
115    [EXT3_XATTR_INDEX_SECURITY] = &ext3_xattr_security_handler,
116#endif
117};
118
119const struct xattr_handler *ext3_xattr_handlers[] = {
120    &ext3_xattr_user_handler,
121    &ext3_xattr_trusted_handler,
122#ifdef CONFIG_EXT3_FS_POSIX_ACL
123    &ext3_xattr_acl_access_handler,
124    &ext3_xattr_acl_default_handler,
125#endif
126#ifdef CONFIG_EXT3_FS_SECURITY
127    &ext3_xattr_security_handler,
128#endif
129    NULL
130};
131
132static inline const struct xattr_handler *
133ext3_xattr_handler(int name_index)
134{
135    const struct xattr_handler *handler = NULL;
136
137    if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
138        handler = ext3_xattr_handler_map[name_index];
139    return handler;
140}
141
142/*
143 * Inode operation listxattr()
144 *
145 * dentry->d_inode->i_mutex: don't care
146 */
147ssize_t
148ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
149{
150    return ext3_xattr_list(dentry, buffer, size);
151}
152
153static int
154ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
155{
156    while (!IS_LAST_ENTRY(entry)) {
157        struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
158        if ((void *)next >= end)
159            return -EIO;
160        entry = next;
161    }
162    return 0;
163}
164
165static inline int
166ext3_xattr_check_block(struct buffer_head *bh)
167{
168    int error;
169
170    if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
171        BHDR(bh)->h_blocks != cpu_to_le32(1))
172        return -EIO;
173    error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
174    return error;
175}
176
177static inline int
178ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
179{
180    size_t value_size = le32_to_cpu(entry->e_value_size);
181
182    if (entry->e_value_block != 0 || value_size > size ||
183        le16_to_cpu(entry->e_value_offs) + value_size > size)
184        return -EIO;
185    return 0;
186}
187
188static int
189ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
190              const char *name, size_t size, int sorted)
191{
192    struct ext3_xattr_entry *entry;
193    size_t name_len;
194    int cmp = 1;
195
196    if (name == NULL)
197        return -EINVAL;
198    name_len = strlen(name);
199    entry = *pentry;
200    for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
201        cmp = name_index - entry->e_name_index;
202        if (!cmp)
203            cmp = name_len - entry->e_name_len;
204        if (!cmp)
205            cmp = memcmp(name, entry->e_name, name_len);
206        if (cmp <= 0 && (sorted || cmp == 0))
207            break;
208    }
209    *pentry = entry;
210    if (!cmp && ext3_xattr_check_entry(entry, size))
211            return -EIO;
212    return cmp ? -ENODATA : 0;
213}
214
215static int
216ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
217             void *buffer, size_t buffer_size)
218{
219    struct buffer_head *bh = NULL;
220    struct ext3_xattr_entry *entry;
221    size_t size;
222    int error;
223
224    ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
225          name_index, name, buffer, (long)buffer_size);
226
227    error = -ENODATA;
228    if (!EXT3_I(inode)->i_file_acl)
229        goto cleanup;
230    ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
231    bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
232    if (!bh)
233        goto cleanup;
234    ea_bdebug(bh, "b_count=%d, refcount=%d",
235        atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
236    if (ext3_xattr_check_block(bh)) {
237bad_block: ext3_error(inode->i_sb, __func__,
238               "inode %lu: bad block "E3FSBLK, inode->i_ino,
239               EXT3_I(inode)->i_file_acl);
240        error = -EIO;
241        goto cleanup;
242    }
243    ext3_xattr_cache_insert(bh);
244    entry = BFIRST(bh);
245    error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
246    if (error == -EIO)
247        goto bad_block;
248    if (error)
249        goto cleanup;
250    size = le32_to_cpu(entry->e_value_size);
251    if (buffer) {
252        error = -ERANGE;
253        if (size > buffer_size)
254            goto cleanup;
255        memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
256               size);
257    }
258    error = size;
259
260cleanup:
261    brelse(bh);
262    return error;
263}
264
265static int
266ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
267             void *buffer, size_t buffer_size)
268{
269    struct ext3_xattr_ibody_header *header;
270    struct ext3_xattr_entry *entry;
271    struct ext3_inode *raw_inode;
272    struct ext3_iloc iloc;
273    size_t size;
274    void *end;
275    int error;
276
277    if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
278        return -ENODATA;
279    error = ext3_get_inode_loc(inode, &iloc);
280    if (error)
281        return error;
282    raw_inode = ext3_raw_inode(&iloc);
283    header = IHDR(inode, raw_inode);
284    entry = IFIRST(header);
285    end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
286    error = ext3_xattr_check_names(entry, end);
287    if (error)
288        goto cleanup;
289    error = ext3_xattr_find_entry(&entry, name_index, name,
290                      end - (void *)entry, 0);
291    if (error)
292        goto cleanup;
293    size = le32_to_cpu(entry->e_value_size);
294    if (buffer) {
295        error = -ERANGE;
296        if (size > buffer_size)
297            goto cleanup;
298        memcpy(buffer, (void *)IFIRST(header) +
299               le16_to_cpu(entry->e_value_offs), size);
300    }
301    error = size;
302
303cleanup:
304    brelse(iloc.bh);
305    return error;
306}
307
308/*
309 * ext3_xattr_get()
310 *
311 * Copy an extended attribute into the buffer
312 * provided, or compute the buffer size required.
313 * Buffer is NULL to compute the size of the buffer required.
314 *
315 * Returns a negative error number on failure, or the number of bytes
316 * used / required on success.
317 */
318int
319ext3_xattr_get(struct inode *inode, int name_index, const char *name,
320           void *buffer, size_t buffer_size)
321{
322    int error;
323
324    down_read(&EXT3_I(inode)->xattr_sem);
325    error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
326                     buffer_size);
327    if (error == -ENODATA)
328        error = ext3_xattr_block_get(inode, name_index, name, buffer,
329                         buffer_size);
330    up_read(&EXT3_I(inode)->xattr_sem);
331    return error;
332}
333
334static int
335ext3_xattr_list_entries(struct dentry *dentry, struct ext3_xattr_entry *entry,
336            char *buffer, size_t buffer_size)
337{
338    size_t rest = buffer_size;
339
340    for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
341        const struct xattr_handler *handler =
342            ext3_xattr_handler(entry->e_name_index);
343
344        if (handler) {
345            size_t size = handler->list(dentry, buffer, rest,
346                            entry->e_name,
347                            entry->e_name_len,
348                            handler->flags);
349            if (buffer) {
350                if (size > rest)
351                    return -ERANGE;
352                buffer += size;
353            }
354            rest -= size;
355        }
356    }
357    return buffer_size - rest;
358}
359
360static int
361ext3_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
362{
363    struct inode *inode = dentry->d_inode;
364    struct buffer_head *bh = NULL;
365    int error;
366
367    ea_idebug(inode, "buffer=%p, buffer_size=%ld",
368          buffer, (long)buffer_size);
369
370    error = 0;
371    if (!EXT3_I(inode)->i_file_acl)
372        goto cleanup;
373    ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
374    bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
375    error = -EIO;
376    if (!bh)
377        goto cleanup;
378    ea_bdebug(bh, "b_count=%d, refcount=%d",
379        atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
380    if (ext3_xattr_check_block(bh)) {
381        ext3_error(inode->i_sb, __func__,
382               "inode %lu: bad block "E3FSBLK, inode->i_ino,
383               EXT3_I(inode)->i_file_acl);
384        error = -EIO;
385        goto cleanup;
386    }
387    ext3_xattr_cache_insert(bh);
388    error = ext3_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
389
390cleanup:
391    brelse(bh);
392
393    return error;
394}
395
396static int
397ext3_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
398{
399    struct inode *inode = dentry->d_inode;
400    struct ext3_xattr_ibody_header *header;
401    struct ext3_inode *raw_inode;
402    struct ext3_iloc iloc;
403    void *end;
404    int error;
405
406    if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
407        return 0;
408    error = ext3_get_inode_loc(inode, &iloc);
409    if (error)
410        return error;
411    raw_inode = ext3_raw_inode(&iloc);
412    header = IHDR(inode, raw_inode);
413    end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
414    error = ext3_xattr_check_names(IFIRST(header), end);
415    if (error)
416        goto cleanup;
417    error = ext3_xattr_list_entries(dentry, IFIRST(header),
418                    buffer, buffer_size);
419
420cleanup:
421    brelse(iloc.bh);
422    return error;
423}
424
425/*
426 * ext3_xattr_list()
427 *
428 * Copy a list of attribute names into the buffer
429 * provided, or compute the buffer size required.
430 * Buffer is NULL to compute the size of the buffer required.
431 *
432 * Returns a negative error number on failure, or the number of bytes
433 * used / required on success.
434 */
435static int
436ext3_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
437{
438    int i_error, b_error;
439
440    down_read(&EXT3_I(dentry->d_inode)->xattr_sem);
441    i_error = ext3_xattr_ibody_list(dentry, buffer, buffer_size);
442    if (i_error < 0) {
443        b_error = 0;
444    } else {
445        if (buffer) {
446            buffer += i_error;
447            buffer_size -= i_error;
448        }
449        b_error = ext3_xattr_block_list(dentry, buffer, buffer_size);
450        if (b_error < 0)
451            i_error = 0;
452    }
453    up_read(&EXT3_I(dentry->d_inode)->xattr_sem);
454    return i_error + b_error;
455}
456
457/*
458 * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
459 * not set, set it.
460 */
461static void ext3_xattr_update_super_block(handle_t *handle,
462                      struct super_block *sb)
463{
464    if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
465        return;
466
467    if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
468        EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
469        ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
470    }
471}
472
473/*
474 * Release the xattr block BH: If the reference count is > 1, decrement
475 * it; otherwise free the block.
476 */
477static void
478ext3_xattr_release_block(handle_t *handle, struct inode *inode,
479             struct buffer_head *bh)
480{
481    struct mb_cache_entry *ce = NULL;
482    int error = 0;
483
484    ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
485    error = ext3_journal_get_write_access(handle, bh);
486    if (error)
487         goto out;
488
489    lock_buffer(bh);
490
491    if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
492        ea_bdebug(bh, "refcount now=0; freeing");
493        if (ce)
494            mb_cache_entry_free(ce);
495        ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
496        get_bh(bh);
497        ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
498    } else {
499        le32_add_cpu(&BHDR(bh)->h_refcount, -1);
500        error = ext3_journal_dirty_metadata(handle, bh);
501        if (IS_SYNC(inode))
502            handle->h_sync = 1;
503        dquot_free_block(inode, 1);
504        ea_bdebug(bh, "refcount now=%d; releasing",
505              le32_to_cpu(BHDR(bh)->h_refcount));
506        if (ce)
507            mb_cache_entry_release(ce);
508    }
509    unlock_buffer(bh);
510out:
511    ext3_std_error(inode->i_sb, error);
512    return;
513}
514
515struct ext3_xattr_info {
516    int name_index;
517    const char *name;
518    const void *value;
519    size_t value_len;
520};
521
522struct ext3_xattr_search {
523    struct ext3_xattr_entry *first;
524    void *base;
525    void *end;
526    struct ext3_xattr_entry *here;
527    int not_found;
528};
529
530static int
531ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
532{
533    struct ext3_xattr_entry *last;
534    size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
535
536    /* Compute min_offs and last. */
537    last = s->first;
538    for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
539        if (!last->e_value_block && last->e_value_size) {
540            size_t offs = le16_to_cpu(last->e_value_offs);
541            if (offs < min_offs)
542                min_offs = offs;
543        }
544    }
545    free = min_offs - ((void *)last - s->base) - sizeof(__u32);
546    if (!s->not_found) {
547        if (!s->here->e_value_block && s->here->e_value_size) {
548            size_t size = le32_to_cpu(s->here->e_value_size);
549            free += EXT3_XATTR_SIZE(size);
550        }
551        free += EXT3_XATTR_LEN(name_len);
552    }
553    if (i->value) {
554        if (free < EXT3_XATTR_SIZE(i->value_len) ||
555            free < EXT3_XATTR_LEN(name_len) +
556               EXT3_XATTR_SIZE(i->value_len))
557            return -ENOSPC;
558    }
559
560    if (i->value && s->not_found) {
561        /* Insert the new name. */
562        size_t size = EXT3_XATTR_LEN(name_len);
563        size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
564        memmove((void *)s->here + size, s->here, rest);
565        memset(s->here, 0, size);
566        s->here->e_name_index = i->name_index;
567        s->here->e_name_len = name_len;
568        memcpy(s->here->e_name, i->name, name_len);
569    } else {
570        if (!s->here->e_value_block && s->here->e_value_size) {
571            void *first_val = s->base + min_offs;
572            size_t offs = le16_to_cpu(s->here->e_value_offs);
573            void *val = s->base + offs;
574            size_t size = EXT3_XATTR_SIZE(
575                le32_to_cpu(s->here->e_value_size));
576
577            if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
578                /* The old and the new value have the same
579                   size. Just replace. */
580                s->here->e_value_size =
581                    cpu_to_le32(i->value_len);
582                memset(val + size - EXT3_XATTR_PAD, 0,
583                       EXT3_XATTR_PAD); /* Clear pad bytes. */
584                memcpy(val, i->value, i->value_len);
585                return 0;
586            }
587
588            /* Remove the old value. */
589            memmove(first_val + size, first_val, val - first_val);
590            memset(first_val, 0, size);
591            s->here->e_value_size = 0;
592            s->here->e_value_offs = 0;
593            min_offs += size;
594
595            /* Adjust all value offsets. */
596            last = s->first;
597            while (!IS_LAST_ENTRY(last)) {
598                size_t o = le16_to_cpu(last->e_value_offs);
599                if (!last->e_value_block &&
600                    last->e_value_size && o < offs)
601                    last->e_value_offs =
602                        cpu_to_le16(o + size);
603                last = EXT3_XATTR_NEXT(last);
604            }
605        }
606        if (!i->value) {
607            /* Remove the old name. */
608            size_t size = EXT3_XATTR_LEN(name_len);
609            last = ENTRY((void *)last - size);
610            memmove(s->here, (void *)s->here + size,
611                (void *)last - (void *)s->here + sizeof(__u32));
612            memset(last, 0, size);
613        }
614    }
615
616    if (i->value) {
617        /* Insert the new value. */
618        s->here->e_value_size = cpu_to_le32(i->value_len);
619        if (i->value_len) {
620            size_t size = EXT3_XATTR_SIZE(i->value_len);
621            void *val = s->base + min_offs - size;
622            s->here->e_value_offs = cpu_to_le16(min_offs - size);
623            memset(val + size - EXT3_XATTR_PAD, 0,
624                   EXT3_XATTR_PAD); /* Clear the pad bytes. */
625            memcpy(val, i->value, i->value_len);
626        }
627    }
628    return 0;
629}
630
631struct ext3_xattr_block_find {
632    struct ext3_xattr_search s;
633    struct buffer_head *bh;
634};
635
636static int
637ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
638              struct ext3_xattr_block_find *bs)
639{
640    struct super_block *sb = inode->i_sb;
641    int error;
642
643    ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
644          i->name_index, i->name, i->value, (long)i->value_len);
645
646    if (EXT3_I(inode)->i_file_acl) {
647        /* The inode already has an extended attribute block. */
648        bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
649        error = -EIO;
650        if (!bs->bh)
651            goto cleanup;
652        ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
653            atomic_read(&(bs->bh->b_count)),
654            le32_to_cpu(BHDR(bs->bh)->h_refcount));
655        if (ext3_xattr_check_block(bs->bh)) {
656            ext3_error(sb, __func__,
657                "inode %lu: bad block "E3FSBLK, inode->i_ino,
658                EXT3_I(inode)->i_file_acl);
659            error = -EIO;
660            goto cleanup;
661        }
662        /* Find the named attribute. */
663        bs->s.base = BHDR(bs->bh);
664        bs->s.first = BFIRST(bs->bh);
665        bs->s.end = bs->bh->b_data + bs->bh->b_size;
666        bs->s.here = bs->s.first;
667        error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
668                          i->name, bs->bh->b_size, 1);
669        if (error && error != -ENODATA)
670            goto cleanup;
671        bs->s.not_found = error;
672    }
673    error = 0;
674
675cleanup:
676    return error;
677}
678
679static int
680ext3_xattr_block_set(handle_t *handle, struct inode *inode,
681             struct ext3_xattr_info *i,
682             struct ext3_xattr_block_find *bs)
683{
684    struct super_block *sb = inode->i_sb;
685    struct buffer_head *new_bh = NULL;
686    struct ext3_xattr_search *s = &bs->s;
687    struct mb_cache_entry *ce = NULL;
688    int error = 0;
689
690#define header(x) ((struct ext3_xattr_header *)(x))
691
692    if (i->value && i->value_len > sb->s_blocksize)
693        return -ENOSPC;
694    if (s->base) {
695        ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
696                    bs->bh->b_blocknr);
697        error = ext3_journal_get_write_access(handle, bs->bh);
698        if (error)
699            goto cleanup;
700        lock_buffer(bs->bh);
701
702        if (header(s->base)->h_refcount == cpu_to_le32(1)) {
703            if (ce) {
704                mb_cache_entry_free(ce);
705                ce = NULL;
706            }
707            ea_bdebug(bs->bh, "modifying in-place");
708            error = ext3_xattr_set_entry(i, s);
709            if (!error) {
710                if (!IS_LAST_ENTRY(s->first))
711                    ext3_xattr_rehash(header(s->base),
712                              s->here);
713                ext3_xattr_cache_insert(bs->bh);
714            }
715            unlock_buffer(bs->bh);
716            if (error == -EIO)
717                goto bad_block;
718            if (!error)
719                error = ext3_journal_dirty_metadata(handle,
720                                    bs->bh);
721            if (error)
722                goto cleanup;
723            goto inserted;
724        } else {
725            int offset = (char *)s->here - bs->bh->b_data;
726
727            unlock_buffer(bs->bh);
728            journal_release_buffer(handle, bs->bh);
729
730            if (ce) {
731                mb_cache_entry_release(ce);
732                ce = NULL;
733            }
734            ea_bdebug(bs->bh, "cloning");
735            s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
736            error = -ENOMEM;
737            if (s->base == NULL)
738                goto cleanup;
739            memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
740            s->first = ENTRY(header(s->base)+1);
741            header(s->base)->h_refcount = cpu_to_le32(1);
742            s->here = ENTRY(s->base + offset);
743            s->end = s->base + bs->bh->b_size;
744        }
745    } else {
746        /* Allocate a buffer where we construct the new block. */
747        s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
748        /* assert(header == s->base) */
749        error = -ENOMEM;
750        if (s->base == NULL)
751            goto cleanup;
752        header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
753        header(s->base)->h_blocks = cpu_to_le32(1);
754        header(s->base)->h_refcount = cpu_to_le32(1);
755        s->first = ENTRY(header(s->base)+1);
756        s->here = ENTRY(header(s->base)+1);
757        s->end = s->base + sb->s_blocksize;
758    }
759
760    error = ext3_xattr_set_entry(i, s);
761    if (error == -EIO)
762        goto bad_block;
763    if (error)
764        goto cleanup;
765    if (!IS_LAST_ENTRY(s->first))
766        ext3_xattr_rehash(header(s->base), s->here);
767
768inserted:
769    if (!IS_LAST_ENTRY(s->first)) {
770        new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
771        if (new_bh) {
772            /* We found an identical block in the cache. */
773            if (new_bh == bs->bh)
774                ea_bdebug(new_bh, "keeping");
775            else {
776                /* The old block is released after updating
777                   the inode. */
778                error = dquot_alloc_block(inode, 1);
779                if (error)
780                    goto cleanup;
781                error = ext3_journal_get_write_access(handle,
782                                      new_bh);
783                if (error)
784                    goto cleanup_dquot;
785                lock_buffer(new_bh);
786                le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
787                ea_bdebug(new_bh, "reusing; refcount now=%d",
788                    le32_to_cpu(BHDR(new_bh)->h_refcount));
789                unlock_buffer(new_bh);
790                error = ext3_journal_dirty_metadata(handle,
791                                    new_bh);
792                if (error)
793                    goto cleanup_dquot;
794            }
795            mb_cache_entry_release(ce);
796            ce = NULL;
797        } else if (bs->bh && s->base == bs->bh->b_data) {
798            /* We were modifying this block in-place. */
799            ea_bdebug(bs->bh, "keeping this block");
800            new_bh = bs->bh;
801            get_bh(new_bh);
802        } else {
803            /* We need to allocate a new block */
804            ext3_fsblk_t goal = ext3_group_first_block_no(sb,
805                        EXT3_I(inode)->i_block_group);
806            ext3_fsblk_t block = ext3_new_block(handle, inode,
807                            goal, &error);
808            if (error)
809                goto cleanup;
810            ea_idebug(inode, "creating block %d", block);
811
812            new_bh = sb_getblk(sb, block);
813            if (!new_bh) {
814getblk_failed:
815                ext3_free_blocks(handle, inode, block, 1);
816                error = -EIO;
817                goto cleanup;
818            }
819            lock_buffer(new_bh);
820            error = ext3_journal_get_create_access(handle, new_bh);
821            if (error) {
822                unlock_buffer(new_bh);
823                goto getblk_failed;
824            }
825            memcpy(new_bh->b_data, s->base, new_bh->b_size);
826            set_buffer_uptodate(new_bh);
827            unlock_buffer(new_bh);
828            ext3_xattr_cache_insert(new_bh);
829            error = ext3_journal_dirty_metadata(handle, new_bh);
830            if (error)
831                goto cleanup;
832        }
833    }
834
835    /* Update the inode. */
836    EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
837
838    /* Drop the previous xattr block. */
839    if (bs->bh && bs->bh != new_bh)
840        ext3_xattr_release_block(handle, inode, bs->bh);
841    error = 0;
842
843cleanup:
844    if (ce)
845        mb_cache_entry_release(ce);
846    brelse(new_bh);
847    if (!(bs->bh && s->base == bs->bh->b_data))
848        kfree(s->base);
849
850    return error;
851
852cleanup_dquot:
853    dquot_free_block(inode, 1);
854    goto cleanup;
855
856bad_block:
857    ext3_error(inode->i_sb, __func__,
858           "inode %lu: bad block "E3FSBLK, inode->i_ino,
859           EXT3_I(inode)->i_file_acl);
860    goto cleanup;
861
862#undef header
863}
864
865struct ext3_xattr_ibody_find {
866    struct ext3_xattr_search s;
867    struct ext3_iloc iloc;
868};
869
870static int
871ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
872              struct ext3_xattr_ibody_find *is)
873{
874    struct ext3_xattr_ibody_header *header;
875    struct ext3_inode *raw_inode;
876    int error;
877
878    if (EXT3_I(inode)->i_extra_isize == 0)
879        return 0;
880    raw_inode = ext3_raw_inode(&is->iloc);
881    header = IHDR(inode, raw_inode);
882    is->s.base = is->s.first = IFIRST(header);
883    is->s.here = is->s.first;
884    is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
885    if (ext3_test_inode_state(inode, EXT3_STATE_XATTR)) {
886        error = ext3_xattr_check_names(IFIRST(header), is->s.end);
887        if (error)
888            return error;
889        /* Find the named attribute. */
890        error = ext3_xattr_find_entry(&is->s.here, i->name_index,
891                          i->name, is->s.end -
892                          (void *)is->s.base, 0);
893        if (error && error != -ENODATA)
894            return error;
895        is->s.not_found = error;
896    }
897    return 0;
898}
899
900static int
901ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
902             struct ext3_xattr_info *i,
903             struct ext3_xattr_ibody_find *is)
904{
905    struct ext3_xattr_ibody_header *header;
906    struct ext3_xattr_search *s = &is->s;
907    int error;
908
909    if (EXT3_I(inode)->i_extra_isize == 0)
910        return -ENOSPC;
911    error = ext3_xattr_set_entry(i, s);
912    if (error)
913        return error;
914    header = IHDR(inode, ext3_raw_inode(&is->iloc));
915    if (!IS_LAST_ENTRY(s->first)) {
916        header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
917        ext3_set_inode_state(inode, EXT3_STATE_XATTR);
918    } else {
919        header->h_magic = cpu_to_le32(0);
920        ext3_clear_inode_state(inode, EXT3_STATE_XATTR);
921    }
922    return 0;
923}
924
925/*
926 * ext3_xattr_set_handle()
927 *
928 * Create, replace or remove an extended attribute for this inode. Value
929 * is NULL to remove an existing extended attribute, and non-NULL to
930 * either replace an existing extended attribute, or create a new extended
931 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
932 * specify that an extended attribute must exist and must not exist
933 * previous to the call, respectively.
934 *
935 * Returns 0, or a negative error number on failure.
936 */
937int
938ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
939              const char *name, const void *value, size_t value_len,
940              int flags)
941{
942    struct ext3_xattr_info i = {
943        .name_index = name_index,
944        .name = name,
945        .value = value,
946        .value_len = value_len,
947
948    };
949    struct ext3_xattr_ibody_find is = {
950        .s = { .not_found = -ENODATA, },
951    };
952    struct ext3_xattr_block_find bs = {
953        .s = { .not_found = -ENODATA, },
954    };
955    int error;
956
957    if (!name)
958        return -EINVAL;
959    if (strlen(name) > 255)
960        return -ERANGE;
961    down_write(&EXT3_I(inode)->xattr_sem);
962    error = ext3_get_inode_loc(inode, &is.iloc);
963    if (error)
964        goto cleanup;
965
966    error = ext3_journal_get_write_access(handle, is.iloc.bh);
967    if (error)
968        goto cleanup;
969
970    if (ext3_test_inode_state(inode, EXT3_STATE_NEW)) {
971        struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
972        memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
973        ext3_clear_inode_state(inode, EXT3_STATE_NEW);
974    }
975
976    error = ext3_xattr_ibody_find(inode, &i, &is);
977    if (error)
978        goto cleanup;
979    if (is.s.not_found)
980        error = ext3_xattr_block_find(inode, &i, &bs);
981    if (error)
982        goto cleanup;
983    if (is.s.not_found && bs.s.not_found) {
984        error = -ENODATA;
985        if (flags & XATTR_REPLACE)
986            goto cleanup;
987        error = 0;
988        if (!value)
989            goto cleanup;
990    } else {
991        error = -EEXIST;
992        if (flags & XATTR_CREATE)
993            goto cleanup;
994    }
995    if (!value) {
996        if (!is.s.not_found)
997            error = ext3_xattr_ibody_set(handle, inode, &i, &is);
998        else if (!bs.s.not_found)
999            error = ext3_xattr_block_set(handle, inode, &i, &bs);
1000    } else {
1001        error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1002        if (!error && !bs.s.not_found) {
1003            i.value = NULL;
1004            error = ext3_xattr_block_set(handle, inode, &i, &bs);
1005        } else if (error == -ENOSPC) {
1006            if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1007                error = ext3_xattr_block_find(inode, &i, &bs);
1008                if (error)
1009                    goto cleanup;
1010            }
1011            error = ext3_xattr_block_set(handle, inode, &i, &bs);
1012            if (error)
1013                goto cleanup;
1014            if (!is.s.not_found) {
1015                i.value = NULL;
1016                error = ext3_xattr_ibody_set(handle, inode, &i,
1017                                 &is);
1018            }
1019        }
1020    }
1021    if (!error) {
1022        ext3_xattr_update_super_block(handle, inode->i_sb);
1023        inode->i_ctime = CURRENT_TIME_SEC;
1024        error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1025        /*
1026         * The bh is consumed by ext3_mark_iloc_dirty, even with
1027         * error != 0.
1028         */
1029        is.iloc.bh = NULL;
1030        if (IS_SYNC(inode))
1031            handle->h_sync = 1;
1032    }
1033
1034cleanup:
1035    brelse(is.iloc.bh);
1036    brelse(bs.bh);
1037    up_write(&EXT3_I(inode)->xattr_sem);
1038    return error;
1039}
1040
1041/*
1042 * ext3_xattr_set()
1043 *
1044 * Like ext3_xattr_set_handle, but start from an inode. This extended
1045 * attribute modification is a filesystem transaction by itself.
1046 *
1047 * Returns 0, or a negative error number on failure.
1048 */
1049int
1050ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1051           const void *value, size_t value_len, int flags)
1052{
1053    handle_t *handle;
1054    int error, retries = 0;
1055
1056retry:
1057    handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1058    if (IS_ERR(handle)) {
1059        error = PTR_ERR(handle);
1060    } else {
1061        int error2;
1062
1063        error = ext3_xattr_set_handle(handle, inode, name_index, name,
1064                          value, value_len, flags);
1065        error2 = ext3_journal_stop(handle);
1066        if (error == -ENOSPC &&
1067            ext3_should_retry_alloc(inode->i_sb, &retries))
1068            goto retry;
1069        if (error == 0)
1070            error = error2;
1071    }
1072
1073    return error;
1074}
1075
1076/*
1077 * ext3_xattr_delete_inode()
1078 *
1079 * Free extended attribute resources associated with this inode. This
1080 * is called immediately before an inode is freed. We have exclusive
1081 * access to the inode.
1082 */
1083void
1084ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1085{
1086    struct buffer_head *bh = NULL;
1087
1088    if (!EXT3_I(inode)->i_file_acl)
1089        goto cleanup;
1090    bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1091    if (!bh) {
1092        ext3_error(inode->i_sb, __func__,
1093            "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1094            EXT3_I(inode)->i_file_acl);
1095        goto cleanup;
1096    }
1097    if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1098        BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1099        ext3_error(inode->i_sb, __func__,
1100            "inode %lu: bad block "E3FSBLK, inode->i_ino,
1101            EXT3_I(inode)->i_file_acl);
1102        goto cleanup;
1103    }
1104    ext3_xattr_release_block(handle, inode, bh);
1105    EXT3_I(inode)->i_file_acl = 0;
1106
1107cleanup:
1108    brelse(bh);
1109}
1110
1111/*
1112 * ext3_xattr_put_super()
1113 *
1114 * This is called when a file system is unmounted.
1115 */
1116void
1117ext3_xattr_put_super(struct super_block *sb)
1118{
1119    mb_cache_shrink(sb->s_bdev);
1120}
1121
1122/*
1123 * ext3_xattr_cache_insert()
1124 *
1125 * Create a new entry in the extended attribute cache, and insert
1126 * it unless such an entry is already in the cache.
1127 *
1128 * Returns 0, or a negative error number on failure.
1129 */
1130static void
1131ext3_xattr_cache_insert(struct buffer_head *bh)
1132{
1133    __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1134    struct mb_cache_entry *ce;
1135    int error;
1136
1137    ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1138    if (!ce) {
1139        ea_bdebug(bh, "out of memory");
1140        return;
1141    }
1142    error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1143    if (error) {
1144        mb_cache_entry_free(ce);
1145        if (error == -EBUSY) {
1146            ea_bdebug(bh, "already in cache");
1147            error = 0;
1148        }
1149    } else {
1150        ea_bdebug(bh, "inserting [%x]", (int)hash);
1151        mb_cache_entry_release(ce);
1152    }
1153}
1154
1155/*
1156 * ext3_xattr_cmp()
1157 *
1158 * Compare two extended attribute blocks for equality.
1159 *
1160 * Returns 0 if the blocks are equal, 1 if they differ, and
1161 * a negative error number on errors.
1162 */
1163static int
1164ext3_xattr_cmp(struct ext3_xattr_header *header1,
1165           struct ext3_xattr_header *header2)
1166{
1167    struct ext3_xattr_entry *entry1, *entry2;
1168
1169    entry1 = ENTRY(header1+1);
1170    entry2 = ENTRY(header2+1);
1171    while (!IS_LAST_ENTRY(entry1)) {
1172        if (IS_LAST_ENTRY(entry2))
1173            return 1;
1174        if (entry1->e_hash != entry2->e_hash ||
1175            entry1->e_name_index != entry2->e_name_index ||
1176            entry1->e_name_len != entry2->e_name_len ||
1177            entry1->e_value_size != entry2->e_value_size ||
1178            memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1179            return 1;
1180        if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1181            return -EIO;
1182        if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1183               (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1184               le32_to_cpu(entry1->e_value_size)))
1185            return 1;
1186
1187        entry1 = EXT3_XATTR_NEXT(entry1);
1188        entry2 = EXT3_XATTR_NEXT(entry2);
1189    }
1190    if (!IS_LAST_ENTRY(entry2))
1191        return 1;
1192    return 0;
1193}
1194
1195/*
1196 * ext3_xattr_cache_find()
1197 *
1198 * Find an identical extended attribute block.
1199 *
1200 * Returns a pointer to the block found, or NULL if such a block was
1201 * not found or an error occurred.
1202 */
1203static struct buffer_head *
1204ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1205              struct mb_cache_entry **pce)
1206{
1207    __u32 hash = le32_to_cpu(header->h_hash);
1208    struct mb_cache_entry *ce;
1209
1210    if (!header->h_hash)
1211        return NULL; /* never share */
1212    ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1213again:
1214    ce = mb_cache_entry_find_first(ext3_xattr_cache, inode->i_sb->s_bdev,
1215                       hash);
1216    while (ce) {
1217        struct buffer_head *bh;
1218
1219        if (IS_ERR(ce)) {
1220            if (PTR_ERR(ce) == -EAGAIN)
1221                goto again;
1222            break;
1223        }
1224        bh = sb_bread(inode->i_sb, ce->e_block);
1225        if (!bh) {
1226            ext3_error(inode->i_sb, __func__,
1227                "inode %lu: block %lu read error",
1228                inode->i_ino, (unsigned long) ce->e_block);
1229        } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1230                EXT3_XATTR_REFCOUNT_MAX) {
1231            ea_idebug(inode, "block %lu refcount %d>=%d",
1232                  (unsigned long) ce->e_block,
1233                  le32_to_cpu(BHDR(bh)->h_refcount),
1234                      EXT3_XATTR_REFCOUNT_MAX);
1235        } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1236            *pce = ce;
1237            return bh;
1238        }
1239        brelse(bh);
1240        ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1241    }
1242    return NULL;
1243}
1244
1245#define NAME_HASH_SHIFT 5
1246#define VALUE_HASH_SHIFT 16
1247
1248/*
1249 * ext3_xattr_hash_entry()
1250 *
1251 * Compute the hash of an extended attribute.
1252 */
1253static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1254                     struct ext3_xattr_entry *entry)
1255{
1256    __u32 hash = 0;
1257    char *name = entry->e_name;
1258    int n;
1259
1260    for (n=0; n < entry->e_name_len; n++) {
1261        hash = (hash << NAME_HASH_SHIFT) ^
1262               (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1263               *name++;
1264    }
1265
1266    if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1267        __le32 *value = (__le32 *)((char *)header +
1268            le16_to_cpu(entry->e_value_offs));
1269        for (n = (le32_to_cpu(entry->e_value_size) +
1270             EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1271            hash = (hash << VALUE_HASH_SHIFT) ^
1272                   (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1273                   le32_to_cpu(*value++);
1274        }
1275    }
1276    entry->e_hash = cpu_to_le32(hash);
1277}
1278
1279#undef NAME_HASH_SHIFT
1280#undef VALUE_HASH_SHIFT
1281
1282#define BLOCK_HASH_SHIFT 16
1283
1284/*
1285 * ext3_xattr_rehash()
1286 *
1287 * Re-compute the extended attribute hash value after an entry has changed.
1288 */
1289static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1290                  struct ext3_xattr_entry *entry)
1291{
1292    struct ext3_xattr_entry *here;
1293    __u32 hash = 0;
1294
1295    ext3_xattr_hash_entry(header, entry);
1296    here = ENTRY(header+1);
1297    while (!IS_LAST_ENTRY(here)) {
1298        if (!here->e_hash) {
1299            /* Block is not shared if an entry's hash value == 0 */
1300            hash = 0;
1301            break;
1302        }
1303        hash = (hash << BLOCK_HASH_SHIFT) ^
1304               (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1305               le32_to_cpu(here->e_hash);
1306        here = EXT3_XATTR_NEXT(here);
1307    }
1308    header->h_hash = cpu_to_le32(hash);
1309}
1310
1311#undef BLOCK_HASH_SHIFT
1312
1313int __init
1314init_ext3_xattr(void)
1315{
1316    ext3_xattr_cache = mb_cache_create("ext3_xattr", 6);
1317    if (!ext3_xattr_cache)
1318        return -ENOMEM;
1319    return 0;
1320}
1321
1322void
1323exit_ext3_xattr(void)
1324{
1325    if (ext3_xattr_cache)
1326        mb_cache_destroy(ext3_xattr_cache);
1327    ext3_xattr_cache = NULL;
1328}
1329

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