xattr.c

linux 内核源代码

		}
		b_error = ext3_xattr_block_list(inode, buffer, buffer_size);
		if (b_error < 0)
			i_error = 0;
	}
	up_read(&EXT3_I(inode)->xattr_sem);
	return i_error + b_error;
}

/*
 * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 * not set, set it.
 */
static void ext3_xattr_update_super_block(handle_t *handle,
					  struct super_block *sb)
{
	if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
		return;

	if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
		EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
		sb->s_dirt = 1;
		ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
	}
}

/*
 * Release the xattr block BH: If the reference count is > 1, decrement
 * it; otherwise free the block.
 */
static void
ext3_xattr_release_block(handle_t *handle, struct inode *inode,
			 struct buffer_head *bh)
{
	struct mb_cache_entry *ce = NULL;
	int error = 0;

	ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
	error = ext3_journal_get_write_access(handle, bh);
	if (error)
		 goto out;

	lock_buffer(bh);

	if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
		ea_bdebug(bh, "refcount now=0; freeing");
		if (ce)
			mb_cache_entry_free(ce);
		ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
		get_bh(bh);
		ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
	} else {
		BHDR(bh)->h_refcount = cpu_to_le32(
				le32_to_cpu(BHDR(bh)->h_refcount) - 1);
		error = ext3_journal_dirty_metadata(handle, bh);
		if (IS_SYNC(inode))
			handle->h_sync = 1;
		DQUOT_FREE_BLOCK(inode, 1);
		ea_bdebug(bh, "refcount now=%d; releasing",
			  le32_to_cpu(BHDR(bh)->h_refcount));
		if (ce)
			mb_cache_entry_release(ce);
	}
	unlock_buffer(bh);
out:
	ext3_std_error(inode->i_sb, error);
	return;
}

struct ext3_xattr_info {
	int name_index;
	const char *name;
	const void *value;
	size_t value_len;
};

struct ext3_xattr_search {
	struct ext3_xattr_entry *first;
	void *base;
	void *end;
	struct ext3_xattr_entry *here;
	int not_found;
};

static int
ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
{
	struct ext3_xattr_entry *last;
	size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);

	/* Compute min_offs and last. */
	last = s->first;
	for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
		if (!last->e_value_block && last->e_value_size) {
			size_t offs = le16_to_cpu(last->e_value_offs);
			if (offs < min_offs)
				min_offs = offs;
		}
	}
	free = min_offs - ((void *)last - s->base) - sizeof(__u32);
	if (!s->not_found) {
		if (!s->here->e_value_block && s->here->e_value_size) {
			size_t size = le32_to_cpu(s->here->e_value_size);
			free += EXT3_XATTR_SIZE(size);
		}
		free += EXT3_XATTR_LEN(name_len);
	}
	if (i->value) {
		if (free < EXT3_XATTR_SIZE(i->value_len) ||
		    free < EXT3_XATTR_LEN(name_len) +
			   EXT3_XATTR_SIZE(i->value_len))
			return -ENOSPC;
	}

	if (i->value && s->not_found) {
		/* Insert the new name. */
		size_t size = EXT3_XATTR_LEN(name_len);
		size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
		memmove((void *)s->here + size, s->here, rest);
		memset(s->here, 0, size);
		s->here->e_name_index = i->name_index;
		s->here->e_name_len = name_len;
		memcpy(s->here->e_name, i->name, name_len);
	} else {
		if (!s->here->e_value_block && s->here->e_value_size) {
			void *first_val = s->base + min_offs;
			size_t offs = le16_to_cpu(s->here->e_value_offs);
			void *val = s->base + offs;
			size_t size = EXT3_XATTR_SIZE(
				le32_to_cpu(s->here->e_value_size));

			if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
				/* The old and the new value have the same
				   size. Just replace. */
				s->here->e_value_size =
					cpu_to_le32(i->value_len);
				memset(val + size - EXT3_XATTR_PAD, 0,
				       EXT3_XATTR_PAD); /* Clear pad bytes. */
				memcpy(val, i->value, i->value_len);
				return 0;
			}

			/* Remove the old value. */
			memmove(first_val + size, first_val, val - first_val);
			memset(first_val, 0, size);
			s->here->e_value_size = 0;
			s->here->e_value_offs = 0;
			min_offs += size;

			/* Adjust all value offsets. */
			last = s->first;
			while (!IS_LAST_ENTRY(last)) {
				size_t o = le16_to_cpu(last->e_value_offs);
				if (!last->e_value_block &&
				    last->e_value_size && o < offs)
					last->e_value_offs =
						cpu_to_le16(o + size);
				last = EXT3_XATTR_NEXT(last);
			}
		}
		if (!i->value) {
			/* Remove the old name. */
			size_t size = EXT3_XATTR_LEN(name_len);
			last = ENTRY((void *)last - size);
			memmove(s->here, (void *)s->here + size,
				(void *)last - (void *)s->here + sizeof(__u32));
			memset(last, 0, size);
		}
	}

	if (i->value) {
		/* Insert the new value. */
		s->here->e_value_size = cpu_to_le32(i->value_len);
		if (i->value_len) {
			size_t size = EXT3_XATTR_SIZE(i->value_len);
			void *val = s->base + min_offs - size;
			s->here->e_value_offs = cpu_to_le16(min_offs - size);
			memset(val + size - EXT3_XATTR_PAD, 0,
			       EXT3_XATTR_PAD); /* Clear the pad bytes. */
			memcpy(val, i->value, i->value_len);
		}
	}
	return 0;
}

struct ext3_xattr_block_find {
	struct ext3_xattr_search s;
	struct buffer_head *bh;
};

static int
ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
		      struct ext3_xattr_block_find *bs)
{
	struct super_block *sb = inode->i_sb;
	int error;

	ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
		  i->name_index, i->name, i->value, (long)i->value_len);

	if (EXT3_I(inode)->i_file_acl) {
		/* The inode already has an extended attribute block. */
		bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
		error = -EIO;
		if (!bs->bh)
			goto cleanup;
		ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
			atomic_read(&(bs->bh->b_count)),
			le32_to_cpu(BHDR(bs->bh)->h_refcount));
		if (ext3_xattr_check_block(bs->bh)) {
			ext3_error(sb, __FUNCTION__,
				"inode %lu: bad block "E3FSBLK, inode->i_ino,
				EXT3_I(inode)->i_file_acl);
			error = -EIO;
			goto cleanup;
		}
		/* Find the named attribute. */
		bs->s.base = BHDR(bs->bh);
		bs->s.first = BFIRST(bs->bh);
		bs->s.end = bs->bh->b_data + bs->bh->b_size;
		bs->s.here = bs->s.first;
		error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
					      i->name, bs->bh->b_size, 1);
		if (error && error != -ENODATA)
			goto cleanup;
		bs->s.not_found = error;
	}
	error = 0;

cleanup:
	return error;
}

static int
ext3_xattr_block_set(handle_t *handle, struct inode *inode,
		     struct ext3_xattr_info *i,
		     struct ext3_xattr_block_find *bs)
{
	struct super_block *sb = inode->i_sb;
	struct buffer_head *new_bh = NULL;
	struct ext3_xattr_search *s = &bs->s;
	struct mb_cache_entry *ce = NULL;
	int error = 0;

#define header(x) ((struct ext3_xattr_header *)(x))

	if (i->value && i->value_len > sb->s_blocksize)
		return -ENOSPC;
	if (s->base) {
		ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
					bs->bh->b_blocknr);
		error = ext3_journal_get_write_access(handle, bs->bh);
		if (error)
			goto cleanup;
		lock_buffer(bs->bh);

		if (header(s->base)->h_refcount == cpu_to_le32(1)) {
			if (ce) {
				mb_cache_entry_free(ce);
				ce = NULL;
			}
			ea_bdebug(bs->bh, "modifying in-place");
			error = ext3_xattr_set_entry(i, s);
			if (!error) {
				if (!IS_LAST_ENTRY(s->first))
					ext3_xattr_rehash(header(s->base),
							  s->here);
				ext3_xattr_cache_insert(bs->bh);
			}
			unlock_buffer(bs->bh);
			if (error == -EIO)
				goto bad_block;
			if (!error)
				error = ext3_journal_dirty_metadata(handle,
								    bs->bh);
			if (error)
				goto cleanup;
			goto inserted;
		} else {
			int offset = (char *)s->here - bs->bh->b_data;

			unlock_buffer(bs->bh);
			journal_release_buffer(handle, bs->bh);

			if (ce) {
				mb_cache_entry_release(ce);
				ce = NULL;
			}
			ea_bdebug(bs->bh, "cloning");
			s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
			error = -ENOMEM;
			if (s->base == NULL)
				goto cleanup;
			memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
			s->first = ENTRY(header(s->base)+1);
			header(s->base)->h_refcount = cpu_to_le32(1);
			s->here = ENTRY(s->base + offset);
			s->end = s->base + bs->bh->b_size;
		}
	} else {
		/* Allocate a buffer where we construct the new block. */
		s->base = kzalloc(sb->s_blocksize, GFP_KERNEL);
		/* assert(header == s->base) */
		error = -ENOMEM;
		if (s->base == NULL)
			goto cleanup;
		header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
		header(s->base)->h_blocks = cpu_to_le32(1);
		header(s->base)->h_refcount = cpu_to_le32(1);
		s->first = ENTRY(header(s->base)+1);
		s->here = ENTRY(header(s->base)+1);
		s->end = s->base + sb->s_blocksize;
	}

	error = ext3_xattr_set_entry(i, s);
	if (error == -EIO)
		goto bad_block;
	if (error)
		goto cleanup;
	if (!IS_LAST_ENTRY(s->first))
		ext3_xattr_rehash(header(s->base), s->here);

inserted:
	if (!IS_LAST_ENTRY(s->first)) {
		new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
		if (new_bh) {
			/* We found an identical block in the cache. */
			if (new_bh == bs->bh)
				ea_bdebug(new_bh, "keeping");
			else {
				/* The old block is released after updating
				   the inode. */
				error = -EDQUOT;
				if (DQUOT_ALLOC_BLOCK(inode, 1))
					goto cleanup;
				error = ext3_journal_get_write_access(handle,
								      new_bh);
				if (error)
					goto cleanup_dquot;
				lock_buffer(new_bh);
				BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
					le32_to_cpu(BHDR(new_bh)->h_refcount));
				ea_bdebug(new_bh, "reusing; refcount now=%d",
					le32_to_cpu(BHDR(new_bh)->h_refcount));
				unlock_buffer(new_bh);
				error = ext3_journal_dirty_metadata(handle,
								    new_bh);
				if (error)
					goto cleanup_dquot;
			}
			mb_cache_entry_release(ce);
			ce = NULL;
		} else if (bs->bh && s->base == bs->bh->b_data) {
			/* We were modifying this block in-place. */
			ea_bdebug(bs->bh, "keeping this block");
			new_bh = bs->bh;
			get_bh(new_bh);
		} else {
			/* We need to allocate a new block */
			ext3_fsblk_t goal = le32_to_cpu(
					EXT3_SB(sb)->s_es->s_first_data_block) +
				(ext3_fsblk_t)EXT3_I(inode)->i_block_group *
				EXT3_BLOCKS_PER_GROUP(sb);
			ext3_fsblk_t block = ext3_new_block(handle, inode,
							goal, &error);
			if (error)
				goto cleanup;
			ea_idebug(inode, "creating block %d", block);

			new_bh = sb_getblk(sb, block);
			if (!new_bh) {
getblk_failed:
				ext3_free_blocks(handle, inode, block, 1);
				error = -EIO;
				goto cleanup;
			}
			lock_buffer(new_bh);
			error = ext3_journal_get_create_access(handle, new_bh);
			if (error) {
				unlock_buffer(new_bh);
				goto getblk_failed;
			}
			memcpy(new_bh->b_data, s->base, new_bh->b_size);
			set_buffer_uptodate(new_bh);
			unlock_buffer(new_bh);
			ext3_xattr_cache_insert(new_bh);
			error = ext3_journal_dirty_metadata(handle, new_bh);
			if (error)
				goto cleanup;
		}
	}

	/* Update the inode. */
	EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;

	/* Drop the previous xattr block. */
	if (bs->bh && bs->bh != new_bh)
		ext3_xattr_release_block(handle, inode, bs->bh);
	error = 0;

cleanup:
	if (ce)
		mb_cache_entry_release(ce);
	brelse(new_bh);
	if (!(bs->bh && s->base == bs->bh->b_data))
		kfree(s->base);

	return error;

cleanup_dquot:
	DQUOT_FREE_BLOCK(inode, 1);
	goto cleanup;

bad_block:
	ext3_error(inode->i_sb, __FUNCTION__,
		   "inode %lu: bad block "E3FSBLK, inode->i_ino,
		   EXT3_I(inode)->i_file_acl);
	goto cleanup;

#undef header
}

struct ext3_xattr_ibody_find {
	struct ext3_xattr_search s;
	struct ext3_iloc iloc;
};

static int
ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
		      struct ext3_xattr_ibody_find *is)
{
	struct ext3_xattr_ibody_header *header;
	struct ext3_inode *raw_inode;
	int error;

	if (EXT3_I(inode)->i_extra_isize == 0)
		return 0;
	raw_inode = ext3_raw_inode(&is->iloc);
	header = IHDR(inode, raw_inode);
	is->s.base = is->s.first = IFIRST(header);
	is->s.here = is->s.first;
	is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;