path: root/fs/ext4/inline.c

/*
 * Copyright (c) 2012 Taobao.
 * Written by Tao Ma <boyu.mt@taobao.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
#include "truncate.h"

#define EXT4_XATTR_SYSTEM_DATA	"data"
#define EXT4_MIN_INLINE_DATA_SIZE	((sizeof(__le32) * EXT4_N_BLOCKS))

int ext4_get_inline_size(struct inode *inode)
{
	if (EXT4_I(inode)->i_inline_off)
		return EXT4_I(inode)->i_inline_size;

	return 0;
}

static int get_max_inline_xattr_value_size(struct inode *inode,
					   struct ext4_iloc *iloc)
{
	struct ext4_xattr_ibody_header *header;
	struct ext4_xattr_entry *entry;
	struct ext4_inode *raw_inode;
	int free, min_offs;

	min_offs = EXT4_SB(inode->i_sb)->s_inode_size -
			EXT4_GOOD_OLD_INODE_SIZE -
			EXT4_I(inode)->i_extra_isize -
			sizeof(struct ext4_xattr_ibody_header);

	/*
	 * We need to subtract another sizeof(__u32) since an in-inode xattr
	 * needs an empty 4 bytes to indicate the gap between the xattr entry
	 * and the name/value pair.
	 */
	if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
		return EXT4_XATTR_SIZE(min_offs -
			EXT4_XATTR_LEN(strlen(EXT4_XATTR_SYSTEM_DATA)) -
			EXT4_XATTR_ROUND - sizeof(__u32));

	raw_inode = ext4_raw_inode(iloc);
	header = IHDR(inode, raw_inode);
	entry = IFIRST(header);

	/* Compute min_offs. */
	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
		if (!entry->e_value_block && entry->e_value_size) {
			size_t offs = le16_to_cpu(entry->e_value_offs);
			if (offs < min_offs)
				min_offs = offs;
		}
	}
	free = min_offs -
		((void *)entry - (void *)IFIRST(header)) - sizeof(__u32);

	if (EXT4_I(inode)->i_inline_off) {
		entry = (struct ext4_xattr_entry *)
			((void *)raw_inode + EXT4_I(inode)->i_inline_off);

		free += le32_to_cpu(entry->e_value_size);
		goto out;
	}

	free -= EXT4_XATTR_LEN(strlen(EXT4_XATTR_SYSTEM_DATA));

	if (free > EXT4_XATTR_ROUND)
		free = EXT4_XATTR_SIZE(free - EXT4_XATTR_ROUND);
	else
		free = 0;

out:
	return free;
}

/*
 * Get the maximum size we now can store in an inode.
 * If we can't find the space for a xattr entry, don't use the space
 * of the extents since we have no space to indicate the inline data.
 */
int ext4_get_max_inline_size(struct inode *inode)
{
	int error, max_inline_size;
	struct ext4_iloc iloc;

	if (EXT4_I(inode)->i_extra_isize == 0)
		return 0;

	error = ext4_get_inode_loc(inode, &iloc);
	if (error) {
		ext4_error_inode(inode, __func__, __LINE__, 0,
				 "can't get inode location %lu",
				 inode->i_ino);
		return 0;
	}

	down_read(&EXT4_I(inode)->xattr_sem);
	max_inline_size = get_max_inline_xattr_value_size(inode, &iloc);
	up_read(&EXT4_I(inode)->xattr_sem);

	brelse(iloc.bh);

	if (!max_inline_size)
		return 0;

	return max_inline_size + EXT4_MIN_INLINE_DATA_SIZE;
}

int ext4_has_inline_data(struct inode *inode)
{
	return ext4_test_inode_flag(inode, EXT4_INODE_INLINE_DATA) &&
	       EXT4_I(inode)->i_inline_off;
}

/*
 * this function does not take xattr_sem, which is OK because it is
 * currently only used in a code path coming form ext4_iget, before
 * the new inode has been unlocked
 */
int ext4_find_inline_data_nolock(struct inode *inode)
{
	struct ext4_xattr_ibody_find is = {
		.s = { .not_found = -ENODATA, },
	};
	struct ext4_xattr_info i = {
		.name_index = EXT4_XATTR_INDEX_SYSTEM,
		.name = EXT4_XATTR_SYSTEM_DATA,
	};
	int error;

	if (EXT4_I(inode)->i_extra_isize == 0)
		return 0;

	error = ext4_get_inode_loc(inode, &is.iloc);
	if (error)
		return error;

	error = ext4_xattr_ibody_find(inode, &i, &is);
	if (error)
		goto out;

	if (!is.s.not_found) {
		EXT4_I(inode)->i_inline_off = (u16)((void *)is.s.here -
					(void *)ext4_raw_inode(&is.iloc));
		EXT4_I(inode)->i_inline_size = EXT4_MIN_INLINE_DATA_SIZE +
				le32_to_cpu(is.s.here->e_value_size);