path: root/fs/quota/quota_tree.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *	vfsv0 quota IO operations on file
 */

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/dqblk_v2.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/quotaops.h>

#include <asm/byteorder.h>

#include "quota_tree.h"

MODULE_AUTHOR("Jan Kara");
MODULE_DESCRIPTION("Quota trie support");
MODULE_LICENSE("GPL");

/*
 * Maximum quota tree depth we support. Only to limit recursion when working
 * with the tree.
 */
#define MAX_QTREE_DEPTH 6

#define __QUOTA_QT_PARANOIA

static int __get_index(struct qtree_mem_dqinfo *info, qid_t id, int depth)
{
	unsigned int epb = info->dqi_usable_bs >> 2;

	depth = info->dqi_qtree_depth - depth - 1;
	while (depth--)
		id /= epb;
	return id % epb;
}

static int get_index(struct qtree_mem_dqinfo *info, struct kqid qid, int depth)
{
	qid_t id = from_kqid(&init_user_ns, qid);

	return __get_index(info, id, depth);
}

/* Number of entries in one blocks */
static int qtree_dqstr_in_blk(struct qtree_mem_dqinfo *info)
{
	return (info->dqi_usable_bs - sizeof(struct qt_disk_dqdbheader))
	       / info->dqi_entry_size;
}

static ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
{
	struct super_block *sb = info->dqi_sb;

	memset(buf, 0, info->dqi_usable_bs);
	return sb->s_op->quota_read(sb, info->dqi_type, buf,
	       info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
}

static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
{
	struct super_block *sb = info->dqi_sb;
	ssize_t ret;

	ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
	       info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
	if (ret != info->dqi_usable_bs) {
		quota_error(sb, "dquota write failed");
		if (ret >= 0)
			ret = -EIO;
	}
	return ret;
}

static inline int do_check_range(struct super_block *sb, const char *val_name,
				 uint val, uint min_val, uint max_val)
{
	if (val < min_val || val > max_val) {
		quota_error(sb, "Getting %s %u out of range %u-%u",
			    val_name, val, min_val, max_val);
		return -EUCLEAN;
	}

	return 0;
}

static int check_dquot_block_header(struct qtree_mem_dqinfo *info,
				    struct qt_disk_dqdbheader *dh)
{
	int err = 0;

	err = do_check_range(info->dqi_sb, "dqdh_next_free",
			     le32_to_cpu(dh->dqdh_next_free), 0,
			     info->dqi_blocks - 1);
	if (err)
		return err;
	err = do_check_range(info->dqi_sb, "dqdh_prev_free",
			     le32_to_cpu(dh->dqdh_prev_free), 0,
			     info->dqi_blocks - 1);
	if (err)
		return err;
	err = do_check_range(info->dqi_sb, "dqdh_entries",
			     le16_to_cpu(dh->dqdh_entries), 0,
			     qtree_dqstr_in_blk(info));

	return err;
}

/* Remove empty block from list and return it */
static int get_free_dqblk(struct qtree_mem_dqinfo *info)
{
	char *buf = kmalloc(info->dqi_usable_bs, GFP_KERNEL);
	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
	int ret, blk;

	if (!buf)
		return -ENOMEM;
	if (info->dqi_free_blk) {
		blk = info->dqi_free_blk;
		ret = read_blk(info, blk, buf);
		if (ret < 0)
			goto out_buf;
		ret = check_dquot_block_header(info, dh);
		if (ret)
			goto out_buf;
		info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
	}
	else {
		memset(buf, 0, info->dqi_usable_bs);
		/* Assure block allocation... */
		ret = write_blk(info, info->dqi_blocks, buf);
		if (ret < 0)
			goto out_buf;
		blk = info->dqi_blocks++;
	}
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	ret = blk;
out_buf:
	kfree(buf);
	return ret;
}

/* Insert empty block to the list */
static int put_free_dqblk(struct qtree_mem_dqinfo *info, char *buf, uint blk)
{
	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
	int err;

	dh->dqdh_next_free = cpu_to_le32