// SPDX-License-Identifier: GPL-2.0-only
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/quota.h>
#include <linux/quotaops.h>
#include <linux/dqblk_v1.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>

#include <asm/byteorder.h>

#include "quotaio_v1.h"

MODULE_AUTHOR("Jan Kara");
MODULE_DESCRIPTION("Old quota format support");
MODULE_LICENSE("GPL");

#define QUOTABLOCK_BITS 10
#define QUOTABLOCK_SIZE (1 << QUOTABLOCK_BITS)

static inline qsize_t v1_stoqb(qsize_t space)
{
        return (space + QUOTABLOCK_SIZE - 1) >> QUOTABLOCK_BITS;
}

static inline qsize_t v1_qbtos(qsize_t blocks)
{
        return blocks << QUOTABLOCK_BITS;
}

static void v1_disk2mem_dqblk(struct mem_dqblk *m, struct v1_disk_dqblk *d)
{
        m->dqb_ihardlimit = d->dqb_ihardlimit;
        m->dqb_isoftlimit = d->dqb_isoftlimit;
        m->dqb_curinodes = d->dqb_curinodes;
        m->dqb_bhardlimit = v1_qbtos(d->dqb_bhardlimit);
        m->dqb_bsoftlimit = v1_qbtos(d->dqb_bsoftlimit);
        m->dqb_curspace = v1_qbtos(d->dqb_curblocks);
        m->dqb_itime = d->dqb_itime;
        m->dqb_btime = d->dqb_btime;
}

static void v1_mem2disk_dqblk(struct v1_disk_dqblk *d, struct mem_dqblk *m)
{
        d->dqb_ihardlimit = m->dqb_ihardlimit;
        d->dqb_isoftlimit = m->dqb_isoftlimit;
        d->dqb_curinodes = m->dqb_curinodes;
        d->dqb_bhardlimit = v1_stoqb(m->dqb_bhardlimit);
        d->dqb_bsoftlimit = v1_stoqb(m->dqb_bsoftlimit);
        d->dqb_curblocks = v1_stoqb(m->dqb_curspace);
        d->dqb_itime = m->dqb_itime;
        d->dqb_btime = m->dqb_btime;
}

static int v1_read_dqblk(struct dquot *dquot)
{
        int type = dquot->dq_id.type;
        struct v1_disk_dqblk dqblk;
        struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

        if (!dqopt->files[type])
                return -EINVAL;

        /* Set structure to 0s in case read fails/is after end of file */
        memset(&dqblk, 0, sizeof(struct v1_disk_dqblk));
        dquot->dq_sb->s_op->quota_read(dquot->dq_sb, type, (char *)&dqblk,
                        sizeof(struct v1_disk_dqblk),
                        v1_dqoff(from_kqid(&init_user_ns, dquot->dq_id)));

        v1_disk2mem_dqblk(&dquot->dq_dqb, &dqblk);
        if (dquot->dq_dqb.dqb_bhardlimit == 0 &&
            dquot->dq_dqb.dqb_bsoftlimit == 0 &&
            dquot->dq_dqb.dqb_ihardlimit == 0 &&
            dquot->dq_dqb.dqb_isoftlimit == 0)
                set_bit(DQ_FAKE_B, &dquot->dq_flags);
        dqstats_inc(DQST_READS);

        return 0;
}

static int v1_commit_dqblk(struct dquot *dquot)
{
        short type = dquot->dq_id.type;
        ssize_t ret;
        struct v1_disk_dqblk dqblk;

        v1_mem2disk_dqblk(&dqblk, &dquot->dq_dqb);
        if (((type == USRQUOTA) && uid_eq(dquot->dq_id.uid, GLOBAL_ROOT_UID)) ||
            ((type == GRPQUOTA) && gid_eq(dquot->dq_id.gid, GLOBAL_ROOT_GID))) {
                dqblk.dqb_btime =
                        sb_dqopt(dquot->dq_sb)->info[type].dqi_bgrace;
                dqblk.dqb_itime =
                        sb_dqopt(dquot->dq_sb)->info[type].dqi_igrace;
        }
        ret = 0;
        if (sb_dqopt(dquot->dq_sb)->files[type])
                ret = dquot->dq_sb->s_op->quota_write(dquot->dq_sb, type,
                        (char *)&dqblk, sizeof(struct v1_disk_dqblk),
                        v1_dqoff(from_kqid(&init_user_ns, dquot->dq_id)));
        if (ret != sizeof(struct v1_disk_dqblk)) {
                quota_error(dquot->dq_sb, "dquota write failed");
                if (ret >= 0)
                        ret = -EIO;
                goto out;
        }
        ret = 0;

out:
        dqstats_inc(DQST_WRITES);

        return ret;
}

/* Magics of new quota format */
#define V2_INITQMAGICS {\
        0xd9c01f11,     /* USRQUOTA */\
        0xd9c01927      /* GRPQUOTA */\
}

/* Header of new quota format */
struct v2_disk_dqheader {
        __le32 dqh_magic;        /* Magic number identifying file */
        __le32 dqh_version;      /* File version */
};

static int v1_check_quota_file(struct super_block *sb, int type)
{
        struct inode *inode = sb_dqopt(sb)->files[type];
        ulong blocks;
        size_t off;
        struct v2_disk_dqheader dqhead;
        ssize_t size;
        loff_t isize;
        static const uint quota_magics[] = V2_INITQMAGICS;

        isize = i_size_read(inode);
        if (!isize)
                return 0;
        blocks = isize >> BLOCK_SIZE_BITS;
        off = isize & (BLOCK_SIZE - 1);
        if ((blocks % sizeof(struct v1_disk_dqblk) * BLOCK_SIZE + off) %
            sizeof(struct v1_disk_dqblk))
                return 0;
        /* Doublecheck whether we didn't get file with new format - with old
         * quotactl() this could happen */
        size = sb->s_op->quota_read(sb, type, (char *)&dqhead,
                                    sizeof(struct v2_disk_dqheader), 0);
        if (size != sizeof(struct v2_disk_dqheader))
                return 1;       /* Probably not new format */
        if (le32_to_cpu(dqhead.dqh_magic) != quota_magics[type])
                return 1;       /* Definitely not new format */
        printk(KERN_INFO
               "VFS: %s: Refusing to turn on old quota format on given file."
               " It probably contains newer quota format.\n", sb->s_id);
        return 0;               /* Seems like a new format file -> refuse it */
}

static int v1_read_file_info(struct super_block *sb, int type)
{
        struct quota_info *dqopt = sb_dqopt(sb);
        struct v1_disk_dqblk dqblk;
        unsigned int memalloc;
        int ret;

        down_read(&dqopt->dqio_sem);
        memalloc = memalloc_nofs_save();
        ret = sb->s_op->quota_read(sb, type, (char *)&dqblk,
                                sizeof(struct v1_disk_dqblk), v1_dqoff(0));
        if (ret != sizeof(struct v1_disk_dqblk)) {
                if (ret >= 0)
                        ret = -EIO;
                goto out;
        }
        ret = 0;
        /* limits are stored as unsigned 32-bit data */
        dqopt->info[type].dqi_max_spc_limit = 0xffffffffULL << QUOTABLOCK_BITS;
        dqopt->info[type].dqi_max_ino_limit = 0xffffffff;
        dqopt->info[type].dqi_igrace =
                        dqblk.dqb_itime ? dqblk.dqb_itime : MAX_IQ_TIME;
        dqopt->info[type].dqi_bgrace =
                        dqblk.dqb_btime ? dqblk.dqb_btime : MAX_DQ_TIME;
out:
        memalloc_nofs_restore(memalloc);
        up_read(&dqopt->dqio_sem);
        return ret;
}

static int v1_write_file_info(struct super_block *sb, int type)
{
        struct quota_info *dqopt = sb_dqopt(sb);
        struct v1_disk_dqblk dqblk;
        unsigned int memalloc;
        int ret;

        down_write(&dqopt->dqio_sem);
        memalloc = memalloc_nofs_save();
        ret = sb->s_op->quota_read(sb, type, (char *)&dqblk,
                                sizeof(struct v1_disk_dqblk), v1_dqoff(0));
        if (ret != sizeof(struct v1_disk_dqblk)) {
                if (ret >= 0)
                        ret = -EIO;
                goto out;
        }
        spin_lock(&dq_data_lock);
        dqopt->info[type].dqi_flags &= ~DQF_INFO_DIRTY;
        dqblk.dqb_itime = dqopt->info[type].dqi_igrace;
        dqblk.dqb_btime = dqopt->info[type].dqi_bgrace;
        spin_unlock(&dq_data_lock);
        ret = sb->s_op->quota_write(sb, type, (char *)&dqblk,
              sizeof(struct v1_disk_dqblk), v1_dqoff(0));
        if (ret == sizeof(struct v1_disk_dqblk))
                ret = 0;
        else if (ret >= 0)
                ret = -EIO;
out:
        memalloc_nofs_restore(memalloc);
        up_write(&dqopt->dqio_sem);
        return ret;
}

static const struct quota_format_ops v1_format_ops = {
        .check_quota_file       = v1_check_quota_file,
        .read_file_info         = v1_read_file_info,
        .write_file_info        = v1_write_file_info,
        .read_dqblk             = v1_read_dqblk,
        .commit_dqblk           = v1_commit_dqblk,
};

static struct quota_format_type v1_quota_format = {
        .qf_fmt_id      = QFMT_VFS_OLD,
        .qf_ops         = &v1_format_ops,
        .qf_owner       = THIS_MODULE
};

static int __init init_v1_quota_format(void)
{
        register_quota_format(&v1_quota_format);
        return 0;
}

static void __exit exit_v1_quota_format(void)
{
        unregister_quota_format(&v1_quota_format);
}

module_init(init_v1_quota_format);
module_exit(exit_v1_quota_format);