/*
 *      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"
#include "quotaio_v2.h"

MODULE_AUTHOR("Jan Kara");
MODULE_DESCRIPTION("Quota format v2 support");
MODULE_LICENSE("GPL");

#define __QUOTA_V2_PARANOIA

static void v2r0_mem2diskdqb(void *dp, struct dquot *dquot);
static void v2r0_disk2memdqb(struct dquot *dquot, void *dp);
static int v2r0_is_id(void *dp, struct dquot *dquot);
static void v2r1_mem2diskdqb(void *dp, struct dquot *dquot);
static void v2r1_disk2memdqb(struct dquot *dquot, void *dp);
static int v2r1_is_id(void *dp, struct dquot *dquot);

static const struct qtree_fmt_operations v2r0_qtree_ops = {
        .mem2disk_dqblk = v2r0_mem2diskdqb,
        .disk2mem_dqblk = v2r0_disk2memdqb,
        .is_id = v2r0_is_id,
};

static const struct qtree_fmt_operations v2r1_qtree_ops = {
        .mem2disk_dqblk = v2r1_mem2diskdqb,
        .disk2mem_dqblk = v2r1_disk2memdqb,
        .is_id = v2r1_is_id,
};

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

static inline qsize_t v2_stoqb(qsize_t space)
{
        return (space + QUOTABLOCK_SIZE - 1) >> QUOTABLOCK_BITS;
}

static inline qsize_t v2_qbtos(qsize_t blocks)
{
        return blocks << QUOTABLOCK_BITS;
}

static int v2_read_header(struct super_block *sb, int type,
                          struct v2_disk_dqheader *dqhead)
{
        ssize_t size;

        size = sb->s_op->quota_read(sb, type, (char *)dqhead,
                                    sizeof(struct v2_disk_dqheader), 0);
        if (size != sizeof(struct v2_disk_dqheader)) {
                quota_error(sb, "Failed header read: expected=%zd got=%zd",
                            sizeof(struct v2_disk_dqheader), size);
                if (size < 0)
                        return size;
                return -EIO;
        }
        return 0;
}

/* Check whether given file is really vfsv0 quotafile */
static int v2_check_quota_file(struct super_block *sb, int type)
{
        struct v2_disk_dqheader dqhead;
        static const uint quota_magics[] = V2_INITQMAGICS;
        static const uint quota_versions[] = V2_INITQVERSIONS;
 
        if (v2_read_header(sb, type, &dqhead))
                return 0;
        if (le32_to_cpu(dqhead.dqh_magic) != quota_magics[type] ||
            le32_to_cpu(dqhead.dqh_version) > quota_versions[type])
                return 0;
        return 1;
}

/* Read information header from quota file */
static int v2_read_file_info(struct super_block *sb, int type)
{
        struct v2_disk_dqinfo dinfo;
        struct v2_disk_dqheader dqhead;
        struct quota_info *dqopt = sb_dqopt(sb);
        struct mem_dqinfo *info = &dqopt->info[type];
        struct qtree_mem_dqinfo *qinfo;
        ssize_t size;
        unsigned int version;
        int ret;

        down_read(&dqopt->dqio_sem);
        ret = v2_read_header(sb, type, &dqhead);
        if (ret < 0)
                goto out;
        version = le32_to_cpu(dqhead.dqh_version);
        if ((info->dqi_fmt_id == QFMT_VFS_V0 && version != 0) ||
            (info->dqi_fmt_id == QFMT_VFS_V1 && version != 1)) {
                ret = -EINVAL;
                goto out;
        }

        size = sb->s_op->quota_read(sb, type, (char *)&dinfo,
               sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
        if (size != sizeof(struct v2_disk_dqinfo)) {
                quota_error(sb, "Can't read info structure");
                if (size < 0)
                        ret = size;
                else
                        ret = -EIO;
                goto out;
        }
        info->dqi_priv = kmalloc(sizeof(struct qtree_mem_dqinfo), GFP_NOFS);
        if (!info->dqi_priv) {
                ret = -ENOMEM;
                goto out;
        }
        qinfo = info->dqi_priv;
        if (version == 0) {
                /* limits are stored as unsigned 32-bit data */
                info->dqi_max_spc_limit = 0xffffffffLL << QUOTABLOCK_BITS;
                info->dqi_max_ino_limit = 0xffffffff;
        } else {
                /*
                 * Used space is stored as unsigned 64-bit value in bytes but
                 * quota core supports only signed 64-bit values so use that
                 * as a limit
                 */
                info->dqi_max_spc_limit = 0x7fffffffffffffffLL; /* 2^63-1 */
                info->dqi_max_ino_limit = 0x7fffffffffffffffLL;
        }
        info->dqi_bgrace = le32_to_cpu(dinfo.dqi_bgrace);
        info->dqi_igrace = le32_to_cpu(dinfo.dqi_igrace);
        /* No flags currently supported */
        info->dqi_flags = 0;
        qinfo->dqi_sb = sb;
        qinfo->dqi_type = type;
        qinfo->dqi_blocks = le32_to_cpu(dinfo.dqi_blocks);
        qinfo->dqi_free_blk = le32_to_cpu(dinfo.dqi_free_blk);
        qinfo->dqi_free_entry = le32_to_cpu(dinfo.dqi_free_entry);
        qinfo->dqi_blocksize_bits = V2_DQBLKSIZE_BITS;
        qinfo->dqi_usable_bs = 1 << V2_DQBLKSIZE_BITS;
        qinfo->dqi_qtree_depth = qtree_depth(qinfo);
        if (version == 0) {
                qinfo->dqi_entry_size = sizeof(struct v2r0_disk_dqblk);
                qinfo->dqi_ops = &v2r0_qtree_ops;
        } else {
                qinfo->dqi_entry_size = sizeof(struct v2r1_disk_dqblk);
                qinfo->dqi_ops = &v2r1_qtree_ops;
        }
        ret = 0;
out:
        up_read(&dqopt->dqio_sem);
        return ret;
}

/* Write information header to quota file */
static int v2_write_file_info(struct super_block *sb, int type)
{
        struct v2_disk_dqinfo dinfo;
        struct quota_info *dqopt = sb_dqopt(sb);
        struct mem_dqinfo *info = &dqopt->info[type];
        struct qtree_mem_dqinfo *qinfo = info->dqi_priv;
        ssize_t size;

        down_write(&dqopt->dqio_sem);
        spin_lock(&dq_data_lock);
        info->dqi_flags &= ~DQF_INFO_DIRTY;
        dinfo.dqi_bgrace = cpu_to_le32(info->dqi_bgrace);
        dinfo.dqi_igrace = cpu_to_le32(info->dqi_igrace);
        /* No flags currently supported */
        dinfo.dqi_flags = cpu_to_le32(0);
        spin_unlock(&dq_data_lock);
        dinfo.dqi_blocks = cpu_to_le32(qinfo->dqi_blocks);
        dinfo.dqi_free_blk = cpu_to_le32(qinfo->dqi_free_blk);
        dinfo.dqi_free_entry = cpu_to_le32(qinfo->dqi_free_entry);
        size = sb->s_op->quota_write(sb, type, (char *)&dinfo,
               sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
        up_write(&dqopt->dqio_sem);
        if (size != sizeof(struct v2_disk_dqinfo)) {
                quota_error(sb, "Can't write info structure");
                return -1;
        }
        return 0;
}

static void v2r0_disk2memdqb(struct dquot *dquot, void *dp)
{
        struct v2r0_disk_dqblk *d = dp, empty;
        struct mem_dqblk *m = &dquot->dq_dqb;

        m->dqb_ihardlimit = le32_to_cpu(d->dqb_ihardlimit);
        m->dqb_isoftlimit = le32_to_cpu(d->dqb_isoftlimit);
        m->dqb_curinodes = le32_to_cpu(d->dqb_curinodes);
        m->dqb_itime = le64_to_cpu(d->dqb_itime);
        m->dqb_bhardlimit = v2_qbtos(le32_to_cpu(d->dqb_bhardlimit));
        m->dqb_bsoftlimit = v2_qbtos(le32_to_cpu(d->dqb_bsoftlimit));
        m->dqb_curspace = le64_to_cpu(d->dqb_curspace);
        m->dqb_btime = le64_to_cpu(d->dqb_btime);
        /* We need to escape back all-zero structure */
        memset(&empty, 0, sizeof(struct v2r0_disk_dqblk));
        empty.dqb_itime = cpu_to_le64(1);
        if (!memcmp(&empty, dp, sizeof(struct v2r0_disk_dqblk)))
                m->dqb_itime = 0;
}

static void v2r0_mem2diskdqb(void *dp, struct dquot *dquot)
{
        struct v2r0_disk_dqblk *d = dp;
        struct mem_dqblk *m = &dquot->dq_dqb;
        struct qtree_mem_dqinfo *info =
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;

        d->dqb_ihardlimit = cpu_to_le32(m->dqb_ihardlimit);
        d->dqb_isoftlimit = cpu_to_le32(m->dqb_isoftlimit);
        d->dqb_curinodes = cpu_to_le32(m->dqb_curinodes);
        d->dqb_itime = cpu_to_le64(m->dqb_itime);
        d->dqb_bhardlimit = cpu_to_le32(v2_stoqb(m->dqb_bhardlimit));
        d->dqb_bsoftlimit = cpu_to_le32(v2_stoqb(m->dqb_bsoftlimit));
        d->dqb_curspace = cpu_to_le64(m->dqb_curspace);
        d->dqb_btime = cpu_to_le64(m->dqb_btime);
        d->dqb_id = cpu_to_le32(from_kqid(&init_user_ns, dquot->dq_id));
        if (qtree_entry_unused(info, dp))
                d->dqb_itime = cpu_to_le64(1);
}

static int v2r0_is_id(void *dp, struct dquot *dquot)
{
        struct v2r0_disk_dqblk *d = dp;
        struct qtree_mem_dqinfo *info =
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;

        if (qtree_entry_unused(info, dp))
                return 0;
        return qid_eq(make_kqid(&init_user_ns, dquot->dq_id.type,
                                le32_to_cpu(d->dqb_id)),
                      dquot->dq_id);
}

static void v2r1_disk2memdqb(struct dquot *dquot, void *dp)
{
        struct v2r1_disk_dqblk *d = dp, empty;
        struct mem_dqblk *m = &dquot->dq_dqb;

        m->dqb_ihardlimit = le64_to_cpu(d->dqb_ihardlimit);
        m->dqb_isoftlimit = le64_to_cpu(d->dqb_isoftlimit);
        m->dqb_curinodes = le64_to_cpu(d->dqb_curinodes);
        m->dqb_itime = le64_to_cpu(d->dqb_itime);
        m->dqb_bhardlimit = v2_qbtos(le64_to_cpu(d->dqb_bhardlimit));
        m->dqb_bsoftlimit = v2_qbtos(le64_to_cpu(d->dqb_bsoftlimit));
        m->dqb_curspace = le64_to_cpu(d->dqb_curspace);
        m->dqb_btime = le64_to_cpu(d->dqb_btime);
        /* We need to escape back all-zero structure */
        memset(&empty, 0, sizeof(struct v2r1_disk_dqblk));
        empty.dqb_itime = cpu_to_le64(1);
        if (!memcmp(&empty, dp, sizeof(struct v2r1_disk_dqblk)))
                m->dqb_itime = 0;
}

static void v2r1_mem2diskdqb(void *dp, struct dquot *dquot)
{
        struct v2r1_disk_dqblk *d = dp;
        struct mem_dqblk *m = &dquot->dq_dqb;
        struct qtree_mem_dqinfo *info =
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;

        d->dqb_ihardlimit = cpu_to_le64(m->dqb_ihardlimit);
        d->dqb_isoftlimit = cpu_to_le64(m->dqb_isoftlimit);
        d->dqb_curinodes = cpu_to_le64(m->dqb_curinodes);
        d->dqb_itime = cpu_to_le64(m->dqb_itime);
        d->dqb_bhardlimit = cpu_to_le64(v2_stoqb(m->dqb_bhardlimit));
        d->dqb_bsoftlimit = cpu_to_le64(v2_stoqb(m->dqb_bsoftlimit));
        d->dqb_curspace = cpu_to_le64(m->dqb_curspace);
        d->dqb_btime = cpu_to_le64(m->dqb_btime);
        d->dqb_id = cpu_to_le32(from_kqid(&init_user_ns, dquot->dq_id));
        if (qtree_entry_unused(info, dp))
                d->dqb_itime = cpu_to_le64(1);
}

static int v2r1_is_id(void *dp, struct dquot *dquot)
{
        struct v2r1_disk_dqblk *d = dp;
        struct qtree_mem_dqinfo *info =
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;

        if (qtree_entry_unused(info, dp))
                return 0;
        return qid_eq(make_kqid(&init_user_ns, dquot->dq_id.type,
                                le32_to_cpu(d->dqb_id)),
                      dquot->dq_id);
}

static int v2_read_dquot(struct dquot *dquot)
{
        struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
        int ret;

        down_read(&dqopt->dqio_sem);
        ret = qtree_read_dquot(
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv,
                        dquot);
        up_read(&dqopt->dqio_sem);
        return ret;
}

static int v2_write_dquot(struct dquot *dquot)
{
        struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
        int ret;
        bool alloc = false;

        /*
         * If space for dquot is already allocated, we don't need any
         * protection as we'll only overwrite the place of dquot. We are
         * still protected by concurrent writes of the same dquot by
         * dquot->dq_lock.
         */
        if (!dquot->dq_off) {
                alloc = true;
                down_write(&dqopt->dqio_sem);
        } else {
                down_read(&dqopt->dqio_sem);
        }
        ret = qtree_write_dquot(
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv,
                        dquot);
        if (alloc)
                up_write(&dqopt->dqio_sem);
        else
                up_read(&dqopt->dqio_sem);
        return ret;
}

static int v2_release_dquot(struct dquot *dquot)
{
        struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
        int ret;

        down_write(&dqopt->dqio_sem);
        ret = qtree_release_dquot(sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv, dquot);
        up_write(&dqopt->dqio_sem);

        return ret;
}

static int v2_free_file_info(struct super_block *sb, int type)
{
        kfree(sb_dqinfo(sb, type)->dqi_priv);
        return 0;
}

static int v2_get_next_id(struct super_block *sb, struct kqid *qid)
{
        struct quota_info *dqopt = sb_dqopt(sb);
        int ret;

        down_read(&dqopt->dqio_sem);
        ret = qtree_get_next_id(sb_dqinfo(sb, qid->type)->dqi_priv, qid);
        up_read(&dqopt->dqio_sem);
        return ret;
}

static const struct quota_format_ops v2_format_ops = {
        .check_quota_file       = v2_check_quota_file,
        .read_file_info         = v2_read_file_info,
        .write_file_info        = v2_write_file_info,
        .free_file_info         = v2_free_file_info,
        .read_dqblk             = v2_read_dquot,
        .commit_dqblk           = v2_write_dquot,
        .release_dqblk          = v2_release_dquot,
        .get_next_id            = v2_get_next_id,
};

static struct quota_format_type v2r0_quota_format = {
        .qf_fmt_id      = QFMT_VFS_V0,
        .qf_ops         = &v2_format_ops,
        .qf_owner       = THIS_MODULE
};

static struct quota_format_type v2r1_quota_format = {
        .qf_fmt_id      = QFMT_VFS_V1,
        .qf_ops         = &v2_format_ops,
        .qf_owner       = THIS_MODULE
};

static int __init init_v2_quota_format(void)
{
        int ret;

        ret = register_quota_format(&v2r0_quota_format);
        if (ret)
                return ret;
        return register_quota_format(&v2r1_quota_format);
}

static void __exit exit_v2_quota_format(void)
{
        unregister_quota_format(&v2r0_quota_format);
        unregister_quota_format(&v2r1_quota_format);
}

module_init(init_v2_quota_format);
module_exit(exit_v2_quota_format);