text: // 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;
  	int ret;
  
  	down_read(&dqopt->dqio_sem);
  	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:
  	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;
  	int ret;
  
  	down_write(&dqopt->dqio_sem);
  	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:
  	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)
  {
          return register_quota_format(&v1_quota_format);
  }
  
  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);
  
  