quota_v1.c

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#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;

    if (!sb_dqopt(dquot->dq_sb)->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;

    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_maxblimit = 0xffffffff;
    dqopt->info[type].dqi_maxilimit = 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:
    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;

    dqopt->info[type].dqi_flags &= ~DQF_INFO_DIRTY;
    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;
    }
    dqblk.dqb_itime = dqopt->info[type].dqi_igrace;
    dqblk.dqb_btime = dqopt->info[type].dqi_bgrace;
    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:
    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,
    .free_file_info     = NULL,
    .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);