export.c

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/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>

#include "gfs2.h"
#include "incore.h"
#include "dir.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "super.h"
#include "rgrp.h"
#include "util.h"

#define GFS2_SMALL_FH_SIZE 4
#define GFS2_LARGE_FH_SIZE 8
#define GFS2_OLD_FH_SIZE 10

static int gfs2_encode_fh(struct inode *inode, __u32 *p, int *len,
              struct inode *parent)
{
    __be32 *fh = (__force __be32 *)p;
    struct super_block *sb = inode->i_sb;
    struct gfs2_inode *ip = GFS2_I(inode);

    if (parent && (*len < GFS2_LARGE_FH_SIZE)) {
        *len = GFS2_LARGE_FH_SIZE;
        return 255;
    } else if (*len < GFS2_SMALL_FH_SIZE) {
        *len = GFS2_SMALL_FH_SIZE;
        return 255;
    }

    fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
    fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
    fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
    fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
    *len = GFS2_SMALL_FH_SIZE;

    if (!parent || inode == sb->s_root->d_inode)
        return *len;

    ip = GFS2_I(parent);

    fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
    fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
    fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
    fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
    *len = GFS2_LARGE_FH_SIZE;

    return *len;
}

struct get_name_filldir {
    struct gfs2_inum_host inum;
    char *name;
};

static int get_name_filldir(void *opaque, const char *name, int length,
                loff_t offset, u64 inum, unsigned int type)
{
    struct get_name_filldir *gnfd = opaque;

    if (inum != gnfd->inum.no_addr)
        return 0;

    memcpy(gnfd->name, name, length);
    gnfd->name[length] = 0;

    return 1;
}

static int gfs2_get_name(struct dentry *parent, char *name,
             struct dentry *child)
{
    struct inode *dir = parent->d_inode;
    struct inode *inode = child->d_inode;
    struct gfs2_inode *dip, *ip;
    struct get_name_filldir gnfd;
    struct gfs2_holder gh;
    u64 offset = 0;
    int error;
    struct file_ra_state f_ra = { .start = 0 };

    if (!dir)
        return -EINVAL;

    if (!S_ISDIR(dir->i_mode) || !inode)
        return -EINVAL;

    dip = GFS2_I(dir);
    ip = GFS2_I(inode);

    *name = 0;
    gnfd.inum.no_addr = ip->i_no_addr;
    gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
    gnfd.name = name;

    error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
    if (error)
        return error;

    error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir, &f_ra);

    gfs2_glock_dq_uninit(&gh);

    if (!error && !*name)
        error = -ENOENT;

    return error;
}

static struct dentry *gfs2_get_parent(struct dentry *child)
{
    return d_obtain_alias(gfs2_lookupi(child->d_inode, &gfs2_qdotdot, 1));
}

static struct dentry *gfs2_get_dentry(struct super_block *sb,
                      struct gfs2_inum_host *inum)
{
    struct gfs2_sbd *sdp = sb->s_fs_info;
    struct inode *inode;

    inode = gfs2_ilookup(sb, inum->no_addr, 0);
    if (inode) {
        if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
            iput(inode);
            return ERR_PTR(-ESTALE);
        }
        goto out_inode;
    }

    inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
                    GFS2_BLKST_DINODE);
    if (IS_ERR(inode))
        return ERR_CAST(inode);

out_inode:
    return d_obtain_alias(inode);
}

static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
        int fh_len, int fh_type)
{
    struct gfs2_inum_host this;
    __be32 *fh = (__force __be32 *)fid->raw;

    switch (fh_type) {
    case GFS2_SMALL_FH_SIZE:
    case GFS2_LARGE_FH_SIZE:
    case GFS2_OLD_FH_SIZE:
        if (fh_len < GFS2_SMALL_FH_SIZE)
            return NULL;
        this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
        this.no_formal_ino |= be32_to_cpu(fh[1]);
        this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
        this.no_addr |= be32_to_cpu(fh[3]);
        return gfs2_get_dentry(sb, &this);
    default:
        return NULL;
    }
}

static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
        int fh_len, int fh_type)
{
    struct gfs2_inum_host parent;
    __be32 *fh = (__force __be32 *)fid->raw;

    switch (fh_type) {
    case GFS2_LARGE_FH_SIZE:
    case GFS2_OLD_FH_SIZE:
        if (fh_len < GFS2_LARGE_FH_SIZE)
            return NULL;
        parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
        parent.no_formal_ino |= be32_to_cpu(fh[5]);
        parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
        parent.no_addr |= be32_to_cpu(fh[7]);
        return gfs2_get_dentry(sb, &parent);
    default:
        return NULL;
    }
}

const struct export_operations gfs2_export_ops = {
    .encode_fh = gfs2_encode_fh,
    .fh_to_dentry = gfs2_fh_to_dentry,
    .fh_to_parent = gfs2_fh_to_parent,
    .get_name = gfs2_get_name,
    .get_parent = gfs2_get_parent,
};