export.c

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/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * export.c
 *
 * Functions to facilitate NFS exporting
 *
 * Copyright (C) 2002, 2005 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>

#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "dir.h"
#include "dlmglue.h"
#include "dcache.h"
#include "export.h"
#include "inode.h"

#include "buffer_head_io.h"
#include "suballoc.h"
#include "ocfs2_trace.h"

struct ocfs2_inode_handle
{
    u64 ih_blkno;
    u32 ih_generation;
};

static struct dentry *ocfs2_get_dentry(struct super_block *sb,
        struct ocfs2_inode_handle *handle)
{
    struct inode *inode;
    struct ocfs2_super *osb = OCFS2_SB(sb);
    u64 blkno = handle->ih_blkno;
    int status, set;
    struct dentry *result;

    trace_ocfs2_get_dentry_begin(sb, handle, (unsigned long long)blkno);

    if (blkno == 0) {
        result = ERR_PTR(-ESTALE);
        goto bail;
    }

    inode = ocfs2_ilookup(sb, blkno);
    /*
     * If the inode exists in memory, we only need to check it's
     * generation number
     */
    if (inode)
        goto check_gen;

    /*
     * This will synchronize us against ocfs2_delete_inode() on
     * all nodes
     */
    status = ocfs2_nfs_sync_lock(osb, 1);
    if (status < 0) {
        mlog(ML_ERROR, "getting nfs sync lock(EX) failed %d\n", status);
        goto check_err;
    }

    status = ocfs2_test_inode_bit(osb, blkno, &set);
    trace_ocfs2_get_dentry_test_bit(status, set);
    if (status < 0) {
        if (status == -EINVAL) {
            /*
             * The blkno NFS gave us doesn't even show up
             * as an inode, we return -ESTALE to be
             * nice
             */
            status = -ESTALE;
        } else
            mlog(ML_ERROR, "test inode bit failed %d\n", status);
        goto unlock_nfs_sync;
    }

    /* If the inode allocator bit is clear, this inode must be stale */
    if (!set) {
        status = -ESTALE;
        goto unlock_nfs_sync;
    }

    inode = ocfs2_iget(osb, blkno, 0, 0);

unlock_nfs_sync:
    ocfs2_nfs_sync_unlock(osb, 1);

check_err:
    if (status < 0) {
        if (status == -ESTALE) {
            trace_ocfs2_get_dentry_stale((unsigned long long)blkno,
                             handle->ih_generation);
        }
        result = ERR_PTR(status);
        goto bail;
    }

    if (IS_ERR(inode)) {
        mlog_errno(PTR_ERR(inode));
        result = (void *)inode;
        goto bail;
    }

check_gen:
    if (handle->ih_generation != inode->i_generation) {
        iput(inode);
        trace_ocfs2_get_dentry_generation((unsigned long long)blkno,
                          handle->ih_generation,
                          inode->i_generation);
        result = ERR_PTR(-ESTALE);
        goto bail;
    }

    result = d_obtain_alias(inode);
    if (IS_ERR(result))
        mlog_errno(PTR_ERR(result));

bail:
    trace_ocfs2_get_dentry_end(result);
    return result;
}

static struct dentry *ocfs2_get_parent(struct dentry *child)
{
    int status;
    u64 blkno;
    struct dentry *parent;
    struct inode *dir = child->d_inode;

    trace_ocfs2_get_parent(child, child->d_name.len, child->d_name.name,
                   (unsigned long long)OCFS2_I(dir)->ip_blkno);

    status = ocfs2_inode_lock(dir, NULL, 0);
    if (status < 0) {
        if (status != -ENOENT)
            mlog_errno(status);
        parent = ERR_PTR(status);
        goto bail;
    }

    status = ocfs2_lookup_ino_from_name(dir, "..", 2, &blkno);
    if (status < 0) {
        parent = ERR_PTR(-ENOENT);
        goto bail_unlock;
    }

    parent = d_obtain_alias(ocfs2_iget(OCFS2_SB(dir->i_sb), blkno, 0, 0));

bail_unlock:
    ocfs2_inode_unlock(dir, 0);

bail:
    trace_ocfs2_get_parent_end(parent);

    return parent;
}

static int ocfs2_encode_fh(struct inode *inode, u32 *fh_in, int *max_len,
               struct inode *parent)
{
    int len = *max_len;
    int type = 1;
    u64 blkno;
    u32 generation;
    __le32 *fh = (__force __le32 *) fh_in;

#ifdef TRACE_HOOKS_ARE_NOT_BRAINDEAD_IN_YOUR_OPINION
#error "You go ahead and fix that mess, then.  Somehow"
    trace_ocfs2_encode_fh_begin(dentry, dentry->d_name.len,
                    dentry->d_name.name,
                    fh, len, connectable);
#endif

    if (parent && (len < 6)) {
        *max_len = 6;
        type = 255;
        goto bail;
    } else if (len < 3) {
        *max_len = 3;
        type = 255;
        goto bail;
    }

    blkno = OCFS2_I(inode)->ip_blkno;
    generation = inode->i_generation;

    trace_ocfs2_encode_fh_self((unsigned long long)blkno, generation);

    len = 3;
    fh[0] = cpu_to_le32((u32)(blkno >> 32));
    fh[1] = cpu_to_le32((u32)(blkno & 0xffffffff));
    fh[2] = cpu_to_le32(generation);

    if (parent) {
        blkno = OCFS2_I(parent)->ip_blkno;
        generation = parent->i_generation;

        fh[3] = cpu_to_le32((u32)(blkno >> 32));
        fh[4] = cpu_to_le32((u32)(blkno & 0xffffffff));
        fh[5] = cpu_to_le32(generation);

        len = 6;
        type = 2;

        trace_ocfs2_encode_fh_parent((unsigned long long)blkno,
                         generation);
    }

    *max_len = len;

bail:
    trace_ocfs2_encode_fh_type(type);
    return type;
}

static struct dentry *ocfs2_fh_to_dentry(struct super_block *sb,
        struct fid *fid, int fh_len, int fh_type)
{
    struct ocfs2_inode_handle handle;

    if (fh_len < 3 || fh_type > 2)
        return NULL;

    handle.ih_blkno = (u64)le32_to_cpu(fid->raw[0]) << 32;
    handle.ih_blkno |= (u64)le32_to_cpu(fid->raw[1]);
    handle.ih_generation = le32_to_cpu(fid->raw[2]);
    return ocfs2_get_dentry(sb, &handle);
}

static struct dentry *ocfs2_fh_to_parent(struct super_block *sb,
        struct fid *fid, int fh_len, int fh_type)
{
    struct ocfs2_inode_handle parent;

    if (fh_type != 2 || fh_len < 6)
        return NULL;

    parent.ih_blkno = (u64)le32_to_cpu(fid->raw[3]) << 32;
    parent.ih_blkno |= (u64)le32_to_cpu(fid->raw[4]);
    parent.ih_generation = le32_to_cpu(fid->raw[5]);
    return ocfs2_get_dentry(sb, &parent);
}

const struct export_operations ocfs2_export_ops = {
    .encode_fh  = ocfs2_encode_fh,
    .fh_to_dentry   = ocfs2_fh_to_dentry,
    .fh_to_parent   = ocfs2_fh_to_parent,
    .get_parent = ocfs2_get_parent,
};