nfs.c

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/* fs/fat/nfs.c
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */

#include <linux/exportfs.h>
#include "fat.h"

static struct inode *fat_dget(struct super_block *sb, int i_logstart)
{
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    struct hlist_head *head;
    struct hlist_node *_p;
    struct msdos_inode_info *i;
    struct inode *inode = NULL;

    head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
    spin_lock(&sbi->dir_hash_lock);
    hlist_for_each_entry(i, _p, head, i_dir_hash) {
        BUG_ON(i->vfs_inode.i_sb != sb);
        if (i->i_logstart != i_logstart)
            continue;
        inode = igrab(&i->vfs_inode);
        if (inode)
            break;
    }
    spin_unlock(&sbi->dir_hash_lock);
    return inode;
}

static struct inode *fat_nfs_get_inode(struct super_block *sb,
                       u64 ino, u32 generation)
{
    struct inode *inode;

    if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
        return NULL;

    inode = ilookup(sb, ino);
    if (inode && generation && (inode->i_generation != generation)) {
        iput(inode);
        inode = NULL;
    }

    return inode;
}

struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
    return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                    fat_nfs_get_inode);
}

/*
 * Find the parent for a file specified by NFS handle.
 * This requires that the handle contain the i_ino of the parent.
 */
struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
    return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                    fat_nfs_get_inode);
}

/*
 * Find the parent for a directory that is not currently connected to
 * the filesystem root.
 *
 * On entry, the caller holds child_dir->d_inode->i_mutex.
 */
struct dentry *fat_get_parent(struct dentry *child_dir)
{
    struct super_block *sb = child_dir->d_sb;
    struct buffer_head *bh = NULL;
    struct msdos_dir_entry *de;
    struct inode *parent_inode = NULL;

    if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) {
        int parent_logstart = fat_get_start(MSDOS_SB(sb), de);
        parent_inode = fat_dget(sb, parent_logstart);
    }
    brelse(bh);

    return d_obtain_alias(parent_inode);
}