linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * fs/isofs/export.c

 *

 *  (C) 2004  Paul Serice - The new inode scheme requires switching

 *                          from iget() to iget5_locked() which means

 *                          the NFS export operations have to be hand

 *                          coded because the default routines rely on

 *                          iget().

 *

 * The following files are helpful:

 *

 *     Documentation/filesystems/nfs/Exporting

 *     fs/exportfs/expfs.c.

 */

​

#include "isofs.h"

​

static struct dentry *

isofs_export_iget(struct super_block *sb,

          unsigned long block,

          unsigned long offset,

          __u32 generation)

{

    struct inode *inode;

​

    if (block == 0)

        return ERR_PTR(-ESTALE);

    inode = isofs_iget(sb, block, offset);

    if (IS_ERR(inode))

        return ERR_CAST(inode);

    if (generation && inode->i_generation != generation) {

        iput(inode);

        return ERR_PTR(-ESTALE);

    }

    return d_obtain_alias(inode);

}

​

/* This function is surprisingly simple.  The trick is understanding

 * that "child" is always a directory. So, to find its parent, you

 * simply need to find its ".." entry, normalize its block and offset,

 * and return the underlying inode.  See the comments for

 * isofs_normalize_block_and_offset(). */

static struct dentry *isofs_export_get_parent(struct dentry *child)

{

    unsigned long parent_block = 0;

    unsigned long parent_offset = 0;

    struct inode *child_inode = d_inode(child);

    struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);

    struct iso_directory_record *de = NULL;

    struct buffer_head * bh = NULL;

    struct dentry *rv = NULL;

​

    /* "child" must always be a directory. */

    if (!S_ISDIR(child_inode->i_mode)) {

        printk(KERN_ERR "isofs: isofs_export_get_parent(): "

               "child is not a directory!\n");

        rv = ERR_PTR(-EACCES);

        goto out;

    }

​

    /* It is an invariant that the directory offset is zero.  If

     * it is not zero, it means the directory failed to be

     * normalized for some reason. */

    if (e_child_inode->i_iget5_offset != 0) {

        printk(KERN_ERR "isofs: isofs_export_get_parent(): "

               "child directory not normalized!\n");

        rv = ERR_PTR(-EACCES);

        goto out;

    }

​

    /* The child inode has been normalized such that its

     * i_iget5_block value points to the "." entry.  Fortunately,

     * the ".." entry is located in the same block. */

    parent_block = e_child_inode->i_iget5_block;

​

    /* Get the block in question. */

    bh = sb_bread(child_inode->i_sb, parent_block);

    if (bh == NULL) {

        rv = ERR_PTR(-EACCES);

        goto out;

    }

​

    /* This is the "." entry. */

    de = (struct iso_directory_record*)bh->b_data;

​

    /* The ".." entry is always the second entry. */

    parent_offset = (unsigned long)isonum_711(de->length);

    de = (struct iso_directory_record*)(bh->b_data + parent_offset);

​

    /* Verify it is in fact the ".." entry. */

    if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {