root/fs/nfs/symlink.c

DEFINITIONS

1. nfs_symlink_filler
2. nfs_follow_link

/*
 *  linux/fs/nfs/symlink.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  Optimization changes Copyright (C) 1994 Florian La Roche
 *
 *  Jun 7 1999, cache symlink lookups in the page cache.  -DaveM
 *
 *  nfs symlink handling code
 */

#include <linux/time.h>
#include <linux/errno.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs.h>
#include <linux/nfs2.h>
#include <linux/nfs_fs.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/namei.h>

/* Symlink caching in the page cache is even more simplistic
 * and straight-forward than readdir caching.
 */

static int nfs_symlink_filler(struct inode *inode, struct page *page)
{
        int error;

        error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
        if (error < 0)
                goto error;
        SetPageUptodate(page);
        unlock_page(page);
        return 0;

error:
        SetPageError(page);
        unlock_page(page);
        return -EIO;
}

static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        struct inode *inode = dentry->d_inode;
        struct page *page;
        void *err;

        err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping));
        if (err)
                goto read_failed;
        page = read_cache_page(&inode->i_data, 0,
                                (filler_t *)nfs_symlink_filler, inode);
        if (IS_ERR(page)) {
                err = page;
                goto read_failed;
        }
        nd_set_link(nd, kmap(page));
        return page;

read_failed:
        nd_set_link(nd, err);
        return NULL;
}

/*
 * symlinks can't do much...
 */
const struct inode_operations nfs_symlink_inode_operations = {
        .readlink       = generic_readlink,
        .follow_link    = nfs_follow_link,
        .put_link       = page_put_link,
        .getattr        = nfs_getattr,
        .setattr        = nfs_setattr,
};