symlink.c

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/*
 *  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/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(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,
};