LXR linux/fs/nfs/symlink.c

   1/*
   2 *  linux/fs/nfs/symlink.c
   3 *
   4 *  Copyright (C) 1992  Rick Sladkey
   5 *
   6 *  Optimization changes Copyright (C) 1994 Florian La Roche
   7 *
   8 *  Jun 7 1999, cache symlink lookups in the page cache.  -DaveM
   9 *
  10 *  nfs symlink handling code
  11 */
  12
  13#include <linux/time.h>
  14#include <linux/errno.h>
  15#include <linux/sunrpc/clnt.h>
  16#include <linux/nfs.h>
  17#include <linux/nfs2.h>
  18#include <linux/nfs_fs.h>
  19#include <linux/pagemap.h>
  20#include <linux/stat.h>
  21#include <linux/mm.h>
  22#include <linux/slab.h>
  23#include <linux/string.h>
  24#include <linux/namei.h>
  25
  26/* Symlink caching in the page cache is even more simplistic
  27 * and straight-forward than readdir caching.
  28 */
  29
  30static int nfs_symlink_filler(struct inode *inode, struct page *page)
  31{
  32        int error;
  33
  34        error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
  35        if (error < 0)
  36                goto error;
  37        SetPageUptodate(page);
  38        unlock_page(page);
  39        return 0;
  40
  41error:
  42        SetPageError(page);
  43        unlock_page(page);
  44        return -EIO;
  45}
  46
  47static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
  48{
  49        struct inode *inode = dentry->d_inode;
  50        struct page *page;
  51        void *err;
  52
  53        err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping));
  54        if (err)
  55                goto read_failed;
  56        page = read_cache_page(&inode->i_data, 0,
  57                                (filler_t *)nfs_symlink_filler, inode);
  58        if (IS_ERR(page)) {
  59                err = page;
  60                goto read_failed;
  61        }
  62        nd_set_link(nd, kmap(page));
  63        return page;
  64
  65read_failed:
  66        nd_set_link(nd, err);
  67        return NULL;
  68}
  69
  70/*
  71 * symlinks can't do much...
  72 */
  73const struct inode_operations nfs_symlink_inode_operations = {
  74        .readlink       = generic_readlink,
  75        .follow_link    = nfs_follow_link,
  76        .put_link       = page_put_link,
  77        .getattr        = nfs_getattr,
  78        .setattr        = nfs_setattr,
  79};
  80