linux/fs/nfs/symlink.c
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   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/string.h>
  23#include <linux/namei.h>
  24
  25/* Symlink caching in the page cache is even more simplistic
  26 * and straight-forward than readdir caching.
  27 */
  28
  29static int nfs_symlink_filler(struct inode *inode, struct page *page)
  30{
  31        int error;
  32
  33        error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
  34        if (error < 0)
  35                goto error;
  36        SetPageUptodate(page);
  37        unlock_page(page);
  38        return 0;
  39
  40error:
  41        SetPageError(page);
  42        unlock_page(page);
  43        return -EIO;
  44}
  45
  46static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
  47{
  48        struct inode *inode = dentry->d_inode;
  49        struct page *page;
  50        void *err;
  51
  52        err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
  53        if (err)
  54                goto read_failed;
  55        page = read_cache_page(&inode->i_data, 0,
  56                                (filler_t *)nfs_symlink_filler, inode);
  57        if (IS_ERR(page)) {
  58                err = page;
  59                goto read_failed;
  60        }
  61        nd_set_link(nd, kmap(page));
  62        return page;
  63
  64read_failed:
  65        nd_set_link(nd, err);
  66        return NULL;
  67}
  68
  69/*
  70 * symlinks can't do much...
  71 */
  72const struct inode_operations nfs_symlink_inode_operations = {
  73        .readlink       = generic_readlink,
  74        .follow_link    = nfs_follow_link,
  75        .put_link       = page_put_link,
  76        .getattr        = nfs_getattr,
  77        .setattr        = nfs_setattr,
  78};
  79
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