1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/nfs/symlink.c
4 *
5 * Copyright (C) 1992 Rick Sladkey
6 *
7 * Optimization changes Copyright (C) 1994 Florian La Roche
8 *
9 * Jun 7 1999, cache symlink lookups in the page cache. -DaveM
10 *
11 * nfs symlink handling code
12 */
13
14#include <linux/time.h>
15#include <linux/errno.h>
16#include <linux/sunrpc/clnt.h>
17#include <linux/nfs.h>
18#include <linux/nfs2.h>
19#include <linux/nfs_fs.h>
20#include <linux/pagemap.h>
21#include <linux/stat.h>
22#include <linux/mm.h>
23#include <linux/string.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 file *file, struct folio *folio)
30{
31 struct inode *inode = folio->mapping->host;
32 int error;
33
34 error = NFS_PROTO(inode)->readlink(inode, &folio->page, 0, PAGE_SIZE);
35 folio_end_read(folio, success: error == 0);
36 return error;
37}
38
39static const char *nfs_get_link(struct dentry *dentry,
40 struct inode *inode,
41 struct delayed_call *done)
42{
43 struct folio *folio;
44 void *err;
45
46 if (!dentry) {
47 err = ERR_PTR(error: nfs_revalidate_mapping_rcu(inode));
48 if (err)
49 return err;
50 folio = filemap_get_folio(mapping: inode->i_mapping, index: 0);
51 if (IS_ERR(ptr: folio))
52 return ERR_PTR(error: -ECHILD);
53 if (!folio_test_uptodate(folio)) {
54 folio_put(folio);
55 return ERR_PTR(error: -ECHILD);
56 }
57 } else {
58 err = ERR_PTR(error: nfs_revalidate_mapping(inode, mapping: inode->i_mapping));
59 if (err)
60 return err;
61 folio = read_cache_folio(&inode->i_data, index: 0, filler: nfs_symlink_filler,
62 NULL);
63 if (IS_ERR(ptr: folio))
64 return ERR_CAST(ptr: folio);
65 }
66 set_delayed_call(call: done, fn: page_put_link, arg: folio);
67 return folio_address(folio);
68}
69
70/*
71 * symlinks can't do much...
72 */
73const struct inode_operations nfs_symlink_inode_operations = {
74 .get_link = nfs_get_link,
75 .getattr = nfs_getattr,
76 .setattr = nfs_setattr,
77};
78

source code of linux/fs/nfs/symlink.c