1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * linux/fs/nfs/symlink.c
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 1992 Rick Sladkey
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Optimization changes Copyright (C) 1994 Florian La Roche
8*4882a593Smuzhiyun *
9*4882a593Smuzhiyun * Jun 7 1999, cache symlink lookups in the page cache. -DaveM
10*4882a593Smuzhiyun *
11*4882a593Smuzhiyun * nfs symlink handling code
12*4882a593Smuzhiyun */
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun #include <linux/time.h>
15*4882a593Smuzhiyun #include <linux/errno.h>
16*4882a593Smuzhiyun #include <linux/sunrpc/clnt.h>
17*4882a593Smuzhiyun #include <linux/nfs.h>
18*4882a593Smuzhiyun #include <linux/nfs2.h>
19*4882a593Smuzhiyun #include <linux/nfs_fs.h>
20*4882a593Smuzhiyun #include <linux/pagemap.h>
21*4882a593Smuzhiyun #include <linux/stat.h>
22*4882a593Smuzhiyun #include <linux/mm.h>
23*4882a593Smuzhiyun #include <linux/string.h>
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun /* Symlink caching in the page cache is even more simplistic
26*4882a593Smuzhiyun * and straight-forward than readdir caching.
27*4882a593Smuzhiyun */
28*4882a593Smuzhiyun
nfs_symlink_filler(void * data,struct page * page)29*4882a593Smuzhiyun static int nfs_symlink_filler(void *data, struct page *page)
30*4882a593Smuzhiyun {
31*4882a593Smuzhiyun struct inode *inode = data;
32*4882a593Smuzhiyun int error;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
35*4882a593Smuzhiyun if (error < 0)
36*4882a593Smuzhiyun goto error;
37*4882a593Smuzhiyun SetPageUptodate(page);
38*4882a593Smuzhiyun unlock_page(page);
39*4882a593Smuzhiyun return 0;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun error:
42*4882a593Smuzhiyun SetPageError(page);
43*4882a593Smuzhiyun unlock_page(page);
44*4882a593Smuzhiyun return -EIO;
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun
nfs_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * done)47*4882a593Smuzhiyun static const char *nfs_get_link(struct dentry *dentry,
48*4882a593Smuzhiyun struct inode *inode,
49*4882a593Smuzhiyun struct delayed_call *done)
50*4882a593Smuzhiyun {
51*4882a593Smuzhiyun struct page *page;
52*4882a593Smuzhiyun void *err;
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun if (!dentry) {
55*4882a593Smuzhiyun err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
56*4882a593Smuzhiyun if (err)
57*4882a593Smuzhiyun return err;
58*4882a593Smuzhiyun page = find_get_page(inode->i_mapping, 0);
59*4882a593Smuzhiyun if (!page)
60*4882a593Smuzhiyun return ERR_PTR(-ECHILD);
61*4882a593Smuzhiyun if (!PageUptodate(page)) {
62*4882a593Smuzhiyun put_page(page);
63*4882a593Smuzhiyun return ERR_PTR(-ECHILD);
64*4882a593Smuzhiyun }
65*4882a593Smuzhiyun } else {
66*4882a593Smuzhiyun err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
67*4882a593Smuzhiyun if (err)
68*4882a593Smuzhiyun return err;
69*4882a593Smuzhiyun page = read_cache_page(&inode->i_data, 0, nfs_symlink_filler,
70*4882a593Smuzhiyun inode);
71*4882a593Smuzhiyun if (IS_ERR(page))
72*4882a593Smuzhiyun return ERR_CAST(page);
73*4882a593Smuzhiyun }
74*4882a593Smuzhiyun set_delayed_call(done, page_put_link, page);
75*4882a593Smuzhiyun return page_address(page);
76*4882a593Smuzhiyun }
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun /*
79*4882a593Smuzhiyun * symlinks can't do much...
80*4882a593Smuzhiyun */
81*4882a593Smuzhiyun const struct inode_operations nfs_symlink_inode_operations = {
82*4882a593Smuzhiyun .get_link = nfs_get_link,
83*4882a593Smuzhiyun .getattr = nfs_getattr,
84*4882a593Smuzhiyun .setattr = nfs_setattr,
85*4882a593Smuzhiyun };
86