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#define NFS_NEED_XDR_TYPES
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/slab.h>
24#include <linux/string.h>
25#include <linux/namei.h>
26
27/* Symlink caching in the page cache is even more simplistic
28 * and straight-forward than readdir caching.
29 */
30
31static int nfs_symlink_filler(struct inode *inode, struct page *page)
32{
33	int error;
34
35	error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
36	if (error < 0)
37		goto error;
38	SetPageUptodate(page);
39	unlock_page(page);
40	return 0;
41
42error:
43	SetPageError(page);
44	unlock_page(page);
45	return -EIO;
46}
47
48static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
49{
50	struct inode *inode = dentry->d_inode;
51	struct page *page;
52	void *err;
53
54	err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping));
55	if (err)
56		goto read_failed;
57	page = read_cache_page(&inode->i_data, 0,
58				(filler_t *)nfs_symlink_filler, inode);
59	if (IS_ERR(page)) {
60		err = page;
61		goto read_failed;
62	}
63	nd_set_link(nd, kmap(page));
64	return page;
65
66read_failed:
67	nd_set_link(nd, err);
68	return NULL;
69}
70
71/*
72 * symlinks can't do much...
73 */
74const struct inode_operations nfs_symlink_inode_operations = {
75	.readlink	= generic_readlink,
76	.follow_link	= nfs_follow_link,
77	.put_link	= page_put_link,
78	.getattr	= nfs_getattr,
79	.setattr	= nfs_setattr,
80};
81