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, 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 page *page;
44	void *err;
45
46	if (!dentry) {
47		err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
48		if (err)
49			return err;
50		page = find_get_page(inode->i_mapping, 0);
51		if (!page)
52			return ERR_PTR(-ECHILD);
53		if (!PageUptodate(page)) {
54			put_page(page);
55			return ERR_PTR(-ECHILD);
56		}
57	} else {
58		err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
59		if (err)
60			return err;
61		page = read_cache_page(&inode->i_data, 0, nfs_symlink_filler,
62				NULL);
63		if (IS_ERR(page))
64			return ERR_CAST(page);
65	}
66	set_delayed_call(done, page_put_link, page);
67	return page_address(page);
 
 
 
 
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};

 
 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};