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
nfs_symlink_filler(struct file * file,struct folio * folio)29 static 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
nfs_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * done)39 static 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 */
73 const struct inode_operations nfs_symlink_inode_operations = {
74 .get_link = nfs_get_link,
75 .getattr = nfs_getattr,
76 .setattr = nfs_setattr,
77 };
78