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 if (error < 0)
36 goto error;
37 folio_mark_uptodate(folio);
38 folio_unlock(folio);
39 return 0;
40
41 error:
42 folio_set_error(folio);
43 folio_unlock(folio);
44 return -EIO;
45 }
46
nfs_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * done)47 static const char *nfs_get_link(struct dentry *dentry,
48 struct inode *inode,
49 struct delayed_call *done)
50 {
51 struct page *page;
52 void *err;
53
54 if (!dentry) {
55 err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
56 if (err)
57 return err;
58 page = find_get_page(inode->i_mapping, 0);
59 if (!page)
60 return ERR_PTR(-ECHILD);
61 if (!PageUptodate(page)) {
62 put_page(page);
63 return ERR_PTR(-ECHILD);
64 }
65 } else {
66 err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
67 if (err)
68 return err;
69 page = read_cache_page(&inode->i_data, 0, nfs_symlink_filler,
70 NULL);
71 if (IS_ERR(page))
72 return ERR_CAST(page);
73 }
74 set_delayed_call(done, page_put_link, page);
75 return page_address(page);
76 }
77
78 /*
79 * symlinks can't do much...
80 */
81 const struct inode_operations nfs_symlink_inode_operations = {
82 .get_link = nfs_get_link,
83 .getattr = nfs_getattr,
84 .setattr = nfs_setattr,
85 };
86