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 | |
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 | |
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(error: nfs_revalidate_mapping_rcu(inode)); |
56 | if (err) |
57 | return err; |
58 | page = find_get_page(mapping: inode->i_mapping, offset: 0); |
59 | if (!page) |
60 | return ERR_PTR(error: -ECHILD); |
61 | if (!PageUptodate(page)) { |
62 | put_page(page); |
63 | return ERR_PTR(error: -ECHILD); |
64 | } |
65 | } else { |
66 | err = ERR_PTR(error: nfs_revalidate_mapping(inode, mapping: inode->i_mapping)); |
67 | if (err) |
68 | return err; |
69 | page = read_cache_page(&inode->i_data, index: 0, filler: nfs_symlink_filler, |
70 | NULL); |
71 | if (IS_ERR(ptr: page)) |
72 | return ERR_CAST(ptr: page); |
73 | } |
74 | set_delayed_call(call: done, fn: page_put_link, arg: 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 | |