blob: 35f1065991441c3f3d02f6749692da739b8492b3 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/smp_lock.h>
26#include <linux/namei.h>
27
28/* Symlink caching in the page cache is even more simplistic
29 * and straight-forward than readdir caching.
30 *
31 * At the beginning of the page we store pointer to struct page in question,
32 * simplifying nfs_put_link() (if inode got invalidated we can't find the page
33 * to be freed via pagecache lookup).
34 * The NUL-terminated string follows immediately thereafter.
35 */
36
37struct nfs_symlink {
38 struct page *page;
39 char body[0];
40};
41
42static int nfs_symlink_filler(struct inode *inode, struct page *page)
43{
44 const unsigned int pgbase = offsetof(struct nfs_symlink, body);
45 const unsigned int pglen = PAGE_SIZE - pgbase;
46 int error;
47
48 lock_kernel();
49 error = NFS_PROTO(inode)->readlink(inode, page, pgbase, pglen);
50 unlock_kernel();
51 if (error < 0)
52 goto error;
53 SetPageUptodate(page);
54 unlock_page(page);
55 return 0;
56
57error:
58 SetPageError(page);
59 unlock_page(page);
60 return -EIO;
61}
62
63static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
64{
65 struct inode *inode = dentry->d_inode;
66 struct page *page;
67 struct nfs_symlink *p;
68 void *err = ERR_PTR(nfs_revalidate_inode(NFS_SERVER(inode), inode));
69 if (err)
70 goto read_failed;
71 page = read_cache_page(&inode->i_data, 0,
72 (filler_t *)nfs_symlink_filler, inode);
73 if (IS_ERR(page)) {
74 err = page;
75 goto read_failed;
76 }
77 if (!PageUptodate(page)) {
78 err = ERR_PTR(-EIO);
79 goto getlink_read_error;
80 }
81 p = kmap(page);
82 p->page = page;
83 nd_set_link(nd, p->body);
84 return 0;
85
86getlink_read_error:
87 page_cache_release(page);
88read_failed:
89 nd_set_link(nd, err);
90 return 0;
91}
92
93static void nfs_put_link(struct dentry *dentry, struct nameidata *nd)
94{
95 char *s = nd_get_link(nd);
96 if (!IS_ERR(s)) {
97 struct nfs_symlink *p;
98 struct page *page;
99
100 p = container_of(s, struct nfs_symlink, body[0]);
101 page = p->page;
102
103 kunmap(page);
104 page_cache_release(page);
105 }
106}
107
108/*
109 * symlinks can't do much...
110 */
111struct inode_operations nfs_symlink_inode_operations = {
112 .readlink = generic_readlink,
113 .follow_link = nfs_follow_link,
114 .put_link = nfs_put_link,
115 .getattr = nfs_getattr,
116 .setattr = nfs_setattr,
117};