]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
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 | #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 | ||
37 | struct nfs_symlink { | |
38 | struct page *page; | |
39 | char body[0]; | |
40 | }; | |
41 | ||
42 | static 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 | ||
57 | error: | |
58 | SetPageError(page); | |
59 | unlock_page(page); | |
60 | return -EIO; | |
61 | } | |
62 | ||
63 | static 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 | ||
86 | getlink_read_error: | |
87 | page_cache_release(page); | |
88 | read_failed: | |
89 | nd_set_link(nd, err); | |
90 | return 0; | |
91 | } | |
92 | ||
93 | static 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 | */ | |
111 | struct 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 | }; |