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/sched.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
27 /* Symlink caching in the page cache is even more simplistic
28 * and straight-forward than readdir caching.
29 */
nfs_symlink_filler(struct inode * inode,struct page * page)30 static int nfs_symlink_filler(struct inode *inode, struct page *page)
31 {
32 int error;
33
34 /* We place the length at the beginning of the page,
35 * in host byte order, followed by the string. The
36 * XDR response verification will NULL terminate it.
37 */
38 lock_kernel();
39 error = NFS_PROTO(inode)->readlink(inode, page);
40 unlock_kernel();
41 if (error < 0)
42 goto error;
43 SetPageUptodate(page);
44 UnlockPage(page);
45 return 0;
46
47 error:
48 SetPageError(page);
49 UnlockPage(page);
50 return -EIO;
51 }
52
nfs_getlink(struct inode * inode,struct page ** ppage)53 static char *nfs_getlink(struct inode *inode, struct page **ppage)
54 {
55 struct page *page;
56 u32 *p;
57
58 /* Caller revalidated the directory inode already. */
59 page = read_cache_page(&inode->i_data, 0,
60 (filler_t *)nfs_symlink_filler, inode);
61 if (IS_ERR(page))
62 goto read_failed;
63 if (!Page_Uptodate(page))
64 goto getlink_read_error;
65 *ppage = page;
66 p = kmap(page);
67 return (char*)(p+1);
68
69 getlink_read_error:
70 page_cache_release(page);
71 return ERR_PTR(-EIO);
72 read_failed:
73 return (char*)page;
74 }
75
nfs_readlink(struct dentry * dentry,char * buffer,int buflen)76 static int nfs_readlink(struct dentry *dentry, char *buffer, int buflen)
77 {
78 struct inode *inode = dentry->d_inode;
79 struct page *page = NULL;
80 int res = vfs_readlink(dentry,buffer,buflen,nfs_getlink(inode,&page));
81 if (page) {
82 kunmap(page);
83 page_cache_release(page);
84 }
85 return res;
86 }
87
nfs_follow_link(struct dentry * dentry,struct nameidata * nd)88 static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
89 {
90 struct inode *inode = dentry->d_inode;
91 struct page *page = NULL;
92 int res = vfs_follow_link(nd, nfs_getlink(inode,&page));
93 if (page) {
94 kunmap(page);
95 page_cache_release(page);
96 }
97 return res;
98 }
99
100 /*
101 * symlinks can't do much...
102 */
103 struct inode_operations nfs_symlink_inode_operations = {
104 readlink: nfs_readlink,
105 follow_link: nfs_follow_link,
106 revalidate: nfs_revalidate,
107 setattr: nfs_notify_change,
108 };
109