xref: /openbmc/linux/fs/nfs/symlink.c (revision 3d3337de)
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 #include <linux/time.h>
14 #include <linux/errno.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/nfs.h>
17 #include <linux/nfs2.h>
18 #include <linux/nfs_fs.h>
19 #include <linux/pagemap.h>
20 #include <linux/stat.h>
21 #include <linux/mm.h>
22 #include <linux/string.h>
23 #include <linux/namei.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 inode *inode, struct page *page)
30 {
31 	int error;
32 
33 	error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
34 	if (error < 0)
35 		goto error;
36 	SetPageUptodate(page);
37 	unlock_page(page);
38 	return 0;
39 
40 error:
41 	SetPageError(page);
42 	unlock_page(page);
43 	return -EIO;
44 }
45 
46 static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
47 {
48 	struct inode *inode = d_inode(dentry);
49 	struct page *page;
50 	void *err;
51 
52 	err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
53 	if (err)
54 		goto read_failed;
55 	page = read_cache_page(&inode->i_data, 0,
56 				(filler_t *)nfs_symlink_filler, inode);
57 	if (IS_ERR(page)) {
58 		err = page;
59 		goto read_failed;
60 	}
61 	nd_set_link(nd, kmap(page));
62 	return page;
63 
64 read_failed:
65 	nd_set_link(nd, err);
66 	return NULL;
67 }
68 
69 /*
70  * symlinks can't do much...
71  */
72 const struct inode_operations nfs_symlink_inode_operations = {
73 	.readlink	= generic_readlink,
74 	.follow_link	= nfs_follow_link,
75 	.put_link	= page_put_link,
76 	.getattr	= nfs_getattr,
77 	.setattr	= nfs_setattr,
78 };
79