xref: /openbmc/linux/fs/nfs/symlink.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 
32 static int nfs_symlink_filler(struct inode *inode, struct page *page)
33 {
34 	int error;
35 
36 	lock_kernel();
37 	error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
38 	unlock_kernel();
39 	if (error < 0)
40 		goto error;
41 	SetPageUptodate(page);
42 	unlock_page(page);
43 	return 0;
44 
45 error:
46 	SetPageError(page);
47 	unlock_page(page);
48 	return -EIO;
49 }
50 
51 static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
52 {
53 	struct inode *inode = dentry->d_inode;
54 	struct page *page;
55 	void *err = ERR_PTR(nfs_revalidate_inode(NFS_SERVER(inode), inode));
56 	if (err)
57 		goto read_failed;
58 	page = read_cache_page(&inode->i_data, 0,
59 				(filler_t *)nfs_symlink_filler, inode);
60 	if (IS_ERR(page)) {
61 		err = page;
62 		goto read_failed;
63 	}
64 	if (!PageUptodate(page)) {
65 		err = ERR_PTR(-EIO);
66 		goto getlink_read_error;
67 	}
68 	nd_set_link(nd, kmap(page));
69 	return page;
70 
71 getlink_read_error:
72 	page_cache_release(page);
73 read_failed:
74 	nd_set_link(nd, err);
75 	return NULL;
76 }
77 
78 static void nfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
79 {
80 	if (cookie) {
81 		struct page *page = cookie;
82 		kunmap(page);
83 		page_cache_release(page);
84 	}
85 }
86 
87 /*
88  * symlinks can't do much...
89  */
90 struct inode_operations nfs_symlink_inode_operations = {
91 	.readlink	= generic_readlink,
92 	.follow_link	= nfs_follow_link,
93 	.put_link	= nfs_put_link,
94 	.getattr	= nfs_getattr,
95 	.setattr	= nfs_setattr,
96 };
97