1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
/*
* linux/fs/nfs/symlink.c
*
* Copyright (C) 1992 Rick Sladkey
*
* Optimization changes Copyright (C) 1994 Florian La Roche
*
* Jun 7 1999, cache symlink lookups in the page cache. -DaveM
*
* nfs symlink handling code
*/
#define NFS_NEED_XDR_TYPES
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/nfs.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <asm/pgtable.h>
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/string.h>
#include <asm/uaccess.h>
static int nfs_readlink(struct dentry *, char *, int);
static struct dentry *nfs_follow_link(struct dentry *, struct dentry *, unsigned int);
/*
* symlinks can't do much...
*/
struct inode_operations nfs_symlink_inode_operations = {
NULL, /* no file-operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
nfs_readlink, /* readlink */
nfs_follow_link, /* follow_link */
NULL, /* get_block */
NULL, /* readpage */
NULL, /* writepage */
NULL, /* flushpage */
NULL, /* truncate */
NULL, /* permission */
NULL, /* smap */
NULL /* revalidate */
};
/* Symlink caching in the page cache is even more simplistic
* and straight-forward than readdir caching.
*/
static int nfs_symlink_filler(struct inode *inode, struct page *page)
{
void * buffer = (void *)page_address(page);
unsigned int error;
/* We place the length at the beginning of the page,
* in client byte order, followed by the string.
*/
error = NFS_PROTO(inode)->readlink(inode, buffer,
PAGE_CACHE_SIZE-sizeof(u32)-4);
if (error < 0)
goto error;
flush_dcache_page(page_address(page)); /* Is this correct? */
set_bit(PG_uptodate, &page->flags);
nfs_unlock_page(page);
return 0;
error:
set_bit(PG_error, &page->flags);
nfs_unlock_page(page);
return -EIO;
}
static int nfs_readlink(struct dentry *dentry, char *buffer, int buflen)
{
struct inode *inode = dentry->d_inode;
struct page *page;
u32 *p, len;
/* Caller revalidated the directory inode already. */
page = read_cache_page(inode, 0,
(filler_t *)nfs_symlink_filler, inode);
if (IS_ERR(page))
goto read_failed;
p = (u32 *) page_address(page);
len = *p++;
if (len > buflen)
len = buflen;
copy_to_user(buffer, p, len);
page_cache_release(page);
return len;
read_failed:
return PTR_ERR(page);
}
static struct dentry *
nfs_follow_link(struct dentry *dentry, struct dentry *base, unsigned int follow)
{
struct dentry *result;
struct inode *inode = dentry->d_inode;
struct page *page;
u32 *p;
/* Caller revalidated the directory inode already. */
page = read_cache_page(inode, 0,
(filler_t *)nfs_symlink_filler, inode);
if (IS_ERR(page))
goto read_failed;
p = (u32 *) page_address(page);
result = lookup_dentry((char *) (p + 1), base, follow);
page_cache_release(page);
return result;
read_failed:
return (struct dentry *)page;
}
|
