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/*
* 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.h>
#include <linux/nfs2.h>
#include <linux/nfs_fs.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
/* 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 = kmap(page);
int error;
/* We place the length at the beginning of the page,
* in host byte order, followed by the string. The
* XDR response verification will NULL terminate it.
*/
lock_kernel();
error = NFS_PROTO(inode)->readlink(inode, buffer,
PAGE_CACHE_SIZE - sizeof(u32)-4);
unlock_kernel();
if (error < 0)
goto error;
SetPageUptodate(page);
kunmap(page);
UnlockPage(page);
return 0;
error:
SetPageError(page);
kunmap(page);
UnlockPage(page);
return -EIO;
}
static char *nfs_getlink(struct inode *inode, struct page **ppage)
{
struct page *page;
u32 *p;
/* Caller revalidated the directory inode already. */
page = read_cache_page(&inode->i_data, 0,
(filler_t *)nfs_symlink_filler, inode);
if (IS_ERR(page))
goto read_failed;
if (!Page_Uptodate(page))
goto getlink_read_error;
*ppage = page;
p = kmap(page);
return (char*)(p+1);
getlink_read_error:
page_cache_release(page);
return ERR_PTR(-EIO);
read_failed:
return (char*)page;
}
static int nfs_readlink(struct dentry *dentry, char *buffer, int buflen)
{
struct inode *inode = dentry->d_inode;
struct page *page = NULL;
int res = vfs_readlink(dentry,buffer,buflen,nfs_getlink(inode,&page));
if (page) {
kunmap(page);
page_cache_release(page);
}
return res;
}
static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
struct page *page = NULL;
int res = vfs_follow_link(nd, nfs_getlink(inode,&page));
if (page) {
kunmap(page);
page_cache_release(page);
}
return res;
}
/*
* symlinks can't do much...
*/
struct inode_operations nfs_symlink_inode_operations = {
readlink: nfs_readlink,
follow_link: nfs_follow_link,
revalidate: nfs_revalidate,
setattr: nfs_notify_change,
};
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