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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/time.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>
#include <linux/namei.h>
/* Symlink caching in the page cache is even more simplistic
* and straight-forward than readdir caching.
*
* At the beginning of the page we store pointer to struct page in question,
* simplifying nfs_put_link() (if inode got invalidated we can't find the page
* to be freed via pagecache lookup).
* The NUL-terminated string follows immediately thereafter.
*/
struct nfs_symlink {
struct page *page;
char body[0];
};
static int nfs_symlink_filler(struct inode *inode, struct page *page)
{
const unsigned int pgbase = offsetof(struct nfs_symlink, body);
const unsigned int pglen = PAGE_SIZE - pgbase;
int error;
lock_kernel();
error = NFS_PROTO(inode)->readlink(inode, page, pgbase, pglen);
unlock_kernel();
if (error < 0)
goto error;
SetPageUptodate(page);
unlock_page(page);
return 0;
error:
SetPageError(page);
unlock_page(page);
return -EIO;
}
static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
struct page *page;
struct nfs_symlink *p;
void *err = ERR_PTR(nfs_revalidate_inode(NFS_SERVER(inode), inode));
if (err)
goto read_failed;
page = read_cache_page(&inode->i_data, 0,
(filler_t *)nfs_symlink_filler, inode);
if (IS_ERR(page)) {
err = page;
goto read_failed;
}
if (!PageUptodate(page)) {
err = ERR_PTR(-EIO);
goto getlink_read_error;
}
p = kmap(page);
p->page = page;
nd_set_link(nd, p->body);
return 0;
getlink_read_error:
page_cache_release(page);
read_failed:
nd_set_link(nd, err);
return 0;
}
static void nfs_put_link(struct dentry *dentry, struct nameidata *nd)
{
char *s = nd_get_link(nd);
if (!IS_ERR(s)) {
struct nfs_symlink *p;
struct page *page;
p = container_of(s, struct nfs_symlink, body[0]);
page = p->page;
kunmap(page);
page_cache_release(page);
}
}
/*
* symlinks can't do much...
*/
struct inode_operations nfs_symlink_inode_operations = {
.readlink = generic_readlink,
.follow_link = nfs_follow_link,
.put_link = nfs_put_link,
.getattr = nfs_getattr,
.setattr = nfs_setattr,
};
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