linux/fs/nfs/symlink.c
Nick Piggin 6fe6900e1e mm: make read_cache_page synchronous
Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.

I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd.  All depending on whether the filler is async and/or can return
with a !uptodate page.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:51 -07:00

82 lines
1.7 KiB
C

/*
* 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.
*/
static int nfs_symlink_filler(struct inode *inode, struct page *page)
{
int error;
error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
if (error < 0)
goto error;
SetPageUptodate(page);
unlock_page(page);
return 0;
error:
SetPageError(page);
unlock_page(page);
return -EIO;
}
static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
struct page *page;
void *err;
err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping));
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;
}
nd_set_link(nd, kmap(page));
return page;
read_failed:
nd_set_link(nd, err);
return NULL;
}
/*
* symlinks can't do much...
*/
const struct inode_operations nfs_symlink_inode_operations = {
.readlink = generic_readlink,
.follow_link = nfs_follow_link,
.put_link = page_put_link,
.getattr = nfs_getattr,
.setattr = nfs_setattr,
};