#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;
- /* 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, page);
+ error = NFS_PROTO(inode)->readlink(inode, page, pgbase, pglen);
unlock_kernel();
if (error < 0)
goto error;
return -EIO;
}
-static char *nfs_getlink(struct inode *inode, struct page **ppage)
+static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
+ struct inode *inode = dentry->d_inode;
struct page *page;
- u32 *p;
-
- page = ERR_PTR(nfs_revalidate_inode(NFS_SERVER(inode), inode));
- if (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))
+ if (IS_ERR(page)) {
+ err = page;
goto read_failed;
- if (!PageUptodate(page))
+ }
+ if (!PageUptodate(page)) {
+ err = ERR_PTR(-EIO);
goto getlink_read_error;
- *ppage = page;
+ }
p = kmap(page);
- return (char*)(p+1);
+ p->page = page;
+ nd_set_link(nd, p->body);
+ return 0;
getlink_read_error:
page_cache_release(page);
- page = ERR_PTR(-EIO);
read_failed:
- return (char*)page;
+ nd_set_link(nd, err);
+ return 0;
}
-static int nfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+static void nfs_put_link(struct dentry *dentry, struct nameidata *nd)
{
- 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;
-}
+ 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;
-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,
+ .readlink = generic_readlink,
.follow_link = nfs_follow_link,
+ .put_link = nfs_put_link,
.getattr = nfs_getattr,
.setattr = nfs_setattr,
};