1 files changed, 117 insertions, 0 deletions
diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
new file mode 100644
index 000000000000..35f106599144
--- /dev/null
+++ b/fs/nfs/symlink.c
@@ -0,0 +1,117 @@
+/*
+ *  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,
+};