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,
+};