11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * JFFS2 -- Journalling Flash File System, Version 2. 31da177e4SLinus Torvalds * 4c00c310eSDavid Woodhouse * Copyright © 2001-2007 Red Hat, Inc. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Created by David Woodhouse <dwmw2@infradead.org> 71da177e4SLinus Torvalds * 81da177e4SLinus Torvalds * For licensing information, see the file 'LICENCE' in this directory. 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds #include <linux/kernel.h> 131da177e4SLinus Torvalds #include <linux/slab.h> 141da177e4SLinus Torvalds #include <linux/fs.h> 151da177e4SLinus Torvalds #include <linux/namei.h> 161da177e4SLinus Torvalds #include "nodelist.h" 171da177e4SLinus Torvalds 18008b150aSAl Viro static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd); 191da177e4SLinus Torvalds 2092e1d5beSArjan van de Ven const struct inode_operations jffs2_symlink_inode_operations = 211da177e4SLinus Torvalds { 221da177e4SLinus Torvalds .readlink = generic_readlink, 231da177e4SLinus Torvalds .follow_link = jffs2_follow_link, 24aa98d7cfSKaiGai Kohei .permission = jffs2_permission, 25aa98d7cfSKaiGai Kohei .setattr = jffs2_setattr, 26aa98d7cfSKaiGai Kohei .setxattr = jffs2_setxattr, 27aa98d7cfSKaiGai Kohei .getxattr = jffs2_getxattr, 28aa98d7cfSKaiGai Kohei .listxattr = jffs2_listxattr, 29aa98d7cfSKaiGai Kohei .removexattr = jffs2_removexattr 301da177e4SLinus Torvalds }; 311da177e4SLinus Torvalds 32008b150aSAl Viro static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd) 331da177e4SLinus Torvalds { 3432f1a95dSArtem B. Bityuckiy struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode); 352b79adccSArtem B. Bityutskiy char *p = (char *)f->target; 3632f1a95dSArtem B. Bityuckiy 3732f1a95dSArtem B. Bityuckiy /* 3832f1a95dSArtem B. Bityuckiy * We don't acquire the f->sem mutex here since the only data we 392b79adccSArtem B. Bityutskiy * use is f->target. 4032f1a95dSArtem B. Bityuckiy * 412b79adccSArtem B. Bityutskiy * 1. If we are here the inode has already built and f->target has 4232f1a95dSArtem B. Bityuckiy * to point to the target path. 432b79adccSArtem B. Bityutskiy * 2. Nobody uses f->target (if the inode is symlink's inode). The 442b79adccSArtem B. Bityutskiy * exception is inode freeing function which frees f->target. But 4532f1a95dSArtem B. Bityuckiy * it can't be called while we are here and before VFS has 462b79adccSArtem B. Bityutskiy * stopped using our f->target string which we provide by means of 4732f1a95dSArtem B. Bityuckiy * nd_set_link() call. 4832f1a95dSArtem B. Bityuckiy */ 4932f1a95dSArtem B. Bityuckiy 502fb1e308SAl Viro if (!p) { 51c7cf0c68SQi Yong printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n"); 522fb1e308SAl Viro p = ERR_PTR(-EIO); 532fb1e308SAl Viro } 542b79adccSArtem B. Bityutskiy D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target)); 5532f1a95dSArtem B. Bityuckiy 562fb1e308SAl Viro nd_set_link(nd, p); 5732f1a95dSArtem B. Bityuckiy 5832f1a95dSArtem B. Bityuckiy /* 592b79adccSArtem B. Bityutskiy * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe 602b79adccSArtem B. Bityutskiy * since the only way that may cause f->target to be changed is iput() operation. 612b79adccSArtem B. Bityutskiy * But VFS will not use f->target after iput() has been called. 6232f1a95dSArtem B. Bityuckiy */ 63008b150aSAl Viro return NULL; 641da177e4SLinus Torvalds } 651da177e4SLinus Torvalds 66