[JFFS2] Add symlink caching support.

Signed-off-by: Artem B. Bityuckiy <dedekind@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 30 insertions, 12 deletions

diff --git a/fs/jffs2/symlink.c b/fs/jffs2/symlink.c
index 7b1820d13712..65ab6b001dca 100644
--- a/fs/jffs2/symlink.c
+++ b/fs/jffs2/symlink.c
@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: symlink.c,v 1.14 2004/11/16 20:36:12 dwmw2 Exp $
+ * $Id: symlink.c,v 1.16 2005/03/01 10:50:48 dedekind Exp $
  *
  */
 
@@ -19,27 +19,45 @@
 #include "nodelist.h"
 
 static int jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
-static void jffs2_put_link(struct dentry *dentry, struct nameidata *nd);
 
 struct inode_operations jffs2_symlink_inode_operations =
 {       
         .readlink =     generic_readlink,
         .follow_link =  jffs2_follow_link,
-        .put_link =     jffs2_put_link,
         .setattr =      jffs2_setattr
 };
 
 static int jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
-        unsigned char *buf;
-        buf = jffs2_getlink(JFFS2_SB_INFO(dentry->d_inode->i_sb), JFFS2_INODE_INFO(dentry->d_inode));
-        nd_set_link(nd, buf);
+        struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
+        
+        /*
+         * We don't acquire the f->sem mutex here since the only data we
+         * use is f->dents which in case of the symlink inode points to the
+         * symlink's target path.
+         *
+         * 1. If we are here the inode has already built and f->dents has
+         * to point to the target path.
+         * 2. Nobody uses f->dents (if the inode is symlink's inode). The
+         * exception is inode freeing function which frees f->dents. But
+         * it can't be called while we are here and before VFS has
+         * stopped using our f->dents string which we provide by means of
+         * nd_set_link() call.
+         */
+        
+        if (!f->dents) {
+                printk(KERN_ERR "jffs2_follow_link(): can't find symlink taerget\n");
+                return -EIO;
+        }
+        D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->dents));
+
+        nd_set_link(nd, (char *)f->dents);
+        
+        /*
+         * We unlock the f->sem mutex but VFS will use the f->dents string. This is safe
+         * since the only way that may cause f->dents to be changed is iput() operation.
+         * But VFS will not use f->dents after iput() has been called.
+         */
         return 0;
 }
 
-static void jffs2_put_link(struct dentry *dentry, struct nameidata *nd)
-{
-        char *s = nd_get_link(nd);
-        if (!IS_ERR(s))
-                kfree(s);
-}