Wrapfs: use d_alloc_root

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/wrapfs/lookup.c b/fs/wrapfs/lookup.c
index 21820d9aaf8a5b03546dcd687ccc234d841d2661..92ccd37499ed98f1b3adfd661a54f7ae65456543 100644 (file)
--- a/fs/wrapfs/lookup.c
+++ b/fs/wrapfs/lookup.c
@@ -136,8 +136,7 @@ static int wrapfs_inode_set(struct inode *inode, void *lower_inode)
        return 0;
 }
 
-static struct inode *wrapfs_iget(struct super_block *sb,
-                                struct inode *lower_inode)
+struct inode *wrapfs_iget(struct super_block *sb, struct inode *lower_inode)
 {
        struct wrapfs_inode_info *info;
        struct inode *inode; /* the new inode to return */

diff --git a/fs/wrapfs/main.c b/fs/wrapfs/main.c
index 19fc074449251e6ee225bf502e4118eff42bce58..130aca66a6d4cee9d0f101ad28b0a9830e5686d7 100644 (file)
--- a/fs/wrapfs/main.c
+++ b/fs/wrapfs/main.c
@@ -12,32 +12,6 @@
 #include "wrapfs.h"
 #include <linux/module.h>
 
-/*
- * our custom d_alloc_root work-alike
- *
- * we can't use d_alloc_root if we want to use our own interpose function
- * unchanged, so we simply call our own "fake" d_alloc_root
- */
-static struct dentry *wrapfs_d_alloc_root(struct super_block *sb)
-{
-       struct dentry *ret = NULL;
-
-       if (sb) {
-               static const struct qstr name = {
-                       .name = "/",
-                       .len = 1
-               };
-
-               ret = d_alloc(NULL, &name);
-               if (ret) {
-                       d_set_d_op(ret, &wrapfs_dops);
-                       ret->d_sb = sb;
-                       ret->d_parent = ret;
-               }
-       }
-       return ret;
-}
-
 /*
  * There is no need to lock the wrapfs_super_info's rwsem as there is no
  * way anyone can have a reference to the superblock at this point in time.
@@ -48,6 +22,7 @@ static int wrapfs_read_super(struct super_block *sb, void *raw_data, int silent)
        struct super_block *lower_sb;
        struct path lower_path;
        char *dev_name = (char *) raw_data;
+       struct inode *inode;
 
        if (!dev_name) {
                printk(KERN_ERR
@@ -89,12 +64,18 @@ static int wrapfs_read_super(struct super_block *sb, void *raw_data, int silent)
 
        sb->s_op = &wrapfs_sops;
 
-       /* see comment next to the definition of wrapfs_d_alloc_root */
-       sb->s_root = wrapfs_d_alloc_root(sb);
+       /* get a new inode and allocate our root dentry */
+       inode = wrapfs_iget(sb, lower_path.dentry->d_inode);
+       if (IS_ERR(inode)) {
+               err = PTR_ERR(inode);
+               goto out_sput;
+       }
+       sb->s_root = d_alloc_root(inode);
        if (!sb->s_root) {
                err = -ENOMEM;
-               goto out_sput;
+               goto out_iput;
        }
+       d_set_d_op(sb->s_root, &wrapfs_dops);
 
        /* link the upper and lower dentries */
        sb->s_root->d_fsdata = NULL;
@@ -102,23 +83,28 @@ static int wrapfs_read_super(struct super_block *sb, void *raw_data, int silent)
        if (err)
                goto out_freeroot;
 
+       /* if get here: cannot have error */
+
        /* set the lower dentries for s_root */
        wrapfs_set_lower_path(sb->s_root, &lower_path);
 
-       /* call interpose to create the upper level inode */
-       err = wrapfs_interpose(sb->s_root, sb, &lower_path);
-       if (!err) {
-               if (!silent)
-                       printk(KERN_INFO
-                              "wrapfs: mounted on top of %s type %s\n",
-                              dev_name, lower_sb->s_type->name);
-               goto out;
-       }
-       /* else error: fall through */
-
-       free_dentry_private_data(sb->s_root);
+       /*
+        * No need to call interpose because we already have a positive
+        * dentry, which was instantiated by d_alloc_root.  Just need to
+        * d_rehash it.
+        */
+       d_rehash(sb->s_root);
+       if (!silent)
+               printk(KERN_INFO
+                      "wrapfs: mounted on top of %s type %s\n",
+                      dev_name, lower_sb->s_type->name);
+       goto out; /* all is well */
+
+       /* no longer needed: free_dentry_private_data(sb->s_root); */
 out_freeroot:
        dput(sb->s_root);
+out_iput:
+       iput(inode);
 out_sput:
        /* drop refs we took earlier */
        atomic_dec(&lower_sb->s_active);

diff --git a/fs/wrapfs/wrapfs.h b/fs/wrapfs/wrapfs.h
index 5c7a4685f0cf1a4264b7bb15340a07b421dacc4b..5762c35433247832e159d9a3109e22192dd59bbb 100644 (file)
--- a/fs/wrapfs/wrapfs.h
+++ b/fs/wrapfs/wrapfs.h
@@ -56,6 +56,8 @@ extern int init_lower_nd(struct nameidata *nd, unsigned int flags);
 extern void release_lower_nd(struct nameidata *nd, int err);
 extern struct dentry *wrapfs_lookup(struct inode *dir, struct dentry *dentry,
                                    struct nameidata *nd);
+extern struct inode *wrapfs_iget(struct super_block *sb,
+                                struct inode *lower_inode);
 extern int wrapfs_interpose(struct dentry *dentry, struct super_block *sb,
                            struct path *lower_path);