Wrapfs: lookup fixes

Don't use lookup_one_len any longer (doesn't work for NFS).
Initialize lower wrapfs_dentry_info so lower_path is NULL.

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

diff --git a/fs/wrapfs/lookup.c b/fs/wrapfs/lookup.c
index e6cc83cc5214848ed10001eb80c97c82025bb8c1..1e462d516b4459cf1edaf3df9c736210a37437cf 100644 (file)
--- a/fs/wrapfs/lookup.c
+++ b/fs/wrapfs/lookup.c
@@ -43,7 +43,8 @@ int new_dentry_private_data(struct dentry *dentry)
 {
        struct wrapfs_dentry_info *info = WRAPFS_D(dentry);
 
-       info = kmem_cache_alloc(wrapfs_dentry_cachep, GFP_ATOMIC);
+       /* use zalloc to init dentry_info.lower_path */
+       info = kmem_cache_zalloc(wrapfs_dentry_cachep, GFP_ATOMIC);
        if (!info)
                return -ENOMEM;
 
@@ -190,17 +191,19 @@ out:
  * Main driver function for wrapfs's lookup.
  *
  * Returns: NULL (ok), ERR_PTR if an error occurred.
+ * Fills in lower_parent_path with <dentry,mnt> on success.
  */
-static struct dentry *__wrapfs_lookup(struct dentry *dentry, int flag,
+static struct dentry *__wrapfs_lookup(struct dentry *dentry, int flags,
                                      struct path *lower_parent_path)
 {
        int err = 0;
        struct vfsmount *lower_dir_mnt;
        struct dentry *lower_dir_dentry = NULL;
+       struct dentry *lower_dentry;
        const char *name;
-       int namelen;
        struct nameidata lower_nd;
        struct path lower_path;
+       struct qstr this;
 
        /* must initialize dentry operations */
        dentry->d_op = &wrapfs_dops;
@@ -209,18 +212,12 @@ static struct dentry *__wrapfs_lookup(struct dentry *dentry, int flag,
                goto out;
 
        name = dentry->d_name.name;
-       namelen = dentry->d_name.len;
-
-       /* Now start the actual lookup procedure. */
 
+       /* now start the actual lookup procedure */
        lower_dir_dentry = lower_parent_path->dentry;
-       BUG_ON(!lower_dir_dentry || !lower_dir_dentry->d_inode);
-       BUG_ON(!S_ISDIR(lower_dir_dentry->d_inode->i_mode));
-
-       /* Now do regular lookup; lookup @name */
        lower_dir_mnt = lower_parent_path->mnt;
 
-       /* Use vfs_path_lookup to check if the dentry exists or no */
+       /* Use vfs_path_lookup to check if the dentry exists or not */
        err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name, 0,
                              &lower_nd);
 
@@ -235,32 +232,38 @@ static struct dentry *__wrapfs_lookup(struct dentry *dentry, int flag,
 
        /*
         * We don't consider ENOENT an error, and we want to return a
-        * negative dentry (ala lookup_one_len).  As we know there was no
-        * inode for this name before (-ENOENT), then it's safe to call
-        * lookup_one_len (which doesn't take a vfsmount).
+        * negative dentry.
         */
-       if (err == -ENOENT) {
-               mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
-               lower_path.dentry = lookup_one_len(name, lower_dir_dentry,
-                                                  strlen(name));
-               mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
-               lower_path.mnt = mntget(lower_dir_mnt);
-               wrapfs_set_lower_path(dentry, &lower_path);
-
-               /*
-                * If the intent is to create a file, then create a dummy
-                * inode and associate with the dentry.
-                */
-               if (flag & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET))
-                       err = 0;
+       if (err && err != -ENOENT)
+               goto out;
 
+       /* instatiate a new negative dentry */
+       this.name = name;
+       this.len = strlen(name);
+       this.hash = full_name_hash(this.name, this.len);
+       lower_dentry = d_lookup(lower_dir_dentry, &this);
+       if (lower_dentry)
+               goto setup_lower;
+
+       lower_dentry = d_alloc(lower_dir_dentry, &this);
+       if (!lower_dentry) {
+               err = -ENOMEM;
                goto out;
        }
+       d_add(lower_dentry, NULL); /* instantiate and hash */
 
-       /* if got here: real errors */
+setup_lower:
+       lower_path.dentry = lower_dentry;
+       lower_path.mnt = mntget(lower_dir_mnt);
+       wrapfs_set_lower_path(dentry, &lower_path);
 
-       /* no need to cleanup, just reset */
-       wrapfs_reset_lower_path(dentry); /* XXX: still needed? */
+       /*
+        * If the intent is to create a file, then don't return an error, so
+        * the VFS will continue the process of making this negative dentry
+        * into a positive one.
+        */
+       if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET))
+               err = 0;
 
 out:
        return ERR_PTR(err);